My cylinders are back from the machine shop. I marked which was front and which was rear prior to dropping them off.

They came back and the marks are now gone. I don't really think it matters after a re-bore and having the bases trued but just thought I would ask...does it matter with the cylinders if they get mixed up? To me it's like buying two new cylinders off the shelf, it don't matter but wanted to double check.

I am pretty sure which one is which but not 100%. I always seem to second guess this chit!

They are blasted and repainted. Took forever for warmer weather to get here in order to paint the cylinders and heads and I am currently dry fitting without rings and measuring deck height, so thought I would double check.

Funny thing is, I get a better match with deck height and squish with the cylinder that I think was originally the rear now sitting in the front of the engine and the same with the other, the front cylinder placed in the rear of the engine and they both match dead ***** on putting me at .035 if I use a .030 head gasket.

So please tell me it don't matter! Thanks, YD

 

Doesn't matter.

(There is just one part number in the MoCo catalog for those. )

 

Thanks Omaha!

 

to get that .035 squish
..what thickness base gasket are you using?

 

Cometic SLS .020 base and a Cometic MLS .030 head gasket.

I also had the cylinder bases trimmed/trued when I had the cylinders bored. It's an easy way to get that nasty old gasket off! Have the machinist do it.

On a side note, I'm a little concerned about the finish left after the machining of the cylinder base. It's not as smooth as the original factory finish. It has a little more "machining marks" and from what I understand, the Cometic SLS base gasket likes a smoother surface. I suppose I could use some hylomar on them. Have not made up my mind. I went with the Cometic SLS because of it's reputation here of curing the base gasket leaks, but now a little concerned because of the machining marks. Don't want to have to take thing apart a second time.

I have a set of Harley base gaskets also (fiber and silicone bead) and they measure .020 as well, but I think they will compress a little. From what I understand, the SLS does not compress.

What's really interesting is the stack tolerances from the factory. I played with the combination of swapping the new pistons, then re-measuring deck height, then moved the cylinders around as well. Moving the parts around till I got some decent numbers. Originally front was to high and rear was too low. YD

 

The crucial thing is for the cylinder base to be truly square to the liner and the surface flat. I suspect the Cometic gaskets will be fine and you have the 'smoother' surface they like.

 

Yes, thanks grbrown, as I mentioned, I have a tendency to second guess or over think stuff, it can keep me out of trouble (sometimes) but ads to the gray hairs. YD

 

Mine are stamped on top F and R

 

This may help you out some.

https://www.rbracing-rsr.com/squishcalc1.html

 

I don't find any markings like that on either of my cylinders. Both have the same part numbers, but no F or R found anywhere. The heads are a different story, they are marked, but not the cylinders.

I wonder if yours were marked by a previous owner for similar reasons as to what I am doing, such as matching up the tolerances for a better squish.

Anthony Paul, thanks for the link, seen that one before but could not find it again. YD