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When temps are below say 50, do you have issues with keeping it running till it warms up?
 

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Yup. Have to babysit it for a good 3-5 min. I have a 750 double pumper that I switched over to a Proform center section and it got a little better. My friend has a 650 Demon with no choke on his 69 camaro and he can turn the key and walk away on cold mornings. Makes me mad
Yup, me too... Thats why I was asking to see if I was in the norm. I would bet your buddies 69 Camaro is running rich...:D
 

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When temps are below say 50, do you have issues with keeping it running till it warms up?
Yup. Have to babysit it for a good 3-5 min. I have a 750 double pumper that I switched over to a Proform center section and it got a little better. My friend has a 650 Demon with no choke on his 69 camaro and he can turn the key and walk away on cold mornings. Makes me mad
Hi ya Slick!:rolleyes:.... Lugnut79 is spot on........common problem with chokeless carbs in cold weather warm up...

other factors in factory carbed engines in cold weather warm up that are lacking in the Hotrods of today are..

blocked or no heat cross over in the intake, heat stove off the exhaust manifold(thermactor), high idle step(choke related), or solenoid...
 

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Yup. Have to babysit it for a good 3-5 min. I have a 750 double pumper that I switched over to a Proform center section and it got a little better. My friend has a 650 Demon with no choke on his 69 camaro and he can turn the key and walk away on cold mornings. Makes me mad
Ditto! My 750 also has the Proform main body and a also have the heat crossover passage blocked.



I just have to sit they a few minutes with my foot on the throttle. I keep it around 1500 rpm for about a minute and then drop it to 1000 rpm for another minute or two. By then it will idle on it's own.
 

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Ditto! My 750 also has the Proform main body and a also have the heat crossover passage blocked.



I just have to sit they a few minutes with my foot on the throttle. I keep it around 1500 rpm for about a minute and then drop it to 1000 rpm for another minute or two. By then it will idle on it's own.
Hey, so what do you think of that proform body? Alot of other forums I read people say that thing is Chinese junk and there trying to copy Demon. I'm thinking about buying one for my 3110-6
 

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Yup, me too... Thats why I was asking to see if I was in the norm. I would bet your buddies 69 Camaro is running rich...:D
You nailed that one! BG are know to be rich.

Unless your looking for full out performance the removal of the choke horn or main body change compared to the ease of operation on the street is not a good trade.

On a vehicle driven on the street it can not be measured. (traction)
If the best Et at the track is your most important thing then the change will show improvement.

My engine is cold natured even when it's 100° out side!:rolleyes: Nature of the beast!

Al
 

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And when it comes to Pro Form!

If you have a 750/850 Double Pumper your better choice is the Holley center section and the same money. Same part used on HP series Holley

Holley # 134-300S or C

IMO
AL
 

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Discussion Starter #9
You nailed that one! BG are know to be rich.

Unless your looking for full out performance the removal of the choke horn or main body change compared to the ease of operation on the street is not a good trade.

On a vehicle driven on the street it can not be measured. (traction)
If the best Et at the track is your most important thing then the change will show improvement.

My engine is cold natured even when it's 100° out side!:rolleyes: Nature of the beast!

Al
My 72 is not going to see much track time. I think I made a bad choice going to a carb like this. I will say it performs very well other then when its cold below 50 deg :rolleyes: I guess I'll just deal with it..
 

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Hey, so what do you think of that proform body? Alot of other forums I read people say that thing is Chinese junk and there trying to copy Demon. I'm thinking about buying one for my 3110-6

Trying to copy Demon?

lol

Who do you think Demon copied?

By the way, all of the Chinese car parts are cheap "copies" of something. The fact that they are cheaper is why people buy them.
 

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Hey, so what do you think of that proform body? Alot of other forums I read people say that thing is Chinese junk and there trying to copy Demon. I'm thinking about buying one for my 3110-6
Quick fuel makes the bodys for proform, if you dont belive me call them and ask. So I would say they are not chinese junk since they are made right here in the USA in Bowling Green Kentucky!:yes:
 

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The 750 Proform DP I have is by far the best carb I've ever owned. No problems, runs great.

Kev
 

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I am running 750 DPumper with a performer intake here in Montana and in the spring it can be chilly in the morn. I sit and idle up so I can back it out of the driveway and then idle it down the road till it will idle on its own. dosen't needmuch persuation but it is the nature of the BEAST:yes:
I guess if you don't like it you could go with an electric choke.
 

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I had a Holley 650 dp with the choke horn but no choke and had no problems when cold.
I just went to a Holley 750HP (no horn) vacuum secondaries and it takes a while before I can back it out of the drive even. My 650 was jetted rich maybe thats the difference.
 

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On my Firebird I ran a 750 Holley that I litterally cut the choke tower off of. It turned out that with my drop based air cleaner, the lid was getting to close to the top of the choke tower and choking the engine when I put it on, so I got out the hack saw, pulled the carb, and cut it off at the track. I don't recommend doing it this way, but I did it in a pinch. I had to use this car for about 6 months as my daily driver in teh winter (ET Street's and all). With 11.5 compression, a huge cam, and 412 cubes, I'd fire it (it always started right away with 3 pumps of the gas), would hold the throttle at 2000rpm for a minute, then it was fine. It probably helped that it idled at 1200rpm. Now when I put this carb on my mom's 350, it takes like 3-4 minutes of feathering the throttle to get it to idle, but that engine idles at 850rpm. I guess it's just the nature of the engine.

As a side note, I've used a few Proform main bodies with very good results. Had nothing but issues with Demon's.
 

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funny thing about this. Got me thinking. On my stock 350 engine with 268 cam and performer and 750 vac sec it would idle cold. When I put the same carb on my LT-1 it idled but wanted to die till it got alittle temp. Same carb on my junk 350 would have warm it up in the morning for about 3-5 mins.
But my 406 with compression and roller cam and single plane intake with an 850 it would idle cold. Hell even my dual 660's on my tunnel ram on my 406 idled cold. I just redid a carb for a guy with a 400 and with a 750 proform body and it won't idle till it gets some temp. I don't know...I know engines need more fuel when cold, ergo the choke to cut off the air supply. Some chokeless carbs I've seen idle cold and some don't Maybe it has to do with the manifold crossover and having iron heads vs alum?

I say if ya can't hold your throttle at 15-1800 for 5 mins then get a choke. Your engine will like you better when its warmed up.
 

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Discussion Starter #18
I would be willing to bet that any engine that idles fine at 800 or so cold (with no choke horn), that carb is running rich. Side note, I'm running a proform base on my 650 and if I ever thought about changing the main body, I would try a proform.


Now a question, other then getting a main body with no choke horn, whats the reason to switching from the Holley main body to the proform?
 

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If the idle circuit is fat enough to let the car idle without a choke when cold then it's pig rich when the engine is warm-period. I've seen a few 750 double pumpers that acted that way.
 

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