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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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 Posted: Thu Feb 11, 2021 9:14 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| Ceckert64 wrote: |
Long time and nothing has happened much. I think I finally got the bearing to were I want. I think next week I’m going to get the parts sent out for machining at DPR. So a couple things, I’m debating just having them do a complete balance on the rotating assembly where they balance pistons, rods, cranks, flywheel, fan. It wouldn’t be that much more expensive for a complete balance with rods and pistons. Is it worth it to just have them do balance that part or should I just do it myself? I’m also thinking that my local machine shop seems pretty good and I’m thinking have them balance the fan.
On another note, I’ve been thinking about getting my original pressure plate rebuilt by Kennedy. I think it is reasonable, any thoughts on that?
On the heads, since the drop test yielded that the valve seats were good in place, would it be fine to have my local machine shop grind the original seats and put a three angle valve job on them along with new valve stems.
Currently for fuel system I’m thinking do modern fuel injection. I have decided not to do D-jet since parts are getting harder to find for them and taking lots of longer trips, I wouldn’t want to be stranded. It’s a great system and I like the D-jet but I don’t think it’s my best option here. I think it would also be and interesting challenge to build my own system and I could learn a lot from it. I also like the prospects of better fuel economy and power from a modern system.
On a tangent, for the transmission I’m going to keep it stock and not touch it unless I have issues with it. But, I would like a little more speed but the ability to keep RPMs lower in at highway driving. So I was thinking since it will have a bit more power than stock, could I swap to 15 inch rims, get some bigger tires and use that a way to reduce the RPMs on the engine as a kind of poor mans change of gearing? Would it cause the engine to run too hot or cause issues?
So what is everyone’s options on all this I’ve come up with? Good, bad indifferent?
Thanks in advance for the help, Aiden |
I think that is a good idea. I love D-jet...if for nothing else but the old/original aspect...and I know how to work on it and mine runs killer.
But...to "reliably" drive with D-jet (Like daily or long distance) you NEED to automatically build a new harness. You need to get away from the excellent, but ancient and no longer available fuel pump and move to a commonly available one. Any of hundreds of part numbers will do.
You also need to have a few spare parts. Even though they RARELY ever break and take decades to wear out.... its like the Karma thing. You can drive it with "0" issues for years....but if you take off on a long haul and dont have a spare TS-1, TS-2, TVS and probably a pair of trigger points in a baggy in the trunk......its the one time in a decade one of those parts will break! 
Let us know how the fan balance goes....but DO NOT let them drill ANY holes or remove ANY metal. The weights are crimped on under the lip of the fan pulley ring. Just simple chunks of like 1/8" steel rod. If you need pictures just let me know.
Ray |
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orwell84
Samba Member
Joined: May 14, 2007
Posts: 2536
Location: Plattsburgh, New York
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| Posted: Thu Feb 11, 2021 9:22 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| Depending on your budget, I would go for heads from Len Hoffman. They are new AMC castings with upgraded hardware. There are other options of similar quality. AMC heads out of the bus are kind of a crapshoot. In 30 years of bus driving, valve failures have been the most frequent problem for me. Heads tend to be the weakest point of the engine. If you rebuild yours, I would have them done by an experienced ACVW person. They are one thing that is more than machine shop 101. |
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RWK
Samba Member
Joined: June 24, 2009
Posts: 1347
Location: S.W. MI
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| Posted: Fri Feb 12, 2021 5:55 am Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| orwell84 wrote: |
| If you rebuild yours, I would have them done by an experienced ACVW person. They are one thing that is more than machine shop 101. |
Yes, new guides are important, alum bronze if you can get them, or a tin bronze. May need seats also, stock seat angle's are somewhat different on T4 heads,vs T1
https://www.anchorbronze.com/single-post/2018/02/13/C90500-Tin-Bronze-for-Valve-Guides
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Ceckert64
Samba Member
Joined: September 16, 2015
Posts: 1955
Location: Manitowoc, WI
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| Posted: Fri Feb 12, 2021 6:50 am Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| raygreenwood wrote: |
I think that is a good idea. I love D-jet...if for nothing else but the old/original aspect...and I know how to work on it and mine runs killer.
