Author Topic: Engine vibration (Read 16915 times)

MACH_ONE · « **Reply #25 on:** May 28, 2015, 08:47:28 pm »

It does sound like a miss match

66FBK · « **Reply #26 on:** May 30, 2015, 09:29:32 pm »

I have had a mismatch running and early 28oz flex plate on a 5L roller engine. a vibration above 2k enough to shake the rear vision mirror around. I have also had a harmonic balance de-laminate and spin the inner & outer about 20 deg. This also caused a vibration . This was hard to pick up and was only when I compared the position of the counter weight with a new one at TDC I was able to prove it. A 50oz harmonic balancer with have 4 bolt holes for the pulley not 3 for the 28oz.

flatchat · « **Reply #27 on:** May 31, 2015, 08:14:54 am »

Have we confirmed that its running correctly on all 8 cyls yet ??

GLENN 70 · « **Reply #28 on:** May 31, 2015, 08:47:47 am »

Strange how you fitted the original flex plate back on and now it has got worse . As others have said ,make sure it is running on all 8 cylinders . Does it get worse as the revs come up ,is it there from idle , does it get better at high revs . Does it have power steering or air cond ,if so take the belts off and try that . It could be a front pulley and you can start the engine with out them on ,BUT only for a short time (water pump) won't be working .

GEOFF289 · « **Reply #29 on:** May 31, 2015, 10:25:28 am »

Starting to look like it actually had the correct flexplate on it and the source is something else if swapping to the other plate made the vibe worse. It should surely be pretty straightforward to determine whether its an old 28 ounce engine or a newer 50 ounce one?

barnett468 · « **Reply #30 on:** May 31, 2015, 10:48:48 am »

Quote from: GEOFF289 on May 31, 2015, 10:25:28 am

It should surely be pretty straightforward to determine whether its an old 28 ounce engine or a newer 50 ounce one?

almost . . If it has a 5.0 casting number, it is most likely it has a 50 oz crank but pulling the oil pan as i suggested will be a positive way to know..

5.0 casting number location is on the rear of the block behind the starter.

289 and 302 casting number location is on the side behind the starter.

.

ants · « **Reply #31 on:** May 31, 2015, 11:02:28 am »

My brother once owned a ski boat with a Cleveland V8 that had a vibration (no backfiring). Took it to an inboard boat specialist who told him motor needed a rebuild which he did and it came back exactly the same. Turned out to be spark plug leads on around the wrong way.
What I'm trying to say is don't overlook the simple things.

dyates · « **Reply #32 on:** May 31, 2015, 01:52:42 pm »

The engine is running on all 8 pots and have checked the leads to make sure that is all correct.Glenn,have not run it with the belts off so will give that a go.So far to date all the external balance motivators have been swapped out or replaced to no avail.

Most of this experience has been done with the car stationary and the vibration increases as the revs come up,took it for a short run and on backing out of the throttle the vibration becomes cyclic and decreases as the engine revs drop.It is not associated to a drivetrain issue.

Have a full set of pulleys off a 302 so will chuck them on before we pull the engine out,the only new addition to this car was fitting AC.

Will keep you all informed,thanks so far everyone.

GEOFF289 · « **Reply #33 on:** May 31, 2015, 04:33:51 pm »

If its set up like mine you can just disconnect the AC belt and leave everything else as is and test drive it as far you want to see if that change is what's behind the vibe.

flatchat · « **Reply #34 on:** May 31, 2015, 05:35:12 pm »

Now rule out compression test , valve lash too tight, broken valve spring, bent valve etc
Then --is the gearbox and tail shaft OEM ie is the tail shaft too long / short ?? as you stated that jacking the g'box improved things-- is a good clue -- maybe disconnect it and run the motor with just a slip yoke
Look forward to a happy ending

GLENN 70 · « **Reply #35 on:** May 31, 2015, 05:56:31 pm »

Does it get worse when revs come up and keep going OR does it settle down at higher revs? .

noblg · « **Reply #36 on:** May 31, 2015, 06:47:29 pm »

Hey guys,
If the engine had been rebuilt. Did they put in a roller heads, ?
Therefore it would need a 50 ounce, flex plate, like the late model windsors.
Or am I on the crystal meth?

GLENN 70 · « **Reply #37 on:** May 31, 2015, 07:09:21 pm »

Yep you are or must be

GEOFF289 · « **Reply #38 on:** May 31, 2015, 07:26:30 pm »

Quote from: noblg on May 31, 2015, 06:47:29 pm

Hey guys,
If the engine had been rebuilt. Did they put in a roller heads, ?
Therefore it would need a 50 ounce, flex plate, like the late model windsors.
Or am I on the crystal meth?

Many, many things I don't know but can't see how a set of heads could upset the reciprocating balance.

flatchat · « **Reply #39 on:** May 31, 2015, 07:52:23 pm »

Umm ya need to know about hallucionogenetics

66FBK · « **Reply #40 on:** May 31, 2015, 09:53:55 pm »

How's this for a theory. Could your engine builder have changed the crankshaft over to a 5L one. I know the rear seal is different. This combo would give you a imbalance or.. or .. maybe a 351W cam which has a different firing order could have been slotted in. Not sure if this would upset things but worth a thought. Might be time to run a few questions past you mechanic.

GLENN 70 · « **Reply #41 on:** June 01, 2015, 09:01:24 am »

I would be looking at the firing order also .seeing the engine has been rebuilt a later model camshaft may have been used with the different firing order . 15426378 old ,13726548 new . A very easy mistake with the camshafts

GEOFF289 · « **Reply #42 on:** June 01, 2015, 09:22:50 am »

Quote from: GLENN 70 on June 01, 2015, 09:01:24 am

I would be looking at the firing order also .seeing the engine has been rebuilt a later model camshaft may have been used with the different firing order . 15426378 old ,13726548 new . A very easy mistake with the camshafts

Would it even run with the plugs all firing at the wrong time Glenn?

GLENN 70 · « **Reply #43 on:** June 01, 2015, 09:41:23 am »

Yes it does still run ,but less power and a vibration . Yes sometime depending on which leads are on wrong it will back fire but not all the leads will do that . Dyates does it seem to be down on power for a fresh rebuilt engine ? .

barnett468 · « **Reply #44 on:** June 01, 2015, 10:15:20 am »

Quote from: GEOFF289 on May 31, 2015, 07:26:30 pm

Many, many things I don't know but can't see how a set of heads could upset the reciprocating balance.

see...you learned something new today . . they are "roller heads".

barnett468 · « **Reply #45 on:** June 01, 2015, 10:18:22 am »

Quote from: noblg on May 31, 2015, 06:47:29 pm

Hey guys, If the engine had been rebuilt. Did they put in a roller heads, ? Therefore it would need a 50 ounce, flex plate, like the late model windsors.
Or am I on the crystal meth?

no...i believe its the liquid kind.

but look on the bright side...at least you're not a lawn bowler .

.

dyates · « **Reply #46 on:** June 01, 2015, 12:14:39 pm »

Glenn70,the engine feels quite strong and not down on power,just has this vibration as the revs increase.The owner is away for a week so will not have a chance to work on it for a while

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Author Topic: Engine vibration (Read 16915 times)