So I bought this old truck with a poorly running 383 it sounded like a flat cam, took it apart and the lifters, timing chain, cam, were all junk, I put a new cam in set it up on TDC adjusted the valves, at this point it would not start, checked all the usual stuff, firing order, tried moving the location of the dist. still no start. Then tried thumb over number one spark plug hole to find TDC found it in a location with no relationship to the timing mark on the balancer or timing tab and it will start and run there. My balancer appears to be a 350 and does not appear to have slipped. it seams to me that it should have a 400 HB after looking at both types of balancers the key way and timing marks are in the same place, my engine is TDC at about the 12 o'clock position, can anyone tell me where I screwed up or where the problem is? I'm stumped, I don't want to run the engine anymore until this gets figured out.
There's a bunch of different covers and balancer marks for different applications. A mismatch is just way to easy to come by. It's not a big deal to run a piston stop test and remark the parts for timing reference. But I agree , make sure you have the correct balancer. The balancer and flywheel/flex plate should match. Some are built to retain the external balance and run 400 stuff, some are built as internally balanced and run the 350 stuff.
The best way to do it is to get an adjustable timing tab and set it up to point to true TDC. Your 383 may require a 400 type balancer that is made for an externally balanced engine, and it may not.
Your timing cover looks to be correct if the center of the timing tab is zero or there abouts. whats that cover off ? whats the best cheap fluid balancer?
You have to be careful if you think about replacing balancer. If it is a 400 cast crank the balancer should be part of an external balance situation. If they used an aftermarket crank that was able to be internal balanced,well another story. It may just be a 350 and thats why it had a 350 balancer. Its too bad you didn't know to check when you had the front cover off to see if it was a cast crank or not. I think I would do the welding rod down on the piston deal and crank it over by hand to check stroke. Best of luck.
Again, the balancer and flywheel need to match. So What flywheel/ flex plate do you have on it? I've not seen a fluid unit that works on both internal and external balance.
Fluid balancer won't make up the difference between internal or external balance. Don't worry about the 350 balancer the majority of 383 stroker kits with aftermarket cranks have been internal balance for years. find top dead center, move the timing pointer to match it.
I think you have an early model timing cover and a late model damper. If that's the case, somewhere around 12 o'clock will be in the ball park and you can run the engine. How bad does the engine shake when you rev it? If it's smooth, then you probably have the right damper and flexplate for the crankshaft. If it has a BAD vibration, then you need to figure out if your engine is internally or externally balanced. If the engine has some miles on it, I'd be inclined to guess the balance is ok and you just need to remark the damper or change the timing cover to a late model item. That a lot of guesses and****umptions though.
This truck appears to have been some kids failed hot rod project (by kid I mean anyone under 65) it has a ton of expensive mismatched parts. the trans is a th400 so the****umption is the flexplate is as well, but if its a 350 there would be vibration and there was some on initial start up, but then the valves are out of whack and the plugs, wires, etc were the ones that came with it. I wasn't looking for a 383, but I ended up with one, the interior of the motor was spotless when I removed the giant high riser intake and giant Holly, they also had a holly electric fuel pump, I replaced with a stock mechanical. Thanks all for the help.
The type of trans won't have anything to with an internal or external balanced flywheel, so just throw that****umption out the window.
When we were kids a friend dropped a 400 in his Chevelle without changing the flywheel. OK at low speed but as soon as the revs picked up it was obviously wrong. Drove the***** out of it anyway cause we were kids. Can you check the flex-plate for weights?
Like this for 400 http://shop.whiteperformance.com/SBC-400-168-TOOTH-FLEXPLATE-EXTERNAL-BALANCE-FOR-2PC-RMS-G101HD.htm
It seems like just yesterday, but it was probably 15 years ago I built a 400 for my brother inlaw, and I think it had a larger fully round balancer, where the 350 seems to be cast with a heavy side.
I think you are over thinking the balancing thing. If it ran when you got it that issue is probably sorted out. Flat lobes on the cam is a whole different thing. Just replace the cam and lifters, etc. See if they put a mark on the balancer for when they first fired it up. Maybe hard to see now. They probably have the wrong cover balancer match. The thumb over the spark plug hole only give you the compression fire stroke, not exact TDC. Need to find TDC with a degree wheel, etc. But, I have gotten the SBC to run by just moving the distributor around until it ran. I have been 180 off at least twice, and once I knew I had correct and rechecked it at least three times and it drove me nuts because I don't like to turn the motor much if it don't fire right off. It was 180 off. I would have bet the farm it was right, but something happened, i.e., people talking, beer, etc.... Anyway, fired right off then. Also, if it don't fire right off, there goes the new cam. Need to get her spinning fast right away. Unless roller obviously. cb1
It looks like I've got it bassakwards and have the correct stuff. I'll adjust the valves to the new timing throw a tune up in and see what I've got. I normally don't go for that much bling, but you should have seen it before with the flamed aluminum high rise valve covers, high rise intake, etc.
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