But...to "reliably" drive with D-jet (Like daily or long distance) you NEED to automatically build a new harness. You need to get away from the excellent, but ancient and no longer available fuel pump and move to a commonly available one. Any of hundreds of part numbers will do.
You also need to have a few spare parts. Even though they RARELY ever break and take decades to wear out.... its like the Karma thing. You can drive it with "0" issues for years....but if you take off on a long haul and dont have a spare TS-1, TS-2, TVS and probably a pair of trigger points in a baggy in the trunk......its the one time in a decade one of those parts will break!
Let us know how the fan balance goes....but DO NOT let them drill ANY holes or remove ANY metal. The weights are crimped on under the lip of the fan pulley ring. Just simple chunks of like 1/8" steel rod. If you need pictures just let me know.
Ray |
Definitely things seem to just go on the old D-jet systems at random, and this last issues is why I decided to not go that route: a week or so ago my Squareback was hard starting, and it progressively got worse and worse and I was having a hard time figuring it out. Turned out I had a bad Thermostat 1, the one that was in the head. It was so out of wack resistance wise it was reading 700omhs instead of 2500omhs cold causing the engine to adjust for being hot flooding the engine. I had a computer go bad on me, the fuel pump transistor broke on it when I went to start it. Also with a T4 d-jet, computers are so much harder to find than T3. But random things like that randomly happen are not desirable. I will probably make a new harness for my Squareback too, I’ve seen a few threads on that. I have probably 2 spares for everything D-jet and always have a bunch in my trunk just in case.
Thanks for the tip on the fan! I’ve seen the balancing weights but I’ve never would have thought about that part of balancing it and making sure the use weights vs removing material. I will also clean and paint the fan before I send it out too. I won’t take it apart though when I paint it.
| orwell84 wrote: |
| Depending on your budget, I would go for heads from Len Hoffman. They are new AMC castings with upgraded hardware. There are other options of similar quality. AMC heads out of the bus are kind of a crapshoot. In 30 years of bus driving, valve failures have been the most frequent problem for me. Heads tend to be the weakest point of the engine. If you rebuild yours, I would have them done by an experienced ACVW person. They are one thing that is more than machine shop 101. |
If the heads I had were off a bus, I would be replacing them more than likely, but since these were off a 411 they’ve lived an easier life than most T4 heads. I will look at a better machine shop at least if I do go the route of keeping the original heads. And when you valve issues with the heads, what exactly were the issues you had? Seats, valves dropping or breaking? I will look into the AMC heads a bit more though. The heads from the 411 also didn’t have to suffer from emissions too.
Thanks for the tip! So is the best head place head flow masters? I know when I talked to MOFOCO they said for their head rebuild they only replaced valve seats if needed  . I’ve decide against using the just because I only got a reply to 1 out the 4 of the emails I sent and that doesn’t make me super confident.
Thanks for the help so far, Aiden
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Clatter
Samba Member
Joined: September 24, 2003
Posts: 7537
Location: Santa Cruz
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| Posted: Fri Feb 12, 2021 9:35 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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FWIW, 1.7 heads will hold on to their seats and resist cracks better than any of the others.
You can check the guides by doing the wiggle test where you measure side-to-side play at the valve head with the valve slightly open (no springs).
Do you have an indicator?
If the guides are good, you might give them a little lapping to see if the seating area isn't pitted and what the valve job looks like.
More often than not,
a set of 1.7 heads from a 411/412 or 914 might just have a bunch of life left in them.
Cleaning up all of the carbon and soot isn't a lot of fun,
But you can get some good heads ready to rock with a little work and luck,.
Guides are good, seats are tight, plug holes not stripped, exhaust studs in decent shape, seats not all pitted out,
Give it a lapping, clean 'em up, and put another 100K on 'em.
Often times, the car was in the junkyard for other reasons than the heads being worn out.
1.7s are tough!
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Bus Motor Build
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Clatter
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Joined: September 24, 2003
Posts: 7537
Location: Santa Cruz
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| Posted: Fri Feb 12, 2021 9:48 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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Your Friendly Local Automotive Machine Shop (FLAMS?  ) can usually always do a valve job, preferably (hopefully) a 3-angle valve job.
Most can also do seats.
A new set of valves is only around $100.
