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Discussion Starter #1
How close have you guys ran valve to valve on a inline head?
Not a lot of overlap in the cam 52-54*@.050 , and good tight valve guides. Do you think i could get away with .015-.018? I am lazy and i dont want to offset bore the guide holes.:rolleyes:
 

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I think they will touch there. Can you cut the margin down a little on the intakes? I can tell you .022" was to tight on a SBF we did bigger intake valve setup on. The center two Cyl on each bank touched but just a little. This was on a cast iron head also.
 

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Discussion Starter #3
I think they will touch there. Can you cut the margin down a little on the intakes? I can tell you .022" was to tight on a SBF we did bigger intake valve setup on. The center two Cyl on each bank touched but just a little. This was on a cast iron head also.

Inline head , margin would have nothing to do with it.:D
 

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.030 min. I'm not brave enough to go tighter.
 

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Discussion Starter #5
.030 min. I'm not brave enough to go tighter.
Im like .025-.028 now and i want to go .020 bigger on the intake valve. I guess i will move the dam guides, I was hopeing 20 people would say they have run it at .015 with no problems at all. You know.
I know better, i just dont want to do the work:(
 

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Inline head , margin would have nothing to do with it.:D
Im not saying to cut the thickness of the margin down. Im just talking about cutting that area of the valve down diameter wise. Chuck the stem up in a bridgport and a good file will get it done but takes some time cutter works much quicker.
 

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Lathe and a carbide would be a better choice than a mill and a file. Lap a valve in and see if there is enough room to take .010" out of the OD, that would put you about .030" and you should be fine there. Or re-cut the seats slightly in if they are already pushed too far out on the valve.
 

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Im like .025-.028 now and i want to go .020 bigger on the intake valve. I guess i will move the dam guides, I was hopeing 20 people would say they have run it at .015 with no problems at all. You know.
I know better, i just dont want to do the work:(
There ya go. ;)
 

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I might have missed it since everyone had an answer already...

but what is the valve length...distance from guide center line... Material... and guide clearance.

and what are you doing with it?

and what is the benefit of the .020" increase in valve diameter?
 

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Discussion Starter #11
I might have missed it since everyone had an answer already...

but what is the valve length...distance from guide center line... Material... and guide clearance.

and what are you doing with it?

and what is the benefit of the .020" increase in valve diameter?
Ex=steel 5/16 .0015-.0016 head of valve is 1.800 from end of guide.
IN= TI 7mm solid stem .0011-.0012 head of valve is 1.600 from end of guide.
Bronze guides.
Center to center of guides is 1.945
Drag race 8500-8800rpm

460cid Pontiac, trying to make 1000hp, i need everything i can get.

I know were you are going with this and with out doing the math, it seems that there is no way they can clip. But math does not take into account the valves doing the hula dance. Thats why i asked what people have got away with.
 

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Ex=steel 5/16 .0015-.0016 head of valve is 1.800 from end of guide.
IN= TI 7mm solid stem .0011-.0012 head of valve is 1.600 from end of guide.
Bronze guides.
Center to center of guides is 1.945
Drag race 8500-8800rpm

460cid Pontiac, trying to make 1000hp, i need everything i can get.

I know were you are going with this and with out doing the math, it seems that there is no way they can clip. But math does not take into account the valves doing the hula dance. Thats why i asked what people have got away with.
what alloys? Can you snug the guides up?

Yes...what i am saying is you CAN run them that tight...but you have to know what you are doing..and plan for the pay off if that makes sense.
 

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Ex=steel 5/16 .0015-.0016 head of valve is 1.800 from end of guide.
IN= TI 7mm solid stem .0011-.0012 head of valve is 1.600 from end of guide.
Bronze guides.
Center to center of guides is 1.945
Drag race 8500-8800rpm

460cid Pontiac, trying to make 1000hp, i need everything i can get.

I know were you are going with this and with out doing the math, it seems that there is no way they can clip. But math does not take into account the valves doing the hula dance. Thats why i asked what people have got away with.
Lot of variables, as usual. Growth is usually a function of diameter but we have temperature, and material differences to consider. In any case all you have is .0075" between the two of 'em. I'm betting you've polished some valves by hand before in a drill press. That chuck has zero clearance and you can move a valve more than .0075" with practically no effort by touching it with some #600 paper. Even that depends on how much is sticking out of the guide during overlap. Find the closest point at overlap and hit 'em with a torch, then push on 'em. It would be interesting.

Hey, if you do it and it doesn't work, post some pics of the carnage. I'm sure you can weld it back together. :)
 

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Discussion Starter #15
Lot of variables, as usual. Growth is usually a function of diameter but we have temperature, and material differences to consider. In any case all you have is .0075" between the two of 'em. I'm betting you've polished some valves by hand before in a drill press. That chuck has zero clearance and you can move a valve more than .0075" with practically no effort by touching it with some #600 paper. Even that depends on how much is sticking out of the guide during overlap. Find the closest point at overlap and hit 'em with a torch, then push on 'em. It would be interesting.

Hey, if you do it and it doesn't work, post some pics of the carnage. I'm sure you can weld it back together. :)

By the math i would have .020 between them. Each valve would have to move .010 to clip. I really think it should be ok. But i will prob just move the guide.
And yes i can stick it back together:cool:These heads are half weld now.LOL
 

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At .020 with that setup I'd run it. But then I'm not paying for it...I've run .025 a ton of times with no indication of touching. At .010 I've seen the inside of a block that wasn't supposed to have a viewing hole.
 

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what are the valve head dia.'s?
 

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