valve job done on heads valves need cutting?

[charger318]

If you get a set of new heads that already have a 3 angle done and you get new SS valves do u need to cut the valve for the seat?

 

[69Bee]

Ideally, you should not. BUT, to be absolutely sure the angles are correct, what would it hurt? To me, it is more of a check to see where the seat hits on the valve. And before you say I can lap them, I do not recommend that.

When I first got my Rottler SG-8 Seat & Guide machine, I did two seats, and lapped one. The seat that I just cut pulled 16 inches of vacuum, and the one that I cut and lapped only pulled about 12 inches. The lapping leaves silicon between the seat and valve, affecting the seal.

The big thing is this; who is to say the guy at the mass production plant set the machine up to cut the seats correctly, and the same goes for the valve plant, maybe the valve angles are off. You should only have to just kiss them, and not grind the **** out of them. I always kiss new valves and they can get damaged in shipping, and every now and then, a valve is not concentric with the stem.

 

[charger318]

So u mean use a little lapping compound and work just alittle not sit there and actually try to cut a seat of course. I was thinking of taking a marker and outlining the seat where the valve should touch and just give it little lapping and see if any marker was left behind????what u think of that?

 

[IQ52]

Many shops, like ours, have a fixture that you drop the valves into to test them. It takes about five minutes.

I do not ever recommended that you lap valves as a final step. Don't like that compound in the seat.

 

[69Bee]

No, do not lap them... I use a dry erase marker, put the valve in, and spin by hand. The seat contact area will show up.

Completely agree IQ52, lapping compound=bad mojo...

 

[bm02tj]

Unless you have adjustable rockers you need to cut valves to length

 

[charger318]

Oh no I'm not worried about the valve length I was just wondering if I had to do anything to my new SS Manley valves for heads that already have a 3 angle valve job done

 

[miller]

Using new valves and checking contact against cut seats, I usually make a wipe of lubriplate on the valve face. Put the valve into the hole, and pop the valve up and down a few times, while rotating it. The lube will show if it's contacting all around, both valve and seat, with a simple wipe off to clean things up.
Of course, you want to match valve to hole, after checking each.

Yeah, I gotta look for some of those Manley SS's myself. All I've ever used.

 

[mike71ssp]

30 degree back cut!

 

[miller]

30 degree back cut!

Yeahda!!

 

[charger318]

What do u mean 30' back cut

 

[IQ52]

Oh no I'm not worried about the valve length I was just wondering if I had to do anything to my new SS Manley valves for heads that already have a 3 angle valve job done

I would absolutely check the Manley valves for roundness. I use Manley valves on occasion but regularly find them to be .003" out of round, unless they are a custom built valve, and then they generally hold to .002" and I still have to dress them.

You can get stainless steel valves from Mancini Racing or off eBay and they will run truer than Manley...........sad but true in my experience.

 

[Cranky]

It's also a good idea to check stem clearances and check ALL of them and the hole that they are going to run in.