Author |
Message |
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Thu Jan 01, 2015 12:11 pm Post subject: |
|
|
Boolean wrote: |
That ring gap is huge. 0.016/0.018 top/second would have been better.
You should get new rings and do it again.
You should aim for a bit more gap on the second ring to reduce ring flutter. |
Sorry about that, I meant to type 0.020", not 0.025". Must have been the New Year's brew. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
|
Posted: Thu Jan 01, 2015 12:40 pm Post subject: |
|
|
I would of been fine with a .010 to .013 ring gap.for a na motor. and why did you effup the piston bore taping it in to the bore for screw in plug???? 1 there is no need to do it at all, and if you do do it you dont drill through into the relief piston bore,you dont even tuch that smaller portion behind the oe plug.as it IS THE SUPPORT FOR THE PISTON!!! I suppose you could run the brass plugh through into the bore than remachine the bore so the plug would be the side wall...but I doubt thats gonna happen. most cases Ive seen done this way have a effed up bore from the piston cocking in the bore due to no support on one side. I gess it might be a good canadate for the ball thingy that bergerman used in his stuff....with a few mods so it works correctly/better.(it needs to be a 2 stage system or totaly re desined to work as it should.) |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Thu Jan 01, 2015 7:18 pm Post subject: |
|
|
mark tucker wrote: |
I would of been fine with a .010 to .013 ring gap.for a na motor. and why did you effup the piston bore taping it in to the bore for screw in plug???? 1 there is no need to do it at all, and if you do do it you dont drill through into the relief piston bore,you dont even tuch that smaller portion behind the oe plug.as it IS THE SUPPORT FOR THE PISTON!!! I suppose you could run the brass plugh through into the bore than remachine the bore so the plug would be the side wall...but I doubt thats gonna happen. most cases Ive seen done this way have a effed up bore from the piston cocking in the bore due to no support on one side. I gess it might be a good canadate for the ball thingy that bergerman used in his stuff....with a few mods so it works correctly/better.(it needs to be a 2 stage system or totaly re desined to work as it should.) |
I didn't drill into the bore. However, when I tapped the hole the tapered part of the tap reached the bore and kicked up a burr which had to be removed. As for why I removed it, removing that plug grants access to the main oil galley above the lifter bores. If it had not been removed then cleaning that galley would have been much more difficult.
I respect your experience so I did go back and take it all apart again for inspection to make sure cocking wouldn't be a problem. I drove a wooden dowel into the back of the plunger and inserted it back into the bore to see if I could get it to cock one way or the other, mostly in the direction of the tapped hole. So far I could not cause it to cock sideways. To be on the safe side I will look at fashioning a brass plug that will be driven all the way to the bore and contoured to match the bore. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
Bajaman65 Samba Member
Joined: January 16, 2007 Posts: 469 Location: Borrego Springs
|
Posted: Thu Jan 01, 2015 7:52 pm Post subject: |
|
|
That is the one plug I never mess with, as Mark said it is to easy to get it effed up and the relief piston wobbles and sticks. I also run .015 to .020 ring gap but .010 - .013 on a NA engine is fine. |
|
Back to top |
|
|
mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
|
Posted: Thu Jan 01, 2015 8:32 pm Post subject: |
|
|
that gally has a plug on the other end.and you can see it good from the piston bore,if needed breakleen can be sprayed into that aera real easy,well that should be spray cleaned real good reguardless whenever your cleaning it. be carfull you dont effup the bore any.that piston seals in more than just the top. it also seals agnist the sides.as it is on the MAIN GALLY.... the end of the main gally any oil pressure the mains see is also seen there. and a loose piston,cocking piston,effed up bore will just let your oil pressure bleed off and go back to the sump unused,but it did use up hp being pumped. I have special reamers and special tap just for that location. some oe plugs seep, sometimes owners that are more than happy to do some of thier own work pull that plug on mistake thinking there saving you work or time...but nothing is saved. I also dont pull the rear oil pressure relief exhaust small plug in the bellhousing mounting flange, spray cleaning is all thats needed. but you can is you want to enlarge the gally as some old books called for,but I see no need to.I do wish it had been driled at a different angle so it didnt spray the #3 exhaust & intake pushrod,cooling that pushrod and filling the 3/4 side valvecover somewhat. and keeping that cylinders lash a little looser..and possiably noiser .those are my thoughts and observations and we all know how I think.... |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Fri Jan 02, 2015 7:05 am Post subject: |
|
|
mark tucker wrote: |
that gally has a plug on the other end.and you can see it good from the piston bore,if needed breakleen can be sprayed into that aera real easy,well that should be spray cleaned real good reguardless whenever your cleaning it. be carfull you dont effup the bore any.that piston seals in more than just the top. it also seals agnist the sides.as it is on the MAIN GALLY.... the end of the main gally any oil pressure the mains see is also seen there. and a loose piston,cocking piston,effed up bore will just let your oil pressure bleed off and go back to the sump unused,but it did use up hp being pumped. I have special reamers and special tap just for that location. some oe plugs seep, sometimes owners that are more than happy to do some of thier own work pull that plug on mistake thinking there saving you work or time...but nothing is saved. I also dont pull the rear oil pressure relief exhaust small plug in the bellhousing mounting flange, spray cleaning is all thats needed. but you can is you want to enlarge the gally as some old books called for,but I see no need to.I do wish it had been driled at a different angle so it didnt spray the #3 exhaust & intake pushrod,cooling that pushrod and filling the 3/4 side valvecover somewhat. and keeping that cylinders lash a little looser..and possiably noiser .those are my thoughts and observations and we all know how I think.... |
I agree that it was a mistake to disturb oil relief bore at all. I know there is a galley plug on the other end, I removed that one too so that I could pass a brush all the way through the case without having to reverse direction while the brush is still in the hole (usually tears up the brush and may break off a piece of the brush which is worse).
