Thread:

pump gas?

If it were mine I would run AV gas or E 85. I dont think I would want to trust 91 or 93 oct. in my new motor at that compression. AV gas here is 4.00 + per gall. E85 2.70 per gall. and race fuel is 7.50+ If you haven't got the carb or carbs you might want to look into the E85 if its available in your area. About 25% more fuel required but an average gain of 5% in HP over AV gas. I converted mine this winter to E85, and looking foward to running it next summer. Also its 105 oct. out of the pump.

Pretty high C/R for pump gas. And don't trust octane boosters.

odfirefighter,

You had another thread on this and myself and a few others answered there, did you not like the answers?

• If you really have 11.7:1 compression with iron heads and that small cam (262/268 adv) with a wide lobe seperation (112) you have way too much compression for pump gas.

• Since you don't know the cc's of your combustion chambers or even what casting they are or how far below deck your pistons will be nobody can figure your compression to see if 11.7 is a good number or not.

• Detonation will kill an engine faster than almost anything else so do you want to gamble over a few bucks for fuel?

Loren

Originally Posted by MR.Magoo

i dont like any of the answers you have given me loren!

oh well you get what you pay for.

Originally Posted by odfirefighter

my bad i originaly posted this here and then thought i may have put it in the wrong area so i posted in the engine section. still new to this and i realy apreciate yalls input and your help. im gonna call the machine shop today and see if they can find the casting numbers for me and once i get the block back i will see where the pistons are sitting in the block. if i need to run race fuel i will. but if i can avoid it i would like to.

theres always methanol, its cheap. and you will never over compression it. plus it smells like fast

Originally Posted by MR.Magoo

yeah i know i actually did start out with some small jets on the tunnel ram like you suggested

So what jetting did you end up with?

Originally Posted by MR.Magoo

well i started out with 68/70 i think now i have forgotten, i took the boat out on monday of this week, and it was popping from the start, pretty sure my timing is off, i am gonna pull the plugs tonight and see what they look like.

Are you using power valves or plugs? I'm running a 69 with a powervalve on the primary and 78s on the secondaries with plugs. So unless your running PVs on both sides that sounds way lean.

Originally Posted by MR.Magoo

well i started out with 68/70 i think now i have forgotten, i took the boat out on monday of this week, and it was popping from the start, pretty sure my timing is off, i am gonna pull the plugs tonight and see what they look like.

did you end up with that frt timing cover along with the shovelnose? i know matt got it from billy , jus wasnt sure if you got it in the trade or not. i know the timing marks on it arent to be trusted, we made a new cut on the indicator when i tdc his 540, then of course his fluidbalancer had a timing tape made into it to read. you may have to do the ole pull a plug and tdc method to see where its at if you've got that timing cover randall.