Valve Lash Question

OldStrattonMan

New member
Im building up a mild raptor with a few upgrades. I have a 94ss cam and 18lb springs, and i bought new valves to go with it. The camshaft said to adjust them both to 006. and my dumb self went way to far on the intake valve. Not being used to these flatheads i went a little to far with the grinder, and my intake is now at 010. Will this still be ok or do i need to order a new valve.
 

1fasttiller

Member
It will be fine, not ideal but OK. Remember, on the flatty its all mechanical. To get the lift stated on the card you need to have .006" lash. If you're at .010 you've lost .004" overall lift. Try it, it might work well for you!
 

flattop1

Dawg 89
it affects opening and closing also .
Summerline used lash caps .
that had to be troublesome.
 

1fasttiller

Member
it affects opening and closing also .
Summerline used lash caps .
that had to be troublesome.
Correct! It will delay the opening of the valve as well. Thats how you get the numbers to match the card when degreeing.
 

OVALTECH1

Premium User
Or you could sink the valve that .004 by cutting the seat a bit deeper.
 

flattop1

Dawg 89
Even get a new valve ?
Or let it rip as is .

Those valves are trickey too cut , not enough not enough not enough too much.
 

OldStrattonMan

New member
Im going to just order a new valve and i thank you guys for the quick responses. Now can someone tell me the easiest way to get the clearence without a valve grinding machine. Does a file work ok for this
 

triton03

Member
Yes you can buy a step block that your valve goes in and you can take off what you want but I will say that a grinder is a big no no
 

1fasttiller

Member
Very easy to build a step block jig for grinding valves. I used a small block of tool steel, drilled down the center for the stem and then came in at a 90* angle and drilled and tapped for a set screw knob to lock the valve in place. I then use this on my file which is locked in the vise.
 

flattop1

Dawg 89
^ ^ Good idea. , ring gap machine works good also .
Might shoot for .002 and end at .006 .
Its tedious at best .
 

95 shaw

Premium User
Very easy to build a step block jig for grinding valves. I used a small block of tool steel, drilled down the center for the stem and then came in at a 90* angle and drilled and tapped for a set screw knob to lock the valve in place. I then use this on my file which is locked in the vise.
might add to this.

use a feeler gauge between the block described and a known flat surface.

I've had amazingly accurate results with a step block jig purchased over 20 years ago.

And, I have a souix valve grinder.
might be tedious, but gives you time to think about other things, lol
 
If you haven't cut the seat, refaced the valve, or lapped the valve to the seat ...
I would start with that before replacing the valve.
Even new valves aren't ground very true, and the airflow you gain by narrowing the margin is worth it alone.

I always do all of my valve, guide, and seat work on a flathead BEFORE setting the valve lash. This shortens the assembly time considerably by not having to take it apart and re-do things time and time again as the valve lash will tighten every time you make a cut on the face of the valve, the seat, or even just lapping with lapping compound.


-----
?Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
30 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 

flattop1

Dawg 89
the reason would be, if you start leaving .004 out of spec ; the chance you let the opening and closing off 4 degrees, then the ignition timing is off 4 degrees, the piston clearance has grown to .008 when you wanted .0025
Next thing you know you got a dog of an engine .
 

sundog

Member
The problem is, something happened he perceives as a mistake which must be fixed so he can have pride in his craftsmanship. Understandable but, lap the valve, run it once and it will be so close the difference in power will be hard to measure. The ignition and piston clearance will not be effected but the pride in ownership should not be underestimated.
 

macker1

Member
If you are able to get more lifters, their not all the same length. This might solve your problem. Also like Brian said you can cut the seats
a little.
 

flattop1

Dawg 89
Question , will the clearance grow as the engine heats up .
I feel as though it does .
 

fatjet87

Member
Negative, as things heat up they expand. Exactly how much they expand I have no clue. I would guess if you have 5 thousandths valve clearance cold, at operating temperature it’s maybe 2 thousandths.
 
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