Not only is it cheap insurance against trouble,
but often the stems of your old valves are worn and stretched, making them thinner.
A set of new valves sometimes will fill the guides up enough that you won't need to replace guides.
(see the cheap junk build in my sig again for more discussion).
Bigger tires are a good way to reduce freeway RPM -but- know that the fan will be turning slower, making less cooling air.
If you stay in the cool areas and don't push it hard with heavy loads on the highway, you can get away with bigger tires,
but more fan spin and more oil pressure makes for a happier long lived motor on the highway pushing a lot of wind in a tall gear when it needs the air and oil the most.
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Ceckert64
Samba Member
Joined: September 16, 2015
Posts: 1955
Location: Manitowoc, WI
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| Posted: Sat Feb 13, 2021 9:49 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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The head needs at least one guide. I messed it up getting a stuck valve out. I thinks these heads should have a lot of life left in them still. The 411 the engine came from had 77,000 and I believe that’s accurate. The car was rusted out, the suspension was about to break free from the body it was so rotted. It had bald winter tires on it, so based on the few things I noticed on it, I’m guessing it had an issue and they just sold it to the junkyard rather than fix it. From what I found the engine was fine. The stuck valve broke when I was taking it out. I have most of the carbon out of the heads. I didn’t see and gouging from debris getting in and destroying stuff.
I do have a FLAM that looks promising, they look really high quality and I will check them out soon.
So with the bigger tires slowing engine speed, I will do some calculations on what it would be at 55mph and 75mph see with changes etc. Is there a rpm where the fan reaches peak output? Because at some point having at such a high RPM, it won’t be good for sustained at some points. There was a thread in the bay forum for max rpm for sustained periods, but for a well balanced T4 what would everyone say is a top end rpm to still be able to get a good life out of it.
Thanks Aiden
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“Joann” 1970 Elm Green Squareback
1972 Sierra Yellow Tin Top Westfalia Camper
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Sun Feb 14, 2021 9:35 am Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| Ceckert64 wrote: |
The head needs at least one guide. I messed it up getting a stuck valve out. I thinks these heads should have a lot of life left in them still. The 411 the engine came from had 77,000 and I believe that’s accurate. The car was rusted out, the suspension was about to break free from the body it was so rotted. It had bald winter tires on it, so based on the few things I noticed on it, I’m guessing it had an issue and they just sold it to the junkyard rather than fix it. From what I found the engine was fine. The stuck valve broke when I was taking it out. I have most of the carbon out of the heads. I didn’t see and gouging from debris getting in and destroying stuff.
I do have a FLAM that looks promising, they look really high quality and I will check them out soon.
So with the bigger tires slowing engine speed, I will do some calculations on what it would be at 55mph and 75mph see with changes etc. Is there a rpm where the fan reaches peak output? Because at some point having at such a high RPM, it won’t be good for sustained at some points. There was a thread in the bay forum for max rpm for sustained periods, but for a well balanced T4 what would everyone say is a top end rpm to still be able to get a good life out of it.
Thanks Aiden |
So....bearing in mind that my type 4 vehicles are not a bus.
When I last drove my 412 as a daily driver.....I worked on the road covering 8 states out of Atlanta. Later I covered Tx, Ok, AR, LA, KS and NM.....my daily miles just around town were rarely less than about 125 to 150 miles per day.
Out on the road....interstate.....my 412 was driven to any client/factory meeting that was 450 miles or less one way. It was about mileage cost versus rent a car flight cost.
I averaged 50k+ miles per year. Highway speeds were typically 65-70 average. On the road out of town typically two weeks per month I rarely drove for less than 3-4 hours non stop.
My tires were 205-60-15...sometimes 205-55-15.... I used sticky tires and went through a set in less than a year. My gearing was 3.73:1 final with 1:1 4th. A bit higher than yours in a bus.
At 70 mph actual....calculated by mile market posts (pre-gps....and lower than stock tires)....my rpm was right at 3600 constant. At 75mph it was right between 3800 and 3900 rpm. I drove a lot of 75 mph when I could....including in oklahoma and Texas summer heat.
