Driveability of high compression cars - Page 5

Stuart Adams · #41 11-17-2005, 03:45 PM

Hope there is no quiz. LOL.

Baldy · #42 11-17-2005, 06:12 PM

I buy the highest octain pump gas and mix it with Av. gas 50/50 mix. This works well on my 427 C.I.

68l30 · #43 11-17-2005, 08:26 PM

I run my 327 on 94 Sunoco....It has a .003 deck (cut pistons & squared the deck front to rear and side to side ) with a true 10.5 to 1 compression.No problems.....My guess is without a true blueprint most 11 to 1 motors are hardly that.I would have been lucky to get 9 to 1 on mine.

Steve

**Mr70** · #44 11-18-2005, 03:11 AM

I run the Jack Podell Lead/Octane additive in my soft valve seated L-78 Chevelle for years now.Just 12 oz. to every 10 gallons of 93 seems to agree with it.
She does run hotter though.

**Xplantdad** · #45 11-18-2005, 03:13 AM

Rick...just pump some fuel out of your Sunoco Gas pump!

@wot · #46 11-18-2005, 03:48 AM

just curious how some of these l78 and l72 cars are tuned. i have 36 degrees of total mechanical advance in by 2750 rpm, no vacuum advance. i nee to mix race fuel to control detonation.

musclcar · #47 11-18-2005, 12:33 PM

my camaro has an 11.5:1 350sbc and i run a mix of either VP MS103 or VP C12 with 91 octane pump gas.i can get all the race gas i need thru our race team and the price is right "FREE".ahh the smell of race gas coming from the exhaust of a healthy sounding street car

**juliosz** · #48 11-18-2005, 04:30 PM

I went through the engine on my 68 Z a couple of years ago. I went with all stock components except for roller tip rockers on my 302. I typically run about 10 gallons of 93 octane to 5 gallons of 110. Many times however, I run straight 93 with no detonation (total timing set to 36 degrees and running R45s). At first, I couldn't believe I could do this but then I read this article in Chevy Hi-Perf and it makes perfect sense to me. So those of you running hi compression + long duration cam may want to take this into consideration.

68l30 · #49 11-18-2005, 05:33 PM

Correct.....I run a high duration cam as well.If I remember correctly it's about 238 or 302 total duration.A lot of cam but very streetable with a 3800 converter and 4.10 rear.It runs very happy in the top end, 6500 +.....I get a little nervous up there though.....

Steve

70CitrusZ · #50 11-20-2005, 11:19 PM

My 70 LT-1 is built with pistons designed to produce 11 to 1 with 64 cc chambers.
Stock solid cam set at .024 and .026 lash
My decks were cut to clean up to parallel, about 7 thou.
I used head gaskets with a .039 compressed thickness.
Before I assembled heads, they were cylinder matched and laid back,and smoothed to eliminate hot spots. After that the chambers measured 61 to 61.5 cc.
I had hardened exhaust seats installed.
So far I have had no problem running 93 octane pump fuel.
Originally I fired it on 100 octane av gas, but found it ran cooler and still without detonation on unleaded 93.
Mark.