After freezing my butt off and many cold weather miles driven I finally solved my Holley's cold weather choke problem. The Holley electric chokes work adequately in cool weather but fail miserably in sub 30 degree weather because of a design flaw. The in-rushing air that pulls the choke pull-off piston down to partially open the choke butterfly cools the coiled spring that is supposed to get hot and open the choke butterfly. So the in-rushing air was offsetting the effect of the choke cap's heating element; a self defeating design.

I ended up scrapping the 20 foot coiled copper tubing/exhaust pipe idea because the heated air lost it's heat because of the distance involved; the heat being absorbed by the long 2-1/2 foot length of rubber hose going to the choke housing. By o-ringing the pull-off piston it now completely seals vacuum; making the fresh air port unneeded and supplying enough force to open the choke butterfly regardless of the coiled spring's tension. And by backing off the piston stop screw 3 turns the piston will now pull the choke butterfly ALL the way open and keep it open as long as the engine is running. Problem solved !!!

Below are three pictures; the 1st showing the fresh air inlet window that directs the outside COLD air against the heated coiled spring, the 2nd showing my modified piston that uses two silicon A/C o-rings, and the 3rd showing the piston stop screw.

 

So it works OK down to -30F+. That's pretty darn good, where the heil does it go down to -30F and who is driving a Corvette or any other sports car that has a Holley on it at that temperature ?

 

I know where it get's to 30 below F. I have a picture of the bank sign in Gallup New Mexico -34 Or the trip down on the Al-Can highway near White Horse Canada and our diesel motor stopped because our - 30 diesel jelled up. A truck came by and had this - 50 additive and we jumped the block heater for about 2 hours before firing it up.


As for driving my Vette it has seen something right above "Zero" F and the central located windshield defrost is pretty poor about keeping ice off the inside of the wind shield

Now that I'm older my vette is up on blocks letting the springs relax until it's warm again! Happy new year

 

How is the cold start with this "fix"?
It would seem to me that the choke being forced open would simply defeat it.
At -30°F startup, I would want the choke to function.

 

Ever been out in -30F or -30C ?(about the same), the last thing you would be doing is starting your Vette. You 'd be hiding inside. Gets that cold here where I live in Canada but I can't remember the last time it was near that cold.

 

I inferred in my first read that he meant -30°F.
After re-reading TBTR's original post, I think he means < +30°F.

Regardless of plus or minus, it still looks like the choke is defeated once the engine starts.

Living in the Deep South, I can't wrap my head around coping with - 30° to -40° temperatures on a regular basis.

 

That looks like a reasonable fix, but have you discussed this issue with anyone at Holley? It's hard to imagine they're not aware of it. It would be interesting to hear their take on the problem.

 

Uh, you misread what I wrote. I said sub 30 degrees; meaning below 30 degrees; not 30 below zero. During my testing I was driving in temperatures of between 20 to 30 degrees.

 

My engine will instantly start and fast idle at 1500 rpm and THEN the butterfly is pulled open............a delay of about 2 seconds because it takes a moment for vacuum to build in the cavernous Air Gap intake manifold. Vacuum would build quicker in a stock short-runner manifold with a minimal plenum volume.

And I wasn't testing in 30 degree below zero weather but rather at sub 30 degree weather; about 50 degrees difference.

 

(EDIT: personal remark removed) I'll repeat the ongoing problem I was dealing with:

1. In 30 to 40 degree weather my choke worked perfectly; instant starting and my choke coming off within 5 minutes and staying off.

2. But when I encountered 20 to 30 degree weather my choke would come off normally WITH MY HOOD OPEN. But when I began driving it my heated choke cap would get cooled off so much my choke would reset itself and then my plugs would get fouled with soot.

So I suspected it was my ram air and 7-blade severe duty clutch fan that was affecting my heated choke cap; cooling it to the point of resetting my choke as I was driving it. So far my modified choke housing is working perfectly as it'll start and fast idle at 1500 rpm almost instantly and with the butterfly being pulled completely open within about 2 seconds of starting.

 

I have a couple of questions.

(1) Why would you drive around with your hood open in cold weather?

(2)How is the choke still working if the butterfly is being pulled open within 2 seconds of starting?

It's all a little confusing for us Old timers.

 

I have a couple of questions.

(1) Why would you drive around with your hood open in cold weather?

(2)How is the choke still working if the butterfly is being pulled open within 2 seconds of starting?

It's all a little confusing for us Old timers.[/QUOTE]


1. I said my choke worked perfectly as long as my hood was open IN MY GARAGE. But when I closed my hood and took it for a chilly drive my choke would reset itself.

2. The purpose of the choke butterfly is to help the engine start. Once the engine is running at 1500 rpm there is no need for a choke.

 

Steve, back in my youth, when I drove a small block Ford as a daily driver and regularly saw sub-30 degree weather in the winters of the north-east, I remember that Ford had a shield that was installed in front of the choke coil.

Even though it was not an electric choke, I never remember having issues with the choke not operating correctly. I also remember that they ran one of the heater hoses across the face of the choke coil (you can see it in the heat shield above) that no-doubt aided in warming the coil as well as keeping it warm as cold air entered the engine compartment.

Is it possible that Ford did have a better idea?

Good luck and thanks for the update... GUSTO

 

The motor will need some choke for as long as it takes for the engine to warm up. I have never had a carbureted vehicle that didn't need the choke to gradually open as it warms up. Pulling the choke open within two seconds of the motor starting is essentially defeating its purpose. Happy motoring!

 

So far I haven't had any trouble because when it starts it immediately goes up to 1500 rpm and stays there until I kick it down.

The purpose of the choke is to provide a momentary rich mixture to help the cold engine start and I think its the rather high 1500 rpm that makes any further choking unnecessary. As my Air Gap has a cavernous plenum and runners it takes a couple of seconds to build up enough vacuum to operate my choke pull off piston. If I feel the choke is getting pulled open too early I'll just restrict the hose that feeds the piston. I have drill bits down to .014" (#80) so I can plug one end of the 3/16" steel nipple and then drill the plug to .014".

None of this happened UNTIL I converted my hood to ram air so that's why I suspect its being caused by the ram air and/or fan wash during very cold weather only. Above 30-35 degrees I didn't have any problem.

Happy motoring................

 

I remember those 2 and 4 barrel AutoLite carburetors that used the shield and heater hose heat to keep the choke cap hot. It really helped to prevent the engine going back to a fast idle upon re-start.

 

Right, but if YOU did that, you'd never hear the end of it on this forum.

 

Maybe you should post your finding over at the Holley forums. http://forums.holley.com/forum.php
I am sure they would be happy to know that you fixed the problem with their carburetors. You should also patent your findings before they find out what you did and steal your idea.

 

They weren't electric chokes, so umm, different operating principal. Happy motoring!

 

I never use a choke even when I lived in the D.C area.double pumper carb ( that should never be used on a street car) 2 pumps car fires hold the throttle above idle a short time and off I went.