What Octane Gas Do you Run?

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Feb 10, 2017 | 01:59 PM

#16

GoinBoarding

Cargo Master

Joined: Mar 2010

Posts: 3,330

Likes: 292

From: Laramie, WY

Quote:

Originally Posted by DeathRangerofDeath

Everything I've read says that these engines are just prone to pinging. Bad combustion chambers. No quench. From what I understand they pretty much just lowered the piston height to drop the compression, which tends to create a ping monster.

Makes a big difference. My old 351W was 8.3:1, some cheap rebuild done long before I got the engine, and had pistons 0.070" in the hole (0.120 squish). I couldn't run more than 10 base timing without pinging, it sometimes would still ping anyway. Broke a ring on that one, no surprise. New 351W is 9.2:1 and 0.042" squish, 15 degree base timing and good to go.

Feb 10, 2017 | 08:50 PM

#17

DeathRangerofDeath

Senior User

Joined: Aug 2006

Posts: 377

Likes: 6

Quote:

Originally Posted by GoinBoarding

A buddy of mine has a Sbc that basically won't run on anything less than 93+ octane boost, he's actually resorted to just buying 100 octane gas at $7/gal. We recently opened it up to get swap heads. It all made sense. He swore it was 0 decked, 12:1, turns out the pistons are ~.070 in the hole, with a .024 gasket... He's actually not even at 9:1, and has way too much cam in it. No wonder it's such a bastahd to tune.