Valve Job Information

[user-9274568]

In my opinion every seat should be touched with a stone. In precision machining, every part isn't finished until it is ground. More precise control over finish and size. (crank, pilot, valve, etc)


Speaking of the VGS, here is my nightmare of a fixture. Addco meets CP.

[Frankshaft]

I have personally seen how much changing a few angles can have on power out put. We're talking extreme case, as much as 100hp!! and that no bullshit. I also love telling this to guys, a flow bench is an intermediate learning tool. I get a kick out of that comment.

has anybody else ever seen +100hp with the "right" valve job with no bowl area blending/smoothing/radiusing?

strictly choosing the right angles and widths.

I will elaborate. Your typical 600-650 hp deal, your not losing or picking up 100+ hp. I said extreme case, this engine was a 680 inch 5 inch bore space deal that ultimately made 1500hp n/a. The thing is, if you built that engine, and it made 1400, you would likely say, that's bad ass, and is seemingly good power, if you didn't know that you could of made 1500, with no other change other than a valve job, you would be surprised. There is a bit more to the story, this engine originally made 1500, it was freshened, the heads were sent to a shop who had a serdi, because, after all, the original builder used a serdi, so he wanted the vale job freshened on a serdi. Well, that shop put on his "performance" profile, that he uses on everything, similar to Joe's cutter above. Part of the issue, was a giant top cut to chamber transition ridge, he just left. That is one of my biggest pet peeves. Shops that cut the seats, and leave a giant ridge. This valve job essentially ruined the heads. Because the valve seat angle was changed so drastically, and with the giant ridge that was plowed into the chamber, ruining its shape, it killed 40 cfm on both sides and destroyed all the positive chamber action. It required cutting out all 16 copper alloy seats, welding the missing aluminum back into the chamber, installing 16 new seats, recutting the proper profile, re establishing the proper chamber shape, and replacing all 16 titanium valves. Boom, power right back. Pretty eye opening.

Chad, that's a pretty sweet set up, I suppose its not to bad to set up because all you have to do is use the base as a roll over. I also mention earlier in the thread, the stone fine finish touch up, is mandatory. It amazes me how guys are SO resistant to that idea. For some reason, using a stone is old school, outdated and makes you less quality than the guy who doesn't. I am taking an EXTRA step to make it better. The funny part, every other machining operation in the automotive side of machining, pretty much uses grinding or some sort of stone cutter. Cap cutter, for resiszing rods and mains, which both uses stones to accomplish, line hone and rod hone, crank grinding, cylinder honing, and, the biggest one, grinding valves, . Its ok for that, but not for doing the seats on the heads, it boggles my mind. I will add, using just stones to do your valve job, is I won't say not possible, but, difficult, you need some sort of seat and guide machine. I will also add, the stone is the best runout gauge there is. One light bump, if it cleans up all the way around, its good. It will instantly show you where your seat would have been leaking and any runout.

[fdicrasto]

I had an interesting situation dealing with both the stone issues vs. Serdi and general valve job mods when I was involved with some APBA marine race engines. Myself and a competitor were using the Merlin iron bbc heads and the competitors shop was telling me & some of my customers that my "old school" valve work(w/stones) was costing horsepower, in other words their stuff was superior. The dyno shop we both used decided to bring me a set of Merlins to prep and compare to the "superior" method of the other guys. The basic combo was 461" bbc for A -production class racing. He informed me that there was 30 hp. diff. Of course I wouldn't be telling this story if it wasn't in my favor but if you feel that valve work with stones is "inferior", I will disagree. Needless to say the time element is greatly in favor of the machined valve work. And bowl and chamber hogging needs definitely are best done using the new school way also. Thats my story and I'm sticking to it. Phil D.

[user-9274568]

Frankshaft absolutely perfectly said on the stones! It boggles my mind as well. I just don't listen anymore. You can take a cylinder head with 1000 runs and if it was properly cut (on a S&G machine) hit it with a stone and call it a day. I have many heads I service that I can and will not cut. You set the chamber size, heights, and hit it with the machine? Crazy to me.

I have a dedicated table as well. I hit everything. I'm like you, it takes time and I feel it's a better end result.

[cgarb]

Chad, Have you noticed that brand new castings that you machine (aluminum mainly), when they come back to you for touch up, are they still concentric or have they moved some?

[modok]

In precision machining, every part isn't finished until it is ground. More precise control over finish and size. (crank, pilot, valve, etc)

Very true.

[pcnsd]

Guys,
Thank you for the insight. Anyone have an opinion on the T&S Seat and guide machine? Stones do appear to produce a finer result in my observation, but you can't cut the throat to size with them. Can you?

[user-9274568]

Chad, Have you noticed that brand new castings that you machine (aluminum mainly), when they come back to you for touch up, are they still concentric or have they moved some?

For the most part they are concentric. BUT, I've seen my share of moved seats.

[user-9274568]

Guys,
Thank you for the insight. Anyone have an opinion on the T&S Seat and guide machine? Stones do appear to produce a finer result in my observation, but you can't cut the throat to size with them. Can you?

I would buy a T&S in a heartbeat. I had an old green VGS and decided to update. If they would have had one in stock, I would have bought one. I know I know, Rottler or Serdi.

[racear2865]

I do have a T & S and I like it quite well and I luv the fixturing but I to kiss with a stone but I would like to ask the people above if you are going dry stone or wet stone.
reed

[modok]

Generally grinding steeper than 70 degrees doesn't work well, or at least.... it's not worth doing if you have another way. Probably Neway makes a 75 degree? That's the only neway I'd ever buy
You also CAN take out a lot of material with aggressive grinding stones, but it's not worth it, kind of a mess and time consuming. Grinding seats will never go away because it's great for just taking off a few thou, but probably that's all they are being used for anymore.

I'm sure there are a FEW that still working on heads made of nothing but iron

But most things have seatrings, and if you can bore counterbores for seatrings, then of course you can rough-in seats the same way, probably. Or you could shape the ID of the seatrings before installing them.....that's REALLY old school....but basically nothing wrong with it. Even if all you have an antique wobbly drill press with an air float.....there are ways to make it work very well. NICe machines are quick, repeatable. I guess the payment on the machine is cheaper than paying some poor guy to fight with it, and YOU KNOW< that's ok. That's how it goes. If you make the guy operate a wobbly machine long enough he will invent a better one. And that's the AMErican way.

[ProPower engines]

I do have a T & S and I like it quite well and I luv the fixturing but I to kiss with a stone but I would like to ask the people above if you are going dry stone or wet stone.
reed

I use a dry stone in my VGS.
I was in contacted radiac about some diamond stones for lack of a better description to avoid the dust when truing up the stones. While it has been a bit more of an investment then I 1st considered they are the cats ass to use in a S+G machine with their driver and they work very well at a lower rpm then say a sioux grinder or any other hand held unit for that matter but for me it was about the extra dust.
And while they do not need touching up and stay consistent in the specific angle they were made in. the selection is getting larger then I 1st thought but that was just because of how well they work and how much I like them because they allow me to just do a final finishing seat kiss on a head on the same machine.
But there is no comparison to just a cutter alone when doing seats