Holley Carburetor Stalls

[George C.]

I am having problems with my rebuilt Holley 4555 carburetor on my 1970 LT-1. The carburetor works fine on cold start up and idles fine at 800 to 900 RPMs in the garage for 15 to 20 minutes during the warm up.

When I drive the car on the highway at speeds of 65 to 70 MPH and come to a stop the RPMs fall off and the car stalls out. I did not have this problem before the carburetor was rebuilt.

Has anyone else had the problem?

[Joe L.]

Re: Holley Carburetor Stalls

I am having problems with my rebuilt Holley 4555 carburetor on my 1970 LT-1. The carburetor works fine on cold start up and idles fine at 800 to 900 RPMs in the garage for 15 to 20 minutes during the warm up.

When I drive the car on the highway at speeds of 65 to 70 MPH and come to a stop the RPMs fall off and the car stalls out. I did not have this problem before the carburetor was rebuilt.

Has anyone else had the problem?

George-----


I'd check to make sure that the primary float bowl level is at spec.

[Timothy B.]

Re: Holley Carburetor Stalls

Have you adjusted the curb idle emulsion screws after the engine is at operating temperature.

[Kenneth T.]

Re: Holley Carburetor Stalls

I had the same problem, good startup, runs good when travelling, pull up to a stop sign......stalls. Found that it was the power valve was leaking, replaced it and everything works great now

[Gene M.]

Re: Holley Carburetor Stalls

I'm assuming you have done the install and set up correctly and know how to set things up. Always inspect outside work. One can't just assume everything was done correctly. Do the parts you can see externally look to be Holley?

Console the rebuilder as to what parts were used to rebuild it. Many of the non Holley parts are just plain junk. If the power valve (that s/b new) is bad as suggested it is an indication of the parts quality................

[Jim T.]

Re: Holley Carburetor Stalls

Good way to check the power valve on Holley is to have engine running and put a finger over the vertical carb vent tube. If engine dies, the power valve needs replacement. The engine will die right away.

[William F.]

Re: Holley Carburetor Stalls

I's pull both float bowls and check to see if a float has a pin hole and is filling up with fuel as well as checking power valve.

[Gerard F.]

Re: Holley Carburetor Stalls

George,

I had a similar problem with my 67/327- 3810 holley and was about to pull my hair out.

It was one of the following two problems, or a combination of both:

1. Vacuum leak in the carb especially in the line between the carb and the vacuum can on the distributor.
Low vacuum will effect your timing at idle, and the low vacuum through the intake will cause a drip, drip, drip of gas at hot idle, flooding and stalling. Put a vacuum gage of the line between the carb and distributor, and find the leak. when you have a steady vacuum at idle then retime to highest vacuum at idle.

2. Fuel pump. If the fuel pump is old and the car has been sitting, a grit develops in the fuel pump and can even pass through the filter. The grit plugs up the float needle and meter body passages and gives you that erratic idle and flooding. I tore my holley apart many times and kept finding this grit in the fuel bowls, that is, until I put in a new fuel pump.

My problem (which I solved ) was one of the two above, or both. It may not be your problem, but worth a check.

[Gary S.]

Re: Holley Carburetor Stalls

George, last year I described virtually identical symptoms (72 LT1) on this forum that was given much of the same advice that you are receiving now. I mentioned to everyone that the carburetor couldn't be out of adjustment because it had been adjusted not more than two thousand miles ago. I took the advice and checked that all out and found it the floats were horribly adjusted. I wound up doing everything, checking power valve and set the floats and now it runs like a scalded ape