OK, Stocker "valve jobs".

[Billy Nees]

This got started in a "Builds" thread and the way Tech is in the 21ST century and the way the Rule Book is written (to resemble a pirate's treasure map), Wazzup?
Anybody?

[Henrys Toy]

Originally Posted by Billy Nees

This got started in a "Builds" thread and the way Tech is in the 21ST century and the way the Rule Book is written (to resemble a pirate's treasure map), Wazzup?
Anybody?

Good morning Billy and to all,
What is it you'd like to talk about?
I thought that the " valve job " question was answered, it is not done the way NHRA used to specify pretty clearly in our Old Rule Books. If you find a better valve face / seat angle for your cylinder head you can perform that as long as you are going to use the Stock Valve size for your engine combination.
Incase I've missed something here, please let me know.
Its tough living under a rock.

Respectfully,
Henry Kunz 1534 H/SA

[Billy Nees]

CYLINDER HEADS
Must be correct casting number for year and horsepower
claimed, per NHRA Technical Bulletins or NHRA accepted.
Porting, polishing, welding, epoxying and acid-porting
prohibited. Combustion-chamber modifications prohibited.
Cylinder heads are additionally restricted in that they must
retain original-size valves at original angles +/- 1 degree
and must be able to hold original cylinder-head volume per
NHRA Specifications. Runner volumes may not exceed
the current Super Stock cylinder-head volumes as listed
on NHRARacer.com. Regardless of the poured volume
measurement, any modifications to intake or exhaust runners
prohibited. Any evidence of modifications from the original
castings will be grounds for disqualifications as determined by
NHRA in NHRA?s sole and absolute discretion. Any aftermarket
steel valve permitted, must retain stock head and stem
diameters. Only engines OEM-equipped with sodium-filled
valves may use sodium-filled replacement valves. Titanium
prohibited except OEM. Hardened keepers permitted. Lash
caps prohibited. Valve-diameter tolerance: +.005-inch or -.015-
inch from NHRA Specs. The following are prohibited: spark-
plug adapters; any grinding in ports or combustion chambers;
removal of any flashings; sandblasting or any other modification
to cylinder head; any film coating of intake and exhaust
runners; any film coating of combustion chamber. Runners
and combustion chamber must retain OEM appearance. Final
Stock Cars Section 11A, page 4STK
acceptance as determined by NHRA in NHRA?s sole and
absolute discretion. External modifications prohibited. Intake
side of head may not be cut into any part of valve cover bolt
holes. Valve-cover bolt holes must remain unaltered and in
their original location. Intake manifold bolt holes must remain
unaltered in their original location. Heat riser passage may be
blocked from intake manifold side of cylinder head. Blocking
passage down in valve pocket prohibited. The following are
permitted: polylocks, jam nuts, screw-in larger-diameter rocker
studs or pinned studs, bronze-wall valve guides, cylinder head
studs. Valve spring umbrellas optional. Cylinder head may have
all of the seats replaced. Any valve job permitted, O-ringing
prohibited. Exhaust plates prohibited.

This is off of TODAY'S NHRA Rules page and as far as I can see, there is no rule revision.

[Billy Nees]

The way I'm reading this, the VALVE must retain the original OEM VALVE angle but ANY "valve job" is legal which I would assume (that word again) means any SEAT angles.

[Charles Stewart]

And if you have the tools, the extra parts and some "research time", you can also explore those two accepted tolerances:
-Cylinder heads are additionally restricted in that they must
retain original-size valves at original angles +/- 1 degree
-Valve-diameter tolerance: +.005-inch or -.015-
inch from NHRA Specs.
It can be negigible or you can have something extra there...

[Rick J]

Is this a "What would you do" type query?

[Stan Weiss]

Cylinder heads are additionally restricted in that they must retain original-size valves at original angles +/- 1 degree


The way I read it, is that it doesn't say anything about valve or seat angles, but is talking about valve incline angle.


Stan

[Mark Yacavone]

Originally Posted by Rick J

Is this a "What would you do" type query?

Okay. Along those lines...
The rulebook seems pretty clear...Okay, it's a little murky, but I read that the valve head angle has to remain OEM, as it's always been.
The valve seat used to allow a 3 angle job, I think a quarter inch wide.
Later, when the use of Serdi type machines, using multiple angle cutters became common, NHRA approved the use of them , at any width.

They also allow the cutter to remove material down below the seat angle and along the sides of the combustion chamber, as long as the machining is done off the guide pilot. I don't see where this is specifically allowed in the rules but it's been done for quite a few years now.
In fact, the latter seems to be specifically prohibited by the book.
Talk about confusing... The guy that reads the book and wants to follow it, is probably leaving a lot on the table.

As far as this thread goes, If anyone is using non-stock valve HEAD angles, please let us in on it and when is it was okayed.
Or is it just a case of creative interpretation ?

[Rick J]

One degree at 5" is .085". More than one way to "use" that -
Get the valve away from the chamber, or away from the cylinder, in a more advantageous location to the throat/bowl, etc...

[Mark Yacavone]

Originally Posted by Stan Weiss

Cylinder heads are additionally restricted in that they must retain original-size valves at original angles +/- 1 degree


The way I read it, is that it doesn't say anything about valve or seat angles, but is talking about valve incline angle.


Stan

Please clarify, or re-state another way.
Thanks