Barrel Shim question

azbob · Posted: Mon Feb 07, 2011 10:55 am Post subject: Barrel Shim question

I've done a few searches on getting the right compression ratio based off my deck height and head volume. I'm not finding a calculator to figure out what size my barrel shims are. I have a head volume of 4600cc, 94mm cylinders(machined to a 1915cc), deck height on one side is .025 and the other side .038. How do I calculate the size of shims I will need off of that to get the proper deck height for compression? And, what would be the proper compression? I'm still new to this engine stuff.
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mharney · Samba Member Joined: June 01, 2002 Posts: 8353

We'll assume that you mean 46cc head volume.

Your camshaft defines reasonable compression.

With your deck height reading 0.015" different between sides, you should at the very least double check all 4, to see if this is true front to back. If it is not, your case needs machine work. If it does, then you will need base shims that are 0.015" thicker on the side that reads a smaller deck to make them the same.

Then you can plug it into a deck height calculator tool online to arrive at the deck you need, and then calculate the spacers.

Ball10 · Samba Member Joined: September 14, 2009 Posts: 44

You need the same deck on both sides, 0,038 is a bit tight but should work.
So 0,038-0,025=0,013 an put that on the 0,025 side.
The deck is there so the pistoins don't hits the heads, and is not for setting CR. You do that with fly cutting the heads. Need more info on cam, heads, carbs etc in order to give advice on CR.
There is a spread sheet in tech section so you can calculate CR-
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azbob · Posted: Mon Feb 07, 2011 11:52 am Post subject:

I've got a pretty nasty cold right now so forgive me if I am asking some real stupid questions or miss making sense, the making sense part is normal Wink

So left and right side of the engine, both need to be the same? I thought this was only when front and back(single side) were different? I measured each and they were the same.

As for the volume, I put in a spark plug and filled a single head with water using a 100cc syringe 46 times up to the flat(where the barrel sleeves would meet the head, not over). So maybe I'm confused here.

The heads were machined and there's no way in hell I'll take them in again based off deck height after what I paid CE to do it. My but still hurts from that bill... Sad

Thanks you two!
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bartman · Posted: Mon Feb 07, 2011 1:22 pm Post subject:

That was probably a 100 unit syringe or 1 cc. About as big around as a pencil? 100ccs is almost 4 ounces. The 50 or 60cc syringe that comes with the cc kits is about an inch in diameter by about 4 inches long

eta: btw, you should get a kit for this. The discs eliminate the fluid's meniscus for better accuracy

azbob · Posted: Mon Feb 07, 2011 1:39 pm Post subject:

bartman, yep, you're right. It was that big. Where do you get these CC kits? I checked CVS, O'Riely's, autozone... and nada. It was super annoying filling and dumping 46 times. Having to do it all over again sounds like a blast.
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Dangermouse · Posted: Mon Feb 07, 2011 1:59 pm Post subject:

bartman · Posted: Mon Feb 07, 2011 2:15 pm Post subject:

The proper syringe helps but you really gotta have the discs to eliminate any inconsistency in the apparent liquid volume

azbob · Posted: Mon Feb 07, 2011 2:39 pm Post subject:

Thanks for the direction guys. I'll get back to doing this. I wonder why the hell they didn't tell just me wtf they cc'd the heads to when they gave them back...
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Max Welton · Posted: Mon Feb 07, 2011 5:24 pm Post subject:

Maybe they didn't measure them. And you didn't ask them to, right? Where did you get the heads done at? Confused

You shouldn't have to ask, of course. When I have heads done at V.W. Performance, Steve marks the chamber volume right on the fin.

Max
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Dale M. · Posted: Mon Feb 07, 2011 8:15 pm Post subject:

As for head CC kits....

http://www.appletreeauto.com/HEAD-CC-MEASURING-KIT/

http://www.chircoestore.com/catalog/product_info.php?products_id=2330

http://www.cbperformance.com/catalog.asp?ProductID=1338

There are several online calculators for calculating CR....

http://www.cbperformance.com/enginecalc.html

http://www.vwparts.net/veedub/X-enginecalc.html

http://www.aircooled.net/gnrlsite/resource/specgeninfo/calcs.htm

Just a few of the many.....

Dale
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azbob · Posted: Mon Feb 07, 2011 10:16 pm Post subject:

azbob · Posted: Tue Feb 15, 2011 11:06 pm Post subject:

Had to step away from the engine for a bit and finally now I'm getting back to this. My CCs were way off and of course, I was doing it wrong. Thanks for steering me in the right direction.

I got some shims that match what I need. three of them are cut the same, the fourth one however is cut different. Is this normal? A defect? I'm not going to write anything off w/o questioning. Confused

Pic - one on the top is the one I'm questioning:

Image may have been reduced in size. Click image to view fullscreen.

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RockCrusher · Posted: Wed Feb 16, 2011 12:00 am Post subject:

Bad Shim. Does it measure the right thickness and fit the cylinder AND fit between the studs without being held up on the inserts?
If so, use it.

RC
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Max Welton · Posted: Wed Feb 16, 2011 7:07 am Post subject:

Bob, if that shim is messed up, Steve Hollingsworth can make you a shim to whatever thickness you need. He has a really trick fixture for doing that. Right there in Phoenix too.

Max
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azbob · Posted: Wed Feb 16, 2011 4:32 pm Post subject:

@ RockCrusher I'll check the clearance tonight. It's pretty tight fit as is since its a 94mm bore. I'm pretty sure the thickness is correct, I'll check again tonight. These shims are a set of .060 BugPack.

@ Max I may be hitting you up for some info for me to contact him if it is messed up.

Thanks you two!
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Max Welton · Posted: Wed Feb 16, 2011 8:06 pm Post subject:

azbob · Posted: Thu Feb 17, 2011 6:08 pm Post subject:

Turns out the flat side, upon further non-beer induced inspection, was cut to the point that it is not usable. I took it back in to CEVW and Dan gave me a new one. So now I'm sitting pretty.

I'm glad I've got the samba to turn to for questions otherwise I'm pretty sure I'd be throwing money out the window. Thanks again!
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