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Discussion Starter #1
Greetings,

I have learned allot about setting up a new carb and adjusting to a degree but I'm still quite new at this. I've made several adjustments in the warmer months to great benefit. But now we are heading into late fall and hitting high 40's and low 50s in Maryland and Northern Virginia. What are you supposed to do to the carb as temps drop?

68' Coupe 302 V8 with a Holley 4160 (600 CFM) + electric choke. Forced to run on 10% ethanol gas. Usually use premium but it runs just as well on regular. 302 is a 74' 302 so not seriously high compression but it's recently rebuilt w/about 1000 miles on it.

Startup is getting more and more difficult when she is dead cold. Seems to run rough and light puffs of black sooty smoke for about the 1st 30 seconds but then starts humming perfectly after she gets going. Once warmed up it's very easy to restart and runs pretty well. But starting to notice some hesitation as temps plummet when I step on gas even warm.

To date I've learned to watch the vaccum guage I bought and get it running nicely when adusting mixture screw, by guage, feel and ear. Usually pulls about 15-16 hg of vaccuum when running happily. I've been able to adjust both idling screws on both sides but have no clue which way to go with them in colder temps. I brought the cold idle cam down a bit after I put her together this summer because startup was ridiculously high RPMs. Now it's idling high enough at startup but not crazy high. Kicks down quickly, then after 3-5 min kicks to idle in 50-60 deg temps.

Jonathan
 

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If you adjusted your choke for summer time, you will probably have to adjust it again for winter. But then leave it that way.

Long ago my dad taught me to pump the gas pedal twice while cranking. That technique has never failed me.
 

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I ‘be found that with that carb, you need to lean out the choke for winter use. Take off air cleaner, Open throttle enough to set choke. (about 1/4 way down and release. Choke flap should just barely close (no pressure). Now start car and test.
I find that at a summer setting, on a very cold day the choke will start to close during driving,due to underhood temps.being cooler, maybe 1/4 way and raise your idle.
 

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Discussion Starter #4
Thanks for the info guys. So I watched a Holley video on how to move the choke housing on an e-choke and looked at it today. There are 3 screws to loosen and I can't get the bottom one until I'm at my garage. But it's already pulled back 2 notches from the center line (must have come that way) and can go back about 3 more. I'll play with moving it back one notch at a time and look at the choke position itself.

I made a video this morning when it was cold. This is typically how it runs cold for about 30-60 sec. I think this morning was high 30's or low 40s. It usually catches on the first crank but sometimes takes two....and one pedal punch before startup.


Looks like it's running pretty rich? Or is this normal? So the cam needs to go left to lean it out. I've heard some people say that 600 cfm is a bit large for a stocker 302. But it runs nicely and idles well when warmed up and has pretty descent power without falling on itself during mild or heavy acceleration.
 

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Definitely sounds like there is probably to much choke. in fact, a lot of too much. Back it off two notches at a time and let it get stone cold again before you try it. Remeber the total notches you back off so you can have a good starting point in the spring. My Edelbrock 1403 manual indicates that you will probably need to fool with it with the change of seasons. Maybe it is DST that does it!
 

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Discussion Starter #6
Definitely sounds like there is probably to much choke. in fact, a lot of too much. Back it off two notches at a time and let it get stone cold again before you try it. Remeber the total notches you back off so you can have a good starting point in the spring. My Edelbrock 1403 manual indicates that you will probably need to fool with it with the change of seasons. Maybe it is DST that does it!

When you say too much choke are you refering to it closing or opening too much? In this case it's shutting almost all the way. I ran it today. Fuel isn't getting enough air so it's not burning well. It improves quickly as the electric choke starts heating and opening it after 30-60 seconds. I moved it with my fingers just slightly opening it and things improved. I'd have thrown it a few notches forward but there is one adjustment screw on the bottom I can't reach with a phillips driver. It's too close to the valve cover. I guess it'll have to wait until it's in the garage 30 miles away on Wednesday.
 

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b17.jpg
I go from the beach to blizzards and have never had to even tweak my 4100. 400,000+ miles and once it's set, I drive all over the US from FL-Montana-Maine-California. Same carb since 1990.
DSC02388.JPG
 

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Did you buy the carb with the choke installed or did you fit it yourself?
 

