stocker cylinder heads

[Mark Faul]

Originally Posted by Mike Taylor 3601

As I understand that is correct,can unshroud to head gasket bore,changing 30 to 45 or ? I think is allowed but have'nt checked,to verify that so I would check on valve angle.
Mike Taylor 3601

You better double check! These are stocker heads, right? This is from the 2013 rule book.

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 www.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. Hardened keepers permitted. Lash caps prohibited. Valve-diameter tolerance: +.005- inch or -.015-inch from NHRA Specs. The following are prohibited: spark-plug adapters; cylinder-head studs; 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 acceptance as determined by NHRA in NHRA’s sole and absolute discretion. 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. 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. Valve spring umbrellas optional. Cylinder head may have all of the seats replaced. Any valve job permitted,O-ringing prohibited. Exhaust plates prohibited.

[Greg Hill]

Originally Posted by Mark Faul

You better double check! These are stocker heads, right? This is from the 2013 rule book.

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 www.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. Hardened keepers permitted. Lash caps prohibited. Valve-diameter tolerance: +.005- inch or -.015-inch from NHRA Specs. The following are prohibited: spark-plug adapters; cylinder-head studs; 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 acceptance as determined by NHRA in NHRA’s sole and absolute discretion. 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. 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. Valve spring umbrellas optional. Cylinder head may have all of the seats replaced. Any valve job permitted,O-ringing prohibited. Exhaust plates prohibited.

The key thing in this is any valve job permitted.

[Mark Faul]

Originally Posted by Greg Hill

The key thing in this is any valve job permitted.

Yes. But can't unshroud

[Mike Taylor 3601]

Might have been told wrong but was told .250'' total or .125''per side bigger than head of valve was took out, and now could be cut to gasket, this unshrouding has to be done off guide center line as guide and seat machine would cut.
Mike Taylor 3601

[R. Thorne]

Refers to max top cut on seat. Thanks.

[Greg Hill]

I was told by more than one tech man that you could do anything in the bowl area as long as it was done with a cutter off the valve guide. Combustion chambers are a different deal.

[Tom Moock]

Greg, I think you are wrong about using a cutter to cut to the bottom of the bowl, According to division 5 tech director. And It's up to person checking your heads if it's legal and you can't appeal there ruling. Tom

[Mark Yacavone]

Tom , One throat cut ,any angle, off the center, as far as the guide boss allows.
Been doing that since '09 out here.
Several teardowns...

[Greg Hill]

Originally Posted by Tom Moock

Greg, I think you are wrong about using a cutter to cut to the bottom of the bowl, According to division 5 tech director. And It's up to person checking your heads if it's legal and you can't appeal there ruling. Tom

Tom, Wayne seems to go by different rules than the rest of the country.

[Alan Roehrich]

Originally Posted by Tom Moock

Greg, I think you are wrong about using a cutter to cut to the bottom of the bowl, According to division 5 tech director. And It's up to person checking your heads if it's legal and you can't appeal there ruling. Tom

Bachelder says different. You can go as deep as the guide or guide boss will let you, so long as the cut is concentric with the guide. I was standing there at the NHRA booth when he said it. The rules are pretty loose regarding the top cut as well.

And they absolutely, positively, will NOT give you an answer in writing regarding angles, or the legality of using a radius seat. Apparently, every tech inspector KNOWS what "looks right" for each individual head.