Bad torque converter
- Thread starter chilwil86
- Start date
fletcherson
Well-Known Member
Check the harmonic balancer to be sure it didn't slip. You can do that by putting the engine at TDC and verify the timing marks. I've never heard of a converter doing that. When they fail, you normally don't have drivability and there is garbage in the tranny fluid. You could un bolt it and see if the vibration goes away, but push it back into the tranny away from the flex plate.
Have puck style engine mounts they are tight, trans mount I have to take a look at. And my engine builder says I've got the correct flex plate and balancer. I'm tryin to exhaust other options before I freak out on the builder. It's been on his engine dyno so I would guess that if it was out of balance he would have caught that.
fletcherson
Well-Known Member
I once put a flywheel on my externally balanced 383 and it did the same thing, it almost shook the car off of the jack stands. Turns out the flywheel wasn't balanced for a 400 sbc as I was told, had it re balanced, problem solved. Have you had the car running ok before or is it a fresh build? Just wondering if it's a new problem caused by a change or if something just isn't right.
choppedtop
Well-Known Member
Check plug wires. Make sure they are correct on dist and to correct plug. Simple things first. Don't ask how I know. Just asking....could one unbolt the t/q and slide it back, secure it, start the engine, just to eliminate it? I doubt if it is the t/q also. I am with flech about the wrong flexplate possibility. I almost put the wrong one on my car, not knowing which to use, balanced or un-balanced.
choppedtop
Well-Known Member
I don't know whether or not your engine is internally balanced or not. If you can figure that out, your can check your flexplate without taking it of to see if you have the right one. A balanced f/p will have a weight on it, the other will be smooth except for the big holes, of course.
fletcherson
Well-Known Member
Is it a stroker motor? If so, internal or externally balanced? Your build sheet should provide that info. If it's not stroked, or a 400sb, that 383/400 flex plate is your problem. You are also right to question the balancer, if it's a smooth, stock, balancer, that sounds like a internal balanced 350 balancer. The stock 400 balancer is big, but has a part cut out of it, unless it's an aftermarket balancer. If you have a mismatched flex plate and balancer, that's a problem, also is the flex plate on the right way? They will bolt on either way and depending on the starter, may even run that way, I found out the hard way on that little nugget. I not sure that the converter would bolt up to an externally balanced flex plate if it was backwards, but the flex plate weight should face the block. From your description, it sounds exactly like what mine did with the wrong flywheel on it. If that's the case, you definitely shouldn't run it till it's right. It's possible someone just mixed up the flex plates before you got it, disconnecting the converter and running it for a minute will tell the tale about it being a engine issue or not. Your builder questioning the converter tells me he thinks it's a balance issue.
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choppedtop
Well-Known Member
I was reading your post on another forum. Did you figure out if the harmonic balancer is the correct one? I really doubt that you have a paper weight there. Problem is on the front or back end of that engine I bet. Keep after it.
Well the engine builder actually called me on sunday and too his credit he is towing the car to his shop for further diagnosis. It is a externally balanced scat 383 rotating assmbly. It has both correct harmonic balancer i can feel the weight behind the balncer and correct weighted flexplate. Wether the flexplate is indexed correctly is another matter but were gonna find that out. He seems to b a stand up dude i dont doubt that. Soooo we'll see
choppedtop
Well-Known Member
There are both. I don't know how you can tell, but I bet someone here does. At least your builder sounds Ok.
So this engine was not balanced then, when it left the builders?
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