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When you say too much choke are you refering to it closing or opening too much? In this case it's shutting almost all the way. I ran it today. Fuel isn't getting enough air so it's not burning well. It improves quickly as the electric choke starts heating and opening it after 30-60 seconds. I moved it with my fingers just slightly opening it and things improved. I'd have thrown it a few notches forward but there is one adjustment screw on the bottom I can't reach with a phillips driver. It's too close to the valve cover. I guess it'll have to wait until it's in the garage 30 miles away on Wednesday.
When I said too much choke I did mean that it was too far closed. Your test of opening it some with your finger proves that. Find an offset Philips head screw driver and go to work
 

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Did you buy the carb with the choke installed or did you fit it yourself?
The reason I asked was that Holley electric choke units DO have a vacuum operated unloader that pops the choke plate open immediately upon receiving a manifold vacuum signal. If this wasn't connected properly then the choke plate will remain shut and the engine will flood (chug and blow black smoke) until heat starts the choke moving. The unloader is operated by a piston and cylinder cast into the choke unit base.
 

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View attachment 736394 I go from the beach to blizzards and have never had to even tweak my 4100. 400,000+ miles and once it's set, I drive all over the US from FL-Montana-Maine-California. Same carb since 1990. View attachment 736395
I think the original carb chokes with the thermostatic spring and heat tube from the exhaust manifold were actually a little bit better with the wide temp swings between summer and winter. At least from my experience. My current car is the first classic car I have owned with an electric choke. Does not really matter to me as I have to put them away for the winter.
 

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Discussion Starter #13
Hey @Woodchuck, the carb came with the electric choke. I don't see any vacuum port on it so i'm guessing it's going to be internal if anything? This was a brand new Holley 4160 and it's been in operation only since April 2019. I'm getting 16-18 hg of vacuum on the manifold so vacuum isn't a problem. It has a full vacuum port I use for the transmission and a ported vacuum that can be used for the distributor. Also the big PCV line is correctly hooked up at the back and clamped down to eliminate any vacuum leaks.

@ 2nd 66 this carb hasn't been around long enough for ethanol to mess it up. I will also be starting it regularly even through the winter. One would think a Holley carb made in 2018-19 would account for 10% ethanol, but getting Ethanol free gas isn't an option in Alexandria, VA or the DC area in general. We have 10%. I've heard premium has less of it but I don't know if that's true.

I did however drain my tank this weekend and replaced the ancient petrified rubber lines under the chassis with 30R7 synthetic rubber fuel line that is built to withstand the ethanol long term.
 

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on my 2100 i adjusted the dial to find a happy medium in winter and then in summer and just split the difference

IIRC im at 3 rich.
I never had to touch it again
 

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Discussion Starter #15
Guys wanted to thank you for all the helpful replies. Got a side screwdriver tool (Harbor Freight rocks) and put the choke from two notches back to two notches forward.
Without a shadow of a doubt it’s starting easier and running clean and smooth on cold startup! A little carb know how goes a long way.

I noticed you don’t see the visible choke plate open up while making the adjustment but it definitely made a big impact on its position when running and the fast idle cam is in place ?
 

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We've gotten so spoiled by modern cars -- turn the key, it starts and is ready to drive instantly. I drove carbureted cars for the first few decades of driving, becuase that's really all there were. Push the gas pedal to the floor to set the choke. Depending on the car and the weather, either hold halfway down while cranking or pump it partway a couple of times -- whatever that particular car likes. Then once it starts, let it warm up for a while before driving. It takes a few seconds in summer, at least a few minutes in winter. And even then, if the weather is cold it's going to balk or stumble a little, probably blow a puff of smoke occasionally, until it's really warmed up. Just part of driving a carbureted vehicle. Back when they were ALL carbureted, even high school girls could master it.

I had one or two cars that liked a slightly different choke setting in winter than they needed in summer. I also found that just setting the choke for good winter starts and leaving it that way, worked year round.
 

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Discussion Starter #18
Yes, exactly why I own a Mustang again. My Audi is awesome. Crazy horsepower, handling and pretty reliable with low maintenance, luxurious. But it's too easy. There is no challenge in owning it. Enter the Mustang. Every time I get somewhere that and didn't have a leak, or a scary moment I have this huge wave of relief and pride in the crap that I built myself is holding up. If I do I'm increasingly knowing how to fix it on the spot. I love the sounds, the smells too. I'm sure we'll remember these things just like you remember the teenage girls mastering chokes and carbs :p when electric cars rule the streets.
 

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I kind of like having a manual choke, real-time adjustments are easy, with no wondering if your choke is open or closed :)
There are those times you forget and leave it on though ...
 

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Y'all are crazy for "preferring" carburetors...there's no upside compared to EFI other than it's fun :)
 
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