Stock piston/ring issues
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Freshman User
Joined: Apr 2014
Posts: 31
Likes: 0
From: Chaplin
Stock piston/ring issues
So I'm rebuilding a 1997 351w for my F250. The engine is in fantastic shape so I'm doing a basic re-ring and gasket job. I bought a federal mogul rebuild kit part# FEM-MK6116D000 I also bought a set of speed pro H336CP pistons just in case I found anything I didn't like. So like I said the engine is in great shape so I went to put the rings on the oem pistons and the oil control ring will not fit in it's groove and I mean IT WILL NOT FIT AT ALL. When I ordered the parts I accidentally ordered a set of summit brand rings for the stock bore so I pulled them out and I have the same problem. For kicks I grabbed the speed pro pistons and the rings drop right in. My question now is do the oem ford pistons have a smaller groove than the aftermarket pistons and is it possible to find a set of oem rings or should I be looking to have the pistons swapped out?
Logistics Pro
Joined: Aug 2010
Posts: 3,716
Likes: 583
From: Chillicothe
Glad you got it figured out. I wasn't able to get to my book till now, but if you need exact numbers, moly rings from speed pro are E-251K and plasma moly rings are R-9903 both for standard bore. For the 336cp pistons
New User
Joined: Dec 2017
Posts: 20
Likes: 0
I’m sure nothing is wrong. I’m a rookie to inside motor. I’m 50 years old Electrician by trade and worked in maintenance facilities all my working career. I’m a dang good parts swapper lol. I had just never been inside motor. I’m learning as I go. Competent I am. Just the unknown. Using any resource to help out. I have chosen one only problem is I can’t seem to just buy one set of rings for one piston in this particular case from Rock-auto.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Yea, you have to buy a whole set, they used to sell single piston ring sets long ago, but not today. Are you looking for rings for a std bore ? Or an oversize piston ? I have a broken set or two of rings that might fit yours. Let me know what size rings and the oversize (or std) and I'll check.
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New User
Joined: Dec 2017
Posts: 20
Likes: 0
That would be awesome . Compression 1.5mm Second groove 1.5 mm oil ring groove 4.0 mm. I can purchase entire set through Rock Auto $63 and local auto part (NAPA) wants $150 same part number.
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Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Std or oversize ? I'll look tonite when I get home. I have two sets stashed at the house. One is .030, don't recall what the other was. One may be metric rings.
Cargo Master
Joined: May 2007
Posts: 2,071
Likes: 36
From: British Columbia
I understand that Ford switched to the thinner metric rings to reduce drag, and to possibly slightly reduce blow by.
Is there any significant difference in performance to consider upgrading from old style pistons and rings to these newfangled metric pieces when rebuilding, for a daily driver truck?
Last time I checked, they were considerably more money.
Is there any significant difference in performance to consider upgrading from old style pistons and rings to these newfangled metric pieces when rebuilding, for a daily driver truck?
Last time I checked, they were considerably more money.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
I understand that Ford switched to the thinner metric rings to reduce drag, and to possibly slightly reduce blow by.
Is there any significant difference in performance to consider upgrading from old style pistons and rings to these newfangled metric pieces when rebuilding, for a daily driver truck?
Last time I checked, they were considerably more money.
Is there any significant difference in performance to consider upgrading from old style pistons and rings to these newfangled metric pieces when rebuilding, for a daily driver truck?
Last time I checked, they were considerably more money.