Cross

iTrader: (10)

Ok after reading another thread I have some questions.

1) I was reading in a thread here in this section that with just the Mr. Gasket .026 Head Gaskets on a Stock bottom end you go from 10.4:1 to 11.5:1 Compression... Is this correct??

2) The Impala Gaskets are .028 if I am not mistaken. Which would you use in a 355 build for reliability? I of course do not mind the extra little bit but there is a fine line between safe and I do live in Tucson AZ where the summers are always 95-109 if not more every year.

Now the main reason I am thinking about this is because I am almost ready to put this thing back together and I have a few questions now.
I went with the Impala Gaskets as I thought originally they were .026 and figured they would be better quality over the Mr. Gasket ones not to mention I am somewhat concerned with the temps here being so high during the summer.

But mainly when I picked everything out I was told my pistons were 10.8:1, I have LT4 heads ported, and that with the thinner head gasket I should be at 11:1 Compression or really close.... But after reading the other thread I am wondering why I am not seeing closer to 12:1 or did the shop just say the wrong compression when we spoke?

I am about to ask the shop to Mill my heads here because I want 11.5:1 at least now and I might as well do it while I am doing everything else.

Thanks everyone!

2XR95Z28

iTrader: (4)

I saw you posted in my thread also i would like to know if there is any calculations we could do with the gasket thickness, how much was milled. and all that? I want to be able to know almost exactly what mine is... Dont mean to steal the thread at all just seeing if there is a calculation out there to figure this out and it could help both the OP and me.

DAVE00

iTrader: (10)

Guys try using this site and plug in all your info to calculate the SCR. Pretty cool tool:

http://www.csgnetwork.com/compcalc.html

Formula350

iTrader: (3)

From the calculations I've used and others used in my thread, it was more around 11.12 for the .026 and 11.06 for the .028 (Impy)

If you started with 10.8, then you'd run around 11.63 for .028 (Impy) and 11..69 for .026

I very well could be wrong (but I'm going off of what Desktop Dyno's CR subprogram is calculating), as I'm using 53cc combustion chamber, 4.040 gasket bore and .046 piston down bore @ TDC. With .051 gasket (stock FBody from my udnerstanding) and .060 down bore @ TDC with 53cc and 4.040 (also stock from my understanding) results in the factory advertised compression of 10.42:1

Cross

iTrader: (10)

Excellent thank you!!

Now the LT4 heads were a little different were they not? Or were the valves just different?
If your right and I am around 11.5:1 then I am happy and will not be touching it.

Formula350

iTrader: (3)

LT4 heads were, according to Capricemgr, based off the B-Body heads (basically aluminum version) with a bit better porting, taller intake ports and yes I believe slightly bigger/better valves.

Again, I'm just relaying info, but Caprice loves to bash people for doing this since so many people give incorrect info. So if I'm relaying wrong info then it's ironically his fault haha But I've heard it from more than just him, so I doubt it.