Bad vibes.

-
aaronk785

aaronk785

Well-Known Member
Joined
Apr 21, 2013
Messages
1,021
Reaction score
851
Location
westmoreland ks.
Have a problem with my friends 360. It has a bad vibration all the time. Its a stock rebuild with stock rods, pistons and crank all from this motors. Has new rings and bearings. Rebuilt stock heads, comp xe262 cam lifter and springs and new timing chain. It runs beautiful, doesn't miss a beat. When we put it together it had a after market 360 balancer, stock flex plate and weighted converter off the old engine that didn't run when he bought it. The balancer looked just like a stock one. Cut out and all. Converter looked weighted right but it vibrated. So I had a nice stock balancer so we put it on just to be sure. No difference. So next we ordered the correct b and m flexplate and used a neutral balance converter, again no difference. I'm stumped. We checked everything. Took off accessories, made sure nothing is wedged or touching. Does it in neutral or while driving. Could it be the tranny, it works fine. Any suggestions would be appreciated. Thanks.
 
There isn't. But I've seen the rear transmission crossmember in a truck application, pack solid with dirt and rocks, making it a "solid mount" and it vibrated!
 
That is the right flex plate for the 904. I wouldn't think it would be in the 904 because you say it does it in neutral. Everything that moves from the crank on back you have swapped out.
 
I don't think its the trans either. All that's turning in neutral is the pump. I will double check the mount. Has anybody had a factory 360 balance be that bad? Next were going to try a 360 flywheel with a open 727 case for the strarter.
 
What’s your vacuum gauge read? Could it just be a dead cylinder, misfire, bad ignition timing, vacuum leak? All it takes is one vacuum leak - especially if it effects mainly just a cylinder or two for an engine to get the shakes. Like the brake booster leaking vacuum.
 
Spark plug wires swapped? I know you said it runs great, but....

Piston PN used?

Did you see the crank and internal parts yourself? Any evidence that the prior owner of the engine had the crank neutral balanced? You'd see some evidenced of weights welded into the large counterweights.
 
Are you saying it is a 360 with a 904 from a van? Never in my life have I seen a 904 behind a 360 in a van or a truck. Something is up with that right off the bat. Can you post some pictures of the balancer?
 
I built the engine. Tore it down from the long block. Came out of a friends plumming van. I've went over every thing twice. All plugs look good, good compression, vacuum. That's the first thing we tried to eliminate. I have no problem checking it all again just incase I missed something. I'm afraid its going to take out the mains cause its bad. Friend said it ran good in the van, but this guy wouldn't know if it was running on 4 cyl. or 8 if you know what I mean.
 
aaronk785 said:
I built the engine. Tore it down from the long block. Came out of a friends plumming van. I've went over every thing twice. All plugs look good, good compression, vacuum. That's the first thing we tried to eliminate. I have no problem checking it all again just incase I missed something. I'm afraid its going to take out the mains cause its bad. Friend said it ran good in the van, but this guy wouldn't know if it was running on 4 cyl. or 8 if you know what I mean.
Click to expand...
Stock pistons? Stock rods?
 
Not at the moment. Car is 15 miles away. I am 100% sure its a 360 balancer. I will get a pic when the weather breaks to be sure. I know the weight is about twice as thick as the one on my cast crank 340, and it came off a 360.
 
This might be a silly question, are you sure it's not a wobble or up/down concentric?
 
This might be stupid.. but I've had one of my old engines vibrate something fierce, found the bellhousing bolts weren't fully tightened. Always gotta check the stupid stuff first.
 
Check to make sure the exhaust isnt touching something that would cause harmonics. I was chasing a vibration before and once the RPMs got up to 1500 or more it would vibrate. Found the exhaust was hitting the torsion bar mount. Its worth a check.
 
You must log in or register to reply here.
-

Back
Top