750 cfm Mighty Demon advice

[Greg Haile]

Guys,

Need advice on running a 750 Mighty Demon on the 460 Super Cobra Jet with no choke. Am I going to have trouble starting the engine without a choke? Don't want to ruin a good starter and battery with excessive cranking.

Thanks
Greg

[Chaplin]

It's really not a big deal. I run the same carb on a 428 in a much colder climate than you (NJ). Give the gas pedal 3 or 4 shots, then hold the throttle about 1/3 of the way down and it usually fires right up. Just requires a little bit of feathering the throttle once it starts to keep it going until it warms up.

[Poolw]

I'm running a 950 Holly with no choke because holly model 4150 doesn't come with one. If I was runnning a 750, I would certainly have a electric choke. Like chaplin said, without the choke it requires a little bit of feathering the throttle untill it warms up.

[TKing]

I have a Demon 750 and it requires a bunch of feathering and stalled 4 or 5 times before it would run and even then ran poorly for about 5 minutes.

I installed a manual choke ($39.00 Summit) and it stalls a lot less and there is a lot less stress on the starter. Still runs poorly until warm.

Tom

[scootter]

I had the 1000cfm Holley and just swithed to a 850 Mighty Demon for my 514 with the SCJ head's. I pump the pedal 2 times let my foot off completly, and it fires right up. Then you have to go into the feathering mode right away. My engine never dies on me.Then I sit in the driveway and warm it up a bit and anoy my nieghbors.
Scott

[RedBarchetta]

Originally Posted by scootter

...Then you have to go into the feathering mode right away. My engine never dies on me. Then I sit in the driveway and warm it up a bit and annoy my neighbors.
Scott

Yup, that pretty much sums up the procedure.

-Dean (750 Mighty Demon user and damn proud of it)

[Tony Radford]

I'm running a 750 Mighty Demon and I have no problem starting it under any conditions. I hold the throttle for a 3,500 RPM idle for a minute or two and she does great.

[Greg Haile]

Thanks for the replys. Sounds like the Summit manual choke is the way to go.

[RedBarchetta]

Originally Posted by Tony Radford

I hold the throttle for a 3,500 RPM idle for a minute or two and she does great.

On a cold start-up?!? If your cylinder walls and piston rings could talk, you would hear a sailor's tongue. Tony, in all honesty, if you have to maintain that kind of idle at start-up, you may want to check your idle settings and circuits (or change the procedure). You're only asking for oil control problems and engine longevity issues.

-Dean

[DAVID GAGNARD]

I've got a chokeless Holley on one car and a chokeless Demon on another...........

With the Holley, one good pump on the gas pedal and hit the switch, usually starts right up, then while holding it at about 800-900 rpms, I put it in first or reverse (depends which way I'm parked), let out the clutch and move the car about one good car length, it makes it "pull some vacum", then she idles fine from then on........

With the Demon I DO NOT have to do the moving trick, just fire it up and let her go, today it was in the 40's and the car started right up,first crank and idled just fine from the get go............

David

[rblong]

The summit manual choke works excellent.

[Greg Haile]

Tom and rblong,

The only manual chokes I see on Summit are for Holleys. Got a part number??

Thanks
Greg

[Madmiles442]

With my Demon 750 it starts up right away, but without feathering, it slowly slows down and finally dies. Repeat, repeat, repeat until the engine is slightly warm. Not sure what this means.
I have a manual choke, but once pulled, the return idle goes up from 900 to 1700. Can't find it sticking anywhere.
I'm pulling the choke off this weekend as I'm tired of accidentally pulling it, then needing to reduce the idle on the carb to get it to throttle back down to a decent idle.

[rblong]

I will look tonight - I think it is the same one.

Mine works perfectly - I start by pushing Acc to floor and pulling the choke - this sets it at max choke and idle. Let off gas and hit the starter - starts right up. Once on 5 second or so push the choke in about 1/2. She starts clearing up and idles 2000 or so. Another few minutes and I hit the throttle which allows choke to hit the second idle point on the cam - push the choke all the way in. Now she is idling at about 1500 with all choke off. When she gets to about 1500 I pop the acc again and she is back to regular idle.

Bruce

[TKing]

Hi Greg:

I bought the manual choke for the Demon at Jegs not Summit. I buy parts from both and forget which one. My receipt shows part number 132-421441. I don't know if that number is Demon part number or Jegs. The cost was $36.99. The kit includes almost everything. I had to fadricate 2 small brackets - one to hold cable at the carb and the other for under the dash. You will not need the bracket at the carb if you have vacuum secondaries.

Someone mentioned a sticking choke. The choke linkage extends through the carburator lip which the air cleaner sits on. Kind of odd because there is no way to prevent the linkage from rubbing on the air cleaner. I had to file a notch in the side of my air filter to prevent the linkage from sticking or binding.

Tom

[rblong]

The part # for the choke I bought was from Summit part # GPT-421441 - It required no mods. I fo not see it in the Summit catalog, but I am looking at me receipt - I paid 34.95 on 1/31/05. Here is a link to it - I would call Summit - it is a Barry Grant part and is made for the carb. Hope this helps.
http://vichubbard.com/shop/product.p...0&page=11&js=n


Bruce

[Greg Haile]

Tom, Bruce

THANKS!! Your help is greatly appreciated. Order is on the way.

Greg