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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Mon Jan 27, 2014 11:20 pm Post subject: Slowly my build begins... |
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Hello all. I thought it was time to share my little 30HP build with you all. Finally the car is in two pieces so I have begun to work on the motor.
After a great compression test and no detectable endfloat, I have decided not to crack open the case just yet, and do what I can top end for this year.
My plan is (purists look away now) work the heads, bigger valves, Speedwell ratio rockers (to compensate for not changing the cam) a custom 28mm intake manifold, an AMR300 charger (alas a pepco is out of my range) and some kind of 'constant depression' carb like a zenith.
So here goes.... first the heads. We have done a bunch of grinding and got some really impressive flow results, easily as much as WW replicas in the intake side.
The intake port is to be welded a little and machined flat for a PTFE gasket to try to prevent heat transfer into the inlet manifold...
Into this we are putting some stainless valves from an 80's eurobox...
32mm intake, 30mm exhaust. They are 1mm longer but we can take care of this... Now as the valves use different keepers etc I could do with some opinions here...
Here is the original valve. From the underneath of spring cap to valve face it measures 96.5mm
and here is a new valve with keeper etc, which measures 97mm
this will of course mean my springs (I am going to use originals) are 0.5mm 'looser'. If anything I want to tighten them up... my question is, are there any alternatives out there that fit into the heads with a minimum of machining? or should I just shim the originals a little.
Shimming underneath anything like approaching 1mm feels like the spring wouldn't be locked in there properly... any thoughts?
And also... how much lift can a stock spring take, can I use my stock cam with 1.25:1 rockers?
Cheers for now, new seats going in etc. pictures and final flow test to follow. M |
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RichardinNZ Samba Member
Joined: September 16, 2011 Posts: 280 Location: Auckland, New Zealand
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Posted: Tue Jan 28, 2014 12:56 am Post subject: |
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Why not go for 33mm Okrasa size valves (from Mr Motorhead/Aircooled Research)? Mine needed new seats but others on here have managed to fit these with their original seats. I also used the Aircooled Research heavy duty springs with original keepers.
Regarding the AMR300; 'wrxter' on the NZ Vee-Dub Nuts used one on his 36hp....it may be worth seeing whether he can offer any hints or tips.
Thanks
Richard _________________ Richard
'58 Beetle; NZ Assembled
Dual Carb 36hp
My Car https://www.thesamba.com/vw/forum/album_page.php?pic_id=1750253 |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Tue Jan 28, 2014 1:22 am Post subject: |
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My valves were only $5 each, and 0.5mm difference is ok with me!
Regarding the seats, I could use the originals but considering the supercharger I need much more meat in there than the stock ones offer...
If anyone has anything to add on this subject I am all ears.
The 32mm valves left very little material, next to nothing if I am honest and the hotter exhaust I feel will need much more than standard.
I have been in touch with a few guys over in NZ / AUS re the AMR chargers.
Running a 145mm power pulley along side my crank pulley and a 60mm one on the charger... should make 7lb boost and give a 9:1 CR |
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spencerfvee Samba Member
Joined: August 19, 2004 Posts: 3071
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Posted: Tue Jan 28, 2014 8:36 am Post subject: |
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Hi nice porting job on your heads .i am with you why spend more money on valves when you only payed $5.00 each .keep up the good work I like people that do there own head porting .it makes there build more fun spencerfvee...
pig-pen wrote: |
My valves were only $5 each, and 0.5mm difference is ok with me!
Regarding the seats, I could use the originals but considering the supercharger I need much more meat in there than the stock ones offer...
If anyone has anything to add on this subject I am all ears.
The 32mm valves left very little material, next to nothing if I am honest and the hotter exhaust I feel will need much more than standard.
I have been in touch with a few guys over in NZ / AUS re the AMR chargers.
Running a 145mm power pulley along side my crank pulley and a 60mm one on the charger... should make 7lb boost and give a 9:1 CR |
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alanhall Samba Member
Joined: February 18, 2006 Posts: 115 Location: Northern California
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Posted: Tue Jan 28, 2014 9:38 am Post subject: |
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what are the dimensions, length, O.D. and wire size (or I.D.) of the stock springs? I may be able to find a spring that is a little longer, but otherwise similar.
Alan |
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Mr. Motorhead Mad Scientist
Joined: January 06, 2004 Posts: 717 Location: Practitioner of 36hp alchemy
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Posted: Tue Jan 28, 2014 11:06 am Post subject: |
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From the description on my web site for the HD springs: "Free length is 43mm just like stock but are just a bit stronger than stock. Stock spec is 73 pounds, these are right at 88 pounds."
