- Joined
- Dec 20, 2007
- Threads
- 127
- Messages
- 1,070
- Location
- Orcas Island in NW Washington State
- Website
- www.mtpickettwoodworking.com
'79 2f , '77 aisan carb, compression 160-170 vacuum 19. I started out last year with a Chinacarb. It ran very well in all respects, until one day it didn't. Instead of investigating I had a '77 carb I found in my attic and had had intended to send to one of the guys here to rebuild. I decided to bolt it on as is and it started and ran flawlessly. Great power on the hills and a silky smooth idle, literally like a watch. This perfection lasted almost a month til about four days ago when I was loading some tools in the back to go to a jobsite. The perfect idle suddenly went really rough and then engine died. It restarted fine and would idle, but not well with the choke knob out about 3/8" . Carb cleaner at the carb base showed some increase in rpms. Idle mixture screw did nothing, even seated. I surfaced the manifolds last year and used a remflex gasket. Tank is new 17 gal aluminum fuel cell with inline filter. Fuel pump new oem. Checked all vacuum hoses which are Mcmaster carr silicone. Fuel level in sight glass right on 1/2. Pulled pcv and capped hose, no improvement.
I pulled the carb and checked the intake floor under carb for cracks with my 2.75 reading glasses on and a LED flashlight. Nothing found. I see daylight through idle mixture passage with needle out, blew some air through just because. I used some 1/16" soft gasket material and made new gaskets above and below the insulator after a careful cleaning. I had one sketchy carb stud which I fixed. Ran exactly the same. I ran it to town and back, 24 miles, still same.
My take on this is there may have been crud in the float bowl that got picked up and sucked into a passage (or jet?) controlling idle circuit. Maybe the idle solenoid, but my take is it wouldn't run at all if it was faulty. Would love to hear about where to blow air or run a piece of wire or monofilament through or somehow to chase this problem down. With the perfection of idle and strong running 5 days ago I hate to send this out for a rebuild, specially since we finally have some summer weather and rig would be down for a long period. Any ideas would be very much appreciated.
I pulled the carb and checked the intake floor under carb for cracks with my 2.75 reading glasses on and a LED flashlight. Nothing found. I see daylight through idle mixture passage with needle out, blew some air through just because. I used some 1/16" soft gasket material and made new gaskets above and below the insulator after a careful cleaning. I had one sketchy carb stud which I fixed. Ran exactly the same. I ran it to town and back, 24 miles, still same.
My take on this is there may have been crud in the float bowl that got picked up and sucked into a passage (or jet?) controlling idle circuit. Maybe the idle solenoid, but my take is it wouldn't run at all if it was faulty. Would love to hear about where to blow air or run a piece of wire or monofilament through or somehow to chase this problem down. With the perfection of idle and strong running 5 days ago I hate to send this out for a rebuild, specially since we finally have some summer weather and rig would be down for a long period. Any ideas would be very much appreciated.