Valve Grinding Equipment

[200cfm]

That one is as old as mine. This evening I cut a 30 back cut on a valve and the margin was consistent all the way around. I think it has to do with the depth of where I seat the valve stem in the collet. Turned out perfect to the eye so I was pleased. Having a hard time with mastering the stone grinder though. I shattered three stones from chatter. I was using a new stone to set the throat at 1.625" and the shock shattered the stone. Installed a new stone from the box and that one did ok but cut looked bigger. I miked the stone an it was 1.640. Yet the box said 1 5/8. So now I have a throat cut that is larger than the others on this head. If I had to do this for a living I would starve.

[blaktopr]

I put my valves in as far as I can, bout 1 to 1.5" up from valve. I have used springs to control the bounce a few times. It helped out some.

[jfholm]

don't complain about what you have guys, I am still using a rotary hatchet.

John

[blaktopr]

John, I don't know why but that is my favorite tool in the shop. It needs some more TLC but I am happy owning it and the seat grinder. I drove from central Jersey to Pittsburg and then to central PA on one trip to pick them both up.

[coulterracn]

[200cfm]

Ok, don't have a bounce spring. So I better secure one. Still having problems with the procedure for sizing the seat, top cut, and bottom cut. Take the common Chevy 1.940 diameter valve. Say you want a 30/45/60 angles with the proper margins. How do you determine the margin diameters without overcutting or undercutting the transistion lines? Which should be layed down first?

And on the throat sizing, where is this actually measured at? I am thinking it starts at the edge of the the 60 cut. But my bowl has one elongated part that extends out and sort of introduces a throat area before the valve throat area. So I have a bowl with sort of like two throats in it. That can't be good. (tom c)

[jfholm]

[color=#000000]Tom,
I usually hit the 45

[coulterracn]

I too use machinist straight dividers. I measure the outside diameter of the valve with calipers and set my margin and adjust the dividers to the same measurement.

I read a thread in another forum where the person make a seat width gauge by flattening a welding rod and grinding it to the preferred seat width.

Once you blend in your 60, 70 or secret angle to the bowl that should be the point of measurement. I've read were some suggest measuring 1" below the valve seat. I'm under the impression that measurement at the valve seat inner radius should extend down into the port 1".

[jfholm]

You like those secret angles don't you Ray :;):

John

[Flash]

[200cfm]

Thanks guys, this morning I went through my "may need one day box" and found a spring that was good in length, size, and strength. Added a brass washer underneath it to protect the bowl, and added a washer on top sized to fit over the pilot and support the spring ends. Made a test cut and bingo, no chatter. Very very smooth and much better control. Spring is strong enough to actually hold off the weight of the grinder end and with a slight preload on the grinder I walked it down for the cuts. Cuts really look nice, so much smoother than before. And when I release the grinder the stone wheel will pop up nice and clear with no dragging to a halt on the seat.

My confidence is back up and plan to place an order for some more stones.

Oh, I discovered a method to trim down the size of the stones. My stone grinder didn't have angle markings above 60 degrees. I found that if I removed the locking adjustor screw completely out I could pivot the diamond cutter up for a vertical down 90 degree trim. This is going to solve a big problem in shaping the bowl and sizing the throats. I will be able to dial in more diameter stone sizes. Made a trial diameter trim on a junk stone and it worked fine. (tom c)

[coulterracn]

[jfholm]

[jfholm]

The spring Tom is now using is kind of critical especially on the steeper inner angles. Without a spring it is easy for the stone to grab and very well may explode. I have had that happen when I was in a hurry and really regretted it. It can leave nasty marks on seat, hurt your forehead where the pieces hit you and cost you a new stone.

John

[coulterracn]

I too have had stones shatter while grinding the steeper angles without the bounce spring. Luckily I haven't been hit by any flying pieces of shattered stone.

I use the bounce spring when grinding all angles now. I think it helps the stones grind a truer seat. I have had seats that were not concentric and the width varied when grounding without the bounce spring.

Grinding seats with stones is considered old fashion with the the 3-angle seat cutters that are available today. You can still grind seats with stones and make power. It's just not as quick or flexible as the newer cutters.

Ray