While a real high pressure spring is going to help with float at high RPM, I don't think it is going to help with cam and lifter longevity especially on a used cam. Some early 25hp engines had an inner spring to dampen the harmonics of valve float (valve float is the bouncing of the valve on the seat). The inner spring was really soft and squishy that did not add a lot of pressure on the valve train. As a side note on your heads, they are very similar to what is in the engine I'm running the Speedwell super charger on...the big difference being my intake is pretty much stock size with the rough edges removed and the exhaust port cleaned and polished out to about 32mm and a stock size exhaust valve. I was shooting for the most port velocity as I could get as the cam is fairly large duration. _________________ 30 years experience in the sales of new and used auto parts!
36 horsepower parts for sale at http://www.aircooledresearch.com/
Or the new site at http://www.bugparts.com
Check out the Bonneville project:
http://aircooledresearch.com/docs/thebonnevilleproject.html#
"All limitations are self imposed."
Some Chinese guy |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Tue Jan 28, 2014 2:45 pm Post subject: |
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I was thinking about using dual springs from a BMC mini, but they are 30mm wide meaning I would have to cut the seat a little. This sounds simple but I am worried about the wall on the intake. Wouldn't like to break through!
the mini springs are designed for the caps I am using... so I would probably make sense to try them, and i can get them in a variety of ratings.
what rating do you think I should be looking for??? |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Wed Jan 29, 2014 8:23 am Post subject: |
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OK... so I sent my heads off to get a couple of cracked fins welded so I have nothing to measure...
does anyone know the STOCK fitted height of a 36hp valve spring????
cheers |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Sat Feb 01, 2014 6:42 am Post subject: |
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34mm.
if anyone is interested. |
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splitpile Samba's Worst Speller
Joined: May 03, 2000 Posts: 5927 Location: back to living where hell meets the suface
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Posted: Sat Feb 01, 2014 9:36 am Post subject: |
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Jaquar springs work great, about 50 dollars from a auto parts store and it gives you a few extra.
I ran my bonneville engine at 6500 rpms without a problem with those. Had valve float at 5000 rpm with the WW Okrassa springs and when rechecking the intake springs they has lost 3 lbs of seat pressure just from running on the dyno, I had .320 lift no coil bind.
PAC also has a direct replacement spring (I need to find the number) I look up my spec sheet for seat and open pressure.
I think I need to start a journal as all my specs are on misc. pieces of paper thrown in a pile _________________ Stocking distributor of "The Funky Green Panels"
www.BUSTORATION.com metal and more for your bus
"no more hacking my sig line" |
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Rome Samba Member
Joined: June 02, 2004 Posts: 9654 Location: Pearl River, NY
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Posted: Sat Feb 01, 2014 10:58 am Post subject: |
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Quote: |
what rating do you think I should be looking for |
My 36hp (US rating; 30hp per your description) 1958 factory repair manual shows that the free height of the stock valve spring is 43mm. Loaded length 28mm. The spring force at 28mm is 74# plus/minus 4 lb. Spring force wear limit is 62#.
By comparison, the larger spring design on the stock 40hp ("34hp") 1200cc engine has a loaded length of 33.4mm, with spring force of 97# plus/minus 7lb.
On the 1300cc single-port engine (50hp US; 40hp elsewhere) as well as later ones, the spring compressed/loaded length is 31mm, with a load force ranging from 117 to 135#.
You should measure the weight of a stock 36hp intake valve, and if you have one, the weight of a stock 40hp intake valve. If your upgraded valve weighs more than the stock 36hp valve, a guideline would be to find a spring that has a higher spring rate than for the stock valve so that it has enough force to pull the heavier valve closed. If you are also using a performance camshaft which has steeper lobes than stock, you'll need to up the spring force more. |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Sat Feb 01, 2014 4:11 pm Post subject: |
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Thanks Rome. Not quite sure what to make of your manual's figures... I measured with a good old fashioned measuring device and it was 34mm from seat of spring to underside of spring cap.
can any one else confirm what is correct?
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Rome Samba Member
Joined: June 02, 2004 Posts: 9654 Location: Pearl River, NY
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Posted: Sat Feb 01, 2014 4:28 pm Post subject: |
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Your actual measurement is most indicative. The spring rates I gave are simply guidelines from the factory measurements so that you can select springs which are stronger than stock if needed. |
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splitpile Samba's Worst Speller
Joined: May 03, 2000 Posts: 5927 Location: back to living where hell meets the suface
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Posted: Sat Feb 01, 2014 4:50 pm Post subject: |
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pig-pen wrote: |
Thanks Rome. Not quite sure what to make of your manual's figures... I measured with a good old fashioned measuring device and it was 34mm from seat of spring to underside of spring cap.
can any one else confirm what is correct?
