Discharge Nozzle?
Thread Starter
2nd Gear Member
Joined: Mar 2007
Posts: 388
From:
Discharge Nozzle?
Car STARTS fine, but that is where it ends. It runs normal for about 3 seconds, then the idle begins to increase and doesnt stop. What the hell can it be?
dont know if it matters but..
68 302,
freshly rebuilt 4bbl holley 4160
edelbrock performer rpm intake
i was thinking maybe a vaccum leak but i dont know.. and i dont know where it would be leaking from..
EDIT l
\/
Fixed it, the throttle was sticking open a little..WD 40 and it was good, also had a bad carb gasekt.
but now i cant get the thing to stop backfiring out the carb.
if you wrap the throttle it backfires, then is good to go.
after a buddy of mine helped me adjust the accelerator pump it still didnt work, so we swapped out the acc. pump discharge nozzle from a 28, to a 26 or 25 cant remember, that seemed to make it worse. He suggested getting a 30 or a 32, do you think this will help??
any other ideas, comments?
dont know if it matters but..
68 302,
freshly rebuilt 4bbl holley 4160
edelbrock performer rpm intake
i was thinking maybe a vaccum leak but i dont know.. and i dont know where it would be leaking from..
EDIT l
\/
Fixed it, the throttle was sticking open a little..WD 40 and it was good, also had a bad carb gasekt.
but now i cant get the thing to stop backfiring out the carb.
if you wrap the throttle it backfires, then is good to go.
after a buddy of mine helped me adjust the accelerator pump it still didnt work, so we swapped out the acc. pump discharge nozzle from a 28, to a 26 or 25 cant remember, that seemed to make it worse. He suggested getting a 30 or a 32, do you think this will help??
any other ideas, comments?
6th Gear Member
Joined: Dec 2005
Posts: 5,212
From: Hills of California
RE: start the car, RPM's increase and increase and increase..etc.
use a large propane torch.
dont light it but let the gas run out at high volume.
with the engine running fog the gas around the intake and carb base. if its a vac leak you will hear it change when the gas gets sucked into the problem area.
a can of carb cleaner works too but not as clean. use the same way.
What does the throttle plate do?
how quickly does it build rpm?
will it continue to build rpm until it red lines????..it should lean out and die at some point not too far up tac if its a vac leak.
-Gun
dont light it but let the gas run out at high volume.
with the engine running fog the gas around the intake and carb base. if its a vac leak you will hear it change when the gas gets sucked into the problem area.
a can of carb cleaner works too but not as clean. use the same way.
What does the throttle plate do?
how quickly does it build rpm?
will it continue to build rpm until it red lines????..it should lean out and die at some point not too far up tac if its a vac leak.
-Gun
6th Gear Member
Joined: Dec 2005
Posts: 5,212
From: Hills of California
RE: start the car, RPM's increase and increase and increase..etc.
does sound like its leaning out.
If your worried about running it, start with the carb. take of it off and inspect the gasket if its broken or really hard get a new one.
check that all vac ports are plugged or the line going to them is good .
check the large bolt in the back of the carb (might not have one) make sure its tight or whatever is goin into that space is sealing.
If none of that works it might be the intake manafold.
What happens if you put the car in gear? auto or manual trans?
If its a vac leak it cant continue to rev for long especially if you load the engine by putting it in gear.
The old war planes of the 1940s like the p40 warhawk were commoly shut down by cutting the fuel to the engine. the engine would rapidly rev for a breif moment as it leaned out and then would sputter to a stop.
In your case I think its getting excess air causing the mix to lean out and rev the engine.
happy hunting
-Gun
If your worried about running it, start with the carb. take of it off and inspect the gasket if its broken or really hard get a new one.
check that all vac ports are plugged or the line going to them is good .
check the large bolt in the back of the carb (might not have one) make sure its tight or whatever is goin into that space is sealing.
If none of that works it might be the intake manafold.
What happens if you put the car in gear? auto or manual trans?
If its a vac leak it cant continue to rev for long especially if you load the engine by putting it in gear.
The old war planes of the 1940s like the p40 warhawk were commoly shut down by cutting the fuel to the engine. the engine would rapidly rev for a breif moment as it leaned out and then would sputter to a stop.
In your case I think its getting excess air causing the mix to lean out and rev the engine.
happy hunting
-Gun
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