History:
Before sitting a couple of weeks the car ran fine.
Afterward, it wouldn't hold an idle and surged at low speeds.
Gas pooled on both sides of the manifold under the secondary throttle shafts.
I thoroughly cleaned the carb twice with carb cleaner and I blew out the orifices with compressed air.
I replaced a leaking accelerator pump gasket.

All seemed good on a single test drive. Today, however, I'm back to square one: The car won't really hold an idle, it surges at low speeds and gas pools a bit below the secondary throttle shafts which are damp on the underside.

Advice would be appreciated,

JamesC

 

Have you replaced the secondary float needle & seat?

 

No, but I've come to believe that's the culprit. I'm waiting for the temps to rise. 4 degrees currently.

JamesC

 

What? You can't work on tiny metal parts when it's 30* below freezing?

12* where I am right now. The only thing touching my car for the next couple months is the battery tender (I say a prayer every night it does it's job without malfunction)! I'm not going out there. It's freaking cold!

 

I hear you!

JamesC

 

I cleaned the secondary needle and seat which seems to have cured the issue. I still need to fine tune the float level.

JamesC

 

A problem I once had on my primaries was that the threads for the needle were beginning to strip so that I could adjust my floats but when I tightened things down it would pull out a little more. This was effectively raising my float level and causing similar symptoms to what you're seeing.

Not saying that's your problem as a bad needle and seat do the same thing and are more common I would think. That was a head scratcher for me though. It caused quite a bit of frustration.

 

Well, I spoke too soon.

After cleaning the needle and seat and adjusting the floats yesterday, the car idled and ran fine on a test run. This morning there was no fuel on the manifold. I assumed (and you know what that means) that all was well. Not so.

This is the second time that I thought I'd resolved the issue—as my first post details.

Any ideas on why the car runs/idles fine one day and not the next?

JamesC

 

do you have a fuel pressure regulator? what about a vented gas cap?
just trying to toss a few things out there.

 

A regulator isn't necessary in my system.

OE cap.

It occurs to me that I didn't remove the idle mixture screws and clean the passageways. Could that possibly be an issue?

JamesC

 

i guess its possible you could have a leaking float, allowing the bowl to flood out residual pressure over time.

it wouldnt hurt to pull the mixture screws out and blow the passages out with compressed air. just note how many turns your at first.

 

I would replace the needle/seat assembly.

Do you have filters behind the inlet nuts? Holley wants you to use both an in-line filter, and the inlet filters.

 

Yes, to the filters.

I thought tomorrow I'd try removing the idle mixture screws, blowing the passages with carb cleaner and compressed air (on car?). Failure there gives thought to buying a rebuild kit, which includes new needle/seats. Recommendations?

JamesC

 

Perhaps a full carb overhaul is in order?
I can only recommend original Holley replacement parts as in my experience, the substitutes are not up to par.
As for the fuel pooling on the manifold, the throttle shafts were the culprit in my case.

 

The driver's side was clear, the pass side appeared to be blocked. The car ran well afterward—but I've been down that road a couple of times before. We'll see.

JamesC