Sputtering - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
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post #1 of (permalink) Old 03-13-2004, 08:15 PM Thread Starter
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Sputtering

Is there a fix for an engine that sputters while going up a hill?
I went wheeling today and the jeep was sputtering and dying while I was climbing some small hills, one of the guys said itís the carburetor, another said it was timing. I checked the timing after the ride and all seems well so before I plop down a couple of hundred for a new carburetor I would like to here from you guys what else could be wrong?

It has some Holly 4 barrel 650-700 cfm on a 304 and it and on the street it runs like a raped ape.
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post #2 of (permalink) Old 03-14-2004, 12:25 AM
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Re: Sputtering

Others here know better, but try adjusting your float so the bowl does not overflow as that may be your problem. I have seen guys throw tons of dough at a new carb only to have the same problem then a experienced (Offroad) guy adjusts the carb a couple times and problem solved.
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post #3 of (permalink) Old 03-14-2004, 08:47 AM
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Re: Sputtering

Holleys are notorious for this. Along with setting the floats a tad lower, you should extend the bowl vent tubes as much as your air cleaner allows (2-2.5 inches). At an upward angle, the fuel in the front bowl sloshes around and splashes out of the vent and into the carb, creating a rich condition, which is compounded by the float levels. Work with it and start saving for the carb swap. The good news is that quadrajets are highly praised as being very good off road, so if you can find a chevy 350 with a doner q-jet and stock manifold, it could be affordable, or use an adapter. [img]images/graemlins/grin.gif[/img]
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post #4 of (permalink) Old 03-14-2004, 10:05 AM
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Re: Sputtering

Going to a Q-Jet would really help - and set the floats in it a little lower than normal too - about 3/16" lower.

But if you stick with the Holley - If it's not a center-fed type, convert it. As suggested modify the external bowl vents, set the floats about 1/8" lower than the bottom of the inspection hole.
Go to a good speed shop - get the "white whistles" for inside the bowl, they extend the vent inside to the middle of the bowl, get "jet extensions" to get the jets to suck from the middle of the bowl, and get spring loaded needles and seats. And get the tapered floats designed for road courses.

Holleys are great street and strip carbs - hard to beat them, but off road's a different story. They don't like to be sloshed or jounced or up-hilled, and they have such tiny passages that a dirt spec you wouldn't notice in your eye will plug them up.

Get the bowl thumb screws, extra bowl gaskets, and a gas cup, you'll be taking them off to clear the grit out every once in a while on the trail.

The biggest advantage of the Q-Jet is the float pivots are in the center of the carb - makes a huge difference.
They used to call the Q-Jet "Quadra-Flush" because they have lots of parts, and "mechanics" didn't understand them and were afraid of them. Times have changed.
Get the book on Q-Jets by HP Books - very helpful and informative.

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post #5 of (permalink) Old 03-14-2004, 10:18 AM
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Re: Sputtering

After running a holley and an edelbrock carb, I agree the qjet is the low budget offroad king. Plus there are so many of them in the junkyards, it is easy to find one in the right size. Heck, I took my dog for a walk and my neighbor gave me one for free. Best money I didn't spend. No more sputtering at any angle. [img]images/graemlins/40BEER.gif[/img]
post #6 of (permalink) Old 03-14-2004, 10:58 AM
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Re: Sputtering

Oh - almost forgot -- Edelbrock makes a "copy" of the Q-Jet.
Yes, it's shiney, pretty, and their hype is they've "improved" on the design. They don't tell you they "cheapened" it or "short-cutted" it. And they don't admit it's not as good.

Best to find a real one - much cheaper too - but not as "Shiney."
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post #7 of (permalink) Old 03-14-2004, 09:52 PM Thread Starter
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Re: Sputtering

If I op for a q-jet which model do I get?
What about adapters, how hard is it to get an adapter?
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post #8 of (permalink) Old 03-15-2004, 10:03 AM
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Re: Sputtering

got mine off of ebay for $35, came off a 77 vette 350.

if you plan on running the choke try to get one that does not have the choke heater in the intake (had to do a little ghetto fabrication to make my choke work). also try to get a non computer controlled one.

if i recall correctly there are not many variations in size or flow of the different q-jets so i would just look for one in reasonably good shape. the most important thing to watch out for is wear on the bushings for the throttle, butterflies, choke, or any other metal shafts that go through the carb. as long as those things are fine, you should be ok.

im putting up some pics later this week of how i mounted mine and hooked everything up.

here are some links for q-jet info...

qjet -1

qjet - 2

qjet -3

oh yeah, as for the adapter... you can find one at
autobone or ADAP or Thief Auto since you're in SoCal. just go to the performance parts section and look for a squarebore to spredbore adapter (should be metal, about an inch thick and have four big holes in it) i had to grind a litte tiny piece of metal off the side of mine to get it to all fit together, but it's an easy swap.

-web
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