cougarfan088

I was just wondering what gap you guys run top and bottom. how much benefit have you guys notcied from individually gapping them?....also what ring grinder are you using?...I have a machine shop to my disposal so im thinking of making my own.

Portmaster

Depends on the piston, type of rings, intended use for the engine. I have a Sunnen electric but I end up using my Powerhouse manual hand crank unit most of the time. I made a stand from a 12 inch brake rotor and piece of roll bar tubing. I just slide it over close and fit the rings. I have no idea how much differance in performance because I won't build a performance engine with anything but file fit rings

cougarfan088

what kind of rings and what kind of gap did you run on yer 347?

uedlose

like said it depends on pistons used ring manufacture but also on if you are gone to run a power adder and what kind of fuel you are gone to burn. I just use a summit ring grinder with a hand crank.

cougarfan088

sry, I should have clarified what engine/build I was talking about. what kind of gap are you guys running with an NA 347 and what rings are you using? or what gap would you reccomend.

Portmaster

Building for a Nitrous shot on my 347 I went .020 on the first and second ring with Forged pistons.

Portmaster

Again it all depends on the piston (Forged, Hyper?, How it will be used (Street, Race, Superchaged, Nitrous?) Tell me exactly what you have Piston make and material, How it will be driven (Street, Race) What type of fuel (Gas, Race Gas,etc) Exact bore size (prob 4.030) and then I can give you a piston ring end gap.

cougarfan088

its going to be a 347 NA, with a small 75 shot(for giggles), pump gas, its going to be a very, very aggressive street car which will probably see some life at the track but it wont live there. 4.030 bore, forged pistons,crank,rods.

I really like the sound of going with a .020-.024 gap. I read somewhere that for the second ring they go with a bigger gap becasue sometimes the ring is cast and it will allow it to expand a little more. I am not quite sure though the reasoning exactly why you would want a bigger gap on the top. high rpms and expansion?

Portmaster

I'd prob go .020 top .022 on the second in your case. A lot will depend on who makes the ring. With just a 75 shot you could prob go .016 and .018 but if you decide you want to get greedy open up the gap.

cougarfan088

I think im going to go with .022 on the bottom and .019 on the top. you think .024 on top would cause too much blow by? or since im going with a 75 shot you think I should have a smaller gap?