engine tuning

[homer]

I am having a sporadic problem with my engine. I have a SA406 (approx 600 miles) that sputters at high rpms when revving in the driveway and sputters at 2000-3500 rpms when accelerating. I have adjusted the carb float leves, the mix screw (1.5 turns out) and the timing to 37 deg at 3200 rpm. I have the occassional nasty backfire (typically small backfires)through the carb when the engine is warming up but not once it has run for while. Any troubleshooting hints would be welcomed.

[Brent]

Homer,
I don't think your situation is carb related. A backfire is usually of no fault of the carb. You probably have an ignition, timing, or valvetrain issue. This motor has been an issue for you for a long time hasn't it. Have you checked the valves to make sure you dont have a lobe down or a rocker way out of adjustment?

What ign. are you using and what dist. are you using?

Good luck.



Brent
4279401
Candy Apple Red/White
402 FE/Toploader/3.54

[homer]

MSD6al ignition with elect dist -- Have not checked the valve lash -- tried readjusting the float levels again and problem seemed to get better only after a puff type choke out of the carb under acceleration. timing is ok have checked it -- must be the valves -- guess I will ned to learn how to check and adjust them

[spd4me]

I remember my SA 396W backfiring through carb once. Like to blew off my eyebrows. The problem was I had leaned out the carbs to much and they weren't getting enough gas. I did the 1.5 turn and added about another half turn. Just enough to where you can feel the engine change. If you have solid lifters and have not adjusted. It's a must. My car got so rough at idle, I though my dash was going to fall off. Checked the valve lash and there were two I could stick my finger under. Set them at hot lash (after warming up motor ) and it ran like a top.