.040 cometic
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From: Hanover, Michigan
.040 cometic Are these ok to run on a street car?
Do I need the 3.910 bore version? tsp has this and a 4.xxx bore as the only other option
I was just doing some searching and some people were talking about them leaking etc...and they have to be properly prepped?
what does this mean? what else can I do besides get the surfaces clean and torque everything down correctly?
Do these require a different torque procedure than a normal gm mls would? I am using gm head bolts.
thanks guys
Do I need the 3.910 bore version? tsp has this and a 4.xxx bore as the only other option
I was just doing some searching and some people were talking about them leaking etc...and they have to be properly prepped?
what does this mean? what else can I do besides get the surfaces clean and torque everything down correctly?
Do these require a different torque procedure than a normal gm mls would? I am using gm head bolts.
thanks guys
.040 will give you a much better quench, just be careful of PTV for your setup. make sure you know what it will change your compression to also. Cometic recommends .030 over your current bore for gaskets. I don't know how large you can go in general though. I've put a 4.130 gasket on a 4.030 bore.
same tq procedure.
same tq procedure.
Thread Starter
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From: Hanover, Michigan
Well....we got the torque procedure nailed.
I have got all the other things you mentioned figured out...but thanks for the heads up.
What gasket bore size is everyone running with the cometic?
I have got all the other things you mentioned figured out...but thanks for the heads up.
What gasket bore size is everyone running with the cometic?
Originally Posted by UltraZLS1
What is the issues I am hearing with sealing?
Would it be a safer bet to run the .045 cometic on a daily driver? better sealing when thicker?
thanks guys
Would it be a safer bet to run the .045 cometic on a daily driver? better sealing when thicker?
thanks guys
This is just empirical observation, but it seems like the majority of sealing issues are with ARP studs and these gaskets. Some guys have sprayed copper sealant on them for additional sealing insurance.
I would say if you torque them down properly and your surfaces are clean and flat you shouldn't have any problems.
As far as quench height, you would be better using the tightest safe quench you can get especially on a DD because quench helps with ping. You really should measure your deck height after the heads are off, and subtract that from your desired gasket thickness to determine the optimum quench. Anywhere from .035" to .040" is what most reccomend, but there have been some running tighter with no issues.