How about this for a fix? Instead of the brass plug idea, what about inserting a shaft into the bore (I have large gauge pins to exactly match the bore size) to fill it up and then dropping something like JB weld into the threaded hole? Theoretically it should drop to the bottom of the threaded hole and land on the shaft, taking that contour. I know JB weld has kind of a bad reputation in some applications, but it's supposed to be rock solid for filling holes, especially threaded ones where it has ample surface area to grab. I've actually never used it so I don't know what kind of thermal expansion properties it has. It would also need to hold up to the piston rubbing against it, although this force would be minimal since it's a side load.
Thoughts, anyone? Who knows the most about JB weld in an application like THIS ONE? Fairly low temp, inside hole with mild abrasion. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
|
Posted: Fri Jan 02, 2015 10:18 am Post subject: |
|
|
I scrub the crap out of the bores,I dont care if the brush dosent last.and reversing the direction can clean it better. |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Mon Jan 05, 2015 5:43 am Post subject: |
|
|
I see no one wanted to touch the topic of the JB Weld . No matter, it's done now. No pictures are possible since it's all the way at the top of the relief bore on the inside, but it turned out very well. The only issue was some shrink-back after the epoxy set up, so there is a small recessed area right in the middle of the 'patch'. Otherwise, the plunger now has a complete and solid surface to support it. It slides so well up and down inside the bore I may do this on all future builds given the ease and low cost with which it was done. It may even be an improvement on the OE design.
I ordered new piston rings since apparently I was mistaken about the gaps being too small. There is much debate around here about how large the gap can be without affecting performance. I wish I owned a simple dyno so I could squash all this BS arguing about ring gaps. I'd dyno it with tight rings then tear it down and put sloppy ones in there just to prove a point and get some good, factual data. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
[email protected] Samba Member
Joined: August 03, 2002 Posts: 12785 Location: Salt Lake City, Utah
|
Posted: Mon Jan 05, 2015 9:34 am Post subject: |
|
|
in the 80's I wore out a set of tools figuring out the ring gap thing once and for all. I gave up after .125" gap, seeing no difference. FWIW. _________________ It's just advice, do whatever you want with it!
Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net |
|
Back to top |
|
|
Quokka42 Samba Member
Joined: December 02, 2010 Posts: 3117 Location: Melbourne, Australia
|
Posted: Mon Jan 05, 2015 7:13 pm Post subject: |
|
|
You wouldn't get good, factual data - any differences would be so small they would be lost in your margin of error. The main reason not to run a larger ring gap than necessary for your application is to reduce blowby, hence carbon and other byproducts ending up in your oil. It is possible to calculate a theoretical increase in power, but it is so tiny that even if your dyno and method were accurate enough to pick it up, it would be easily outweighed by a number of other factors on your assembly.
If you are racing or running turbo, open up the gaps to give yourself a margin of error - you will be changing oil more frequently anyway. _________________ There has only ever been one man who was perfect, and they nailed Him to a cross. |
|
Back to top |
|
|
mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
|
Posted: Mon Jan 05, 2015 7:49 pm Post subject: |
|
|
loose works and tight dosent.and it isant tight untill they touch so set them for the app.(usage,piston type,fuel,timing etc) the hyperutectic pistons run a lot hotter than forged pistons do, so as a result they require a loosser/wider gap than a non hyperutectic piston (cast or forged) I would add .001 per inch at min. thus the gaps we hear about in the aa piston sets(hyperutectic) but depending on may things a tigher or losser may be what is needed. |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Wed Jan 07, 2015 7:01 am Post subject: |
|
|
Nice, thanks for the responses on the ring gaps. I'll still put the new rings I ordered in (Deves) and save the set I opened up for a pure stock build or rebuild.