These rpms are not a problem for a type 4.....in a lighter car like mine. In a bus your results may vary. Yes....oil temps were high at about 220°F.....but it got an oil change about every 5-6 weeks max (sometimes sooner) depending on miles covered and a filter change every other oil change.
It was a 1.7L with 8.2:1 compression and later 8.4:1 when head gaskets were deleted. It actually ran cooler that way.
Head temps were 380-390 when I finally got a gauge.....and peaks on sharp grades to 400....but never for more than a minute or two.
It may not have answered your question.....but the fan speed will not be the issue. The type 4 fan will not have any problem with sustained 75 mph putting out enough cooling air.....rpm wise. It does not seem to have stall or stack up issues in those rpm ranges.
It will be about weight, aerodynamics and load with a bus. Will you be putting more heat load in than the system can handle?
Jake Raby would probably know more than anyone about this as he did tons of research. There are some 3/4 side flow volume issues with type 4 shroud and sheet metal issues.
Ray |
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Ceckert64
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Joined: September 16, 2015
Posts: 1955
Location: Manitowoc, WI
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| Posted: Wed Feb 17, 2021 8:54 am Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| raygreenwood wrote: |
So....bearing in mind that my type 4 vehicles are not a bus.
When I last drove my 412 as a daily driver.....I worked on the road covering 8 states out of Atlanta. Later I covered Tx, Ok, AR, LA, KS and NM.....my daily miles just around town were rarely less than about 125 to 150 miles per day.
Out on the road....interstate.....my 412 was driven to any client/factory meeting that was 450 miles or less one way. It was about mileage cost versus rent a car flight cost.
I averaged 50k+ miles per year. Highway speeds were typically 65-70 average. On the road out of town typically two weeks per month I rarely drove for less than 3-4 hours non stop.
My tires were 205-60-15...sometimes 205-55-15.... I used sticky tires and went through a set in less than a year. My gearing was 3.73:1 final with 1:1 4th. A bit higher than yours in a bus.
At 70 mph actual....calculated by mile market posts (pre-gps....and lower than stock tires)....my rpm was right at 3600 constant. At 75mph it was right between 3800 and 3900 rpm. I drove a lot of 75 mph when I could....including in oklahoma and Texas summer heat.
These rpms are not a problem for a type 4.....in a lighter car like mine. In a bus your results may vary. Yes....oil temps were high at about 220°F.....but it got an oil change about every 5-6 weeks max (sometimes sooner) depending on miles covered and a filter change every other oil change.
It was a 1.7L with 8.2:1 compression and later 8.4:1 when head gaskets were deleted. It actually ran cooler that way.
Head temps were 380-390 when I finally got a gauge.....and peaks on sharp grades to 400....but never for more than a minute or two.
It may not have answered your question.....but the fan speed will not be the issue. The type 4 fan will not have any problem with sustained 75 mph putting out enough cooling air.....rpm wise. It does not seem to have stall or stack up issues in those rpm ranges.
It will be about weight, aerodynamics and load with a bus. Will you be putting more heat load in than the system can handle?
Jake Raby would probably know more than anyone about this as he did tons of research. There are some 3/4 side flow volume issues with type 4 shroud and sheet metal issues.
Ray |
Good information, thank you! The bus gearing is a 5.428:1 differential with a 0.82:1 4th
I'm sure the engine will be a bit hotter because the bus is about 1,000lbs heavier than the 411/412s and much less aerodynamic. I guess too, I can have all the gauges installed, monitor conditions and change variables such as speed, load, wind (Going with or against).
On Jake Raby, I might have this wrong, but was one of his modifications to rivet/bolt down the cooling flap down on the 3/4 side? I think I remember seeing that somewhere but it may of been someone else.
So I have been doing some thinking over the last few days...
I was thinking about the fuel injections and think I might change my mind again on the plan. I was thinking for simplicity's sake, just going with the stock dual carbs to begin with. I was thinking since this is my first engine build it would be easier to for trouble shooting to have a basic system vs trying to build my own system and then have troubles with it. I was thinking I could do modern EFI as a later addition. I would be looking at the stock 72 system which is pre-emission destruction system with the air pump and EGR. So would the dual carbs be good with higher compression? How are they on cold/hot starts? Gas mileage? Issues with altitude? I'm interested any thoughts on this.
