Piston clearance

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Model T Ford Forum: Forum 2018: Piston clearance
Top of pagePrevious messageNext messageBottom of page Link to this message  By CHRIS SHEPPARD on Tuesday, June 12, 2018 - 06:46 pm:

I'm new to asking questions here. My question is I have a 19 model that had an engine knock, when I pulled the rods and pistons out they were cast iron pistons and heavy rods. I am going to order new pistons and rods , the rod journals are 1.237 - 1.241 diameter. will this give me to much side clearance on the sides ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Tuesday, June 12, 2018 - 07:52 pm:

Chris, new rods on journals which vary as much as your measurements show is not a good mix. Your crankshaft needs grinding and rods selected to suit, or vice versa.

Hope this helps.
Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Tuesday, June 12, 2018 - 08:28 pm:

Chris,

If the journals are round and not tapered then you can fit the rods. For instance if one journal is 1.237 and the next one is 1.241 then you are in luck. However if one journal is 1.237 one end and 1.241 the other or 90 degrees out then you need to do as Allan suggested and grind the crank, or buy a new crank.

If you are in luck and can fit the rods, the best way in my opinion is to use the yellow Time Saver lapping paste, available from the parts houses.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By CHRIS SHEPPARD on Tuesday, June 12, 2018 - 08:57 pm:

THANKS


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Thompson Graham NC on Tuesday, June 12, 2018 - 09:52 pm:

What does your cylinder bores measure. Philip


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Tuesday, June 12, 2018 - 10:31 pm:

With skill and patience it might be possible to file the rod journals round, then polish with emery cloth. A rod journal tapered or out of round by 0.004 will not hold its adjustment.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Wednesday, June 13, 2018 - 06:40 am:

Ted,

I have polished one journal on a 1923 Buick using emery cloth that had a small amount of surface damage but still round and not tapered. For out of round or tapered journals, I would recommend a re grind over filing.

Neil


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