nilknarf007 Posted March 27, 2020 Author Share Posted March 27, 2020 The continued high idle does indicate a vacuum leak. Try the smoke test, again. 10 degrees BTDC should not cause hard starting. Mine is @ 16-17 degrees BTDC with no starting difficulty. The harmonic balancer ring may have shifted. Using a vacuum gauge, see what is indicated @ idle speed. It should be approaching 20" Hg. And, if you do have a miss, it likely will be seen as a twitch/jerk in the needle of the vacuum gauge. Going to 4 degrees BTDC will definitely cause sluggish performance, especially since with the original distributor, there is no advancing of the timing at higher RPMs. Just thought I would post an update. I put in a new YF carb as a replacement for the YFA. Also installed an HEI distributor, with new plug wires and properly gapped plugs, and timed it to 6 degrees BTDC with the vacuum advance disconected. This thing runs like a dream. No idling issues anymore, and much improved power. I'm taking it on a 300 mile interstate trip this weekend so I'll get a good reading on the gas mileage. Hopefully it's better than the 11 mpg I've been getting. Link to comment Share on other sites More sharing options...
1986F150Six Posted March 27, 2020 Share Posted March 27, 2020 Just thought I would post an update. I put in a new YF carb as a replacement for the YFA. Also installed an HEI distributor, with new plug wires and properly gapped plugs, and timed it to 6 degrees BTDC with the vacuum advance disconected. This thing runs like a dream. No idling issues anymore, and much improved power. I'm taking it on a 300 mile interstate trip this weekend so I'll get a good reading on the gas mileage. Hopefully it's better than the 11 mpg I've been getting. I'll bet the gas mileage will be improved. Later, after this trip to establish a baseline, bump the timing to 10 degrees BTDC and adjust the idle speed. Drive and listen for pinging. If no pinging, go to 11 or 12 degrees. At some point, pinging or a resistance to start will occur. Then you retard the timing just enough to stop that. Please keep us informed! Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 27, 2020 Share Posted March 27, 2020 I'll bet the gas mileage will be improved. Later, after this trip to establish a baseline, bump the timing to 10 degrees BTDC and adjust the idle speed. Drive and listen for pinging. If no pinging, go to 11 or 12 degrees. At some point, pinging or a resistance to start will occur. Then you retard the timing just enough to stop that. Please keep us informed! Congrat's! Such a good feeling when a plan works. And David is right about the advance. Dial in as much as you can w/o pinging or kick-back on starting and the MPG will come up some. Link to comment Share on other sites More sharing options...
Sac79 Posted March 27, 2020 Share Posted March 27, 2020 Congrat's! Such a good feeling when a plan works. And David is right about the advance. Dial in as much as you can w/o pinging or kick-back on starting and the MPG will come up some. Looking forward to hearing your findings. Which HEI carb did you go with? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 27, 2020 Share Posted March 27, 2020 Just thought I would post an update. I put in a new YF carb as a replacement for the YFA. Also installed an HEI distributor, with new plug wires and properly gapped plugs, and timed it to 6 degrees BTDC with the vacuum advance disconected. This thing runs like a dream. No idling issues anymore, and much improved power. I'm taking it on a 300 mile interstate trip this weekend so I'll get a good reading on the gas mileage. Hopefully it's better than the 11 mpg I've been getting. Congratulations! And please make another thread (topic) about your trip and impressions you get about your truck now that it is running well. Link to comment Share on other sites More sharing options...
nilknarf007 Posted March 27, 2020 Author Share Posted March 27, 2020 Looking forward to hearing your findings. Which HEI carb did you go with? The HEI distributor was from CRT Performance, got it on eBay. The carb was a PARTOL YF I got on Amazon. Link to comment Share on other sites More sharing options...
Sac79 Posted March 27, 2020 Share Posted March 27, 2020 The HEI distributor was from CRT Performance, got it on eBay. The carb was a PARTOL YF I got on Amazon. Good luck on your drive this weekend. Link to comment Share on other sites More sharing options...
Recommended Posts