I've got my short block all assembled now, and I was wanting to verify that the machine shop 0 decked my block like I paid for, so...what is the correct way? Can I just bring the #1 to TDC and use a straight edge and see if I can get a feeler gauge under it?

If that is the correct way then my pistons are .013 in the hole Please tell me I'm doing this wrong, I'm gonna be pissed if I have to take it apart and back to the machine shop...

 

First you have to find TDC which is not easy. If you have a cam degree wheel you need to put a dead stop in there and rotate the motor both ways up to the dead stop and get the same reading + and - of zero on your degree wheel. After you get that then you can use a depth mic or something that is straight and feeler guages like you said.

You also want to make sure everything is Tqed down and the bearings are all in as well.

Bret

 

Everything is all torqued down properly and the bearings are in the bottom end with assembly lube and all.

I was hoping it might just be that I wasn't accuratly finding TDC. I guess I'll go try what you said and see where I'm at.

But...if they are .013 in the hole, is it ok to run a thinner gasket than the .036 cometics that I had planned? Or should I tear it all apart and go back to the machine shop and raise hell? I'm really trying hard to keep my quench area under .040...honestly I was looking for .036 so I hope it was just my mistake and not theirs.

 

If you run the cometics you need to make sure the finish is correct on the block and heads.

 

I told the machine shop what gaskets I planned to run, and when I got it back the surface is alot smoother than ones I've built in the past...almost glossy. I'm not sure what grit they used, but its alot smoother than I thought it would be.

 

Forgot to mention that instead of Cometic you could also run the thinner Impy head gasket. It's 0.029 so that would pull your quench closer to what you were looking for. I assume you have done all the math for the DCR and SCR and you are good to go on that and don't have to worry about running too thin a gasket?

 

Well, I've figured my SCR to be 11.7 :1 using a 0 decked block and .036 x 4.040 cometic gasket. I don't know how to figure DCR, but I know the cam specs are needed for that, which I of course have but I can't reveal out of respect for Bret and Lloyd.

Maybe Bret will chime in again, I'm sure he has some idea what my DCR will be...

Or if someone can give me a formula I can figure it out myself...

 

I understand on the cam specs cause I have one too, but PM Brett about your DCR, I'm sure he will know it.

 

Good idea, I guess I'm gonna go find TDC the correct way first and find out if I even have a problem here. If not, it's all good. But if so, then I'll figure out the best solution at that point.

Thanks for all the help I'll post up what I find.

 

That cam is designed for 11.5-12:1 compression so your DCR will be fine. The only way IMHO to adjust DCR is to get the valve events right for the motor THEN adjust the SCR to get the most DCR you can without detonation problems.

Find out your issue first and then you can look at other options in terms of gaskets. Cometic can make you them as tight as .030", but there is the .026" Mr Gasket pieces as well.

Bret

 

Thanks for the info Bret, I'll check figure out what I need to do (if anything) in the next night or two and post up my findings

 

I had to move recently so I just got around to being able to mess with the car again last night and here's what I came up with...

(crappy phone pic, but you get the idea)


I found TDC useing the piston stop method and then verified it with a dial indicator. I found that all my pistons were .005-.006 in the hole. So at this point, I figure that going with Cometics that are .030 thick with a 4.040 bore is my best bet. That puts my compression ratio at 11.74 to 1 and quench at .035-.036. Looks to me like everything is gonna work out fine that way. Anyone agree or disagree or have any better ideas?

 

That's basically what I did. My head gasket is .028" so I had the machine shop leave the pistons .007" in the hole for a quench of .035".

 

That will work.

Bret

 

Awesome, thanks guys

I'm gonna go ahead and order new head gaskets and degree the cam tonight, this thing might actually run before the year is over after all!!!