Low rough Idle
Thread Starter
Advanced
Joined: Sep 2005
Posts: 93
Likes: 0
From: Everett WA
Low rough Idle
recently I've noticed the rpms on my '78 at idle have been dropping I'm now idling at 500 rpm and its very rough at idle. I've also had problems with the car stalling when it is restart hot. Car runs great once it gets moving.
My guess is a carb problem. I'm from a different generation of gear heads and I've never actually used a carb before. Give me a fuel injector any day. I was also considering the timeing could be off but everything is tight so I don't see how it could have slipped.
Any suggestions?
My guess is a carb problem. I'm from a different generation of gear heads and I've never actually used a carb before. Give me a fuel injector any day. I was also considering the timeing could be off but everything is tight so I don't see how it could have slipped.
Any suggestions?
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
If you've never worked with a carburetor before you will need get a manual so you can learn the names of the parts.
As far as the idle problem goes, the first thing you will need to do is check the ignition timing. The stock initial advance is probably something like 8 degrees BTDC. The engine will idle smother and have better throttle response if you raise this up to 12 degrees.
Generally a rough idle can be cured with the idle mixture screws. With the engine off turn the idle mixture screws in and gently seat them, counting the number of turns. Now turn them back out to where they were and start the engine. If you counted a different number of turns on the screws (say one was 2 turns and one was 3 turns) back both screws out 3 turns. You always want to move these two screws the same number of turns so that you keep both sides of the engine even.
Now, with the engine up to operating temperature, back each screw out 1/4 of a turn at a time until the engine RPM stops going up. Once you reach this point turn each screw back in 1/8 to 1/4 turn. You will notice the RPM will go down slightly. This is a good clean idle. Use the idle speed screw to set the idle speed at whatever you want (say, 600 RPM in gear).
You're done, for now.
BigBlockk
Later.....
As far as the idle problem goes, the first thing you will need to do is check the ignition timing. The stock initial advance is probably something like 8 degrees BTDC. The engine will idle smother and have better throttle response if you raise this up to 12 degrees.
Generally a rough idle can be cured with the idle mixture screws. With the engine off turn the idle mixture screws in and gently seat them, counting the number of turns. Now turn them back out to where they were and start the engine. If you counted a different number of turns on the screws (say one was 2 turns and one was 3 turns) back both screws out 3 turns. You always want to move these two screws the same number of turns so that you keep both sides of the engine even.
Now, with the engine up to operating temperature, back each screw out 1/4 of a turn at a time until the engine RPM stops going up. Once you reach this point turn each screw back in 1/8 to 1/4 turn. You will notice the RPM will go down slightly. This is a good clean idle. Use the idle speed screw to set the idle speed at whatever you want (say, 600 RPM in gear).
You're done, for now.
BigBlockk
Later.....