While I'm waiting on the new rings and rocker assembly I looked around for some other stuff that needed to be done. Checked out the clearance of the cam gear bolts to the oil pump. It was about 0.080". I did find that the bolt heads varied in height quite a bit though, so if anyone reads this and realizes they need to do it, be sure you check the clearance of all three bolts, not just one and done.
I started the preparations for rocker geometry checks by determining where full and half lift were on #1 intake. The head of an M8 socket cap bolt is almost exactly the same diameter as the ID of the lifter cup, so I worked it a little and got it to fit exactly down in there so I could measure lift at the lifter.
I marked the aforementioned positions on my degree wheel. Total lift was 0.382" compared to advertised 0.383" so we're good. I also threw a stock rocker arm shaft and lifter on the head and played with the geometry a little using an adjustable pushrod. The new rocker assembly I'm getting is a SCAT 1.1:1 so it should be close to the VW stocker, hopefully. Don't know what differences there are in the shaft mounting blocks so we'll see when it gets here.
Went ahead and did flywheel endplay as well. I put on the bigger two of the three shims and tightened the wheel down to 200ft-lb. I use the following setup instead of a flywheel locking tool because I don't trust that tool to not break the case at higher (insane) torques.
Used dial indicator to measure the endplay as usual. Without the 0.024mm shim in there the endplay was right at 0.0050", a bit on the large side. I'm shooting for 0.004" which is about the middle of the road on the tolerance, and I don't want to be too tight. I put the third shim in and it brought it right where I want it to be. Note that the shims had to be deburred a little since they are stamped and there are miniscule burrs around their circumference.
Took out all the spring-loaded pushrods and put them all together. They came with two different seals, the red ones are much tougher and more rigid than the white ones. Any suggestions from anyone on which ones to use? I like the red ones due to that spring pressure they'll be under...
Before I closed up shop I took out the new exhaust from CB and test fitted it with the new heater boxes.
Ahh... so nice to have it slide right into place on a stock-width engine. I will clean and coat the exhaust with some sort of header paint before it goes on the engine. The heater boxes are primed already so I hope they used hi-temp primer. With my luck they probably didn't. I think I'll heat it up with a torch and see what happens. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
[email protected] Samba Member
Joined: August 03, 2002 Posts: 12785 Location: Salt Lake City, Utah
|
Posted: Wed Jan 07, 2015 9:18 am Post subject: |
|
|
The red pushrod tube seals will split, crack, and leak within 6 mos. Use the white ones. _________________ It's just advice, do whatever you want with it!
Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Wed Jan 07, 2015 10:23 am Post subject: |
|
|
[email protected] wrote: |
The red pushrod tube seals will split, crack, and leak within 6 mos. Use the white ones. |
Thanks, John. I'll use the white ones. Also thanks for the info you posted about the piston ring gaps. I know you're a busy guy with ACN but if you ever get time I'd like to hear more about your testing. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Thu Jan 08, 2015 11:52 am Post subject: |
|
|
Got the SCAT rocker arm kit today and took me about 5 minutes to decide they need to go back. One rocker shaft was damaged in a few spots, bad enough that the rockers didn't slide smoothly on or off the shaft, and the other shaft had a bow of 0.016". I don't know what the tolerance on the bow is, or even if there is one, but it should not be more than a thousandth or two on a ground shaft.
I have a new set of CB 1.25s I can put on it but I had originally decided not to do that for two reasons: One, the heads aren't ported and I felt the additional valve lift would be a waste. I want the bottom end strong, not the top end. Second, I only have single HD springs and 1.25 just barely starts to get into the dual spring realm, although, it is just a W100 so I personally think it'll be OK. I've never put one above 5,000rpm, and 4,500rpm is very rare. I could spend the extra $$$ and have the heads mildly ported to justify the extra valve lift. Add a couple ponies too. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Thu Jan 08, 2015 7:32 pm Post subject: |
|
|
I'm going to take a stab at mildly porting these mostly stock heads. Obviously this is no light or easy task, but I'm pretty good with stuff like this and I have several scrap heads to try on first. Plus I have the wealth of Samba knowledge to draw on .
Here's what they look like now:
I have some stage 1 ported heads from the exact same casting (same supplier) to kind of use as a guide.
I pulled out these old scrap heads to start the practice on:
Transferred the pattern from the ported heads to the old scrappers:
Time to go at it. I worked on roughing it out for about a half hour.
I like the results so far, but I can't feel my fingers anymore. It's only like 10° in NC right now and my shop heaters can't contend. I'll pick it up tomorrow. I know I'll have to measure the volume of these chambers after I get done to make sure they match... got a method lined up for that.