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According to my without guesswork VW service books
book 1 up to 1960 says spring free length 43 mm (1.7")
loaded length 28mm (1.1")
book 2 from 1960 says spring free length 47.9mm (1.89")
loaded length 34.3mm (1.35")
book 3 from 60 on list the same as book 2
From what I see it appears loaded length is where the valve would be at full lift because it gives a spring pressure of 73.6 lbs with a wear limits to 61.6 lbs (from book 1) which appears to be for a 25/36hp engine and the specs from book 2 and 3 are for a 40hp engine, bastard 40 hp maybe?
None of the books list an installed height _________________ Stocking distributor of "The Funky Green Panels"
www.BUSTORATION.com metal and more for your bus
"no more hacking my sig line" |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Sun Feb 02, 2014 1:08 am Post subject: |
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oh, ok... so if loaded length is 28mm, and this is at full lift of 7.3mm then it follows that at 'relaxed' fitted length the spring is 35.3mm or so.
so... the BMC double springs I was planning on using should be good, having a fitted length of 35.5 - 36mm and a selection of strengths.
my only concern now is cutting the seat to 30mm wide and not breaking through the wall of the inlet as the porting has made this quite thin!
wish me luck |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Sun Feb 02, 2014 3:09 am Post subject: |
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would I also be right in thinking the 1mm tappet clearance would bring me back to the 34mm I had measured? |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Sun Feb 02, 2014 4:34 am Post subject: |
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also, weight of valves is as follows
inlet new 54g
inlet old 50g
exhaust new 53g
exhaust old 53g
so is this enough to worry about having stronger springs? if so how much stronger to close that inlet? |
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Rome Samba Member
Joined: June 02, 2004 Posts: 9654 Location: Pearl River, NY
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Posted: Sun Feb 02, 2014 7:59 am Post subject: |
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You did your homework- good!
It appears I opened a can of worms here. I also noticed different values in my "Without Guesswork" editions compared to the original workshop manuals for the 40hp engine. I would regard the WG as more accurate, since they were published long after the manuals. Field tests on VWs being driven x-thousands of miles could've provided more usable/updated values than original factory spec's.
If the valve spring is wound concentric (not beehive) and the windings are constantly spaced apart, then the spring pressure will develop linearly. That is, you press the spring down with 40# and it moves say 10mm. Apply 40 more # and it moves down another 10mm. You can plot these values on graph paper with a straight line (force applied vs millimeter compression distance). Your difference in weight of your intake valves is 8%, so draw a new line 8% higher than the one for the stock springs. This is Physics 101. That higher line would provide a guideline for the new springs, if using a stock cam.
8% is still at the tolerance of stock spring variations, so if you use the stock cam and stick with the maximum stock engine rpms, I think you'll be OK with the new valves.
The simplest method would be to buy springs matched to any type of upgraded camshaft from the same supplier. It'd be great to have a spring compressor to verify the spring rate, but that is usually a specific workshop tool.
I designed a home-made one using a $13 digital scale from the dollar store, a 31mm long section of PVC pipe in which you position the spring, a small 1.5 volt lamp and a battery pack holder. The 31mm pipe is the spec from VW for the later valve springs. |
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pig-pen Samba Member
Joined: December 04, 2012 Posts: 570 Location: United Kingdom
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Posted: Sun Feb 02, 2014 9:40 am Post subject: |
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ah yes... I could plot a line, but do I not need two values to start with? the relaxed lbs and the open lbs??? then i can draw a line, then plot my new line...
or have I got that wrong?
so far I only have 73.6lbs at full lift... which seems really low to me? but I guess if the workshop manual says so...then it must be right.
but I have read elsewhere that they are 73lbs at full height! so I dunno what to believe without a gauge.
I need another number to draw my first line... |
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splitpile Samba's Worst Speller
Joined: May 03, 2000 Posts: 5927 Location: back to living where hell meets the suface
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Posted: Sun Feb 02, 2014 10:25 am Post subject: |
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pig-pen wrote: |
ah yes... I could plot a line, but do I not need two values to start with? the relaxed lbs and the open lbs??? then i can draw a line, then plot my new line...
or have I got that wrong?
so far I only have 73.6lbs at full lift... which seems really low to me? but I guess if the workshop manual says so...then it must be right.
but I have read elsewhere that they are 73lbs at full height! so I dunno what to believe without a gauge.
I need another number to draw my first line... |
On my spring compressor it appears approx 25 on the seat and 80 open. I can retest some springs here later when I have time. I have a set of stock, WW, Mr Motorheads , Jaquar, PAC and some behive that I am also trying to make work. My new supercharged engine has 70 on the seat and 150 open if my memory serves me correctly. WEB Camshafts grinds my cams and does the lobe design to work properly with the stock 36hp lifters.
I haven't had ant cam/lifter problems running at 6500 on one engine and 7500 on the other. I believe Blackline/Wakefeild engine turns 8K with no issues _________________ Stocking distributor of "The Funky Green Panels"
www.BUSTORATION.com metal and more for your bus
"no more hacking my sig line" |
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