"I have a .040" over 400 with stock #16 heads and ram air IV cam, q-jet w/ iron intake, 9:1 CR. No problems with pump gas (91 octane). " Gorgeous for sure. Even using 75cc for the 16s on Wallace Racing's CR calculator I get 10.2:1, unless it is way down in the deck height.
"The point is that the gasoline we have now is a little lower in octane, but not drastically lower in octane compared to the old days. There's only about 2 octane real difference between 1970's advertised 100 octane Premium(research method) and today's 93 posted octane Premium(r+m/2 method)."
Then why do so many older original setup motors Chevy Pontiac etc detonate like heck on it?
"I was unable to operate my '67GTO in its stock configuration (067 cam and closed chamber 670 heads) on pump gas without pinging. That was the original, never-been -opened engine, and 94 octane at the time." "When I tore it down for an inspection and freshen up, I found that it had four broken pistons, caused by detonation I never heard"
Another reason to why chance it unless you are class racing and need that extra few HP.
__________________
Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune [email protected]
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
1964 Corvette Coupe 327 4 speed
Last edited by Skip Fix; 03-07-2011 at 01:16 PM.
|