I bought a set of JE/SRP forged pistons for my 383 buildup. On the sheet supplied by srp it says that the normal operating clearance is .002-.0025 .
It also states that some applications such as marine, DRAG RACE, NITROUS and forced induction may require additional clearance, .001-.003 .
These are 4.030 -16cc dish pistons for forced induction/nitrous use, for my daily driver, wich will see regular trips to the drag strip and some nitrous (100hp)

I have 6 inch rods with a 3.75 stroke crank. rings on these pistons are 1/16 1/16 3/16

My question is what do I need to set the clearance at ?
Should I stick to the "recommended" .002-.0025 or go with more clearance?

Also, what ring gap should I run ? The rings are "Classic race" from total seal.

Thanks for your time and responses !!

Charles

 

Set them as a street engine. You're not using NOS all the time like a drag motor would. A 100 shot doesn't need special piston to bore clearance. If you were going to do a 400+ shot then you need some more clearance but then that's also an engine that isn't going to run 100,000+ miles on the street.

Rule of thumb for normal rings is to gap rings .004" per inch of bore for the top ring and .005" per inch of bore for the second ring. Gap the top ring at .016" and the second ring at .020"

You're building a street engine that's going to see limited racing. You're not building a race engine. Use the specs supplied for a street engine.

 

Thanks !

I know the 100 shot is not much compared to what some people run... I was just wondering if I was better off using larger gaps and more clearance for the occasional nitrous shot.

But since this is a street engine predominantly, I think it makes sense to use street specs

 

Keep it on the low side. Do a decent(500mile) breakin before you squeeze.

basically, ditto what that guy said :-D

 

Don't use "rules of thumb" for ring gap end clearance. It is HIGHLY variable depending on what the design and material of the piston is. CALL THE PISTON MANUFACTURER AND ASK THEM. NOT the ring manufacturer- the piston manufacturer. You may find it is significantly different that what you were going to set it at.

You don't want to know what happens in a boosted/nitroued motor if you butt the top ring gap together. Very little left to salvage from the motor. Ask me how I know.