FrontEngineDragsters.Org Forum
Technical => Matt Shaff's Engine Shop => Topic started by: Mister_Fitz on May 11, 2014, 02:03:28 AM
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I'm just about to adjust the piston ring end gap of my new rings and a question came up..
I have and old FED with a 350" SBC. The engine is alcohol injected with a Enderle stack injection. The bore is 4.00" and it has forged Arias pistons.
The block is half filled with blockfiller and there is water in that part of the block that is left and in the heads. No water pump or radiator. E.g. not a normal working cooling system.
I have also had some plans on skipping the water which causes lots of extra work filling and draining.
I have got some new gapless top rings from Total Seal.
They recommend:
Top = 0.026"
2nd = 0.022"
But this is most likely for regular engines with a working cooling system that will keep the engine at a more constant temperature.
Will that fact that I run my engine with out a working cooling system affect the piston ring end gap?
Is it a good or bad idea to increase the end gap just to make sure the rings will not butt due to heat?
I have also read that the gap of the 2nd ring should be larger that the top ring gap. In this case the top ring is gapless so I suppose there will not be any pressure building up between the rings?
Are there any rule of thumb or best practices regarding the piston ring end gap on this type of engines?
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Mr Fitz,
I'll let the pros speak, but here's my 2 cents in the meantime.
I think your ring gaps are OK for your setup, as long you don't use nitro, nitrous or boost. They in the ballpark of what I used on my alky SBC 400 (Speed-Pro rings: Top: 1/16" - Plasma-Moly Ductile Iron ; 2nd: 1/16" - Cast Iron).
In doubt, you could also call Total Seal.
My block is tall filled, no radiator, but I circulate water with a small electric pump. I'm tempted to ditch the pump at some point, but I don't think I will ever go all dry.
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I never use less gap for second, I suggest you dont either.
Second ring is not for compression sealing, its only purpose is keeping oil from the top ring.
If there is less gap on second, pressure will build up between the rings from the microscopic leak from the top ring. This pressure will lift the top ring off its lower seat in the piston and cause it to flutter and lose seal.
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IMO your gaps are plenty. I ran almost exact same gaps on 526 heim and thats with .310 more bore and with blower at 58% od.If you build enough heat to cause ring ends to butt you have more problem than no cooiling system.
As for cooling and ring gap I do not think there is a sepc for with or w/o and if there was differance they would list it.The same way they have na,blown and nitrous spec's.
I would go with total seal's specs after all they made the rings and have lot more information on rings and their functions than I do.
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I would agree with wide open . You will almost never go wrong with the manufacturer's recomendation . Weather you run a water pump or not dose not matter just don't get it too hot .Bill
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I have emailed Total Seal with this question and got the following answer:
"Might not be a bad idea to increase the gaps .002-.003” just to be safe."
So that's what I will do and hopefully I don't have to worry about this again.