Thanks, Aiden
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“Joann” 1970 Elm Green Squareback
1972 Sierra Yellow Tin Top Westfalia Camper
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Clatter
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Joined: September 24, 2003
Posts: 7537
Location: Santa Cruz
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| Posted: Wed Feb 17, 2021 10:15 am Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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I wouldn't be in too big of a hurry to put huge tires on, unless you plan on re-gearing accordingly.
More than a couple of my friends have done this,
And, yeah it looks really rugged/cool,
But the motor ends up getting lugged hard because of it.
If you really want to take long trips loaded on the highway running fast,
having the fan turn too slow is a bad thing.
Alternately,
A good friend put shorter tires on his bus,
And it went over 125,000 miles on the same motor.
A bunch of cooling air from the fan, along with a bunch of oil flow from the pump is a good thing for a motor worked hard.
Have everything spin-balanced and you definitely won't have to worry about it.
Carbs have their own issues. Not insurmountable, but still, they need occasional babysitting.
All of my carbed cars, i put a switch in to shut off the (electric) fuel pump.
Because the fuel today evaporates off and leaves goo if the car sits,
I shut the pump off and run the bowls dry before storing it.
Otherwise, when you go to drive it, no startstart...
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Ceckert64
Samba Member
Joined: September 16, 2015
Posts: 1955
Location: Manitowoc, WI
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| Posted: Wed Feb 17, 2021 3:22 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| Clatter wrote: |
I wouldn't be in too big of a hurry to put huge tires on, unless you plan on re-gearing accordingly.
More than a couple of my friends have done this,
And, yeah it looks really rugged/cool,
But the motor ends up getting lugged hard because of it.
If you really want to take long trips loaded on the highway running fast,
having the fan turn too slow is a bad thing.
Alternately,
A good friend put shorter tires on his bus,
And it went over 125,000 miles on the same motor.
A bunch of cooling air from the fan, along with a bunch of oil flow from the pump is a good thing for a motor worked hard.
Have everything spin-balanced and you definitely won't have to worry about it.
Carbs have their own issues. Not insurmountable, but still, they need occasional babysitting.
All of my carbed cars, i put a switch in to shut off the (electric) fuel pump.
Because the fuel today evaporates off and leaves goo if the car sits,
I shut the pump off and run the bowls dry before storing it.
Otherwise, when you go to drive it, no startstart... |
Thanks for the tire tip. I was looking at it as a possible way to get around regearing. Did your friend with the 125,000 do any/much highway driving?
So I will do spin balance only on the parts and balance the rest myself.
True, my carbed bug can be a pain but actually less than my FI. The last issue was the accelerator pump clogged after sitting a year  Even after my engine sat for years before I got it, it started the next day without a carb clean or anything. How hard is it to tune dual carbs? Hard or just time consuming?
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1972 Sierra Yellow Tin Top Westfalia Camper
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nogoodwithusernames
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Joined: November 10, 2014
Posts: 599
Location: CA, USA
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| Posted: Wed Feb 17, 2021 3:51 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| raygreenwood wrote: |
It was a 1.7L with 8.2:1 compression and later 8.4:1 when head gaskets were deleted. It actually ran cooler that way.
Head temps were 380-390 when I finally got a gauge.....and peaks on sharp grades to 400....but never for more than a minute or two.
Ray |
Ray, reading through your reply this part caught my eye. A while back I was trying to find good temps to make sure I stay below during summer for my 1.7 T4 that's in my Squareback. After some searching I felt like it was running hot at around 370° on the fwy (75ish mph) is that acceptable though? What's considered too hot or the danger zone for a T4 head?
My specific application is rebuilt from a stock 1.7 out of a 914 (so domed pistons), deleted head gaskets and under cylinder spacers for a small bump in compression with a C25 cam. Stock heads with new valves and guides (stock size) stock rockers, added swivel feet and corrected geometry, stock crank and rods.
Cheers,
Derek
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71 Squareback, 1.7l T4 w/ crank trigger fuel and spark
(Conversion thread https://www.thesamba.com/vw/forum/viewtopic.php?t=732508&highlight= or https://shoptalkforums.com/viewtopic.php?f=1&t=151375&sid=f0542d44a322d290c29d6609fac7f215 )
74 914, 2.0L w/ D-Jet
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Feb 17, 2021 5:37 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| Ceckert64 wrote: |
......So I have been doing some thinking over the last few days...
