Ive had same issue in a boat repower 350 to 383 had huge vibration, I put a balanced harmonic balancer 8 inch dia that fixed 100%. No need to pull engine. I use same rear flywheel in boats as a manual transmission in cars so I would call the crankshaft co and see if front balancer will fix
I’m trying not to, I know at this point I feel it happened for a reason I’ll probably like the big block better. Thanks for commenting and watching I’ll be posting all the progress. 👊🏻
If it was me I'd buy one of the excellent 3.75" Stroker Cranks that's internally balanced. You could then use the same flywheel you have now and it would be all done at home. Scat may sell one they're not too high either. New bearings yes.
That’s my plan at this point I’m going to order a Scat kit for it, I’m still installing my big block while I take my time making the stroker right with some way nicer parts.
Always liked the 396-402 engines, my favorite is the L88 427 Maybe put a fuel-injected FiTech 2x4 dual quad system on your 402 with a little work you can pull 625 - 650 HP Keep us updated man!
I like your thought process I would love to put F.I. on the big block maybe I can swing that. But for now it’s getting all the fuel and spark from the 383 which is a 750 Demon carb and MSD setup. I will definitely be posting update videos throughout the build, thanks for being a dedicated viewer 🙌🏻
Been doing this kind of thing for 45 years, 20 years as a Chevy mechanic. Buy a new 400 flexplate. Take your manual flywheel lay it face down on the bench, lie your new flex plate on top of it, lining up mounting bolt holes EXACTLY. Mark your flywheel in the same place as the counterweight on the flex plate, knock off the weight and weld it to your flywheel. Add a 400 harmonic balancer and go. I have done this countless times over the years, never had a problem. If you haven't put too many miles on, you should be fine. Drive it, have some fun with it before you spend a ton of money fixing something that aint broke...
That’s just crazy enough to work, I’m sure you have pulled that off as you have said I’ll think about it. Thanks for the advice you have given me the best solution I’ve heard so far. 🙌🏻
that flywheel is either neutral balance or has a offset weight. so you need an externally balance flywheel or internally balanced. I dont see they need to take apart the engine at all. maybe they balanced the crank for forged pistons? wtf
Take the 383 apart, send the entire rotating assembly to a machine shop, they will be able to figure out whether it is internal or external balance, then have them get you the correct balancer and flexplate / flywheel, then have them balance it. Fix it right and learn from your mistakes. Thats how you will learn.
Aw shucks. I was pretty close to committing the same error. I have a truck with a 6.5 Detroit Diesel, I use it for towing. The engine has been abused for years and runs horribly, which is how I got the truck for cheap. About 2 months ago, I was walking about the local salvage yard, and there, sitting in a corner was a junk 6.5 engine. I got the silly idea that, I need the truck, I can't afford to have it down for long, but if I had another engine, rebuilt and ready to go, then I could swap engines and be back on the road with little down time. That engine was seized, so they gave it to me for cheap. I managed to strip it down to the bare block, liked the condition of the block and the rods, so I ordered pistons & rings 0.030 over. I got the pistons, but I'm still waiting on rings (and rod bearings). As I wait, I called a few shops to ask about how much it would be to bore and balance the bottom end. Only one told me to bring in the harmonic balance + the flex plate. I asked why, and he said that the engine was externally balanced, and it can't be balanced without both. I can follow torque procedures outlined in an instruction manual, I have also swapped engines in the past following the step by step instructions in a Haynes or Chilton's book. In my car, I also rebuilt my 4T65E transmission following the instructions in a book. I can turn a wrench, but otherwise, I know little about engines. I was going to go with whoever was the "lowest bidder". But after that call, I think I'm going with them, even if they're not exactly cheap.
You won't be sorry going with the big block I have a 427 60 over so it's a 439 it's got afr heads Howard's roller cam srp forged pistons forged crank and the good gm dimple rods the engine makes great power I wish I could find a nova I had a 72 back in 1977 and 78 that was a hot Lil street car but I'll be putting the big block in my 88 g body monte carlo SS.
Damn that’s a tough setup 💪🏻 I’m hoping to build my other big block 454 with nicer parts like yours but first I’m gonna slap this 402 together just so I can get some seat time before summer ends. Love me some G body specially the Monte Carlo’s, thanks for watching brother 🙌🏻 and keep between the ditches.
