Thread: ring gap

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the KB pistons on got from summit, they only talk about gaping the top ring, but all three must be gaped right?

if you have the hyperutectic ( spelling ? ) type pistons they recommend setting the top ring gap as these pistons have a thicker deck and tend to run hotter in the top ring area ..you should`nt need to set the second gap and certainly not the oil ring gaps

Yes they are hyper, thanks.

KB s need top ring gap to be open up more or they will butt .2 ring should be checked but should be .016 or so

While we are on the subject of ring gap, I've always been told about .004 per inch of bore, but he guy who is doing Dan's engine says that is old info. He recommends .006 per inch of bore. What do you guys say about that? (forged pistons)

Don

Originally Posted by Itoldyouso

While we are on the subject of ring gap, I've always been told about .004 per inch of bore, but he guy who is doing Dan's engine says that is old info. He recommends .006 per inch of bore. What do you guys say about that? (forged pistons)

Don

if he opens up the bore then the end gap will be bigger .005 is fine i am building a Nos 632 right now .that end gap is .007 top ring @032 with a 4.600 bore. shock and mild stuff .005 is fine with cast or forged i built many this way your not going to butt them

Thanks, Pat.

Don

come time you have any question call me or pm me if you want i help were i can .my helper coming in on friday so should have the pan off so i know whats up with the bbc so far it looks fine one heads is eatten by salt but nothing block looks ok so far

Oh, good. I think the block should be ok, but you never know with a marine engine.

Don

been slow going i let you know soon.i just been under the weather need to fine some energy some were

Edit-Edit-edit

The Icons send out a chart and it depends on use

well yes but more will not hurt 005x bore size is fine on a street rod yes i go by the chart and pat mccarthy chart as well bigger gap never hurts .but less will...watch the problems you will have. on bore its Pie or very close but fast way is to think 001 more wall clearance = 003 ring end gap most guys will not put the pistons in at low end spec.. so adding more piston to wall you end up with more gap so file rings many times are a wast of money if you still need more end gap then you can file the drop in rings

That makes sense, Pat. When he told me to add more gap my first thoughts were that you would get leakage past there, but he said no way. He also said they see only about 3 hp difference between tighter gaps and more gap. Aside from the obvious fact that drop in rings call for no filing normally, what makes them different so that you don't need to do that?

Don

Don-because of the fact the reason why you are building this engine,if it where me,I would say there isn't such thing as "drop in" rings and all need to be checked.The top ring on my 383 we added .004 to it in ring gap and the rest where dead on.