Well I believe it's just the stock cam. Oh yea, come to find out it was not a 50oz. flex plate, it was a 28oz. but when I put a 50oz. on it with the 50oz harmonic balance the vibration got worse. I'm at my wits end with this one. Anyone have a 331 they want to sell cheap?
I had a shake when I first assembled a 5.0. New 50 oz balancer, new 50 oz (supposedly) flex plate, new torque converter. Turns out the new flex plate wasn't balance correctly. See this thread. http://mmb.maverick.to/showthread.php?t=69549 If you can get your hands on a 50 oz flex plate that you know is correctly balanced you can check the one you have. If you want I can send you an email with pictures of how I did that and found the problem. But, if your vibration is only at low speeds I don't think its a balance issue. Believe balance problems usually shake worse at high speeds and misfires shake less at high speeds.
Maybe the flex plate was right and the balancer is incorrect? It could be a 28oz crank with a 50oz balancer. (wrong balancer)
I would hate to be in this situation. It's alot of work to be swapping parts to find out that there is a problem over and over. Wish there was a color codeing or something.. Good luck.
It's the stock cam, it doesn't smooth when i gass it, the cycle just vary a bit but the vibration gets stronger from 2500-up
Well when the vibration was first noticed it had a 28oz. flex plate and a 28oz. balancer. I assumed that was the reason for the vibration. There's no miss, it runs great. The 50oz balancer and flex plate are new, so I don't know what else to do.
Well you should definitely NOT be using a 50oz balancer! The 289 engines were all 28oz engines. You can't mix and match flexplates and balancers with crankshafts. This is most likely your problem.
I'm going to check the balancer, is there a way to know if it's a 28oz or 50oz or should i weigth them?
Wait, I'm getting confused on who has the 289 and who has the 85 engine! h20, sorry but you should have started your own thread! But to both of you: If you have an early engine you must use 28oz balancer AND flexplate. If you have later engine (after 81? Somebody correct me here) you have to use 50oz balancer AND flex plate. Angusbull, are you POSITIVE it's an 85 motor and not a 72 motor like you initially thought it was? How did you determine what year the engine is?
Your balancer's outer ring may have slipped, this will throw the crankshaft's balance out of whack. Get the #1 piston at TDC of the firing stroke, then look to see if the timing pointer lines up with the 0* mark on the balancer. If it's not, then the outer ring has slipped.
