Have to get some steam holes drilled and also holes for temp. sensors. Can anyone tell me the sensor hole size for a 89 car?? Is bumping the compression ratio from 9.7 to 1 up to 10.5 to 1 a good move at this time?? Building 406 with 12.5cc dish top KB's, zero deck block, and .039 thick headgaskets. Cam has 226I and 234E at .050 and .512I and .531E lift on a 111 degrees lobe seperation. Any advise?? Thanks, Jack

You could use the victor reinz #5746 gasket which is .026, or the gm .028 gasket.

Get the victor reinz from Napa, and the gm one from the dealer, can't remember the part number.

What size are your combustion chambers?

[This message has been edited by 89gta383 (edited November 29, 2001).]

I'm not sure on the sensor hole size. On the gasket; I stuck with the fel-pro (the "premium" gasket) as they have the water passage for the inner cylinders enlarged while the outer holes remain small to increase coolant flow around the two inner cylinders to help with the heating problems. It's helped on mine. I'm 'fraid they only come in .039 though, so you couldn't bump the comp. ratio with them.



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86 406

Chambers are the 74cc as the valves are unshrouded better than the 68cc per AFR tech, and better swirl on mixture. Already have Felpro 1014 which are .039 compressed. Just wondering if milling the heads a little to get to around 10.5 to 1 is going to make enough of a gain in hp to do the extra expense at his point?? Will check on car for sensor size hole but hoping someone could keep me out of the cold of the last few days---------
Thanks for the help,
Jack

Sensors are 3/8" NPT.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4, 2300 stall TC. Ported World 305 heads, Crane PowerMax 2050 cam. ZZ3/4 intake, oil pump, pan & baffle. Accel HEI SuperCoil & module. Hooker 2055 headers, 3" Catco cat & 3" catback w/dual-opposite Flowmaster 80. 2.93 limited slip. Spohn SFCs waiting to be installed. AMSOIL syn lubes bumper-to-bumper. Daily year-round driver. Best ET, speed TBD...
57 Bel Air, my 1st car. '66 396, 9.7:1 forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 700 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

And then what? He is running 0 deck on the block, I would not even think about running a .026 or .028 gasket.

As for compression, with that cam you could run 10.5 with proper tuning. It might be ok anyway.