putz54143

i am looking at a 347 will it run on pump gas? 10.5 to 1

JMD

With aluminum heads and the right cam, yes, just how "right" of a cam will vary.

Without the aluminum heads you will be pushing your luck, with aluminum heads and a stockish cam just a maybe.

Rule of thumb used to be that aluminum heads buy about one point of cr, and a cam with a lot of duration will buy som cr also.

The real answer is we will need more info before we can give you an accurate GUESS...

putz54143

eagle crank and rods
srp forged pistons
comp valve train # 31-250-4 grind #fsxe284h-10
roush world heads
vic jr intake
msd dis
true roller

Starfury

The aluminum or the cast iron world heads? If cast iron, I doubt it. That's a lot of compression on cast iron heads.

67mustang302

Personally I wouldn't run compression that high on pump fuel without a custom cam.

JMD

Frankly, imo, if those are aluminum heads, I think you can swing it with that cam.

Very close to Jim's 408, , in c/r and cam, I have never heard a hint of pre-ignition in it, not at 4,000 ft, and not at 400' elevation, (although I think the stroke and size of the 408 helps some)

67mustang302

The problem with running high compression on pump fuel and getting an ots cam to work safely, is often you have to give up a bunch of performance to have safety.

eZ

Im running 10.7-1 on my 347 with aluminum heads and a comp cam xe282hr cam. no pre-ingnition and im in california running 91oct.

putz54143

well i bought it 2000. only 150 miles on it

frdnut

That is the compression ratio I am running with my 408 as well..It runs just fine on pump gas..In fact it seems to love all the initial timing I can give it with no hint of detonation...