O.K. so once again were freaking out here! we just installed and started my brother in laws 383 stroker built by red line performance in ny, forged and aluminum everything, and everything was fine until we test drove it ; at aproximately 1500rpm some major vibration starts happening even in park. it feels like it's coming from the engine but i am not sure. what could it be? what could i check? this thing was stinkin' expensive and we live about 4 hours away from this shop so i need to know what i'm *****ing about when i call. PLEASE HELP!! thanx
400s are externally balanced. if they forgot to balance the internals, you need a 400 spec harmonic balancer and a flywheel weight. happens all the time
I'd bet it's just the wrong flywheel. Did you get it, or is it one the shop provided? Some 383 "kits" are internally-balanced (my Lunati kit was) but the 400-based ones are external. Check with the shop to ensure you've got the right flywheel/balancer for the setup you've got. Don't run it again until you figure this out. Odds are it's an easy fix, but it'll probably require dropping the trans for access. Good Luck- I hope it's simple... ~Scotch~
****! this doesn't look good. we've done a bunch of tests, here's what we've found: -first of all it's not a 400 crank it's built "some other way" using a 350 crank. red line said to check the pulleys because it was the only thing that did not come from them. it wasn't that. besides we're talking major vibration here, not some knocking or rattling. -we pulled the ****** and t.c. and it still does it -we tried another fly wheel and it's not that either any other ideas befor i call these guys tomorrow and freak?!? thanx
If the crank was offset ground to get a little more stroke "that" would be a suspect.... Or a bore job that was not done correctly[one bore out of line]
We had a similiar problem on a small block that we built. It was a stupid thing that we did, check the plug wires. We had two of them crossed and it would idle fine and at 1500-2000 rpm, it tried to come out of the frame. The best I remember, it was #5 and #7.
transmission/ t.c. wont be the problem. another non external balance flywheel will not cure the problem. You need to define "built another way" What parts did they sell you? Any shop capable of creating this should easily have the answer. Its either wired wrong, which it would run like **** and not rev worth a damn, or really is out of balance, in which case your thrust bearing is probably already damaged.
Hmmm....Maybe a 377 (400 block/350 crank). Still, if it's got a vibration now, and it's been dyno'ed at the shop where it was built (and it didn't have a shake then), it may be as simple as crossed plug wires. I'd double-check plug wire routing (18436572) and if you're still fighting a vibration, insist someone from the engine shop check it out. I worked at several pro race engine shops, and I was the guy they'd send to check on problems 'in the field' so I know good shops have no problem doing so. ~Scotch~
alright here we go again... after some advice i checked to see if every cylinder was firing because apparently if one doesn't it can feel like a unbalanced engine/crank when revving (news to me!) i found the #5 spark plug to be super clean (the rest were dirty like normal) even though it has spark when i pulled it out i held it to something metal. i tried a different wire just in case but it's still vibrating. any clues??
This may be unrelated to your vibration but a super clean plug sometimes is a sign of a leaking head gasket. The water or coolant is getting into the combustion chamber and it makes the plug really clean. Then again, if enough is getting in there to cause a miss that would certainly cause it to shake. -Scott
What do you have for exaust on the car? A few years back I put 3" pipes & Flowtech 3" Afterburner muffs on one of my cars, dumping right before the rearend. At about 1300 -1500 rpm, (even in park), there would be this horendous sound & vibration that went through the whole car! I put a balance tube between the pipes, and that helped some. Italked to my engine builder, and he explained "exaust harmonics" to me. The pipes were so big that turbulance built up at a certain point (rpm) and caused a vibration in the system. I recently had a simalar problem with another car, that I bolted header muflers on. Had to move the mufflers back from the headers 2 ft. to get rid of it. I know it sounds crazy, but it worked for me!
back to the basics...are you sure all of the valves are opening? #5 might be clean because it bent the pushrod and the rocker arm slid off to one side, not allowing the valve to open. if the machine shop adjusted the valves by feel, it is a distinct possibility they over adjusted one valve, and when oil pressure came up, it bent the rod.happened to me several times. I now adjust my own valves.
Your problem is probably that you didn't build it yourself and the builder is 4 hours away. if you catch my drift. Figure it like getting food from the Drive Thru, they know youre going to be too far away to do anything about it when you discover its a problem. There are a gazillion reasons why it could vibrate, everything from what has been mentioned to whatever else you can think of. You are running forged and aluminum everything? So I ***ume that you are running aluminum rods forged aftermarket crank, forged pistons, etc. Best thing you can do is call the builder and run it past him. Single exhaust won't make it vibrate, crossing 5&7 will make it backfire way before to reach your vibration point. The fexplate/flywheel and harmonic damper are things to look at but you need to know the build first to be sure. that brings you back to your starting point make a long distance call.
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