Got my stock DZ back from engine builder had it broken in and dyno'ed ran with sunoco race fuel 110. Do i need to go higher octane or is 110 good, i can get up to 118 what did they recomend for these bad boys THANKS TC
69 z fuel choice
X77Z28MP
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Got my stock DZ back from engine builder had it broken in and dyno'ed ran with sunoco race fuel 110. Do i need to go higher octane or is 110 good, i can get up to 118 what did they recomend for these bad boys THANKS TC
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Holy smokes... is it built for racing? What's the compression??
If it's a stock street build, run 93 in it.
If it's a stock street build, run 93 in it.
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2,361 Posts
You dont have to but running it on VP racing fuel will make that motor a lot happier.....and smells good to...
All stock GM parts 11 to 1 compression 30/30 cam,aftm sprimgs ,30 over he ran 110 race fuel on dyno that mouse roared easly up to 7900 rpm and wanted to go higher, That smell of sunoco i will never forget.... :thumbsup:
Gotta love 302s.. 7900rpms.. Hahaha! So what kinda numbers did it put down on the dyno? I would run what ever your builder recommends and then see how it runs on the street. Then adjust accordingly.
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2,284 Posts
Maybe run 93 octane with a water methanol injection system, what does the builder say?
I run California 91 and MMO. It is built stock and runs just fine. I have 18 initial and 18 mechanical at 2800 RPM. If it is a true 346 adv duration 30-30 use pump premium. If you have a quicker closing intake timing that may change things. Other states have 92 or 93 I think.
I should have said DC not SC.
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I wonder what Chevrolet was telling it's buyers to use back when the Z/28's were new. Of course octane ratings changed in the early seventies as well with todays r+m/2 method for 93 octane being equal to about 96 research octane which was the method used in the sixties.
My 302 has been running since being rebuilt 8 years ago. I used advice from Jerry M. and John Z. That would be a wise thing to do for you. There is nothing magic about these engines. The 30-30 (true to original grind) was a very "sloppy", for a lack of a better word, design using long easy ramps with not very special springs that had a very late intake valve closing angle. Can't build cylinder pressure until the intake valve closes. If you have a "modern" cam that needs high spring pressure because the intake valves snaps shut and builds cylinder pressure fast then you would have to look at things a little closer. Many people that rebuild 302s are frustrated because they want them to perform better so they use a cam that operates differently from the original. Your choice of fuel is up to you. Give Jerry a call and look thru John Z's old posts and get the real info. Also I hope you set up your distributor as John Z advocates to have full time vacuum advance.
Nice HP numbers. Torque readings?
Good luck and have fun!
Nice HP numbers. Torque readings?
Good luck and have fun!
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14 Posts
I would be surprised if GM was not recommending ethyl fuel for the 302 back in '69 which would have to be at least 100 research octane and a few points higher than todays pump premium of 92 or 93. Also lead may have had a benefit to engines beyond just octane and lubrication perhaps? My car seems to run better with it. I was a young teenager in 1969 and do not recall the typical pump octanes of the day. some areas had many choices.
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