NHGuy
Captain
- Joined
- May 21, 2009
- Messages
- 3,631
Hi, 89 5.7 Alpha 1, carb tag 5.7L 5.7 INB 1347-9662, engine serial C315645. It has Thunderbolt IV ignition.
I recently put in a new distributor sensor, not for a problem - just cause I didn't like the look of the old one. It was pretty rusty and ugly. I did spark plugs (NGK) the week before. I was getting dieseling last year, I could just run the motor at 1500 rpms or so for a short stint to cool it down below 160 to get a shut down. My thermostat is the correct (140 degree?) one.
It ran well for a few days, no dieseling. I thought, good. Maybe that problem is solved. In my stupidity I leaned out the mix thinking it would help. Now I'm getting some dieseling on shutoffs after a long run.
After some reading it looks as though I ought to recheck the timing and reset the mixture screws richer-not leaner. My timing light is 90 miles away. So today I started them off at 2 turns from the seats. I turned them down separately to the stops, not hard - just to the inner limits. I didn't perceive the stumble I expected. So I put em each at 2 & 3/4 and tried enriching from there. I had them out to 4.5 or almost 5 turns and got no stumble. How far can I go? Is this evidence that the needles and seats are bad? Any thoughts are welcome.
Right now it's 95 degrees out, the water is 82 degrees and the temp creeps up to about 175 or 180 if I run at idle for a while, so I ran the motor in neutral for a couple of minutes when I came in to lower the temp. I got the temp gauge down to 150 or 145, tried a shut down and it dieseled. So I turned the ignition back on put it in gear and stopped it that way.
Think I should go richer? My daughter will bring me my timing light tomorrow afternoon. but in the meantime, how many turns are there in the mix screws on the Rochester 4 V?
Oh and do we go 8 degrees BTDC at 650 RPM? That's how I read the instructions.
I'm going to try richer in the meantime. Can the screws come out too far?
I recently put in a new distributor sensor, not for a problem - just cause I didn't like the look of the old one. It was pretty rusty and ugly. I did spark plugs (NGK) the week before. I was getting dieseling last year, I could just run the motor at 1500 rpms or so for a short stint to cool it down below 160 to get a shut down. My thermostat is the correct (140 degree?) one.
It ran well for a few days, no dieseling. I thought, good. Maybe that problem is solved. In my stupidity I leaned out the mix thinking it would help. Now I'm getting some dieseling on shutoffs after a long run.
After some reading it looks as though I ought to recheck the timing and reset the mixture screws richer-not leaner. My timing light is 90 miles away. So today I started them off at 2 turns from the seats. I turned them down separately to the stops, not hard - just to the inner limits. I didn't perceive the stumble I expected. So I put em each at 2 & 3/4 and tried enriching from there. I had them out to 4.5 or almost 5 turns and got no stumble. How far can I go? Is this evidence that the needles and seats are bad? Any thoughts are welcome.
Right now it's 95 degrees out, the water is 82 degrees and the temp creeps up to about 175 or 180 if I run at idle for a while, so I ran the motor in neutral for a couple of minutes when I came in to lower the temp. I got the temp gauge down to 150 or 145, tried a shut down and it dieseled. So I turned the ignition back on put it in gear and stopped it that way.
Think I should go richer? My daughter will bring me my timing light tomorrow afternoon. but in the meantime, how many turns are there in the mix screws on the Rochester 4 V?
Oh and do we go 8 degrees BTDC at 650 RPM? That's how I read the instructions.
I'm going to try richer in the meantime. Can the screws come out too far?