I have a 71 455 Buick engine in an a-body right now that is all stock except for headers. I have an 800 cfm Q-jet that I bought from Poston's that seems to be working fine & I still have the orig distributor w/points. I have about 100 miles on the points & I have a dwell meter & set the dwell at 30 deg like the emissions label says. Now to my problem...in low gear when I stomp on it, it pulls fine until 3k & starts to break up up to 5k, I manually shift the th400 into second & its fine in all the rest of the gears. My timing is set at 12 degrees before tdc, total timing I'm assuming is around 30 to 32 deg. Also, with the vacuum adv hose disconnected, where should the timing be set?
If it ONLY does this in first gear, are you CERTAIN that it's an engine problem? Check the trans fluid. If it's burnt, you may have slipping clutches. Any chance you're spinning the tires from 3000 to shift point? Either one would cause some vibration that could be mis-interpreted as engine misfire.
Good responses...definitely not spinning tires, trans a possibility, maybe it does it in other gears I usually run out of road, it feels like it's choking itself of air or fuel or spark. Cyls have 150 psi compression, the carb has to be good, I tried a Pertronix drop in ignition, but it never got spark & I had to send it all back, reinstalled the points & ran fine except for this. My friend says put in hei..ok maybe that would solve the problem, but points worked in all types of cars for years so I need to make this work.....
I had the same symptons and found that my secondary met rods were too rich..might be something to check??????? :beer
Do you have adequate fuel pressure at higher rpms? It sounds like the breaking up comes in at 3000 rpm, then you shift at 5000 rpm where it clears out, Izzat right? Try a new condenser as well. Sometimes they partially fail and give weird symptoms. Buy a quality US made one if you can. One with the wire emanating from a molded rubber end instead of the cheap-o drilled cardboard end on some condensers.
Thanks for the info C9, I my fuel pressure is good. I think I have the cheapo points in there. I'm going to replace & then try again, It doesnt clear up at 5k rpm, I believe its breaking up from 3k-5kprm the whole time, then I manually shift into second & Rpm's drop & it runs fine. It's gotta be points. If it clears up, I'll update the site. Thanks..
