Who is running high compression and still using Pump Gas?

I know Greg Cook does it, but how? Aren't you running like 13.5:1 compression? I thought that there was a limit? Is the size of your cam allowing this?

Thanks
Jeff Given
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My dad's bone-stock '70 300hp Cleveland gets by on 92 octane with a shot of 104+ in every tank.Don't ask me how,the thing is supposed to be 10.7 or 11:1 depending on which manual you believe!

The trick is to use a cam with lots of overlap, this will bleed off cylinder pressure, making the engine act like it has lower compression.
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They say Alum. heads are more forgiving as well

Robert
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talking iron heads...what is considered a lot of overlap?

Thanks a lot!

Jeff Given
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my motor has 13:1 compression, and still uses 93 octane, as a matter of fact i still drive it to work weekly. just time the motor to normal idle, and curve the distributor total advance down according to what the motor likes.this is easily done on the dyno. my particular advantage is that the 4V clevo heads arent ping-prone, so i can still use more timing than makes peak power...but i also have alot of cam. 270int, 282ex dur@.050 with .657int .644ex lift.it makes 410rwhp on 93 octane, out of 306 c.i. hope that helps...Duke

My 429 SCJ is stock except for an 850 DP & a set of headers. I use 87 octane just to drive it around & it's 11.3 to 1 & has 200 PSI cylinder pressure...
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On 2003-04-05 17:54, fasteach wrote:
my motor has 13:1 compression, and still uses 93 octane, as a matter of fact i still drive it to work weekly. just time the motor to normal idle, and curve the distributor total advance down according to what the motor likes.this is easily done on the dyno. my particular advantage is that the 4V clevo heads arent ping-prone, so i can still use more timing than makes peak power...but i also have alot of cam. 270int, 282ex dur@.050 with .657int .644ex lift.it makes 410rwhp on 93 octane, out of 306 c.i. hope that helps...Duke
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Geese! What RPM did you make that power at?!

I am surprised at all the posts regarding high compression iron heads and pump fuel! Out of curiosity, could I get by with a lower octane from my cleveland? Its a flat top motor with quench heads. Cam is 246 256 @.050 lift is 564 589 I believe the timing is set at 37*. I will be driving it next week for spring break when I go home, and I am already broke [img]/phpBB/images/smiles/icon_frown.gif[/img] Maybe I should ante up, and charge gas on me Credit card [img]/phpBB/images/smiles/icon_smile.gif[/img]

So I guess 13:1 on pump gas is the highest in here anyways....I bet that thing really BANGS!

JG
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Hah, well just to throw a wrench in the works, my Bronco used to ping all the time 'till I found the sweet spot on the distributor curve and vacuum advance. Dished, 8:1 pistons, but I've got a really mild cam, 260/272 adv. duration, and 112 lobe center.
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I am running 10:5 in a stock 5.0 H.O(rebuilt of course with new pistons) stock cam home ported E7s and 14* timing on 92.
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