piston rings

[kurt v]

Can i leave the bottom oil ring off the pistons or is it really needed ?
59a motor with merc crank and pistons . 4 ring pistons.

thanks kurt

[KiWinUS]

I leave the 4th ring off and use the multi piece steel oil ring in third groove.

[tubman]

I did it on my last build. It worked out great, but the rotating assembly really should be balanced to account for the change in piston weight.

[flatjack9]

I have never rebalanced after leaving that ring off., which I do on all my builds. Engines still as smooth as can be.

[tubman]

I would rebalance any engine rebuilt with the possible exception of where all the original components (crankshaft, rods, and pistons) have been reused.

It's just good practice.

[petehoovie]

Sponsored Links (Register now to hide all advertisements)

From 'Rumble Seat's' Flathead Tips - https://web.archive.org/web/20160318...lest/intro.htm

RINGS: Ford originally came with 4 ring pistons to decrease excessive oil consumption. Rings contribute the most friction of any engine component. Check the drag on one piston in a cylinder using 4 rings and then again after removing 1 oil ring. Amazing! Increased friction causes a build up of heat as well as a reduction in hp. The added friction of the 4th ring causes an engine to run hotter.... something we really don’t need in our flatheads. To overcome friction requires hp...... hp I’d sooner be using for fun things. Why not change and run 3 rings which have 25% less drag than 4 rings do? Makes sense to me. Recent engines normally have only 3 rings and they last well past 100K miles.

[tubman]

I read on the H.A.M.B. that the fourth oil ring was added to solve an oil consumption problem that was prevalent with some of the very first Ford V8's. Over the years, piston ring technology evolved, but for some reason Ford never chose to take advantage of it, and Ford pistons were 4-ring until the end of the flathead era.

There was some concern expressed that leaving the fourth ring out would destabilize the piston in the bore, but when you realize that it is the piston that stabilizes the rings, that goes out the window.

Jack, how much does that fourth ring weigh? It sounds like reducing the rotating mass of each piston/rod assembly by the same amount doesn't make a lot of difference in overall balance.

[Benson]

delete