I was thinking about the fuel injections and think I might change my mind again on the plan. I was thinking for simplicity's sake, just going with the stock dual carbs to begin with. I was thinking since this is my first engine build it would be easier to for trouble shooting to have a basic system vs trying to build my own system and then have troubles with it. I was thinking I could do modern EFI as a later addition. I would be looking at the stock 72 system which is pre-emission destruction system with the air pump and EGR. So would the dual carbs be good with higher compression? How are they on cold/hot starts? Gas mileage? Issues with altitude? I'm interested any thoughts on this.
Thanks, Aiden |
The stock Solex system works very well (when rebuilt properly), great cold starts and driveability year round, huge altitude changes may effect it, but most early FI suffers from the same issues. And it's been around forever so there's manuals and lots of proven tuning knowledge.
As for RPM's I'd prefer to keep it on the higher side, better cooling and power, use a good muffler and put a foam mattress in the back to cut down the noise.
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Ceckert64
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Location: Manitowoc, WI
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| Posted: Wed Feb 17, 2021 6:14 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| busdaddy wrote: |
| Ceckert64 wrote: |
......So I have been doing some thinking over the last few days...
I was thinking about the fuel injections and think I might change my mind again on the plan. I was thinking for simplicity's sake, just going with the stock dual carbs to begin with. I was thinking since this is my first engine build it would be easier to for trouble shooting to have a basic system vs trying to build my own system and then have troubles with it. I was thinking I could do modern EFI as a later addition. I would be looking at the stock 72 system which is pre-emission destruction system with the air pump and EGR. So would the dual carbs be good with higher compression? How are they on cold/hot starts? Gas mileage? Issues with altitude? I'm interested any thoughts on this.
Thanks, Aiden |
The stock Solex system works very well (when rebuilt properly), great cold starts and driveability year round, huge altitude changes may effect it, but most early FI suffers from the same issues. And it's been around forever so there's manuals and lots of proven tuning knowledge.
As for RPM's I'd prefer to keep it on the higher side, better cooling and power, use a good muffler and put a foam mattress in the back to cut down the noise. |
Thank you! I probably won’t be driving the bus if it is much less than 20 degrees out, but that is still decently cold, not 20 below 0 like today though
So more RPM is a good thing in busses then. Having it fully balanced will help a lot too. Good thing it’s a westy, factory equipped noise suppression mattress I guess
So I was looking at cams and I was thinking a 494 webcam would be a good choice. [quote=“Webcam”] Designed for increased torque with added RPM performance. Requires Exhaust System, High Compression Piston, Performance Valve Spring Kit, and New lifters required.[/quote]
I was reading on STF and they were saying it’s good for carbs or aftermarket EFI. When it says requires exhaust system, does it also mean the heater boxes/headers for the exhaust need to be changed? I would like to keep stock heater boxes for defrost but I will have a gas heater if I need to get upgraded headers.
nogoodwithusernames, I’m interested in the answer to this question too
Thanks, Aiden
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“Joann” 1970 Elm Green Squareback
1972 Sierra Yellow Tin Top Westfalia Camper
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Wed Feb 17, 2021 6:32 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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Ceckert64 said:
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On Jake Raby, I might have this wrong, but was one of his modifications to rivet/bolt down the cooling flap down on the 3/4 side? I think I remember seeing that somewhere but it may of been someone else. |
Going off memory, the tacking down of the cooling flap on the 3/4 side was "part" of his research and testing. The problem is that if the flap bar is not perfectly straight and/or the thermostat does not rotate it fully and if the rpm is high....meaning fan volume high.....the flap does not seal well over the oil cooler.
What this causes is a ramp that causes the air to roll as it passes over the lip. Its curved so it acts just like the back of a wing. This turbulence causes some problems with a clear shot of high density, high static pressure air getting to where it needs to go.
That causes minor issues with cooling air....but it actually causes more issues with the air inlet for the oil cooler which is on the inside end of the flap inside of the shroud. If the flap does not seal....the oil cooler can lose air pressure. And...this is mainly an oil temp thing.