This is great fun. No reward without risk (great risk, in this case... but more fun!). Comments and advice welcome. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Sat Jan 10, 2015 8:15 pm Post subject: |
|
|
I have come to the conclusion that the decision to mildly port the 'super stock' heads was an error. I jumped into that without looking at the facts first, such as the flow demand on the heads compared to what they can provide in their current state. Luckily I only practiced around with some scrap heads so no harm done, and I learned a lot in the process.
The super stock heads flow around 118cfm at 0.450 lift, similar to the 044 heads from CB (these are 043's). According to any of a half a dozen online calculators, the engine will only demand 90cfm at 4500rpm (my usual max) and 90% volumetric efficiency - which is probably a stretch for a 2-valve cylinder design. Therefore the heads shouldn't be the primary restriction. I would guess the carbs or manifolds are more likely to provide a greater restriction than the ports on these heads. Porting them would only slow air velocity, and I don't want that.
Knowing what I know now about the head flow and the demand on the heads, I will not be using the 1.25:1 ratio rockers from CB. It would be an absolute waste. I will wait for a new 1.1:1 kit from SCAT to come in. _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
modok Samba Member
Joined: October 30, 2009 Posts: 26776 Location: Colorado Springs
|
Posted: Sat Jan 10, 2015 11:36 pm Post subject: |
|
|
Yep, right idea.
I'd say the stock ports are already near the right "size" for the stock valve size, you can only straighten them out a little. Go much bigger and you lose too much velocity. |
|
Back to top |
|
|
bugguy1967 Samba Member
Joined: January 16, 2008 Posts: 4341 Location: Los Angeles, CA 90016
|
Posted: Sun Jan 11, 2015 12:26 am Post subject: |
|
|
To be honest, wasn't digging that port job anyways. Also, the guides need to be slid out of the port to really do a port job. I just had a machine shop do a half port on a set of super-cheap heads that I picked up. After I noticed it, I gave them right back so they could do the job properly. _________________ "A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine" |
|
Back to top |
|
|
marbleknight Samba Member
Joined: February 04, 2013 Posts: 127 Location: Lincolnton, NC
|
Posted: Fri Jan 16, 2015 7:28 am Post subject: |
|
|
Got the second SCAT rocker kit in so I started in on the rocker assembly. I had ordered a bunch of rocker shims of different sizes in advance so I would have everything I needed to shim each of the rockers down to 0.003-0.005" side play.
It was immediately apparent that the rocker shaft blocks would need to be milled down on one side. Otherwise rockers for #1ex #2in #4ex and #3in could not sit in the right position on the valve stem AND have a shim in between the rocker and block. I did not want have the rockers in direct contact with the blocks.
I put just the rockers on the shaft with the blocks and center spacer and put it on the head. I stuck shims in where needed to test fit and see what shims would be required to move the rockers into position so they are slightly offset from the valve stem centerline. After a few times of test fitting and disassembly / reassembly I found the right combination of shims to give all the rockers the proper sideplay. Here are pics of how they are offset very slightly on the valves:
I'm not sure I really believe that they NEED to be offset after seeing videos of valve spring harmonics at high RPMs and valves turning like mad on their own, but I figure a little can't hurt. I aimed for 0.5mm at the most.
Next I threw in the adjustable pushrod and checked out the rocker geo a bit. My goal was to get the centerline of the rocker adjusting screw parallel to the centerline of the valve stem at half lift. It was off at first so I used some shims under the rocker blocks to bring it a little more in line. I didn't measure the shims but I'm guessing I used 0.090" to get to this situation at half lift:
By the way, the courier adjuster has been unscrewed one full revolution from being totally bottomed out against the lifter. I figured this would be a good starting point.
Being satisfied with the alignment at half lift, I cranked it on down to full lift to see how it looked.
The courier ball is a bit forward on the valve stem, but the flat on the ball is fully on the stem. I marked it up and did a 'swipe' just to be sure, although it's not much of a swipe with these ball adjusters. They just stay pretty much in the same place while the ball rotates in its housing.
I think that will do it for the geo, if anyone sees anything freaky then shout.
Oh and by the way, I don't recommend this rocker kit. This is the second set I got from SCAT after sending the first one back and I still don't like the quality of it. The balls in the courier adjusters don't rotate freely enough (some were outright stuck and had to be loosened up with penetrating oil), the center spacers are too short leaving 0.300" to shim up, and some of the adjusters are very hard to turn. And then this happened when I snugged a nut down on one of the blocks, which really sucked:
It's a cheaper kit so you get what you pay for I guess. I'll have to use an old stock rocker block and mill it down to replace the broken one.
Before closing up shop I degreed the cam using #1 intake's lifter. Everything was within a degree according to the cam card.
For those of you that build a lot of performance engines, do you degree the cam at every lifter or just check it at one and assume it's OK everywhere else? _________________ 1974 Bug - 1791 (85.5 x 78mm) "Stock Stroker"
1974 Bug - 2021 (92TW x 76mm) |
|
Back to top |
|
|
|