Cylinder wall taper

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Model T Ford Forum: Forum 2016: Cylinder wall taper
Top of pagePrevious messageNext messageBottom of page Link to this message  By Allen Brintnall on Thursday, August 25, 2016 - 10:30 pm:

I have about 8 thou. taper on my 26 TT. What can I get away with and not have piston slap noise? Standard bore, good steel pistons. Allen Brintnall S.W. Mo.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Spencer Vibert - Granby ,CT on Thursday, August 25, 2016 - 10:36 pm:

Allan you could get away with that on a car that is just used for parades and not having more than 500 a year put on it. If it were me and I want to really drive it I would bore it to the next size


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Thursday, August 25, 2016 - 10:48 pm:

I suspect you have heavy cast iron Pistons. I classify any iron piston as bad. You have excessive clearance. The block needs to be bored and you need new aluminum Pistons.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allen Brintnall on Thursday, August 25, 2016 - 10:55 pm:

Spencer: Thanks for your input. I realize it is marginal, but I know it will not get a lot of miles put on it, I just don't want to hear piston noise. 6-8 is pretty consistent with my dial gauge. Allen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Blake, Kansas City on Thursday, August 25, 2016 - 11:04 pm:

I agree with Royce ........and also Spencer, provided your intent is very limited use.

I commented in a previous post regarding the general subject of cylinder taper from my machine shop experience.

http://www.mtfca.com/discus/messages/599638/664161.html?1470146164


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allen Brintnall on Thursday, August 25, 2016 - 11:05 pm:

Royce: You are right, cast iron. I just didn't want to bore it if I didn't need to. Allen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allen Brintnall on Thursday, August 25, 2016 - 11:21 pm:

Gary; Thanks for the explanation about heat transfer and your input. Allen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Friday, August 26, 2016 - 02:15 pm:

You can scuff the cylinders lightly with a home or emery cloth and install new piston rings. It won't be perfect but it will work. You might want to do a dry and then a wet compression test before you do anything.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allen Brintnall on Friday, August 26, 2016 - 03:00 pm:

Thanks Ted, I deglazed the cylinders, new valves with oversize stems, new adjustable tappets, good crank, rear main cap to get end play right, I just have a little too much clearance for a perfect piston fit. I am concerned about the possibility of piston slap noise. I want it to work, it doesn't have to be perfect. Thanks. Allen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould, Folsom, CA on Friday, August 26, 2016 - 05:57 pm:

Since you've done a valve job and deglazed the cylinders, I suggest you replace the rings and run it. My guess is you'll be surprised how well it runs.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Blake, Kansas City on Friday, August 26, 2016 - 09:51 pm:

Not sure if anyone does this anymore but it is possible to knurl pistons to reduce clearance. I did it decades ago on an engine (not a T) I didn't want to spend any money on. Essentially after knurling, the piston will be too big for the bore which means you then have to hand fit them to the bores. It can also allow for straightening out the bores with a good rigid hone. Keep in mind most pistons are tapered and cam ground, meaning they are not actually cylindrical in shape. You will need to be good with a micrometer as you work the areas raised by knurling down to the proper clearance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allen Brintnall on Friday, August 26, 2016 - 11:53 pm:

Thanks guys for your input. I enjoy following this forum. Allen Brintnall S.W. Mo.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Blake, Kansas City on Saturday, August 27, 2016 - 12:13 am:

Allen,

I sent you a PM.


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