[Diy_efi] Timing table change needed with CR increase?

[Greg Parmer]

FWIW--partsamerica.com (advance auto parts) has thin steel gaskets for anyone
wanting to go the *higher* CR route.

SBC part 1094 is .015" compressed (3.2cc/cyl)...substantially different
(thinner) than your typical PermaTorque gasket.

(EFI content--EBL rocks!  
http://www.thirdgen.org/techboard/diy-prom/321767-embedded-lockers-hud-ultimate.
html) 

-greg


> -----Original Message-----
> Bob, embossed steel shim gaskets they were. The two offered were
> .016" and .019" thick. # xxxx336 and # xxxx708 rings a bell, but
> memory is questionable after having my bell rung a couple of times.
> 
> Actually, that was a trick used by racers as well; to double up on those
> gaskets for purpose of better hi-compression sealing and durability.
> 
> GAS
> 
> ----- Original Message -----
> > Back in the old days Chevy used to ship the hyper 327s and 409s
> > with two headgaskets per side, cut an advertised 11.25:1 down to
> > about 10.25:1. I seem to remember these as being the thin beaded
> > steel gaskets.
> >
> > Robert W. Hughes (Bob)
> >
> >> With the 90s LTx variety of 350, GM defied accepted rules by altering
> >> the CR on a particular engine/head combo solely by increasing the head
> >> gasket thickness. OEM GM gasket choices were a pre-compressed
> >> .029" and .049". In the process, the quench distance on typical OEM
> >> assembled engines could exceed 065". That generation of SBC can be
> >> considered to be respectably knock resistant, PCM ignition retard
> >> capability notwithstanding.