But the bigger problem he noted...for cylinder and head cooling.... is that if you look closely at the volume of the area under the sheet metal...which is kind of wedge shaped from front to back....the area around #3 especially the backside where it is really tight up against the forward side of the upper AND lower sheet metal.......the high static pressure of the air crams in here, causes turbulence and makes it very hard for the air to turn or duct downward through the fins.
One of the ways he said...IIRC...that he verified that this static pressure "stack up" was happening...was to put some judicious vent holes in the upper sheet metal back near #3 and he was able to get better airflow through the fins because it vented the static pressure.
I found the same thing by accident while I was testing airflows with a hot wire anemometer. I sacrificed a tin set and drilled holes here and there to check airflow and static pressure. At one point of drilling holes on the left side...head temp improved. Airflow out the bottom improved. I did not know why at the time.
The third problem that I noted as well through my testing has to do with how the fan shroud "allocates" air to each side.
Part of this is how long the air charge spends in the fan and how many rotations that air gets up against the "compression fence" that surrounds the periphery of the fan in the shroud....before its released into either a duct for left or right.
The left side is releasing its charge early and over a wider area to feed a higher volume inside of the shroud...which feeds the lower heater duct, the oil cooler inlet and the cylinder shroud inlet.
The right side is a straight shot with a 90* turn.
While the left side loses some velocity...which could help it....it actually gains static pressure from that high volume area feeding it. I have long though about putting some "islands" of poly coated foam inside the left side of the shroud to take up some of the dead space and then test again.
Simply put, the left side of the shroud is a lot more complex. You have a bit less overall volume going through the areas of the head and cylinders on #3/4 side for this variety of reasons.
I have thought for quite some time...and will probably do it because its simple...of getting rid of the thermostat in my 412 and running a sheathed cable from a nice push/pull knob made from a lighted defroster knob to the flaps....to keep them tight closed for warmup and tight open when warmed up. I would put a bright blinking light in the knob for when they are closed. Ray |
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Wreck
Samba Member
Joined: July 19, 2014
Posts: 1216
Location: Brisbane
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| Posted: Wed Feb 17, 2021 11:07 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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I would recommend a mocal thermostat sandwich plate and run a quality oil cooler with fan like a setrab . Tuck it up and out of the airflow under the bus . Run the fan through a thermo switch .
That way your oil is at a regulated temperature and you have the extra cooling capacity when needed .
The research I did a while ago put the max CHT at 400f , there is not much information for VW’s but if you go off other air cooled engines that do have a lot of running manuals ( Jabiru, Lycoming etc) they all seem to say constant use the CHT should not be above 360f (180c) .
CHT is something you should aim for the low end of the scale . The amount of dropped seats and cracked heads on buses is evidence of that . Extra oil cooling of the heads by a simple trick by the late Ray Vallero of drilling a small hole in the pushrod to act as a sprinkler should be done to every bus engine in my opinion .
An 1 1/2” empi thunderbird copy header will use the stock heater boxes and work quite well on your size engine . |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Wed Feb 17, 2021 11:19 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| Wreck wrote: |
I would recommend a mocal thermostat sandwich plate and run a quality oil cooler with fan like a setrab . Tuck it up and out of the airflow under the bus . Run the fan through a thermo switch .
That way your oil is at a regulated temperature and you have the extra cooling capacity when needed .
The research I did a while ago put the max CHT at 400f , there is not much information for VW’s but if you go off other air cooled engines that do have a lot of running manuals ( Jabiru, Lycoming etc) they all seem to say constant use the CHT should not be above 360f (180c) .
CHT is something you should aim for the low end of the scale . The amount of dropped seats and cracked heads on buses is evidence of that . Extra oil cooling of the heads by a simple trick by the late Ray Vallero of drilling a small hole in the pushrod to act as a sprinkler should be done to every bus engine in my opinion .
An 1 1/2” empi thunderbird copy header will use the stock heater boxes and work quite well on your size engine . |
Yes....and by the way...i should have answered the question in my last post....but my temperatures of 385* F with momentary peaks to 400* F...were in 100* +heat in the summer in Texas.
My spring and fall temps were 355* to 365* maximum....and sometimes n the winter it struggled to reach 325 to 340* F.
