wilyesteve
Seaman Apprentice
- Joined
- Mar 10, 2011
- Messages
- 38
Newly rebuilt longblock 5.7, alpha one in 21ft Sea Ray, Rochester 4bbl - manifold choke. New plugs, wires, cap & rotor. Coil "looks" ok, i.e. not leaking.
Engine will have a hard time starting in idle, but will start if you throttle it and then back off... I'm thinking idle jets are clogged... It will idle when it feels like it when cold... But then there are other problems too:
Engine will max out at 3400 rpms with a 19p 4 blade brand new aluminum prop.
I took a temperature reading with a laser and the port exhaust manifold was 180 degrees and the starboard manifold was 145 degrees at idle. After running at 2500 rpm, both sides are more equal in temperature...
I have turned the idle mixture screws all the way in and then 2 turns out and then out further... to no avail...
After running for an hour or so, when going back to the dock, the idle will waver between 1000 and 1400 about once per second. This makes me think vacuum leak, but I have sprayed carb cleaner around the carb base and manifold gasket and see no change in rpm. Could there be an internal leak in the carb?
Summary: Should I spring for a new (reman) carb or is there something else I should be looking at? Since one side is heating up hotter, I'm thinking it's more fuel related than spark. If I do get a new carb, should I stick with the Quadrajet?
Sorry for the length, but I didn't want to forget anything. I have a video of the wavering idle that I can try to post later... Thanks for any help.
Engine will have a hard time starting in idle, but will start if you throttle it and then back off... I'm thinking idle jets are clogged... It will idle when it feels like it when cold... But then there are other problems too:
Engine will max out at 3400 rpms with a 19p 4 blade brand new aluminum prop.
I took a temperature reading with a laser and the port exhaust manifold was 180 degrees and the starboard manifold was 145 degrees at idle. After running at 2500 rpm, both sides are more equal in temperature...
I have turned the idle mixture screws all the way in and then 2 turns out and then out further... to no avail...
After running for an hour or so, when going back to the dock, the idle will waver between 1000 and 1400 about once per second. This makes me think vacuum leak, but I have sprayed carb cleaner around the carb base and manifold gasket and see no change in rpm. Could there be an internal leak in the carb?
Summary: Should I spring for a new (reman) carb or is there something else I should be looking at? Since one side is heating up hotter, I'm thinking it's more fuel related than spark. If I do get a new carb, should I stick with the Quadrajet?
Sorry for the length, but I didn't want to forget anything. I have a video of the wavering idle that I can try to post later... Thanks for any help.