built sb Chevy v-8 problems Help!!!!

[jasonvess]

Best way to mount a york

Ok i hope someone can help me out here, I am constantly fuel fowling spark plugs in my motor, and it is just not running good.

I am running regular pump gas in it, but the guy that built the motor says it must have 110 octane fuel or higher, and that is why it is not running well

here are some motor specs
350 Chevrolet V-8, bored .040 over, crane roller rockers, 305 duration 525 lift comp cam, 10.5 to 1 forged pistons, steel rings, Trick flow .001 longer rods, Trick Flow twisted wedge aluminum heads 2.05 valves, edelbrock aluminum intake, complete MSD Ignition system, and Edelbrock 750 cfm manual choke carb

Motor does not spark knock on pump gas, therefor i didn't think it would need high octane fuel, I am at a loss,

does anyone have experience with a motor like this, does it actually need high octane fuel, I am having a hard time finding it locally to try it.

any ideas?????

 

[Sparky-Watts]

RE: Attempted theft

You might try looking in the local auto parts store for some octane booster. I'd guess the guy that built it should know, so yeah, it probably does need high octane fuel.

 

[88Wrangles]

what octane pump fuel are you putting in it.

If it's not 92 octain (or whatever premium is where you live) then I would try that. If that is what you're using already, try some higher (110 or so) octane fuel and see if that helps. Then you can at least eliminate some things.

If not that, it could be running too rich. Try adjusting the carb a little and see what happens.


I don't know though. My 454's built up real good like that and it never fouls plugs on pump gas.

 

[Inspector-Gadget]

I don't necessarily have an answer to your question, but perhaps I can provide something to ponder.

When car manufactures design an engine for a street vehicle, that engine is cammed, carbed/injected and a whole lot of other stuff in ways that make the engine suitable as a reliable power plant for a utilitarian street vehicle.

If car manufactures were in the business of building dragsters, those dragsters might come from the factory equipped with engines much like the one you received from your hop-up artist -- powerful, but of low reliability and very finicky, unsuited for everyday driving.

By way of example, there was a time when Porches and VW Beetles had essentially the same engine. In VW-form, that engine was a very reliable, low performance power plant. In Porsche-form, hopped up and fine-tuned to within an inch of its life, the engine was a screamer, but also a total pain in the butt to keep running well as a daily driver.

Draft horses were not designed to compete in the Kentucky Derby. Racing thoroughbreds were not designed to pull plows.

Dependant upon your driving conditions, you just might have a wonderful -- yet totally inappropriate -- engine in your Jeep.

On a more practical and helpful note, try a few tankfuls of high-octane gas and see what happens.

Regards,

Gadget

PS: I might also ask your engine builder where he thinks you will find "110 octane or higher fuel"?

 

[BigDaddys88YJ]

I don't have any experience with a 350 in a jeep or with all the mods that you have but when I had my 85 blazer I bought the same edelbrock carb for my 350 rebuilt .30 over and I could never get it to run right so I went back to the quadrajet and it ran fine but that is just my experience.

 

[88Wrangles]

RE: Recovery Points

I don't have any experience with a 350 in a jeep or with all the mods that you have but when I had my 85 blazer I bought the same edelbrock carb for my 350 rebuilt .30 over and I could never get it to run right so I went back to the quadrajet and it ran fine but that is just my experience.

Ya, I'm really starting to think it just needs to played with a little to see if that's the problem.


Gadget, you made some very good points!!! I love the way you explain stuff too :lol: 8) :wink: :lol: :lol:

 

[Sparky-Watts]

Re: RE: Attempted theft

You can buy 110 octane at the local dragstrip here. Don't have to be a drag racer, either. The pumps are right outside the entrance, so I've heard (never been there). It ain't cheap, though. Something like $5 a gallon.

 

[Junkpile]

RE: Carb question

That's too much compression for pump gas, even with aluminum heads. What chamber size are those pistons supposed to be used with to produce the 10.5:1 CR? The TF heads you have are 67cc chambers aren't they? You may have a little less than that, plus that cam should help some with it too.

Who set it up and got it running initially? Was it fired up on regular gas? Was the timing retarded until it stopped knocking on regular gas? Get some higher octane fuel and then do a basic retune and see where you are at then. I'd say a few gallons of 110 mixed with some 93 would do the job. You don't need a tank full of 110 for that engine.

I think the 110 octane was around $3.50 a gallon at the BP station last year. I'd hate to think about what it's up to now. That's one part of getting the CJ going again this summer that I'm not looking forward to

 

[88Wrangles]

wow, 110 octane fuel at BP? That is sweet!!!!!!

 

[jackal]

RE: Re: Extra Wide Tires

I would say the carb is too rich, flooding, blown power valve, choke stuck, or a possible leak in the inside of it. Are you running a fuel pump with more than 5 psi pressure? this could make the needle and seats not shut off. Are the float levels set correctly? If so , adjust them a little lower. If you don't already have an MSD type of ignition ,you need to get one. With an engine like this idling (OR ATTEMPTING TO) in traffic it needs help burning the gas that the cam is dumping in. ( OR it will foul the plugs). Check your vacuum and get the appropriate power valve that corresponds with the reading. I have a 71 chevelle drag car that I used to drive on the streets a few years ago and it took a while to dial it in. I ran 2x4bbls and nitrous, roller cam ,etc.
If you let it run rich too long it will wash down the rings in the motor.

You can talk to the builder of the engine and see if he can help you tune it, but some of the best builders don't know how to tune the motor once it is in and running .
I worked at a Holley carb race shop for 9 years and it helped me a lot.

Also I have a 300 horse 350 in my cj7, but I am running a 2 bbl holley til I get the Holley EFI put on.

Later,
Jackal