304 not idling

matt1u2

New Member
Joined
Apr 23, 2009
Location
florence,sc
I have a 77 cj5 with a 304. It has been rebuilt and has a new fuel pump. It has a holley 4 barrel. To the poroblem. It will only idle when I have the choke almost closed and the idle turned up. Eventually it will quit running and then it is harder to start.

Where should I be looking?

how would I set the timing?

Thanks for any advice.
 
begin by looking for an MC2100 carb and throw that Holley as far away from your Jeep as possible. I had one and it gave me nothing but problems. not to mention it sucked off road. Yes you can modify them and tweak them to run right, but why bother when the 2100 runs great, and it's stupid simple to work with.

If it only runs with the Choke almost closed and idle turned up, then it sounds like you are running WAY lean.

Things I had to constantly dick around with on my Holley were float level, debris on the float needles. Yes even with new filters, Strainer baskets, and completely cleaning out the carb, shit still got through to the needles. Also had issues with having to constantly tune the mixture screws with the slightest change in the weather.

Start by pulling out your mixture screws. inspect the ends and make sure they aren't scratched. if they are, don't drop a dime in the carb, just replace it with a 2100. If all looks good, screw them in and LIGHTLY seat them all the way down. now back them out 1.5 turns each.

Try idling it now and let us know what happens.
 
Before I did that I would seek out the obvious. Vacuum leaks. When you have to close the choke that cuts down on the air flow. May be getting it's air somewhere else via a vacuum leak.
 
matt1u2 said:
thanx, I'll look for leaks but I did consider getting rid of the holley.
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IF you have a Holley that's not worn out, they are simple to work on, and easy to get parts for. I have had them before and they work great. Biggest issue for me has been if they back fire, then it usually takes out the power valve. But they bring the suck for off road use. The Truck avenger is a little better, but I still see(hear) them stumble when bouncing on the trails.

The MC 2100 is an awesome carb as well, works well on a Jeep.

Another option is a good running qaudra Jet. I run one of those for years.

If you want to go with the 2BBL carb, I have a intake you can have if you want to come get it, I ain't shipping
 
matt1u2 said:
I am building it for trail so I think I may try to find an mc2100.
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and most likely a stock intake. Chances are, that you have an Edlebrock Performer intake. Seems that combo is VERY common.

Not sure if there's an adapter plate to go from the 2100 to that intake (or whatever intake you may have).
 
matt1u2 said:
I am building it for trail so I think I may try to find an mc2100.
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Chip what the heck are you thinking!! If he's building it for off road he needs to throw away all all the carbs(Keep your Holley throttle plate) and propane it. I fought a carb for a year then propaned it and it was the best thing I ever done. I installed it for about $750(could be done alot cheaper) and was way simple. There is no adjustment what so ever and has never missed a lick in the eight times I've wheeled w/ it. If your interested just ask Chip or me we'll put you in the right direction. A choked out motor is embarassing I know.
 
mbalbritton said:
begin by looking for an MC2100 carb and throw that Holley as far away from your Jeep as possible. I had one and it gave me nothing but problems. not to mention it sucked off road. Yes you can modify them and tweak them to run right, but why bother when the 2100 runs great, and it's stupid simple to work with.

If it only runs with the Choke almost closed and idle turned up, then it sounds like you are running WAY lean.

Things I had to constantly dick around with on my Holley were float level, debris on the float needles. Yes even with new filters, Strainer baskets, and completely cleaning out the carb, shit still got through to the needles. Also had issues with having to constantly tune the mixture screws with the slightest change in the weather.

Start by pulling out your mixture screws. inspect the ends and make sure they aren't scratched. if they are, don't drop a dime in the carb, just replace it with a 2100. If all looks good, screw them in and LIGHTLY seat them all the way down. now back them out 1.5 turns each.

Try idling it now and let us know what happens.
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I do not know much about carbs. i found to needle screws on either side of the carb. I checked them and one was set at .5 turns and the other was slightly passed .5 turns. I took them out and other than some carbon looked ok. I cleaned them and set them to 1.5. Have not tried this setting yet because I wanted to make sure i did what you suggested.
 
matt1u2 said:
I do not know much about carbs. i found to needle screws on either side of the carb. I checked them and one was set at .5 turns and the other was slightly passed .5 turns. I took them out and other than some carbon looked ok. I cleaned them and set them to 1.5. Have not tried this setting yet because I wanted to make sure i did what you suggested.
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sounds like you're at the starting point as for where the Needles should be.

but like Chip said, Check for Vacuum Leaks first. If you have vacuum leaks, you'll be chasing your tail trying to tune the carb.

Also, as Lockedup said, if you have the money, Propane is a good option. Or Hell, Check with CaverDave on here, He put Fuel injection on his 304 for just a few hundred bucks.

But for now, go check all the rubber hoses coming off the carb or intake. Check the connections, bend the hoses and look for cracks. If all looks good, fire it up and let us know if it'll idle.
 
Checked for leaks. All lines are new. There are to vacuum ports on the passenger side that are not used and are capped off.

Still does not idle. Throttle response is good.
 
I have the screws backed out 3 turns and my brother tweaked the timing and it was idling with idle at a normal rait. Had a slight hesitation when hitting the gas so I think I'll adjust the screws to see if it will illiminate the problem. Happy for now that it is idling.
 
matt1u2 said:
I have the screws backed out 3 turns and my brother tweaked the timing and it was idling with idle at a normal rait. Had a slight hesitation when hitting the gas so I think I'll adjust the screws to see if it will illiminate the problem. Happy for now that it is idling.
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Now that I helped you get it idling hook the tow bar to it and get it to the trails I am looking forward to seeing how much it can take with out breaking. :flipoff2:
 
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