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Help with new crate 302 that wont idle

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
Its usually close to the head on the block. My experience with Atk was good with a Ford 302. Had an issue with a Toyota engine where the 6 piece main thrust bearing was assembled wrong. When I took the problem to them it took about a week and a half for them to ship me a replacement engine. But they stepped up and honored their warrenty. Read and understand their warrenty before you buy. It has serious limitations for self installers. They follow their warrenty to the letter. I would buy from them again for a stock engine. I would not buy a performance engine from them. For the money spent for performance I want to start with known good cores and buy exactly what I want and do my own assembly.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
1100 rpm in gear stopped is loading the converter and building heat in your tranny fluid. Your also into the fuel inrichment slots in the carb. I suspect you are dealing with a vacuum leak issue and covering up for it with extra fuel enrichment. At idle pull the hose off the vacuum canister on the distributor and see if there is vacuum on the hose. Do you know what the timing is set at?
 

73azbronco

Contributor
Bronco Guru
Joined
Nov 11, 2007
Messages
7,796
background on your c4? rebuilt? stock?

Modulator leaking?

What is the vacuum reading right before it starts to stumble and die? Does it start to die then vacuum drop, or does vacuum start to drop then stumble?


Does it rev when in idle? No stumble on rev?


What the heck is a turnkey rebuild?
 

B RON CO

Contributor
Bronco Guru
Joined
Jun 29, 2016
Messages
2,412
Loc.
Statesville, NC
Hi, so you say it idles fine in neutral, with 20" vacuum. When you start it in the driveway does it good? Does it rev up and seem normal? Can you lower the idle to 700 rpm in park?
If it runs good in park, and revs up, and doesn't shake all over with 20" of vacuum I would think the problem could be in the tranny.
I am no tranny guy but maybe the trouble is in the torque converter, input shaft or front pump. Maybe one of the tranny experts can say if problems here could cause your problem.
Good luck
 
OP
OP
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twood9mm

New Member
Joined
Jul 7, 2018
Messages
28
Loc.
so cal
1100 rpm in gear stopped is loading the converter and building heat in your tranny fluid. Your also into the fuel inrichment slots in the carb. I suspect you are dealing with a vacuum leak issue and covering up for it with extra fuel enrichment. At idle pull the hose off the vacuum canister on the distributor and see if there is vacuum on the hose. Do you know what the timing is set at?

1100 in netural but in gear it drops to about 700 (when it does idle for 10 seconds). Did try the dist vacuum line and it has vacuum. timing is 10 degress
 
OP
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twood9mm

New Member
Joined
Jul 7, 2018
Messages
28
Loc.
so cal
background on your c4? rebuilt? stock?

Modulator leaking?

What is the vacuum reading right before it starts to stumble and die? Does it start to die then vacuum drop, or does vacuum start to drop then stumble?


Does it rev when in idle? No stumble on rev?


What the heck is a turnkey rebuild?

C4 rebuilt. Vacuum does not move, stays at 20 in netural or in gear (drive). "turnkey rebuilt" is for rebuilt ready to drop in (all components there), not a long block.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
Distributor vacuum line at idle should have no vacuum on it. You need to move this line at the carb to the ported vacuum port. Most distributors are set up for ported vacuum. Check the instructions on the Holly carb you have. You will have to reset timing again. This makes a big difference especially at idle. 700 rpm in gear is good.
 
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twood9mm

New Member
Joined
Jul 7, 2018
Messages
28
Loc.
so cal
Hi, so you say it idles fine in neutral, with 20" vacuum. When you start it in the driveway does it good? Does it rev up and seem normal? Can you lower the idle to 700 rpm in park?
If it runs good in park, and revs up, and doesn't shake all over with 20" of vacuum I would think the problem could be in the tranny.
I am no tranny guy but maybe the trouble is in the torque converter, input shaft or front pump. Maybe one of the tranny experts can say if problems here could cause your problem.
Good luck

Didn't think of that. It starts right up and seems normal. Can lower rpm to 700 in park but then it drops when in gear. torque converter is stock.
 
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twood9mm

New Member
Joined
Jul 7, 2018
Messages
28
Loc.
so cal
Distributor vacuum line at idle should have no vacuum on it. You need to move this line at the carb to the ported vacuum port. Most distributors are set up for ported vacuum. Check the instructions on the Holly carb you have. You will have to reset timing again. This makes a big difference especially at idle. 700 rpm in gear is good.

Good suggestion. I called Holley and downloaded the instruction manual. However, mine is connected correctly. I misspoke about the vacuum at idle to the distributor. My fuel tank is new as are the fuel lines but Just for the heck of it, I am going to change the fuel filter. I decided to make another attempt at a local shop. They are a well know dyno shop thats been there for over 40 years. They will put scopes on it and hopefully, we can narrow this down. Cant get in for a week but I will let all know the results.
 
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twood9mm

New Member
Joined
Jul 7, 2018
Messages
28
Loc.
so cal
Help with new 302 that wont idle, cont. Mystery solved

Hi, been thinking about the idle and I keep coming up with a couple of things. Besides young guys mostly don't know or want to know about carbs, I would triple check the basic stuff. First, check and make sure the high idle cam on the choke side is completely off. Next remove and plug any vacuum hoses from the carb and intake manifold to eliminate these as a source of a vacuum leak. Next remove the carb and all the gaskets and spacers and make sure they are all right side up and lined up properly. Make sure the holes in the gaskets are not hanging up the throttle plates. There should be no sealer used. I've re- used carb gaskets before that should not be a problem, unless a gasket or spacer is ruined or cracked. Just snug down the carb nuts, medium snug. No muscle power. If you take the carb off you can verify the throttle plates are completely closed, and in the transfer slot area in the venturis. Good luck

Finally solved the mystery. Went to a well know (40 yrs) dyno shop that specializes in classics. You were the closest to the solution and by that I mean the carb was bad. It was supposed to be a brand new holley truck avenger however, we discovered that someone had tried to modified it for whatever reason. Dyno shop said it wasn't a factory job so builder or seller(?). Idle circuits were really messed up. One bowl didn't have any fuel in it at all. Four other "Bronco" shops and one dyne shop didn't find it.I have a new fitech I was going to install but didn't want to try that until the mystery was solved. Turns out, had I done so I would have saved a lot of money and time. Now, Im not sure if I will go the fitech route. Anyone have experience with the fitech?
 
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