Vibration around 1300 rpm then goes - when at a standstill

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deppmobile
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Joined: Mon Oct 03, 16 4:00 pm

Vibration around 1300 rpm then goes - when at a standstill

Post by deppmobile »

Having successfully broken in the cam, and just chasing down a few bits and pieces, I now have another problem :help:

Engine idles nicely at around 800 RPM, but when you then bring the revs up there's some nasty vibration around 1300 rpm which then goes and once again it's smooth - with 727 in neutral.

Things I've checked:
Engine mounts
Tranny mounts
Tranny fluid level
Anything else that seems to be rattling loose.
Specifically rember torquing up the flex plate onto the engine and the torque converter
And had the 3 clunks as the converter went onto the splines

This is the 318 poly swap to a 360, the 318 being internally balanced. I fitted a B&M weighted flexplate so I could use the original torque converter. (No problems with it when it was previously fitted behind the 318.)

Am I missing something obvious? Really doing my head in :pale:
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deppmobile
Posts: 131
Joined: Mon Oct 03, 16 4:00 pm

Re: Vibration around 1300 rpm then goes - when at a standstill

Post by deppmobile »

Not sure of this will be of use to anyone, but finally solved the problem. Moral of the story is check and check again!

Turns out I had done everything right, but the aftermarket harmonic balancer the engine builder had given me was the wrong one :(

A lot of research found that the after market company have the same base balancer for both 360 and 318 engines, but convert it to suit the externally balanced 360 with a big weight bolted to it! You guessed it - the one that came with the engine didn't have the weight. But I wasn't to know it needed one.....

Thankfully, the weight is available separately, so more cash sent to the US economy, and all bolted up and vibration has gone :thumbright:

Set me about a month back, but onto the last few bits and hopefully the Belvedere will ride again!
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Blue
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Location: Straight outta Royston

Re: Vibration around 1300 rpm then goes - when at a standstill

Post by Blue »

Glad you've sorted it!
I won't mention that I have one of those weights in my toolbox that I left off the damper for a neutral balance application....
“This ain’t no party, this ain’t no disco, this ain’t no foolin’ around”
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deppmobile
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Re: Vibration around 1300 rpm then goes - when at a standstill

Post by deppmobile »

:shock:
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DaveB
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Re: Vibration around 1300 rpm then goes - when at a standstill

Post by DaveB »

At least you had the sense to investigate, most just ignore it, I take it your engine builder aint a mopar guy.
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