Holley double pumper tries to stall in gear, idles fine in neutral.

This carb has been sitting around for a while, and after a year, it runs rough. It used to idle at 550 and drop to 500 in gear, now I have it idling at around 900 and when I put it in gear cold, it dies. When warmed up, it drops to around 500 and it is hesitating on takeoffs, nearly dying on me.

Runs great at speed.

Where should I start looking? Is this idle mixture issue?

I smell absolutely no gas in the exhaust, when it used to be pretty stinky before.

 

Troubleshoot as usual. Make sure both pumps are firing solid streams.

From there it's always best to disassemble and clean everything since it's considered normal maintenance once the carb has sat with dried fuel. Too many orifices with crud doesn't usually help matters and basic cleaning keeps you from chasing your tail around as you start from a fresh baseline.

 

Grab a holley kit and tear it down and refresh it. Standard holley maintenance.

 

My car was doing the same. Runs great in neutral, crappy in gear when at a stop. If I drive the car, its great.

Carb needs rebuilt, and adjust your idle screw

 

Tore it down and rebuilt it last week after it leaked into my cylinders. It was nasty. And all the non-stick gaskets were dissolved and swollen, and had to be scraped off. Lots of crud in the bowls, too.

So now, I guess it is time to re-tune it...

 

Why have you raised the idle?

 

I raised the idle because I hoped it would stay idling better when I am stopped and in gear.

I did not soak the carb last week, just blew it out, so maybe I will pull it off and do that this afternoon, and reassemble it tomorrow. Let it soak overnight. Wouldn't hurt it one bit.

 

It's not a fouled plug or two is it?

 

What number power valve are you running compared to your vacumn number idleing in gear should be 2 lower. If a 6.5 then try a 4.5 and so on

 

I have it torn down and soaking, rebuild kit is on order to be picked up tomorrow.

I will go from there.

If this doesn't fix it, then the next thing I look at is my HEI distributor. It is brand new, and the only thing I have changed that would affect the way it runs, other than old gas and letting the carb sit.

Spark plugs are all new, etc, and shouldn't be an issue.

Power valve is 4.5. We put that one in when we tuned it on the dyno. I can double check the vacuum when I get it running again, so not going to mess with it, even though I do have a few other sizes. New power valves come with my rebuild kit, so I will swap in a new one.

 

Hey! What is ya'll's take on putting oil on the blue gaskets before reassembly?

To keep them from sticking later...

 

Use Vaseline or chapstick instead.

 

Yes, Chapstick works great! Scoop, I hope you changed the oil...

 

Changed the oil yesterday before I drove to the alignment shop.

Didn't see or smell any gas in it, but at least I have peace of mind that I have clean oil and the correct amount.

I happen to have Chapstick laying around the house!

 

Holley changed their recommendation some years back. Instead of "2 lower", it is now Half of the vacuum reading. Example: 11" of vacuum at idle, install a 5.5 PV.