Cylinder spacer, copper head gasket, or both?

[albert67]

I am building an 86x94 motor. The heads have 59cc chambers and I would like the compression around 9.2:1. It looks like I would need about .080 of deck. My question is what is the best way to do this? Should I just add a .080 cylinder spacer, or go .060 with the spacer and add a .020 copper head gasket. Kinda seems the same but maybe I am missing something. Any other options?

[Ohio Tom (DdK)]

Either way works. It's more about what's available to stack up to get the deck you are after.

[superdrag]

Some people swear by copper head gaskets, some don't.  I don't use them.

[roscoesvw]

I use copper head gaskets on my 9.3 motor, no problems.

[brookester60]

I used both on mine. No problems.

[J Dotson]

I don't think anybody makes a .020 copper gasket, maybe .040 is smallest.
Thats what CB and Bugpack have anyway.I 'll use a copper gasket if i have to or both sometimes as well.I like a tight deck and will reshape the combustion chambers in the head also.

[1836vw]

Why do people shim the cylinder to get their compression?  This is where they leak.  Cut the top of the piston or buy longer cylinders and cut them. 

[Clinton DdK]

Why do people shim the cylinder to get their compression?  This is where they leak.  Cut the top of the piston or buy longer cylinders and cut them. 

If sealed right they shouldn't leak. I prefer to use the good machined spacers if possible not everyone has access to a lathe or mill.

[superdrag]

At a minimum you need to deburr the cheap, chinsy spacers so the thickness is close to as advertised.

[1836vw]

The cylinder shim is pressed from a piece of steel. 
 
The weakest part of the VW motor is the case saver on large displacement motors.  Why did VW change from the 10mm stud to the 8mm?  Do you think it was because of the real estate left on the case where the stud is to the cylinder?  The shim will make the cylinder rock on the case.   

[Donny B.]

Not all cylinder spacers are pressed from a sheet of steel.  Some are blanchard ground.  They cost more, but work without leaking.  Speaking from experience. 

I have also used copper gaskets in the had with great success.  Remember copper dissipates heat much faster than aluminum.  Good heat transfer and good seal as copper is softer than most aluminum.

[flat top]

I use both and set up my motor based on the copper gasket and the spacer to get the comp.  I want.  never had a problem and I run 14.5 to 1 in my race engine....  If you buy good spacers instead the cheap ones you will n ot have problem with sealing...


Wayne

[Kevin Alexander]

All I have ever used are the cheap spacers from CB and with a thin bead of Ultra Black RTV I have never had a leak and never had an issue.

[maui]

Jus go 0 deck and 60 copper and be 9.5+1. No big deal.

[neil68]

I am building an 86x94 motor. The heads have 59cc chambers and I would like the compression around 9.2:1. It looks like I would need about .080 of deck. My question is what is the best way to do this? Should I just add a .080 cylinder spacer, or go .060 with the spacer and add a .020 copper head gasket. Kinda seems the same but maybe I am missing something. Any other options?

Albert,

On my 84 x 94 set-ups (three so far), I've used the minimum cylinder shims required, in order to keep the cylinder down inside the case, for better support of the piston skirts at the bottom of the stroke (depends on your rod length and whether your case was decked, etc).  I usually shim only to get the piston close to the top of the cylinder and then add either a 0.040" or 0.060" CB copper head gasket to allow for adequate clearance DH.  Personally, I like the copper as being a good sealer to the heads as well.  It's also has the added benefit of keeping the burn out of the cylinder and up in the heads...

[Ohio Tom (DdK)]

1. VW went to 8mm head studs because they had issues with the 10mm ones pulling the inserts out of the case. Bascially, the 10mm didn't have enough "give" in them to accomodate the thermal expansion of the motor. The 8mm will stretch, thus not stressing the case as much.

2. Just because a shim is used doesn't mean it will rock or leak.
Care must be taken to make sure whatever spacer is used sits properly on the case and clears the studs and inserts. This is where trial assembly is important.  Studs that hit the cyls or spacers will create "stress risers" and that's where stuff will break, warp and leak. When assembling the cyls, they should slide into the case spigots by hand. Any tight fitting will case issues for sure.

Put a Raceware head stud in an aluminum case with inserts and you will not have failures upto high HP levels. The weak link becomes something else.

[GaryW]

I use both and set up my motor based on the copper gasket and the spacer to get the comp.  I want.  never had a problem and I run 14.5 to 1 in my race engine....  If you buy good spacers instead the cheap ones you will n ot have problem with sealing...


Wayne

[albert67]

Thanks for all the replies. I am using a 5.5" rod and like the idea of keeping as much of the cylinder as possible in the case for support at the bottom of the stroke. I will use a cylinder spacer that puts the piston at .010 below the top of the cylinder and then use a .060 copper head gasket. Thanks again.

[WV-VW]

I have a new set of long barrels for sale, if your interested. I thought I was going to build a MONSTER street motor, but my bank account said otherwise .. Just trim to fit and eliminate the spacers!