Technical flathead four ring piston

What about leaving the bottom oil ring off? Positive improvement or neg.

 

Back in the day, guys who were bucks down and wanted to go fast for a little while took a hacksaw and cut the piston skirt off at the groove for that 4th ring.
Dave

 

This is for a 34 truck street use.

 

The guys that did stuff like that were bucks down, trying to make the next race, and needing some pistons. Had these old 4 ring stock type in the junk box and too broke to buy a set of solid skirt 3 ring racing pistons. The 4th ring was below the wrist pin and they just sawed it off and filed it smooth and flush with top edge of ring groove.
Not something I would recommend for street or racing, but especially not for street.
Dave

 

If you are using a modern ring pack with a good 3 piece oil ring, I say no problem leaving the bottom ring off.

 

i would leave it on. If you want a 3 ring piston, buy 3 ring pistons

 

the 4th oil control ring was used by many manufacturers as a means to control oil and limit piston slap in an era where worn motors were kept going longer after the factory clearances were reached or exceeded. It used to be a "trick" to recondition an engine using the 4 ring piston and leave the 4th ring out. Once the motor had done miles and started using a bit of oil you would drop the sump - lower the piston and slip the 4th ring in. VOILA instant oil control untill that part of the bore wore too. We have better metal these days moly rings as an example.
4 ring pistons will work OK on 3 rings

 

Yep, that's what I'd do! With the modern rings, you don't need the 4th ring.

 

Dave , Sounds like something I would have done, poor mans performance update ,less friction, go faster, smoke like hell.....Hahahahahh

 

Another fact in leaving the 4th piston ring out was that in newly rebored engines the 4th piston ring starved the piston wall of not enough oil to lube the bottom of the bore and you could get premature bore wear or piston grip. Most of the this rings function was to control oil consumption in a worn engine. If the engine was not worn then it was not needed. The reason I know this is because my Dad taught me this when I was a nipper (early to mid sixties) helping him i his car repair shop - by the time I was old enough to do work on my own vehicles (mid seventies) 4 piston ring set ups had been superseded

 

Mac V and JWL avised to leave them on so I left them on. Thanks for all the imput.

 

Yup x2

T

 

In the old days, like the 40s and 50s it was common to leave off the 4th ring to reduce friction and weight. It did contribute a little extra HP at the expense of a slight increase in oil burning.

With modern rings you shouldn't need the 4th ring at all. New cars stopped using a second oil ring in the 50s.