Maybe I wasn't clear... I meant are the pointer and ballancer compatible(matched)... There were different locations for the pointer over the years and if the timing marks on the ballancer are not compatible with the pointer you're going to have problems...
You know this is something i'm not sure of, tell ya what i'm gonna do, I will go out and bring it up to TDC on the compression stroke and time from there, the pointer is from a 1970 engine and the balancer is from a 1974 engine.
Those two parts are compatible. Get the #1 at TDC, then look to see where the pointer is aligned with on the balancer. If it's not where it should be, the balancer's outer ring has slipped.
Will do, didn't get time to do anything today, had to run around too much and check on shipping quotes.
Well now it seems it may have been just a valve or two sticking, ran a quart of Dexron II through the carb and it's much better, about all the backfiring through the exhaust is gone and it seems to have more power now.
Bringing this back up because the backfiring is still present and it really came out on my test drive, I have read on the net that a 351w will run with a 302 cam in it and timed to a 351w firing order but will run rough and backfire during acceleration, idle seems to be ok according to others but seems to run like it has a large cam or vacuume leak, it is during acceleration the problems manifest, I am going out and time my 351w to the 302 firing order and see what happens, if it will even run at all, I'll let ya know.
Well it did "run" but not well at all set to the 302 firing order, back to the drawing board, I guess a leakdown test is in order
Dragging this back up because I have the "new" heads on the engine and I have backfiring through the exhaust, the old heads did have some very slightly bent valves and I'm pretty sure that caused the backfiring through both the carb and exhaust, I have moved the dizzy around, checked the timing twice again, made sure the dizzy is advancing and hooked up to the vaccum properly, I can almost eliminate the backfiring but not all, it idles great but gunning it still produces backfiring, I can hold it at about 2500 RPM and it will intermittenly backfire, I guess I need to look at the cam? I don't know, open for more suggestions......
cheese whiz dude! what a PITA this has been for you. hate to backtrack through all the posts so I'll just ask again to see what you've done so far. 1. You're sure that the rotor's lead is clocked slightly ahead of #1 TDC of compression, right? 2. Checked the timing marks on the chain gears? 3. Valves are adjusted correctly? Adjustable or non-adjustable? 4. Carb is set and functioning correctly?.. squirters, float levels, power valve good?.. how long ago did you go through it? 5. What is the vacuum reading like?.. fairly steady?.. only fluctuates with the miss/backfires? let's keep it shorter with just those q's for now.
ok then.. Now the most obvious questions. Sounds very much like a timing issue so far. Did you put a timing light on it yet? Be sure to rev it to see if the vac advance is pushing your total number too far out. Massive vac advance(and/or combined with a slightly lean carb setting to begin with) can easily cuase lean misfires like you're describing here. Also be sure that the port you're running the vac pot off of is not ported(pulls more pot advance as the carb flows more air).. but is instead running off manifold vacuum which go's away under abrupt throttle changes as vacuum drops. An easy peazy quick and dirty test would be to just disconnect the pot and plug the carb or manifold port for a minute to see what happens.
Can you pull plug wires one at a time to see if that effects the backfire??? If it does you probably have wiped exhaust lobe(s) on the cam... When this happens there is usually enough valve opening to let the burned gasses out at low rpm, but with the valve not opening far enough, some combustion remains in the cylinder backing up into the intake manifold on the next intake cycle...
Gonne try and check out some more things, we have heavy rains and flash flood warnings today so I might not get to it.
