Vibration during acceleration

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Model T Ford Forum: Forum 2017: Vibration during acceleration
Top of pagePrevious messageNext messageBottom of page Link to this message  By Wilf Bradbury on Friday, July 28, 2017 - 01:41 pm:

1914 roadster, vibrates/shudders when accelerating through15- 25 mph and is worse when under load. Once up around 30 35 mph fairly smooth.
Have tried reducing spark which helps a very little mixture change no effect. Engine was rebuilt using high compression pistons. quite noticeable when going up hill. Otherwise at low speed very smooth, easy to start and will idle very low rpm smooth.
Puzzled


Top of pagePrevious messageNext messageBottom of page Link to this message  By David L Corman on Friday, July 28, 2017 - 02:32 pm:

U-Joint ?????


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Friday, July 28, 2017 - 03:42 pm:

Do you have the 2 wood side blocks between your motor mounts and frame?? If not, add them, along with the side bolts which some leave off, and test it out again.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Bourgeois on Friday, July 28, 2017 - 03:53 pm:

Jerry,
Do you have a picture of the wood side blocks that your talking about? I don't recall wood block between the motor mounts and the frame.

Steve


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wilf Bradbury on Friday, July 28, 2017 - 03:55 pm:

Jerry ,
Yes I've tried that .thanx
Daves suggestion about the U joint is something I had not considered. knowing the history of the car that might be worth a look!
Also a good time to check for babbit thrust washers!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, July 28, 2017 - 04:27 pm:

It's possible it could be an ignition problem. Especially with high compression pistons. It takes stronger spark to fire under high compression which is what happens when you accelerate and the high compression pistons will increase the compression beyond normal. Spark plugs or ignition coil problems on on or two cylinders could cause this problem.

A symptom of a loose universal joint would be a noticeable clunk when you back off the gas. If it clunks when you give it gas and when you back off the gas you have something loose in the drive train which could be a U joint. That doesn't fit the description of the vibration.

Also engine or transmission balancing could be a problem but are usually more noticeable at higher speeds.

Other vibrations which are not in the engine would be wheel shimmy or wheel balance problems.
Norm


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