Motor Vibration

whirnot

whirnot

Well-known member
Being new to model A's I am not always sure what to expect. At higher rpm's a seem to have a fair amount of engine vibration. Don't you love the quantifying amount? It is less noticable when under a load such as going uphill. I am wondering if repalcing the motor mount rubber would lessen it or if it may be just normal.

I have a insert engine that was put in about 5 years ago, and I think the car has been used a very little amount since.
 
Yep, Bill is right. The stock Model A does not have a counterweighted crank. But still... vibrations in a new insert engine? Maybe it wasn't well-balanced. Or maybe the flywheel wasn't balanced. Do you know any of this history?

I'll refer you to a good resource: Page 1-28 of the Model A Ford Mechanic's Handbook, Volume II, by Les Andrews. (green book)

I used this resource and a few things helped me. New fan, new front motor mounts, new distributor, new carb. But my engine still rattles yer knuckles.
 
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Hi Bill,

Humble opinion:

Very normal question; however, a very sincere 1930's question/answer response for excessive engine vibrations might be:

Who last assembled the engine with inserts? Was it:

A. A reputable engine rebuilder many heard of; or,

B. The guy down the street with a tent, who repairs fly swatters & tooth brushes for a living?

Really a very tough question to answer with little details.

Hope this helps.
 
It is an H&H engine. It may be normal, I really only notice it at high RPM's and especially in a decelerating mode, ie downshift. When running it with my head under the hood (obviously not usually at highway speeds) it purrs like a kitten.
 
Hi Bill,

If you or the car are in Bend, go talk to Bill Barlow. He is a great engine rebuilder and can answer your questions maybe by taking a drive in one of his cars? Being 'new' it may be that is normal for your car or not. I know my car will vibrate a bit downshifting, but w/o being there it is hard to tell.

Mike
 
Example: '60's, Jaguar Mark 2 Sedan, notably a VERY smooth car! One was sold 3 times because of a HORRIBLE roar throughout the car. I found a motor mount bolt was too long, causing metal to metal contact between motor mount bracket & frame. Put a shorter bolt & car was Perfectly Quiet!
Point being, what can we expect from a Model A? It is what it is.
On Minerva, I did FAM's front & rear, rubber exhaust hanger, good weatherstripping on trunk & doors, all new door rubber bumpers, etc. She was like a DIFFERENT CAR!!
Lots of work & expense, I won't do it on Vermin, I'll just leave him stock & ENJOY the "stock" experience. Bill W.
 
Sounding more and more like it is normal. like suggected I just need to go for a spin in a few more A's
 
Chief's friend spent $$$$$$$$$$$$$$$$$$$$$$ to build the PERFECT '29 Town Sedan. It DIDN'T go HMMMMMM! & he sold it, VERY SAD. Bill W.
 
Make sure your engine, transmission, and torque tube are properly lined up. Mine was a little off when I got the car.. I made some adjustments and my car goes down the road with much less vibration than before.
Mike
 
whirnot said:
It is an H&H engine. It may be normal, I really only notice it at high RPM's and especially in a decelerating mode, ie downshift. When running it with my head under the hood (obviously not usually at highway speeds) it purrs like a kitten.
Click to expand...
:eek:
 
The 1928 cars had the solid motor mounts on the front crossmember with little in the way of cushioning vibration. I understand that Ford would happily cut down the '28 front crossmember and put a later front motor mount with some flex to cushion the vibration. Not everybody took Ford up on that, however, so there are still lots of solid front motor mounted Model A's out there. Yours isn't one of those, I don't suppose???

BTW, those of you who acquired '28s with the solid front motor mount, did you convert them over, or Not??? This is supposedly a purist-leaning forum, so did you modify the '28 A's or leave them stock, even if stock meant a lot more engine vibration?
 
My huckster vibrated more for a time after I installed the rebuilt engine. As I used it more and it became broken in more, some of the vibrations seemed to go away. But like mentioned, the old Model A does vibrate. Also what do you mean by high RPM's? Are you doing 60 MPH or in the 30 to 40 MPH range. If the 60 range, that could cause more vibrations.
 
On my A it seemed smooth at first ,but after about 30,000miles it got a slight vibe on deceleration, like a dunce I left it for another 5000mls before taking a shim from the mains,clearance was front .002 center.005 and rear .007,
after setting them all at .0015 the eng was back to smooth.but it only lasted a few thousand miles and the vibe was back.
this time I took the engine out and removed the crank to look at the mains,they were cracked ,
I thought from not taking a shim out soon enough.
I then fitted insert mains and the eng was a bit better,but still with the vibe on deceleration.
Later I had the exhaust port rot through into the water jacket ,so I transferred all the rods ,crank and pistons into another block,I had to bore the block to fit the used pistons from the old engine,I reassembled the engine and noticed straight away that it was MUCH smoother than before.

Later I changed my A from a home made open cab and fitted a closed cab.
Guese what the vibe is back,
Maybe not a vibe ,but a drumming noise when on the deceleration about 48mph.
All this time the babbited rods have never needed adjustment.
Lawrie
 
Hi Bill,

Heard from an engine re-builder about 10 years ago experiencing engine vibrations after rebuild -- he then took it all apart, re-weighed pistons & rods, etc., etc. etc.

Put engine back together --same vibrations.

Removed fan belt -- no vibrations.

Exchanged water pump "&" fan -- no vibrations.

So few are this lucky; but fan belt removal is one easy test.
 
Are you feeling the vibration or perhaps just hearing the vibration. If it is more hearing it especially on decelaration could be your spark and advance anti rattlers are bad. They can make a heck of a racket and vibrate the steering column / wheel.
Dave
 
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