360 vibration

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Toluene56

Toluene56

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Ok. I have recently rebuilt the 360 that was in my dart. Got it all put together with the correct clearances and such, broke the cam in and have been driving it off and on for the last few weeks.


But.... The engine is vibrating, when it didn't before. All I did was new beArings/rings/camshaft.

The engine has a 360 balancer that is new with the corresponding b&m flex plate and a neutral converter.
It vibrates from idle to about 1800-2000rpm after that its smooth as glass and pulls like a freight train.

The motor mounts are new. It doesn't look like the exhaust is touching anywhere but it does seems very rigid even with rubber mounts. It does seem that the trans mount needs to be replaced..will that cause it to vibrate in park/idle?
Btw the spark plugs looked beautiful when I pulled them.
I am at a loss :banghead:
 
You forgot to balance the rotating assembly.....
Put your old dampner, flexplate, and convertor back in.... Problem solved.
 
If you havent changed pistons it's probably a tuning issue. If it smoothes out as rpm is raised it's not mechanical imbalance. It's a dead hole.
 
racerhog said:
You forgot to balance the rotating assembly.....
Put your old dampner, flexplate, and convertor back in.... Problem solved.
Click to expand...

Its same flex and converter as before ,old balancer did the same thing.


Next I'm going to go through spark plugs again and double check see if there's a dead cylinder or something.

It did get a bit better when the new balancer was put on.. And a little better still when I replaced the eddy with the holley.
 
racerhog said:
You forgot to balance the rotating assembly.....
Put your old dampner, flexplate, and convertor back in.... Problem solved.
Click to expand...

He never changed the motors balance, just bearings rings and cam? bearings and rings would hardly alter the old balance, cam is not a factor....doesnt say if the "new" balancer flexplate and convertor were used on the old motor...I would check that rear trans mount frst, by far the cheapest and easiest thing to replace...but my money is on the new balancer. Can you put your old one on and test again? I think the 360 LA and the 360 Magnum are different weights.
 
I went from the old balancer to the new one because of the vibration... Made sense that it was a balancer from what I've read and what people have told me.

the B&M flexplate and neutral converter were in before the engine overhaul and worked fine before.

this is the new balancer I bought
http://www.summitracing.com/parts/SUM-163318/
 
I have that identical balancer, made by Pro-race (pro-street on side?) does it have the big balance weight bolted in the back cavity? It should. no weight is neutral 318, small weight is 340 cast and large weight is 360. Maybe try it without the weight if the B&M is taking all the balance to the back? http://www.pro-race.com/prostreetapplication.htm
 
Yes it has the weight.

I was thinking about trying that...looks like I'll have to pull the balancer to get to the weight... which sucks..



It started idling at about 800 in neutral... and the vibration was almost completely gone. Still had a little bit from 1000 - 2000rpm but not as bad..
Hopefully it is a tuning issue.

Btw the plugs are a little golden but not too dark and not too light, Just about right and there is a beautiful blue arc of pain from the MSD system. So thats all good.
 
Did you try disconecting the belts to see if something up front could be out of balance (p/s, alt, water pump, a/c)
 
hahaha.. wow.. it just never ends..

So now float level won't set in the carb. It was doing the same thing with the edelbrock, I guess it's time to get a fuel pressure regulator and a pressure gauge. Knock this out and see how it does. :banghead:
 
i had a vibration in mine.. for sure it sounded like bearings.. lower end..
ended up being the headers touching the pan.. easy fix.. but i chased a lot of loose ends before i figured it out..
 
yeah headers aren't touching, one of the first things I checked. But now that I have found this fuel pressure issue. Perhaps this is the main problem i'm having. It's dripping into the intake, so it makes sense it would run rough at idle and up to a certain rpm till fuel consumption catches up. :dontknow:
We'll see.. gonna have to wait a few days till I can run down to summit and get pressure gauge and regulator.


I really just wanna take my car out and hammer on the skinny pedal, it's such a good stress relief.
 
So you rebuilt the engine, right? Did you balance the crank with the new pistons, damper and flexplate? Did you change anything on the rods(new ARP bolts or something)? Did you have the rods balanced?
 
Same.rods as before but one was resized. Supposedly all checked so they would be.OK.

Other than that all the same rods pistons as before. Same flexplate and tq converter as before.

The vibration is only from 1000 to 2000 rpm. After that its nice.and smooth. Everything vibrates pretty bad at those rpms. I have found a fuel issue that I will fix in the coming days. But I don't think that will completely alleviate the problem. I have an irking suspicion that the resized rod isn't helping. Hopefully it will stay together long enough for me to save up and build the engine I want.
 
I think I found the culprit! And this has taught me to always double check things my friends tighten!
bellhousing bolts weren't even tight! Next time i'll do it all myself, so I at least know where to look first.

Either way, so far 98% of the vibration is gone. YAY!:headbang:

Now I just need to fix the carb issues and some other little things.

Thanks for all the suggestions FABO friends.
 
yeah.. me either.. my girlfriend gave me the idea to check what my buddy was working on when he was helping. So really she fixed it. lol
 
eh not really.. I fixed her duster in like 10min. So I kinda deserve it. lol
 
Toluene56 said:
yeah headers aren't touching, one of the first things I checked. But now that I have found this fuel pressure issue. Perhaps this is the main problem i'm having. It's dripping into the intake, so it makes sense it would run rough at idle and up to a certain rpm till fuel consumption catches up. :dontknow:
We'll see.. gonna have to wait a few days till I can run down to summit and get pressure gauge and regulator.
Click to expand...

Better change the oil before you drive it again. Gas dripping into the intake is washing down the cylinders. Had it happen to me, fuel pressure was @9psi into a Holley until I put a fuel regulator on. I changed the oil 3x before I got rid of the gas smell on the dipstick.
 
we are having a lot of vibration coming from my 360 we were using the wrong flex plate and long tube headers once my new B and M is in and the new tight tube headers are on there should be no problems on my end I hope
 
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