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300 with 4bbl wont idle.

jebadiah04

Rooster Snorkler
849
27
Been a while since i posted here...hiiii


Anyways problem im having is what i believe is carb related.

Bought my old truck back. I think its been sitting for a few years.

Fuel pump was bad...changed that. So now it starts up. Tough starts but will start.

But it wont run for more than a few seconds.

It will continue to run as long as im jamming on the gas and the accelerator pump is squirting. as soon as i stop pumping the gas it dies right away 3 seconds later. And i have to pump it a few more times before it will refire.

Heres what ive done so far


Cleaned carb...no change
Screwed with mixture nobs. No change...now backed waaay out.
Screwed with timing. No change.
Cleaned carb again...no change.
plugged off all vac linea...no change
Cleaned car b AGAIN. No change.


Carb is an edelbrock 500 performer.
Truck is an 86

Offy intake.



Thanks in advance.
 

jebadiah04

Rooster Snorkler
849
27
Still my thought too. Ideas where?

Sent from my mudwhistle via lemmiwinks.
 

SuperCab

Moderator
Staff member
10,068
547
Montana
Been a while since I took an edelbrock apart... Maybe take the idle screws out and blow compressed air through the holes when you have it disassembled.

Other than that they are very simple... Not much to go wrong.
 

DNFXDLI

The Token Canadian
Staff member
Is there any short pieces of rubber fuel line by the tank?...had that problem with a 79 Bronco...was sucking in air up the fuel line.
Have you pulled the fuel line off at the carb and checked the volume?
 

jebadiah04

Rooster Snorkler
849
27
So after further inspection...the fuel goes through the main jets up the body into the venturis, back down the body, through the mixture screws and into the barrels. Somewhere in there it was plugged.



Sent from my mudwhistle via lemmiwinks.
 

jebadiah04

Rooster Snorkler
849
27
Is there any short pieces of rubber fuel line by the tank?...had that problem with a 79 Bronco...was sucking in air up the fuel line.
Have you pulled the fuel line off at the carb and checked the volume?

Duncan,

Fuel was golden


Now i need a head gasket. :mad:

Sent from my mudwhistle via lemmiwinks.
 

DNFXDLI

The Token Canadian
Staff member

jebadiah04

Rooster Snorkler
849
27
Easy fix on a 300. :)

Sent from my mudwhistle via lemmiwinks.
 

jebadiah04

Rooster Snorkler
849
27
I did one once, not too big of a deal. Should be able to do it in a day if you have everything ready...

Took me an hour even! 23 minutes remove time. 35 back on!

Water spraying from the head problem is fixed. But it still wont run

Sent from my mudwhistle via lemmiwinks.
 

DNFXDLI

The Token Canadian
Staff member
Gotta carb you can swap out to try?
 

jebadiah04

Rooster Snorkler
849
27
Yeah. Ill throw my double pumper off the BBC on there

:D

Sent from my mudwhistle via lemmiwinks.
 

1970Custom

They call me Spuds
14,107
447
Middleton, ID
Might be walking into the same issues there Tater, I had a 600cfm Holley on my 300 and it struggled to idle with that much fuel.
 

Fellro

Moderator
Staff member
It is both fuel and flow likely, just too much for the cubes it is controlling. Unless the motor is built up to use the additional of both, it will not respond well. It is no different than throwing a huge carb on a small V*8
 

jebadiah04

Rooster Snorkler
849
27
Should work to get it running. Wont get near enough fuel to run well. But at least i know the carb works.

Sent from my mudwhistle via lemmiwinks.
 

dustybumpers

don't play well w others

jebadiah04

Rooster Snorkler
849
27
Thats my next thing if swapping carbs doesnt do it. I never pulled the manifolds off when i did the head so i dont know. But its almost the last thing to check

Sent from my mudwhistle via lemmiwinks.
 

dustybumpers

don't play well w others
The offenhauser manifolds have a habit of breaking outside ears off too, watch for that when you remove it.
 

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