Ray |
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Clatter
Samba Member
Joined: September 24, 2003
Posts: 7537
Location: Santa Cruz
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| Posted: Thu Feb 18, 2021 9:36 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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494 is way too much cam for a bus.
I’d say 86 if carbs or 73 if FI..
If you load up a bus full of camping gear,
And run the highway WFO in 4th keeping up with highway traffic way into the mountains on a hot summer day,
Your heads will go over 435.
They say that’s the absolute “pull over and stop” limit.
I have had mine hotter than that, and they survived.
But that don’t make it right.
We used to run these things cross country.
Across the desert, into Mexico..
I lived in Phoenix.
Short tires helped.
Solex and other simple carbs handle today’s gas and it’s goo better than Webers and their copies.
Those have emulsion tubes with tiny holes that goo up.
They do run better when they’re right, however..
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Bus Motor Build
What’s That Noise?!? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Fri Feb 19, 2021 8:11 am Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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| nogoodwithusernames wrote: |
| raygreenwood wrote: |
It was a 1.7L with 8.2:1 compression and later 8.4:1 when head gaskets were deleted. It actually ran cooler that way.
Head temps were 380-390 when I finally got a gauge.....and peaks on sharp grades to 400....but never for more than a minute or two.
Ray |
Ray, reading through your reply this part caught my eye. A while back I was trying to find good temps to make sure I stay below during summer for my 1.7 T4 that's in my Squareback. After some searching I felt like it was running hot at around 370° on the fwy (75ish mph) is that acceptable though? What's considered too hot or the danger zone for a T4 head?
My specific application is rebuilt from a stock 1.7 out of a 914 (so domed pistons), deleted head gaskets and under cylinder spacers for a small bump in compression with a C25 cam. Stock heads with new valves and guides (stock size) stock rockers, added swivel feet and corrected geometry, stock crank and rods.
Cheers,
Derek |
Sorry.....should have answered this.
370° is about spot on in moderate weather.....anything from say 40° to about 85°. Above that and it can be as high as 385-390°.
What is the danger zone? You will hear different answers. The bay bus guys say that seeing 400°F is common so must be "normal".
However.....bus drivers also run low compression, somewhat miserable cams, big decks and heavy loads.....and have failure rates with valve seats and exhaust studs......that are virtually unseen in type 4 "CARS". A hallmark of excessive head temperature.
The other issue is that running tighter deck and compression.....is more efficient combustion. As long as you can fuel properly for it and control ignition advance...your head temps will run cooler. The heads will last longer.....seat recession and drop outs are a rarity.
To be fair.....on bay buses....they are also fighting the fuel system. If L-jet were a little more easily adjustable (and this also somewhat goes for ignition too)......I think a lot of the excessive head temps can be controlled.
So as a number?.....personally ai think anything north of 390°.....actual......is bad.
And by actual.....I mean when you see 390° on whateber gauge you are using.....is that the ACTUAL head temperature.....or are you +/- 10° to 15° ?
Ray |
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Ceckert64
Samba Member
Joined: September 16, 2015
Posts: 1955
Location: Manitowoc, WI
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| Posted: Mon Feb 22, 2021 9:00 pm Post subject: Re: Type 4, 1700cc engine rebuild for a bus, what to do, suggestions |
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Good info for head temps. Higher compression should help a bit too.
The hole cut into the engine tin improving cooling is interesting.
As for the external oil cooler, I have don’t really like the idea of those. I can just see them getting gummed up, hit by rocks, lines coming off.
Dual carb time!  Today I had a snow day because roads were “Bad” so I go drive 120 miles round trip to the junkyard
After a lot of searching and digging through a foot of parts and moving engines inside of a school bus to find the parts. I found the rest of the air cleaner setup, balance tubes, linkages. I also found a 73-74 dual carb air cleaner, balance tube, air cleaner bracket and ended up with 3 left hand dual carburetors. First pic is 72 parts, second is 73-74
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1964 sunroof Beetle Restoration "Herbie"
“Joann” 1970 Elm Green Squareback
1972 Sierra Yellow Tin Top Westfalia Camper
“Fitz” 1971 Westfalia Poptop |
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