Engine knock

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Model T Ford Forum: Forum 2017: Engine knock
Top of pagePrevious messageNext messageBottom of page Link to this message  By vincent c bassani on Friday, December 01, 2017 - 06:35 pm:

my 25 open express has a knock that comes and goes. can improperly adjusted spark advance cause this? i use regular gas with a lead additive, is that ok ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Blake, Kansas City on Friday, December 01, 2017 - 09:05 pm:

The octane of today's fuels almost makes spark knock impossible in a stock model T, no matter where you have the advance lever. And a lead additive is not necessary given the low valve spring pressure used in a T.

Please elaborate on the specifics of how the knock comes and goes.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, December 01, 2017 - 09:21 pm:

Some knocks come when you slack off the gas and just go along at an even speed. Usually a rod knock. The knock which comes when the engine is pulling hard is usually either a main bearing or a loose piston. A constant double knock is quite often a loose wrist pin. A knock which usually happens at idle can be a loose pulley or the pin through the front crankshaft pulley. Some knocks are caused by the cam bearing or loose valves.

Some knocks are noticeable in a cold engine and go away as the engine warms up.

So you need to describe the knock a little better to be able to pinpoint it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charles Weisgerber- Vancouver WA. on Friday, December 01, 2017 - 10:23 pm:

In addition to what Norman mentioned; if you are running a re-ground cam shaft you could have excessive end-play causing the front lobe of the cam to hit the notch in the front cam-bearing now and again This is a relatively easy fix by installing a kit designed for the purpose. The major vendors carry it. Just some thoughts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By tommy coffey on Friday, December 01, 2017 - 10:27 pm:

I just shimmed my crank pulley. It was making a knocking sound.


Top of pagePrevious messageNext messageBottom of page Link to this message  By vincent c bassani on Saturday, December 02, 2017 - 09:22 am:

thanks so much. i will provide more info as i monitor it closer.


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