Minimum distance between valves

[gmrocket]

Rather than waste my time answering questions, I'll just let someone else do it.

Good idea....since I already know from experience .027 is fine.

So your "no personal experience" .060" "answer" that you seen somewhere is of no use to me.

[panic]

Honi soit qui mal y pense

[Newold1]

Sorry but your Norman - French sarcastic humor is lost on me and probably most others here.

Survey Says use .030" minimum in most uses and if you live closer to the edge .020" may get you by! Do I get a second here?

[Rick360]

i checked those measurements before, they are...

.027" between valves when seated with a little slop in the guide..about .001 more than it should be
guide to seat is 1.425", its not a tall head so that helps
11/32 stem
2.00" guide length

dont know cam yet so did a check at .500" , spread distance increased to .0385" and pinched together it was .0155"

these were run like this and no problems. im moving the guides in the heads they are going in and would like to get them as close as possible so everything fits better. reducing it to .020" is what i would like

Did some calcs using your numbers. When I use .004" guide clearance on both valves I get the numbers you measured. The lift at overlap would probably be closer to .250", that reduces side-side movement by .001 combined from your measured so gap between valves when pushing together would be .0163" at .250 lift. With guide clearance of .002 on both valves keeps the valves apart more to .0217" at .250 lift

IMO with new guides and .020 valve gap when on seat should be enough unless your valves are really bouncing around in there or when the guides get worn.

Rick

[midnightbluS10]

Rather than waste my time answering questions, I'll just let someone else do it.

What was the point in even posting that? Are you implying eveyone else is wrong?

And what's with the "Shame on him who thinks...."

[KnightEngines]

.020 is not enough, youd be suprised how much valves whip around at higher rpm.
I run a lot of stuff at .028 to .035 without problems, but at .020 they've touched & knocked around the margins.

[gmrocket]

.020 is not enough, youd be suprised how much valves whip around at higher rpm.
I run a lot of stuff at .028 to .035 without problems, but at .020 they've touched & knocked around the margins.

Earlier you said with Ti valves I could probably get away with .020 or even less...what changed?

[gmrocket]

i checked those measurements before, they are...

.027" between valves when seated with a little slop in the guide..about .001 more than it should be
guide to seat is 1.425", its not a tall head so that helps
11/32 stem
2.00" guide length

dont know cam yet so did a check at .500" , spread distance increased to .0385" and pinched together it was .0155"

these were run like this and no problems. im moving the guides in the heads they are going in and would like to get them as close as possible so everything fits better. reducing it to .020" is what i would like

Did some calcs using your numbers. When I use .004" guide clearance on both valves I get the numbers you measured. The lift at overlap would probably be closer to .250", that reduces side-side movement by .001 combined from your measured so gap between valves when pushing together would be .0163" at .250 lift. With guide clearance of .002 on both valves keeps the valves apart more to .0217" at .250 lift

IMO with new guides and .020 valve gap when on seat should be enough unless your valves are really bouncing around in there or when the guides get worn.

Rick

Makes sense....thanks

this .027" set was in a really harsh environment before, 15:1 comp 750hp and a 400 shot for over 1100 and more rpm than it will see now....it won't be sprayed this time

So I'll try .020" and see how it works out

[KnightEngines]

Earlier you said with Ti valves I could probably get away with .020 or even less...what changed?

I also said near perfect valve train control - the sort of near perfection that requires spintron time & $$$$ parts.
Using 'normal' parts & educated guesses as to valve train components (like we all do for the vast bulk of engines) I wouldn't go much under .030", certainly not under .025"

[gmrocket]

Earlier you said with Ti valves I could probably get away with .020 or even less...what changed?

I also said near perfect valve train control - the sort of near perfection that requires spintron time & $$$$ parts.
Using 'normal' parts & educated guesses as to valve train components (like we all do for the vast bulk of engines) I wouldn't go much under .030", certainly not under .025"

I don't think a Ti valve is a normal part...it'll have del west valves, Ti retainers, Ti locks, PAC springs, T&D shaft rockers. Quality push rods, Lift in the .800" to .850" range and a lobe that won't have really aggressive ramps.. but big .050" numbers in the 285+ range.

There are no odd or wierd angles in the valve train..simple shallow 6 deg valve angle, pushrods are almost dead parallel.

In reality probably wouldn't see much over 7k

[KnightEngines]

Entirely your call, but I'd keep it above .025" - you may well be fine, but I'm not gonna be the guy that said you will have no problems & then get called bad words if it doesn't work out!

If you do run it at .020" then pull the heads after a little run time & check that all is good.

[gmrocket]

Entirely your call, but I'd keep it above .025" - you may well be fine, but I'm not gonna be the guy that said you will have no problems & then get called bad words if it doesn't work out!

If you do run it at .020" then pull the heads after a little run time & check that all is good.

Ya, I wish someone else would have done the dirty work, I hate experimenting with $2000 valves .

One of the real pluses is the shallow head and short valve seat to guide distance...the valve isn't out there dangling in the wind.

I would never blame anyone else for what my final decision is it don't work..I try to do my best research and go from there. If it don't work out, I'll post the results