Then something is amiss. Because most 383's use a 400 balancer and either 400 flexplate or flywheel. It shouldn't make any difference whether it's a flex or a fly.
I'm curious what the actual problem is with yours. Some fly wheels have holes drilled in them for balance and some fly wheels have weights welded to them. Flex plate, whatever, the torq converter is the weight difference and again, a balanced part. Every part is individually balanced and one of them lost a weight or a bolt holding a rotating assembly fell out, like a torque converter bolt or a clutch bolt maybe, engine compression off on a cylinder maybe? It's obvious engine related and not drive line as you figured out so anything forward of the transmission input shaft I'd imagine can do that and should be able to be fixed unless something catastrophic happened inside one of the cylinders.
I took it out of an automatic car and installed it in a 4 speed car, so it went from being balanced with a flex plate to being unbalanced with a flywheel.
Yes you’re correct, but I have a factory 400 crank that’s not internally balanced so a neutrally balanced vibration dampener and flywheel would not work. I would need to buy an aftermarket internally balanced crank and rebuild.
The harmonic balancer would have to be weighed and the flywheel would have to be weighed and drilled until they match then spun while attached to the crank to check harmonics, definitely something out of my expertise that’s machine shop stuff. Correct me if I’m wrong.
Distributor is a brand new MSD I’ve had it in and out a few times nothing wrong with it. The shake is very extreme a distributor wouldn’t cause this amount of vibration.
Don't sweat it buddy...
Time for a upgrade, nothing is ever a problem...
Keep going forward!
Thanks bro!! I appreciate your words 👊🏻
Ive had same issue in a boat repower 350 to 383 had huge vibration, I put a balanced harmonic balancer 8 inch dia that fixed 100%. No need to pull engine. I use same rear flywheel in boats as a manual transmission in cars so I would call the crankshaft co and see if front balancer will fix
I had the same issue with my 383. It just needed the correct flywheel. Been running it hard for the last 3 years.
Don’t beat yourself up… shit happens … keep us posted on progress
I’m trying not to, I know at this point I feel it happened for a reason I’ll probably like the big block better. Thanks for commenting and watching I’ll be posting all the progress. 👊🏻
If it was me I'd buy one of the excellent 3.75" Stroker Cranks that's internally balanced. You could then use the same flywheel you have now and it would be all done at home. Scat may sell one they're not too high either. New bearings yes.
That’s my plan at this point I’m going to order a Scat kit for it, I’m still installing my big block while I take my time making the stroker right with some way nicer parts.
Always liked the 396-402 engines, my favorite is the L88 427 Maybe put a fuel-injected FiTech 2x4 dual quad system on your 402 with a little work you can pull 625 - 650 HP Keep us updated man!
I like your thought process I would love to put F.I. on the big block maybe I can swing that. But for now it’s getting all the fuel and spark from the 383 which is a 750 Demon carb and MSD setup. I will definitely be posting update videos throughout the build, thanks for being a dedicated viewer 🙌🏻
Been doing this kind of thing for 45 years, 20 years as a Chevy mechanic. Buy a new 400 flexplate. Take your manual flywheel lay it face down on the bench,
lie your new flex plate on top of it, lining up mounting bolt holes EXACTLY. Mark your flywheel in the same place as the counterweight on the flex plate,
knock off the weight and weld it to your flywheel. Add a 400 harmonic balancer and go. I have done this countless times over the years, never had a problem.
If you haven't put too many miles on, you should be fine. Drive it, have some fun with it before you spend a ton of money fixing something that aint broke...
That’s just crazy enough to work, I’m sure you have pulled that off as you have said I’ll think about it. Thanks for the advice you have given me the best solution I’ve heard so far. 🙌🏻
that flywheel is either neutral balance or has a offset weight. so you need an externally balance flywheel or internally balanced. I dont see they need to take apart the engine at all. maybe they balanced the crank for forged pistons? wtf
Take the 383 apart, send the entire rotating assembly to a machine shop, they will be able to figure out whether it is internal or external balance, then have them get you the correct balancer and flexplate / flywheel, then have them balance it. Fix it right and learn from your mistakes. Thats how you will learn.
