Dieing under load .....at times

[Bartonatl]

A little help please. All Opinions welcome.
My bronco recently started stalling at red lights and when I am maneuvering from reverse to forward over very short distances. It's gotten to where when I stop, it's safer to throw it in neutral.
Is that a carb adjustment or timing...????..
It's a new holly 4 barrel , 750 cfm I think, I've had it in for a couple of years. 302 automatic.....Any advice is appreciated as I will dig in to it this weekend.

 

[Blue Bastard]

Maybe developed a vacuum leak? But a carb issue is very possible if you only drive it short distances and let it sit for long periods of time.


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[Bartonatl]

Yeah I don't drive it in winter and it has been sitting while I did my hydroboost install. Maybe it needs a squirt of carb cleaner???.... Seems to run ok when I'm on the gas and will idle in park all day long.

 

[Blue Bastard]

You could try some "snake oil" like sea foam or the like. Try adding some of that to the gas to "clean" the carb. But with the kind of fuels we get out of the pump, carb issues are eminent. Might have to open her up and give it a clean.


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[68stang73]

Sounds like a good carb tuning is needed. But 750 is huge for a 302. Is it stock? Where is your timing set at and where does it usually idle at? My mustang has a big cam and its tricky to get timing and carb just right so it doesn't die at idle or at stop lights. A looser TQ converter will help too.

 

[k13evin]

Sounds like a good carb tuning is needed. But 750 is huge for a 302. Is it stock? Where is your timing set at and where does it usually idle at? My mustang has a big cam and its tricky to get timing and carb just right so it doesn't die at idle or at stop lights. A looser TQ converter will help too.

Just about to say the same thing. That's way to much carb for a 302 even a 600 is pushing it

 

[Bartonatl]

I don't think it's a 750 holly. I'll confirm tomorrow when I get to work. Just wondered it suddenly dieing like that is an indication of carb adjustment or timing issue.
It does have a very aggressive cam, BTW .

 

[k13evin]

Does it only die in drive? Or in park to? Have some one put it in gear and bump the idle up some. It could have idle it self down some. But yes make sure the timeing is set and all vac lines are plugged up. And there is no air leaks. Maybe snug the carb to the plate some to. They will back out some times.

 

[Bartonatl]

Idles fine in park. Actually have the idle a bit too high to compensate for the issue. I'll check the carb bolts and fuel supply line.

 

[k13evin]

I would check that. Maybe ajust the idle mix screws

 

[jckkys]

The '69-'70 Boss 302 Mustangs had a 780 CFM Holley. These were race cars that Can Am rules required a small number to sold to the public. They were not intended to be good street performance cars and they weren't. A 600 Holley is more than enough for a 460 truck engine. I have to ask, WTF is a Boss Hogg racing cam? My searches come up empty. When you say under load, are you talking about idling in drive? A long duration big overlap cam isn't going to idle well in drive with a low stall speed torque converter and the over size carb is going to make it worse. Careful adjustment of the idle mixture screws may help but a smooth idle may not be achievable with your combination of parts.

 

[Bartonatl]

Ok, pretty sure it's a 600 cfm 4 barrel. Idles ok in park and nuetral. But in drive I need to feather the gas. When it dies, it's dead intantaneous. So the idle mix screws are a good place to start??? Any recommendations as to in or out first ?? Thanks for the info guys.. Trying not to have to take it to a shop.

 

[jckkys]

If you gave us some idea what the specs are in this mythical Hogg racing cam we may have some idea how to get the truck to idle. Cams meant for racing are often incompatible with stock type torque converters.

 

[Bartonatl]

I'll check with my engine builder on the cam and torque converter. It has run well before so I'm thinking its out of adjustment. Also , watching videos on holly adjustments last night, there was mention of diff nozzles and diff cams based on vehicle size... I have so much to learn....... As usual i know just enough to screw something up. I really appreciate yalls know how .

 

[redhorseshoe]

Mine did the exact same thing after rebuilding the stock carb about six months ago. As others have stated, a proper carb tuning fixed everything.

 

[Bartonatl]

Success so far today... Advanced the timing a bit and reset the idle mix screws. Both were way too far out AND they were not set the same. So far... No stalls. Thanks so much for the input ! And I'm still looking in to the cam question. ��