I have a 73 Duster. I runs fine when it is cold, but when it is at operating tempature, it idles rough in gear. I have done a complete tune-up, checked for vacuum leaks, set timming, installed new carb and 2 bbl manifold with new gaskets of course, installed fuel pressure regulator. Like I said, runs fine when it is cold. If I put the car in neutral, it runs fine. Runs great off idle. Anyone have any ideas? The car has done this ever since I have owned it.

ripster1@tampabay.rr.com

Is the heat riser valve free to move?

Orionsax7@cs.com

Spring was broken on heat riser. I do have it in the closed posistion though (counter-clockwise).

Ripster1@tampabay.rr.com

When was the last time you adjusted the valves? If you can't remember the last time they were done, that should be next. Make sure the motor is at operating temp when you do adjust the valves.

bmazur3@home.com

I agree, valve lash set on the tight side will cause a rough idle when the engine is hot.
DD

Sounds like what was going on with my 73 Scamp when I got it a couple of years ago. When looking for vacuum leaks I discovered a plugged vacuum line. Someone had stuck a fuse in there and when they removed it the steel end stayed behind. the friend who I got the car froms said it had been running like that for years.


ejones@seanet.com

Yes I did adjust the valves. Made sure the engine was good and heated. .10 on intake, .20 on exhuast.I cured alot of my problem. The car was my 94 year old Granmothers. She passed away in Dec and left the car to me. It sat for 5 years. I had to replace the fuel tank. It was full of rust. Blew out the fuel lines. Installed a 2 bbl intake, Brand new Holley 2300 series 350 cfm 2bbl...sweet! I also rerouted fuel line from fuel pump, installed fuel pressure regulator. But you know what, I never thought about changing the fuel pump. It had to be full of crap too. The fuel filter never had been all the way full before. Should have known, thought it was vapor locking. 80% of my rough idle is gone. The engine has 84,000 easy miles. All original except for the few engine modifications. Is .10 on the intake too tight? What kind of fuel pressure should I be running? My pressure regulator only goes to 5 1/2 lbs but the carb seems to be maintaining good fuel level. This car is really starting to run sweet. Next up killer exhaust, ignition upgrade, and that is it on the engine until I wear it out. Then will do total rebuild.

ripster1@tampabay.rr.com