Thread: More Edelbrock Hot Hard Starting Problems

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Sorry for such a long post. I'll keep it as short as I can. I've got at fresh rebuilt 327 with PBM Thunder heads (World Products S/R), Performer intake, and an Edelbrock 1405 600cfm carb. I'm running an L79 pcv system. The engine runs great but I've got the typical problem that many others have with the car not wanting to start after getting it hot and trying to crank it after sitting for 10 or 15 minutes. Of course it's flooding due to boiling fuel. I've tried one of their 1/2" wooden spacers, then a 1" phenolic spacer, and now one of their insulator gaskets but without spacers. Nothing has worked so far. When it does this the only way to crank it is to mash the pedal to the floor to clear it out. If you have just drove it about 30 or 40 miles on a hot day like today it's really bad. I like the carb and it does great other than this. Good acceleration and plenty of kick but I've got to do something. I didn't put the block off plates in the intake gaskets when I put the motor together, which I know would help but at one time I thought I was going to run a Quadrajet that I have so I would need those unblocked for the choke unit in the intake. I really hate to have to pull the intake to do this since I'll have to get the a/c compressor out of the way and take the bracket off to do it and I'm not sure that would cure it. I understand part of it is the Ethanol in the gas we use these days. I would change carbs and go with a Holley Street Avenger or send my Quadrajet off for rebuild and tuning by Sean Murphy if I knew they wouldn't have the problem. Can anyone here that's had this issue tell me if they switched to a Holley or Quadrajet and cured this problem? Is a Quadrajet prone to suffer from this? I've never heard of them having these issues but I don't know. I see so many Edelbrocks at car shows I go to as I did today. I saw a bunch of them and 90% of them had no spacer or insulator gasket. I like them and they are easy to work on but I've had it. Any ideas, opinions, or suggestions are welcome.

its not the carb... it is heat ....try a alum heat sheild under the carb and use a wood or phenolic . make sure your only making 5 psi with the pump. check floats maybe to hi set them abit lower. check fuel lines that are away from heat source

Originally Posted by pat mccarthy

its not the carb... it is heat ....try a alum heat sheild under the carb and use a wood or phenolic . make sure your only making 5 psi with the pump. check floats maybe to hi set them abit lower. check fuel lines that are away from heat source

I'm running a stock fuel pump and I have the fuel filter away from the engine I'm using a rubber line. I took the carb apart earlier this week and checked the float levels. The book says 7/16" between the top of float and top of carb and 15/16" to 1" drop. They measure 7/16" and 15/16" drop so you are saying I can have them drop lower and it might help? Thanks for the suggestions.

Originally Posted by tidefan66

I'm running a stock fuel pump and I have the fuel filter away from the engine I'm using a rubber line. I took the carb apart earlier this week and checked the float levels. The book says 7/16" between the top of float and top of carb and 15/16" to 1" drop. They measure 7/16" and 15/16" drop so you are saying I can have them drop lower and it might help? Thanks for the suggestions.

try it if it will not help set them back to stock spec is the carb flooding when hot car stops running or just not restart after getting hot ? what is hot ? what is your temp?

Restarting after sitting for 10 or 15 minutes and temperature is 180 down the road, 190 at idle or in traffic. Less if weather is cooler. I have a 4 row brass/copper radiator, high flow water pump, clutch fan and radiator shroud.

Originally Posted by tidefan66

I'm running a stock fuel pump and I have the fuel filter away from the engine I'm using a rubber line. I took the carb apart earlier this week and checked the float levels. The book says 7/16" between the top of float and top of carb and 15/16" to 1" drop. They measure 7/16" and 15/16" drop so you are saying I can have them drop lower and it might help? Thanks for the suggestions.

Tidefan66,
When Pat says to drop the level a bit he's referring to the top of float/top of carb measurement (7/16") not your drop measurement. That TOF/TOC sets the fuel level in the bowl, and the idea is that a slightly reduced level might help. What vehicle is this in? Wonder if you've done anything that's trapping the heat under the hood with no place to go? Just a thought... I believe the insulating spacer beneath the carb is a good thing to keep, and if you can find an area station that does not add ethanol it would be a good test of that theory to run the tank nearly dry, then add five gallons or so of known good gas. One other thought, a friend told me a few days ago that he notices a big difference in starting by adding the prescribed amount of STABIL to his gas, even in hot weather - can't swear to that, but might be worth a try?

Originally Posted by rspears

Tidefan66,
When Pat says to drop the level a bit he's referring to the top of float/top of carb measurement (7/16") not your drop measurement. That TOF/TOC sets the fuel level in the bowl, and the idea is that a slightly reduced level might help. What vehicle is this in? Wonder if you've done anything that's trapping the heat under the hood with no place to go? Just a thought... I believe the insulating spacer beneath the carb is a good thing to keep, and if you can find an area station that does not add ethanol it would be a good test of that theory to run the tank nearly dry, then add five gallons or so of known good gas. One other thought, a friend told me a few days ago that he notices a big difference in starting by adding the prescribed amount of STABIL to his gas, even in hot weather - can't swear to that, but might be worth a try?

It's in a 66 Chevy II. I had a 350 in it with the same carb but over the winter I built this 327 since that's what I wanted in the first place. I had some hard starting issues when the carb was on that engine but I put a 1/2" wood spacer between the carb and intake and it solved the problem. It's been so long since I built the 350 but I may have put the block off plates in the intake gaskets on that one. I'm sure it would help but it's a lot of trouble to take the intake off. I'll drop the float level a little and I may put the 1/2" spacer on top of the insulator gasket as well. I would like to keep this carb if possible but if I was pretty sure a Holley or Quadrajet would work better I would swap in a second. We do have some stations here and there that sell non ethanol gas so I may try that. I'm thinking the Quadrajet is a way to go since they originally worked with the passage open under the intake on count of the choke. Stabil might be worth a shot too. I know I'm tired of working on it. I like to work on these old cars but I don't like having to deal with the same problem over and over. Right now I just want to enjoy it.

When your talking about it starting hard, is your starter turning the motor over easy? Heat shield between the starter and block. I had that issue before.

Originally Posted by Trjohn57

When your talking about it starting hard, is your starter turning the motor over easy? Heat shield between the starter and block. I had that issue before.

Yes it is. It's a mini starter.

I changed the float level from 7/16" to 1/2" but now it doesn't want to idle at all or run very good. Did I go too much or the wrong way?

Originally Posted by tidefan66

I changed the float level from 7/16" to 1/2" but now it doesn't want to idle at all or run very good. Did I go too much or the wrong way?

You went the right way, increasing the delta which drops the level. However, the float level is what establishes the static head on the jets, and it sounds like your engine is very sensitive to that static head. You might be able to rejet the mains and adjust your idle mixture to account for the lower level, but it's going to be some hassles. If it were mine I would put it back at 7/16" and chase the heat problem. Do you have room to put on a metal heat shield beneath the carb that extends out and up from the manifold to reflect the heat away from the carb body?

Well I'm ready to chunk the Edelbrock. I just don't know whether to have my Quadrajet rebuilt and tuned or buy a Street Avenger. Any thoughts?

Buy the Holley. Had the same problems. To much heat under the hood. Motor to hot. The Holley works fine. Gave the edelbrock to a guy with a 289 in a T-Bucket and it works fine.

i`ve had 750 holleys on everything from 289`s to 460`s .. worked well on all .. i`ve an edlebrock on my V6 pinto now .. it is hard to start when hot also .. you remember old chryslers had vapor lock and hard start problems years ago with the afb carbs ..

well thats funny i have afbs on some blower cars and they do run warm allways start up