My Holley 2 bbl is running rich, so far I've adjusted the idle mixture, pulled it apart, checked the needle and seat, installed a brand new power valve (#45) and adjusted the mixture again, but I can't seem to get it quit running rich.

The rest of the engine is fine, it's a fresh re-build, ignition timing set perfect, new points (dwell set at 25) new plugs wires, cap rotor, everything else checks out.

Any ideas? Is it time to jet it down a bit?

Sam

 

If it's a 500, it's designed to run rich. The 50 cc accellerator pump doesn't help either. Changing to a 30 cc pump and jetting it down 4 sizes would be a start. Where'd you set the initial timing at ?

 

Does the 2bbl have a power valve? If so, what is it's number, and what vacuum are you pulling at idle?

 

You didn't mention what Holley you have, what is the list #/ part#? Replacement carb or a factory Ford unit? Was it on the truck before, and did it run OK then? Many Holleys that get picked up at swap meets and such have been played with and can be way out of spec, they usually run very well in stock configuration, double pumpers and such come jetted safe-rich. If it's a factory-type setup, make sure it has the correct jets and such and all adjustments are baselined, floats right, pump at .020 travel left at the end of stroke etc. Power valve would probably be more like an 85 for a stock engine. If it happened to be a 500 (doubtful) just changing the pump itself to the standard 30cc version only changes the volume of fuel available, the actual pump shot is controlled by the pump cam and shooter size. The only reason the big REO pump is needed is when the shooter & cam send more fuel than a 30cc pump holds. IF it had a big pump (doubtful) you could try a smaller shooter and working with the cam without changing the pump- the cam & shooter will still send the same amount of fuel. IF it was a 500 (again, doubtful), you'd probably be better off just switching out to a more pickup-friendly unit or an Autolite 2100 for a stock engine- the 500 was made for spec-class-legal roundy-rounders and would not be the best choice for a DD pickup

 

Thanks for the help! Part of the issue was I was tuning it too lean, getting a lean misfire, and smelling the gas from that. My shop teacher set it up for me today at a much richer setting, runs much better, but it's still got room for improvement.

Initial timing is at 12 degrees. It pulls about 17 inches of vacuum at idle, it's got a #45 powervalve in it. The float is set to spec, no idea what the jets or accelerator pump sizes are.

It's a brand new carb, just bought it 3 months ago. Part # 0-4412-C I had it on my old engine, and the carb was great until a real hard backfire killed the powervalve.


Sam

 

I would definitely get it back up to around a #85 power valve, you're pulling pretty good vacuum, and that 45 doesn't open until the vacuum gets down to 4.5". The lowest vacuum PV I've ever had to use is a #35, and that was with around a .700 lift cam- you shouldn't need a 45

 

The 500 comes with a 50 powervalve, so your 45 is real close. And contrary to what Gene has said, the 500 can be a great carb for a daily driver. I've used three of these carbs on 4-5 different engines (from 302's to 400's) over the past thirty + years. It's one of Holley's better and most reliable carbs. Enjoy.

 

Thread cleaned. You two can take your differences elsewhere, behavior such as this will NOT BE TOLERATED.

A big SORRY to the original poster.

 

Thanks Krewat, don't really want a re-peat of my old thread.

Anyway, I called Holley's tech line today and he confirmed that I need a different powervalve, he recommended a #65. But today I was more concerned with my spark plugs, one was bad and causing a misfire. I decided to just get a whole new set of plugs and now it runs GREAT! I have an electronic ignition kit heading my way too, that should help even more.

Sam