What is the compressed height of factory L98 Head Gaskets???

Thanks

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Matt

1987 GTA L98 MD8 GW6

"Stop Lights timed for 35Mph are also timed for 70Mph"

 

Matt,

There have been varying numbers quoted in the past, but my information is that the original gasket compressed thickness was designed at 0.039". I've seen some quoted at 0.041", and some as low as 0.021".

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Later,
Vader
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"What a Day..."
Adobe Acrobat Reader

 

According to the MMVA (Manufacturers Motor Vehicle Specifications) for 1987 U.S. Passenger Cars, Chevrolet Motor Division, General Motors Corporation, the compressed head gasket thickness for the L98 is 0.021 inches.

Other specs include:

Bore Spacing (cl to cl): 4.40"
Cylinder Block Deck Height: 9.025"
Deck Clearance (minimum): 0.025" below
Minimum Combustion Chamber Total Volume (cm**3): 75.47 with piston at TDC and all components in place torqued to specifications.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig): 12.57 @ 111 mph.
Former Paxton (6-psig) & former 50-hp nitrous: 12.04 @ 114 mph.
Current ATI D1SC (Initially 10-psig): Projecting high 11's.
Future ATI D1SC (15-psig): Gotta catch them pesky 26-psig boosted TTA's!!

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

[This message has been edited by Willie (edited April 23, 2001).]

 

Ok, next question..... What is the compressed height of the Felpro # 7733PT-2 Head Gasket?? It is the one that Trick Flow recommends using with their 23* heads so that will be the one I will be using but I cannot find any info on the compressed height of it - not even on the Felpro package??? Any help is appreciated....

Matt

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Matt

1987 GTA L98 MD8 GW6

"Stop Lights timed for 35Mph are also timed for 70Mph"

 

That is the el cheapo gasket at about $15/piece at summit. The better/best gasket is the 1010 that they also list. That is the gasket you see people using on their AFRs and such. The 1010 is about $35/piece.

Do a search under the topic "gasket" or "head gasket" on the TPI and aftermarket review boards.


James

 

Arent those aluminum heads? Those gaskets shouldnt be used with aluminum heads. And just about every Felpro gasket is .039 compressed or close enough. They do have some others, but thats a good starting point. Thats what the 7733 are.

 

Yeah, remember to use gaskets that corespond to the correct type of heads you have or are buying. The thickness that most professional engine builder use is 0.040" but some crazy people like "Pat Musi" have gone as far as to use 0.015". NO kidding. But stick with the 0.040". If you need less compression use a copper gasket, they are about 0.060" Have a nice day.

 

No wonder my car makes 9.5:1 stock compression!! With a .039 or .041 gasket the compression would suck and then it wouldn't have been 190HP stock!!

 

The recommended parts sheet that came with the heads has the 7733PT-2's listed as the head gasket to use for "mild engines". The 1010 is listed for "high output engines up to 4.155" bore (will not indent aluminum heads)" so upon further reading and advice from you folks........... I will use the 1010's. Thanks for the input.

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Matt

1987 GTA L98 MD8 GW6

"Stop Lights timed for 35Mph are also timed for 70Mph"

 

coincidentally, i called felpro earlier today and found that the 7733pt2 gaskets are 4.125 bore and .038 compressed thickness. why is it a bad idea to use these on aluminum heads? i was planning on putting them on my vette l98 w/Al heads because they came with the car.

 

The steel fire ring in the 7733's will brinell the aluminum heads. Basically, it will leave a nice, slightly compressed area where the ring from the head gasket touches it. It can cause a combustion leak over time. Get the right gaskets.

 

Unless the factory has changed their assembly parts, I don't recall them ever using a composite head gasket on a factory installation. A factory steel shim head gasket is usually in the .018-.025" range. I have some .018" factory gaskets hanging in the garage.

The composite head gaskets from Felpro are usually .039 or .041"

 

i used the 1010 on my L98 with TF heads.