New Carb....but Jeep still hesitates...Help???

[Stormrider]

Ok, so I just put on a new Holley 2300 carb today because I was thinking that was my problem since that's only thing that I didn't replace during the restoration but it's still doing the same thing.

It idles good and and revs up good in neutral but when you drive especially in 2nd gear, it hesitates and jerks, then if you floor it, it will go. Does anyone know what could be my problem?

It is a AMC 304 V8 4spd with a Holley 2 barrel. I just rebuilt the motor with new everything. I don't have a charcoal canister, liquid check valve or roll over valve if that makes a difference. I just have a clear inline fuel filter right before the carb. It almost seems like either the timing is off or it's not getting enough fuel when it does that but I want to know what you guys think.

 

[Farmer Mike]

My guess would be to lean or to much timing. Lean could be a vacuum leak at the intake gasket.

 

[7D8CJ]

Vacuum leak or retarded timing are most common

 

[JR74CJ5]

Both of the above would be my guess, maybe a crossed vac line somewhere?

Also have read 3 posts similar to this lately...

I believe all 3 had it solved with a new fuel filter, the 1 in and 2 out (one to carb, one return line) type... Though i never understood this, as i have a AMC 304 with clear glass filter too, and runs like a champ...

May sound weird but also a possibility you've got some exhaust leak going on?

One last thought, what type of distributor do you have? If points, check, clean gap or replace them... Also check your spark plugs out...



~ JR

 

[Old Dog]

I agree with the vac. leak and or timing off. could also just need the carb adjusted.

 

[Stormrider]

Well, even though the instructions from Holley say that all the screw are set adjusted and set from the factory, I went ahead a tweaked them a bit. I adjusted my timing and the fuel mixture and it seems to run better. Of course it was already warmed up though. I will see how it runs cold tomorrow. I will also check for a vacuum leak. I hear something from the back of the carb but not sure where. It surges at idle when the engine is cold. I have an electric choke on it and I set it at about 1/8" when cold.

Like I said, I have a clear inline filter at the carburetor. I did notice today that at one point it only had about 1/4 gas in the filter and at other times it was like 3/4 full. Is this normal?

 

[Stormrider]

Both of the above would be my guess, maybe a crossed vac line somewhere?

Also have read 3 posts similar to this lately...

I believe all 3 had it solved with a new fuel filter, the 1 in and 2 out (one to carb, one return line) type... Though i never understood this, as i have a AMC 304 with clear glass filter too, and runs like a champ...

May sound weird but also a possibility you've got some exhaust leak going on?

One last thought, what type of distributor do you have? If points, check, clean gap or replace them... Also check your spark plugs out...



~ JR

I will check all of those things out. I have a HEI distributor. I will check out my spark plugs also. I think that I put some Champions in the motor but someone told me that I should run Autolite. Any thoughts? I know that I will need an oil change soon even though I have only put about 500 miles on the rebuilt motor because I checked it out and it was kind of dirty and smell alot of gas. Probably from me revving and gassing it the past couple of weeks trying to tune it.

Thanks for the help guys!

 

[JR74CJ5]

Like I said, I have a clear inline filter at the carburetor. I did notice today that at one point it only had about 1/4 gas in the filter and at other times it was like 3/4 full. Is this normal?

I'm not sure its "normal" but mine also does that too...

It seems to run fine, even on the trails, so I'm not too worried yet...

and also, the best time to set and tweak the carb / timing is at normal operating temp.

What i do is get it all to normal opp temp, unplug the vac line to the distributor (vac advance) set the timing (I actually set it to the spec'ed 5 degree this time...) and then the idle to (mine anyways) specified 750 RPM, then adjust the carb mixture screws... Then I drive it, come back mess with mixture screws, drive it etc...

Finally got mine running greatly now



~ JR

 

[JR74CJ5]

I will check all of those things out. I have a HEI distributor. I will check out my spark plugs also. I think that I put some Champions in the motor but someone told me that I should run Autolite. Any thoughts? I know that I will need an oil change soon even though I have only put about 500 miles on the rebuilt motor because I checked it out and it was kind of dirty and smell alot of gas. Probably from me revving and gassing it the past couple of weeks trying to tune it.

Thanks for the help guys!

Just seen this... So the setting of the timing will be slightly different then mine...

Did you re-gap the plugs to HEI gap instead of normal gap? Think it's .045 not .035 or something like that... as far as the type / brand of plugs, Not sure its terribly important, unless you are trying to squeeze every horse out of it...

 

[Stormrider]

Update. I fixde my hesitation problem after pumping gas today. I somehow hooked the fuel return line to the bottom of the carb because that's how the PO had it hooked up and idiot me didn't even bother to check. I should have checked. Anyways it was pulling vacuum or gas in my case into the carb and flooding it especially when tank was full. So I bought myself the correct fuel filter with the 1 in and 2 out and hooked the fuel return line to it and that fixed my problem! Thanks for all the help guys.

Oh, one other question. When I squeeze my gas filler hose, I see gas dripping out from where the hose goes into the tank. I tightened it as tight as it will go and broke one clamp so I replaced it and was it was still doing the same thing. Do you guys think that's it's because of pressure in the tank and that my 2 vent lines are plugged? Should I try to locate the almost impossible to find liquid check valve, roll over valve, and charcoal canister and hook them all up or just leave it? Would it be ok it I just leave the 2 vent line open or maybe just put a plug in them?


Storm.