Hi All: Trying to figure out a the cause of a slight stumble at mid-throttle. Here are the details. '28 AV8. 292 c.i. flathead, Potvin 3/8th cam, Edelbrock Slingshot with two 97's. .043" jets and #67 power valve. Fuel pump is a Charlie NY converted early OHV Cadillac that is high volume, but correct 2.75 pressure. Ignition is a Petronix unit. I had NOS Stellings air cleaners on it. They are the wire mesh element type. I thought they may be choking it out, but it does the same with open stacks. Carbs are adjusted correctly and timing is set correctly as well. When I get on it, between approx. 2,500-3,750 rpm, the motor will slightly stumble and cough like it's lean, but once to the floor corrects itself and run really strong. The car spins the tires in 1st & 2nd at will. It only does this when getting on it in 2nd gear. Another detail that I'm not sure could be contributing is I haven't installed the thermostats yet. The engine runs around 160-170 when fully warmed up. Running straight water, new Walker rad and Skip's pumps. Looking at plugs, they actually look like it's the mixture is good. I haven't pulled over and pulled the plugs right after it happens. Maybe that should be my next step. I'm thinking it's not getting enough fuel. Otherwise, the car runs super strong and idles great. I have a pair of 48's I was thinking of putting on to see if that helps. I may fool with the advance a little as well. Any thoughts welcomed.
Stock crab with Petronix. I set it by driving it and adjusting as I went. Found the optimal spot for driving. I do not have a timing mark on the pulley. I wish I did do that.
Well, found out what was causing the stumble. I ordered new, larger jets. While taking out the old ones, I noticed they were about clogged closed. I'm surprised it ran as well as it did. New .046 (up from .043) and it runs like a new car.
@banjorear great to hear it’s running great and problem solved. We need to see a picture of the hotrod as she sure sounds awesome
Thank you. Relieved it was something simple. Here you go. I can't figure out how to post them larger than thumbnail size.
Thank you. I've had this car for a long time. Kids, moves, jobs, life, etc. put it on the back burner. It was originally on an A frame and started building it that way, but I always wanted it on a '32 frame. When it came time to get serious about it again, I switched over to a '32 frame. I'm very happy I did. Feel free to reach out to me if you have any questions. I did add those "extra" legs behind the K that someone is selling. Makes a world of difference and really stiffens the frame up. When the car is on a lift, I can open the doors which speaks to how much strength those rearward legs add to the K member.
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