Troubleshooting rough idle at temp?

[Broncofan76]

I was hoping you guys might have some insight into an issue. I have a rough idle at higher temps and only when stopped at stop lights etc. It also is hard to start when warm. It runs great at speed (around town anyway 15-40mph) but once I sit at a light for a few seconds it starts to run rough and if I don't put a foot on the gas and brake at once it will choke out completely and be difficult to start. I attributed my issues to various vacuum leaks that I have now fixed but still having some trouble although it running much better now. Last symptom for now is that it occasionally sputters and wont shut down completely when I turn the key off (ignition advanced too much?)
Some info on the truck:

rebuilt 302, cam, new performer intake/gaskets, new edelbrok1403 carb, no vacuum leaks, trans modulator and ignition advance hooked up correctly, hydroboost brakes, 180 degree thermostat that seems to pop at 180 as it should, truck runs a little on the warm side due to an undersized radiator but never gets over 220 - have replacement on hand but no time yet. I think the problems start around 200-210 degrees but can test some more if this is important.

Any help would be appreciated. And thanks to Phred for the help so far.

 

[blubuckaroo]

I have an Edelbrock 1403 too. When I first got it I struggled with the same issues you described. I called Edelbrock and learned a couple things about this carb. The carb doesn't like heat from the engine. They suggested a thermal isolator gasket under the carb and exhaust heat crossover block off under the intake. Also Edelbrocks are more sensitive to excessive fuel pressure than some of the other brands. Even the pressure of a Carter 4070 was too much for mine and I needed a pressure regulator. I lowered the float level a bit too. These fixes weren't that difficult and outweighed going to another carb. I would suggest that anyone using this carb needs to get the specific tuning kit for it. The are mixture and vacuum control adjustments that are needed for your specific engine and elevation. If you're running it out-of-the-box, you're missing out on really nice carb.

 

[Hubba]

I had the same problems with my Edl. Installed a Mr. Gasket fuel presure reg. and it all went away. about $30.00 at any parts house.

 

[Broncofan76]

That is great news! thanks guys. I am on my second brand new edelbrock (first 1406 and now 1403) and replaced the intake while I was at it results - were about the same.

I checked with my parts store and they have both the insulator as well as the pressure reg waiting for me to pick up tomorrow. I have never installed a fuel pressure regulator before - what is the ideal pressure I'm looking for? looks like some come in a predetermined pressure output while others are adjustable? I guess something with a dial/indicator would be ideal to confirm the pressure? or just get a preset one and go with it?
thanks again.

 

[blubuckaroo]

I would keep it at 4 psi. My Cagle automatic regulator that keeps it at 2 psi then increases to full pressure when the engine vacuum drops.

 

[Hubba]

I run my reg @ 5 psi. works great. I think Edlb. recomends 9psi or less. Some oem pumps can somtimes exceed 14psi.

 

[Lennardlector]

Same issue here. Edel 1403 Vapor lock and fuel pressure issues. Rebuilt, cleaned, recleaned, adjusted floats, needles, etc and still floods periodically. Ended up running new rubber fuel line routed from pump over and behind carb insulated with heat sheath. A little better with hot starts. So I ordered a phenolic spacer as well as the Holley 12-803 regulator (4-9psi) with fittings, summit gauge and reducer. I've researched this to death and talked to a bunch of local classic mustang dudes and they all have this same remedy. Keep it at 5-5.5 and you're good.

Dont get the mr.gasket reg, it has a rubber diaphragm that Bursts almost instantly and you'll spring a leak. Read 1000 reviews on amazon and other sites,
And the guys at my local oreillys say that item is a 100%, as it gets returned 100% of the time. I don't think mr gasket products are all poop, but that item is.

 

[Lennardlector]

Btw, edelbrock 1 inch spacer, Holley reg, (2) 3/8 barb fittings, I summit gauge, and 3/8 to 1/8 reducer ran just over $100 shipped to my door.

 

[Broncofan76]

I did the spacer and the regulator at 5lbs and everything smoothed out considerably! Thanks for the help.
3 carbs (one holley and edl 1406 and now 1403), 2 intake mans. (summit and not edl performer), new gaskets, 2 fuel pumps, fuel lines, fuel filters, etc etc and now finally the issue is fixed with $54? dammit. ha ha. At least I learned how to instal a carb in about 20 mins flat.
thanks for the info guys!