stacking cylinder base shims?

[whackit]

Any reason not to stack the cylinder base shims? I need 1.75mm of shim so I will need to stack 3 shims (1mm + .5mm + .25mm). I have heard that some people have custom base shims machined. I would rather not wait for that though unless it's really a better way to go. Also, I'm planning to use some curil, I assume this needs to go on all 3.

[sww914]

I did it years ago on my engine, no leaks (from there). Obviously a single shim would be better but CurilT has served me well.

[Henry Schmidt]

A solid platform for the cylinders and heads is paramount for engine longevity.
I would avoid stacking more than two gaskets on a street (low performance) engine. On an engine with high cylinder pressures (high compression or turbo) I would limit the gaskets/spacer to one.
The 4.0 engine we just just built had no base gasket. This required that we dimension the engine on paper before the cylinders and pistons were made.

[whackit]

so does anyone know where to get a .75mm base gasket or have a 1.75mm one made?

PS. Henry your stud kit is great!

[Henry Schmidt]

Talk to Charles @ LN engineering.

www.lnengineering.com

ph: 815-472-2939

[ninesixfour]

Originally Posted by Henry Schmidt

I would avoid stacking more than two gaskets on a street (low performance) engine.

When you do stack two gaskets, do you use anything between them for sealing purposes? My heads were cut 0.020 so I was going to add a 0.5mm gasket to the stock 0.25mm one. Also, the Victor Reinz ones that came with my rebuild kit are a black material and the 0.5mm ones I ordered separately are copper. Can I mix and match these?

[Steve@Rennsport]

Totally agree with Henry,....two gaskets is maximum and I never do that on a high-compressiopn or Turbo motor.

In some cases this is a real PITA since one sometimes needs to machine the bottoms of the cylinders to juggle deck height, CR and the need for a single base gasket.

[ninesixfour]

Originally Posted by Steve@Rennsport

Totally agree with Henry,....two gaskets is maximum and I never do that on a high-compressiopn or Turbo motor.

In some cases this is a real PITA since one sometimes needs to machine the bottoms of the cylinders to juggle deck height, CR and the need for a single base gasket.

Anything between the two gaskets? Is adding a 0.5mm gasket to the original 0.25mm one enough to warrant concern over the cam thrust plate alignment?

[Steve@Rennsport]

Originally Posted by ninesixfour

Anything between the two gaskets?

Nossir.

Is adding a 0.5mm gasket to the original 0.25mm one enough to warrant concern over the cam thrust plate alignment?

Not generally.

[ninesixfour]

Originally Posted by Steve@Rennsport

Nossir.

Not generally.

Great. Thanks for the feedback Steve. Any reason I can't use two gaskets that are different materials as I referenced above?

[Steve@Rennsport]

Originally Posted by ninesixfour

Great. Thanks for the feedback Steve. Any reason I can't use two gaskets that are different materials as I referenced above?

I would sure make a big effort to use gaskets of the same material.

[Henry Schmidt]

Originally Posted by ninesixfour

Great. Thanks for the feedback Steve. Any reason I can't use two gaskets that are different materials as I referenced above?

I would think that the material is actually the same (copper). The VR gaskets are just coated. If you try a little gasket remover it should come right off.

[ninesixfour]

Thank you Henry and Steve. I will stack the two copper gaskets.

[fred cook]

You should have your cylinder heads CC'd so that you will know just how much volume you will need to regain. I am gathering parts for a short stroke engine for my SC and bought a set of twin plugged Carrera cylinder heads that had supposedly been cut. When the CC numbers came in on these heads, they were actually a half CC larger in volume than a single plug Carrera head. Don't take away compression if you don't have to do so!

[ninesixfour]

I had assumed that the original motor came with the 0.25mm gaskets, but I just found one in my teardown pile and it is 0.5mm. I had 0.020 removed from the heads (0.5mm) so do I need to use the 1.0mm gasket instead of 0.75?

In other words, do you always add back in gasket material what was removed from the heads or is it OK to be 0.25mm short? This is a bone stock 82 Euro 3.0 with 9.8:1 compression.

[Steve@Rennsport]

Originally Posted by ninesixfour

I had assumed that the original motor came with the 0.25mm gaskets, but I just found one in my teardown pile and it is 0.5mm. I had 0.020 removed from the heads (0.5mm) so do I need to use the 1.0mm gasket instead of 0.75?

In other words, do you always add back in gasket material what was removed from the heads or is it OK to be 0.25mm short? This is a bone stock 82 Euro 3.0 with 9.8:1 compression.

JMHO,.......020" is a quite a bit of material to remove from the heads and will result in raising the CR of your engine. Make sure you use new timing chains.

Base gaskets are used to set & adjust deck height and you really need to measure that value for yourself to know what combination of base gaskets to use.

[ninesixfour]

Originally Posted by Steve@Rennsport

JMHO,.......020" is a quite a bit of material to remove from the heads and will result in raising the CR of your engine. Make sure you use new timing chains.

Base gaskets are used to set & adjust deck height and you really need to measure that value for yourself to know what combination of base gaskets to use.

In terms of piston to valve clearance, isn't deck height measurement meaningless without taking into consideration the machining that has been done to the heads?

Also, were there any motors delivered from the factory with 0.5mm gaskets? I assumed they all had 0.25 as stock.

[Steve@Rennsport]

Originally Posted by ninesixfour

In terms of piston to valve clearance, isn't deck height measurement meaningless without taking into consideration the machining that has been done to the heads?

Unless one has taken a LOT more off the heads than you have and race-type CR's are used along with high lift cams,...piston to valve clearances have mostly to do with piston dome shape and dimensions as well as camshaft profiles. In other words, it depends completely on the specifications of the engine.

Also, were there any motors delivered from the factory with 0.5mm gaskets? I assumed they all had 0.25 as stock.

Most of them used .25mm ones. The thicker versions were used to allow the engine builder to adjust deck height after a valve job was done and the heads were resurfaced. In some cases, one machines the bottoms of the cylinders when one cannot hit the targeted deck height value with various thickness of gaskets.

[ninesixfour]

I have stock 9.8:1 Euro 3.0 pistons. I will CC the heads when they get here Monday, get 4 deck height measurements, do some math, and report back. My current deck height measurement at the flat section of the piston only, with 0.75mm of gaskets installed, is 1.25mm.

[Steve@Rennsport]

Originally Posted by ninesixfour

I have stock 9.8:1 Euro 3.0 pistons. I will CC the heads when they get here Monday, get 4 deck height measurements, do some math, and report back. My current deck height measurement at the flat section of the piston only, with 0.75mm of gaskets installed, is 1.25mm.

Do the piston measurements and find out exactly what your CR is. The factory's specs are always higher than measured and given what you have, you really need to know this.

The issue is remaining compatible with pump gas so you do not have more serious issues later on. You may need a timing adjustment if you find the CR is bit high. These engines tend to run somewhat lean on US ethanol fuels that exacerbates any tendency for detonation.

Shoot for 1.00mm,......040". Too much deck height makes the engine more prone to detonation, too.