302 on street today additives? - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 9 (permalink) Old Sep 29th, 02, 07:46 AM Thread Starter
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im intrested in talking to people who have a 302 with 11 to 1 compression.are you using lead additive? and are you having predetanation problems on 92 octaine gas. what plugs are you using and what are your jets #S. i have no pinging with my set up with octain boost.
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post #2 of 9 (permalink) Old Sep 29th, 02, 08:10 AM
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I am running one. If you have a tight quench (.035") or so, you should be fine with pump premium or maybe add a little leaded race fuel to pump up the octane a bit. I am still working on the jetting thing myself. It realy depends on the carb you are running.

The factory setup had a 780 CFM 4053 vacuum secondary carb with a 6.5 power valve in the primary and a 8.5 power valve in the secondary. They had .025 shooters in both positions, they had 68's in the front and 76's in the rear for jetting from the factory but I know someone that had their 302 car on a dyno and they ended up with 72's in the primary and 76's in the secondary. He was running stock exhaust manifolds so if you run headers, you might want to go up a size or 2 on the jets.

I am tuning in a 650 DP for my car. I figure I will set it up close to the above dyno jetting and try a step higher on the jets for a baseline as I am running 1-3/4" headers instead of cast iron manifolds. It is difficult to get an aftermarket style carb with 2 power valves other than the $550 factory replacement but I doubt I will need the extra power valve anyway as it only works when the secondaries are open and I don't run that way except on relatively flat ground and WOT so why bother with the extra power valve? I figure I can jet it a little fatter and be done with it. Hope this helps.

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post #3 of 9 (permalink) Old Sep 29th, 02, 03:34 PM
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I run a 50/50 mix of pump premium and 110 octane leaded racing gasoline. I run the factory 780 cfm 4053DZ carb with stock jetting. Air-fuel ratio testing on the chassis dyno shows it running a bit rich with that jetting.
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post #4 of 9 (permalink) Old Sep 29th, 02, 07:18 PM
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My Mako has a '70 LT-1 that pings with straight high octane pump gas. I use the octane boost additive to make it stop. Of course it stops pinging with 76's 100 octane fuel, but why pay $4 a gallon?

Camaro - '68 327 Coupe, '86 Z-28 IROC 305 TPI
Corvette - '73 Mako Shark II, '82 Cross-fire, '01 Coupe
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post #5 of 9 (permalink) Old Sep 30th, 02, 07:34 PM
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Most of the time I only use the 92/93 octane pump gas and have never heard any knocking. The only thing I notice sometimes is when I turn it off it acts like it wants to keep running. Once in awhile I will add some 110 octane Turbo Blue racing fuel which seems to stop the running problem after it's turned off, plus I love the smell, and it seems to help the gas mileage on those road trips to a car show.

1969 Z28, Fathom Green, DZ302, M20, 3:73, deluxe black and white houndstooth interior, PS, TW, AM/FM factory radio, console with gauges, comfort grip steering wheel.
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post #6 of 9 (permalink) Old Oct 1st, 02, 06:19 AM
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I used a composition head gasket in place of the stock steel shim on mine to lower compression a bit. It seems to run okay on 93, but I don't really put my foot into it much anymore. When I took it to the drag strip, I did mix in a few gallons of 108.
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post #7 of 9 (permalink) Old Oct 1st, 02, 09:00 AM
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Mine is all stock except for 72/76 jetting, no detonation on 93 octane pump premium.

'69 Z28 Fathom Green
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post #8 of 9 (permalink) Old Oct 1st, 02, 09:36 AM
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You guys are lucky to have 93 octane pump gas. No such luck in Northern California. 91 is as good as it gets here.

Has anyone done a compression test to check cylinder pressure? If so, what average PSI did you see?
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post #9 of 9 (permalink) Old Oct 1st, 02, 07:47 PM
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I think the highest cylinder pressure that I have been able to run 91 pump with, is right around 188 to 192 psi. But the only way I have been able to keep this thing together has been to really pay attention to the intake valve timing, hence the use of a MSD Digital 7 Programmable. IMO, about 180-185 psi would be max on the pump gas we have out here on the Left Coast.

'67 RS Camaro, Road Race/Autocross (with license plate) 630hp S/B on pumpgas, 4-speed, 13" brakes in 16" Vintage 45 wheels. 60-0 in 96 ft, +1.02g/200 ft skid pad.
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