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Engine vibration #1317260 Wed Jul 10 2019 10:38 PM
Joined: Feb 2001
Posts: 1,034
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Dusty Offline OP
Shop Shark
As an interim engine , while I finish rebuilding the new one , I fitted a '54 235 to my '40. It's great , pulls much stronger than the original 216 , I'm kinda thinking I might keep it .

BUT .

It has a nasty , high frequency vibration , worst thru 1200 to 1800 rpm . Right where I normally drive . Really tingly thru the gear shifter .

Engine runs dead smooth and quiet at idle , not too bad at 2500 rpm (on the road) . I've been fantasizing that an engine builder just bored one cyl .............. LOL .

I fitted a new clutch assy at the time , had the flywheel and pressure plate balanced .

Now I'm wondering if the harmonic balancer is bad .

Has anyone had a similar experience . What was your fix . Thanks ,

Last edited by Dusty; Wed Jul 10 2019 10:39 PM.
Re: Engine vibration [Re: Dusty] #1317263 Wed Jul 10 2019 10:51 PM
Joined: Dec 2003
Posts: 1,077
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MikeE Offline
Shop Shark
If you have a running 235, I would not bother rebuilding the 216. My first thought would be a rod or main bearing that has too much clearance. Only a long shot guess. Did you run the engine before you installed the transmission? Another guess would be something in the trans. How is the compression? I am now out of hallucinations, anyone else?


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Re: Engine vibration [Re: Dusty] #1317277 Thu Jul 11 2019 12:53 AM
Joined: Mar 2004
Posts: 3,755
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Mike B Offline
Shop Shark
Are you sure it's coming from the engine...could it be a bad U-joint?

Mike B smile

Re: Engine vibration [Re: Dusty] #1317283 Thu Jul 11 2019 01:23 AM
Joined: Feb 2001
Posts: 1,034
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Dusty Offline OP
Shop Shark
First up , the truck was running perfect , smooth , just how you would expect a nice 78 year old 216 to run . I decided to change it due to the cracked block.

The 235 was a free engine , no history , sat on the garage floor for a long while . Compressions are 150 +_ 5psi . I started it on the floor . Sounded as good as you can guess with no exhaust pipe .

I swapped out the sm420 , for the original 4spd as I had fitted new bearing to the original box some years ago . It is a good g/box.

The vibrations are totally evident when just revving the engine at standstill .

No noise from bearings , no piston slap , a little valve lifter from 2 , just shakes .... (new engine mounts)

Still pondering dud harmonic balancer .

Re: Engine vibration [Re: Dusty] #1317292 Thu Jul 11 2019 02:10 AM
Joined: Feb 2004
Posts: 18,689
H
Hotrod Lincoln Offline
Boltergeist
Set the idle screw to the RPM where the shake is most evident, then start disconnecting spark plug wires one at a time to make sure all the cylinders are firing. A tachometer and a vacuum gauge will help isolate a cylinder miss- - - - -little or no drop in RPM and/or vacuum means you've got a weak cylinder. You can also run the engine for short time with the fan bet removed to rule out an unbalanced fan, or problems with the water pump or generator.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Engine vibration [Re: Dusty] #1317461 Fri Jul 12 2019 04:56 AM
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Posts: 983
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Truckrolet Offline
Shop Shark
I think the key thing here is you had the flywheel and pressure plate balanced. Why? And it maybe the problem.


Ret, Machinist , Industrial Engine
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Re: Engine vibration [Re: Dusty] #1317465 Fri Jul 12 2019 05:30 AM
Joined: Feb 2001
Posts: 1,034
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Dusty Offline OP
Shop Shark
Trucko , I had the balance job done to try to eliminate this issue.

Re: Engine vibration [Re: Dusty] #1317466 Fri Jul 12 2019 05:31 AM
Joined: Feb 2001
Posts: 1,034
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Dusty Offline OP
Shop Shark
Jerry , I will give your suggestions some work this weekend . Thanks .


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