QuestionQUESTION: Howard,
What else do I need to do for my engine to run smooth? I had mention to you before that my engine is running really rough. I did as you said, I took a compression test, as follow from #1 and so on 130, 125, 125, 130 psi I set the timing to factory specs at 2 after TDC then I adjusted the pot on the carb. counterclockwise however, there is no change other then the rpm is now set at 900 and it fluctuates between 900-1100 rpm can you tell me what this all means and what to do next? thank you your help is highly appreciated. also I kept turning the set screw more and more until it wouldn't move anymore but still no change.
Minnie.
ANSWER: A hunting RPM going up and down by itself is normally an indication of a intake air leak somewhere. The test for an air leak is to warm it up an let it idle and while it goes up and down slowly start restricting the air going into the carburetor. If as you slowly start closing off the air supply it at any time smoothes out or speeds up then that is a sure indicator that it is an air leak.
An air leak can be in a vacuum hose or the intake manifold gasket or even the carburetor gasket.
Did you have a rich condition? Is that why you leaned the carburetor out?
Howard
---------- FOLLOW-UP ----------
QUESTION: Howard,
Sorry I meant CLOCKWISE my mistake, I richen the carb, because according to you the plugs indicated a lean condition, no change though. I have a new intake gasket on there already, I have also tighten all and replaced some of the vacuum hoses. I slowly restricted the air on the carb. with my hand and the engine smooth out with the rpm's going high. you said this is an indication of intake leak, the only thing I can think of is the bottom bolts are not tight enough. it is very difficult to get under there with a regular open end wrench, is there any other kind of tool that you would recommend using to get these bolt tight enough? if it isn't the bolts then what else can it be? Thank you
Minnie.
AnswerIf you get the smooth running and faster idle by restricting the air intake, that is a sign you have an intake leak or a vacuum leak in a vacuum hose. So you must start testing to find out what is leaking. Just trying to tighten some bolts is not the procedure. Some mechanics use an oil squirt gun and pump oil on the seams of the intake manifold while idling to search for the leak. Some mechanics use a propane torch to spray raw propane as it gets into areas that oil can't reach. HOWEVER THIS PRACTICE IS DANGEROUS AS THE RAW PROPANE CAN EASILY IGNITE!!!
Also you need to start pinching off all vacuum hoses at idle looking for an RPM change.
Unless you already found the leak and found that the manifold was loose, it is a waste of time tightening bolts. Find the leak first then do what is necessary to correct it.
Howard
