Gentlemen,

I have a rebuilt stock 455 and I have a 650 Edelbrock on it and as long as it's not hot outside my carb runs great but when it's hot the carb seems to choke up and doesn't run well like a 455 should. Everyone I speak to says I need a new carb some suggesting a 650 holley while others are suggesting a 750 carb(which sounds like too much IMO). Any suggestions? Will a new carb fix my problem? Is a 650 too small or is a 750 too much? Let me know your thoughts... Thanks

 

Could you describe a little more by what you mean by 'choke up'?

And when does it happen? Like, idling? Wide open throttle? Low RPMs or High?

 

Not sure about your problem but IMO a 750 vacuum secondary would be right for a stock 455.
I have a 670 on my 355.

 

For instance, if I get out on the road and open it up on the street and then I come to a light or I'm just cruising afterwards, it wants to cut off like it's not getting the proper gas. As long as the engine hasn't warmed up then the car runs like a champ but if the temp gets up to about 190° or higher it doesn't drive the same. Am I making sense?

 

I also had a guy who has a 70 challenger and he said he was having the same problem and he made a make shift cold air intake because he said the problem was when he would hit the gas that the carb would suck in the heat from the headers. Any thoughts on this idea?

 

Yeah, that makes sense. Have you taken the air cleaner off while it's warm? Is the choke all the way open?

 

Well, the first thought is that neither your Olds nor the Challenger had this problem when they were new, and they didn't need makeshift stuff to run right. Second, 650 is definitely too small for a 455.

Resist the "advice" to hit this car with a Holley stick. You'll find the Holley is a great carb for wide open throttle racing, but not so much for daily street use. My personal preference for all around street driving is a properly set up Qjet. You find that people who don't have the skill or patience to properly understand and adjust a Qjet are the ones suggesting the use of a Holley. My second choice would be a properly sized Ebrock. Others here recommend the Demon but I have no personal experience with them.

 

Interesting you said that because when I had my QJet on my previous motor I didn't have this problem but every since I got the electric choke 650 Edelbrock it has not run properly and I refuse to even proceed with the rest of the build on this car until I get it running properly... Thanks for the info & reminder