I am nothing more then a backyard hacker so I like to eliminate the low hanging fruit. Start with the fuel pump like Harv suggested. If not making a discernible noise, take the valve cover off and locate the troublesome lifter and adjust it. Then, head to the carb again, adjust the idle screw so it’s idling at the correct specification, then adjust the idle mixture, turn in until it stumbles, then back it out a little bit at a time until it smooths out, then a little more. Readjust idle speed, then double check your timing. That should get you in the ball park.
Couple of other things to check. Fuel filter. Also fuel pressure. These carbs don’t like a lot of pressure. They need 3 1/2 pounds minimum, 4 1/2 max. A rebuilt or new pump could be putting out 6 or slightly more. Not really what you want. So I would check the running pressure with an external gauge. Also, double check the vacuum advance is working. If the diaphragm is split or broken, you have a vacuum leak that is just adding insult to injury.
What kind of air cleaner are you running? If one of those little chrome cleaners, your probably adding to your problems. They don’t flow enough air.
Oil, every one has there favorite. Mine has been Brad Penn for quite a few years. 10w30. It’s now called penn grade 1. It’s a semi synthetic. Uses Pennsylvania crude as a base stock (always known as a superior base stock), with a zinc package, and a synthetic additive package. made at the former Kendall refinery in Bradford pa, (home of the zippo lighter. My daughter went to college in Bradford so I know the area), Clings nicely to the rockers over the winter and I have not had any failures with any of the motors I have built using the stuff. I also use their break in oil.
So the short answer is yes, I would use one.
Last edited by Dragsix; 10/15/2019 12:39 AM.
