I have a 350 2bbl in my '71 Skylark and I get a popping noise when accelerating, it gets worse under hard acceleration. I can also here it if I rev the engine while in neutral. Does anyone know what might be causing this? I've tried adjusting timing, replacing the springs in the distributor (I tried lighter springs and heavier springs, neither of them helped), adjusting air fuel mixture, and replacing the fuel pump and filter. I had a 4 bbl intake and carb on it at one point and the noise wasn't as bad when I was running that setup. I'm pretty sure it's not spark knock.
Check the firing order first. If that's Ok then perhaps bad plug wire/wires? That's the first place I'd look.
The firing order is all right, and I forgot to mention that I also replaced all the spark plug wires.
I hate to say it, but after the easy stuff checks out, pull the valve covers and rocker assemblies so you compare lift at all intake lobes, then compare exhaust lobes. A dial indicator with a magnetic base makes this easier while you turn the engine over by hand. Unfortunately more than once for me the same symptoms occurred because of one or more flat cam lobes. Devon
Is it a miss, or a pop through the carb or exhaust? Was the "pop" there prior to changing out the plug wires? Do you have a tach? If so, check with tach to see if it ever becomes erratic. Possible low or high tension circuit short/loose connection at coil. Double check the crimps and assembly of the coil wire...
I have a bad lower ball joint that pops when the engine torques. Every time I take off hard, you can hear it pop once. Changing it this weekend though! :grin: Maybe his noise is body/suspension???
I bet the intake and exhaust valve seats and valves are burned and not closing all the way.. Does it sound like popcorn popping under the hood at wide open throttle???
That's actually exactly what it sounds like, I guess I'll just have to replace the cam/lifters/valves over the summer. Would it help to put lead additive in the gas until I can replace the valves?
No, if that's the problem, additive will not help. But don't jump to conclusions yet. You have plenty of suggestions for diagnostics. Don't waste money on parts until you know what's giving you the problem! Devon
Do a compression test.. If it is low, squirt some oil in the cylinder, if it is still low then the valves are not sealing.. Exact same problem I had. Engine ran OK, but a WOT it sounded someone lit a pack of firecrackers off in the intake..
I had this issue due to a high lift can poor break In and wrong push rods. 5 cam lobes were junk and I wrecked the block it was a 68 gs 350-4
The problem is the coil is not firing enough electric to fire off the plug. Reset the points to the correct setting or replace them if you have them, then reset the timing. The coil needs to be checked also this is probably the problem.
Thanks for the idea. Yesterday I advanced the timing a few degrees and adjusted the air fuel mixture to get more fuel to the carb, added octane boost and lead additive to the gas and it seems to be running a lot better, but it's still making the popping noise, just not nearly as loud as before. Does anyone know where I could buy an electronic ignition conversion kit? I'd rather do that than replace the points.
Petronix has an electronic replacement for your points or you can swap in an HEI distributor from a later model Buick 350.
Do you know what year they started using HEI distributors? I'll make a few phone calls and see if I can pick one up.
I think that started in 73 or 75. I think if you just replace the points with a good set the popping will go away. The points can get pitted and this will just cause all kinds of problems with the timing and coil saturation to give a good spark. When the points change in the gap this changes the timing in the engine. Advancing is helping your engine but this is not going to cure the problem.