That’s the plan, I also had ring seal issues with the engine which hopefully the machine shop can shed some light on. Thanks for the advice 👍🏻
Aw shucks. I was pretty close to committing the same error. I have a truck with a 6.5 Detroit Diesel, I use it for towing. The engine has been abused for years and runs horribly, which is how I got the truck for cheap. About 2 months ago, I was walking about the local salvage yard, and there, sitting in a corner was a junk 6.5 engine. I got the silly idea that, I need the truck, I can't afford to have it down for long, but if I had another engine, rebuilt and ready to go, then I could swap engines and be back on the road with little down time. That engine was seized, so they gave it to me for cheap. I managed to strip it down to the bare block, liked the condition of the block and the rods, so I ordered pistons & rings 0.030 over. I got the pistons, but I'm still waiting on rings (and rod bearings). As I wait, I called a few shops to ask about how much it would be to bore and balance the bottom end. Only one told me to bring in the harmonic balance + the flex plate. I asked why, and he said that the engine was externally balanced, and it can't be balanced without both. I can follow torque procedures outlined in an instruction manual, I have also swapped engines in the past following the step by step instructions in a Haynes or Chilton's book. In my car, I also rebuilt my 4T65E transmission following the instructions in a book. I can turn a wrench, but otherwise, I know little about engines. I was going to go with whoever was the "lowest bidder". But after that call, I think I'm going with them, even if they're not exactly cheap.
Good choice brother get it balanced 👍🏻
You won't be sorry going with the big block I have a 427 60 over so it's a 439 it's got afr heads Howard's roller cam srp forged pistons forged crank and the good gm dimple rods the engine makes great power I wish I could find a nova I had a 72 back in 1977 and 78 that was a hot Lil street car but I'll be putting the big block in my 88 g body monte carlo SS.
Damn that’s a tough setup 💪🏻 I’m hoping to build my other big block 454 with nicer parts like yours but first I’m gonna slap this 402 together just so I can get some seat time before summer ends. Love me some G body specially the Monte Carlo’s, thanks for watching brother 🙌🏻 and keep between the ditches.
I did the same thing. Put a 400 style flywheel in it. It will be fine
That’s what I did and she’s shaking a lot
Then something is amiss. Because most 383's use a 400 balancer and either 400 flexplate or flywheel. It shouldn't make any difference whether it's a flex or a fly.
@@michaelphelps5064wrong. Many aftermarket 383 rotating assemblies are internal balance but they can be purchased either way. Internal is better.
I'm curious what the actual problem is with yours. Some fly wheels have holes drilled in them for balance and some fly wheels have weights welded to them. Flex plate, whatever, the torq converter is the weight difference and again, a balanced part. Every part is individually balanced and one of them lost a weight or a bolt holding a rotating assembly fell out, like a torque converter bolt or a clutch bolt maybe, engine compression off on a cylinder maybe? It's obvious engine related and not drive line as you figured out so anything forward of the transmission input shaft I'd imagine can do that and should be able to be fixed unless something catastrophic happened inside one of the cylinders.
I took it out of an automatic car and installed it in a 4 speed car, so it went from being balanced with a flex plate to being unbalanced with a flywheel.
Shit happens keep trucking, no replacement for displacement
usually, when the vibration damper is not neutrally balanced, the flywheel is not neutrally balanced
Yes you’re correct, but I have a factory 400 crank that’s not internally balanced so a neutrally balanced vibration dampener and flywheel would not work. I would need to buy an aftermarket internally balanced crank and rebuild.
Change harmonic balancer to match flyweel
The harmonic balancer would have to be weighed and the flywheel would have to be weighed and drilled until they match then spun while attached to the crank to check harmonics, definitely something out of my expertise that’s machine shop stuff. Correct me if I’m wrong.
What about distributor failure?
Distributor is a brand new MSD I’ve had it in and out a few times nothing wrong with it. The shake is very extreme a distributor wouldn’t cause this amount of vibration.
just thhrow a external balanced flywheel in it
Did that and that’s what is shaking
Man, that sucks.
Yes it did, but luckily I had a spare big block sitting there to replace it. I’m still going to repair the stroker though.
@@atomicspeedgarage I love a story with a happy ending.
Yes very happy I’m out banging gears this morning in it 😁