To port or not to port?

[JimStC]

For a 4.6L 2V is it a 175 lb or 150 lb penalty. The rules seem to say both.
Thanks,
Jim

[Biff]

2950 base, 175# to port

[JimStC]

I see that in the rules but I also see rule# 1.17d that says 150lb weight added. Has there been a NMRA clarification of the apparent contradiction in the rules?
Thanks

[Biff]

most likely because it used to be 150, then they gave the base weight a 25 lb penalty. and now the 25lb penalty has been moved from the base weight to the ported heads.
2950 base
175 to port

[Jason Reiss]

This is from the online rulebook, so it looks like it's corrected...

1.17d) HEADS, PORTING: Prohibited. (*Porting only permitted on 4.6L Ford OEM 2-Valve '96-'04 cylinder heads with 175 pound weight adder.) Runners and combustion chambers must retain OEM appearance. Final acceptance at the discretion of NMRA Technical Department.
1.17e) HEADS, WELDING/EPOXY: Prohibited.
1.17f) HEADS, VALVES: Maximum valve sizes for 302W heads is 1.850” intake/ 1.550” exhaust. Maximum valve sizes for 4.6L two-valve heads are 1.850” intake/ 1.452” exhaust. Maximum valve sizes for 4.6L three-valve heads are 1.368" intake and 1.514” exhaust. Maximum valve sizes for 4.6L four-valve heads are 1.487” intake/ 1.211” exhaust. Valve stem size in guide area must be 11/32” for 302W heads. Valve stem size in guide area must be 0.274” for 4.6L heads. Undercut stems permitted. Aftermarket steel valve permitted, titanium/exotic valves prohibited. Bronze lined or replacement guides permitted.
1.17g) HEADS, MILLING: Permitted. See combustion chamber volume. Cylinder heads must maintain original production valve angles + or – 2 degrees.
1.17h) HEADS, PUSHROD SLEEVES: Prohibited.
1.17i) HEADS, COMBUSTION CHAMBER VOLUME: Minimum combustion chamber volume for 302W heads is 52.0 cc. Minimum combustion chamber volume for 4.6L 2-valve heads is 40.0 cc. Minimum combustion chamber volume for 4.6L 3-valve heads is TBA cc. Minimum combustion chamber volume for 4.6L 4-valve heads is 49.0 cc.
1.17j) HEADS, PORT PLATES/ADAPTER PLATES: Intake and/or exhaust port plates/adapter plates prohibited.
1.17k) VALVE JOB: Any valve job permitted.

PERMITTED CYLINDER HEAD LIST, PARTS NUMBER:
These are the only permitted cylinder heads and part numbers for competition in this category. If your cylinder head is not on this list, it is prohibited.
1) Stock Ford OEM 5.0 HO Cast Iron Cylinder Heads. (*Deduct 250 lbs.)
2) FRPP/SVO GT-40 Cast Iron Cylinder Heads
3) FRPP/SVO GT-40P Cast Iron Cylinder Heads
4) Stock Ford OEM 4.6 Cylinder Heads **
5) FRPP/SVO 4.6 2-valve **

Note: Stock factory OEM heads are those cylinder heads that are factory production line installed on production vehicles as recognized by NHRA.

* These heads permitted a 250 lb. deduction from base weight
**Porting permitted with 175 lb. weight penalty to base weight

[KenB]

I would try ported first since it's proven. If that doesn't work for you, you can always unport them later.

[f/s 4valve]

I would try ported first since it's proven. If that doesn't work for you, you can always unport them later.

wouldnt that make them magic heads if you unport them.

[KenCook]

lol
only one team has magic heads

[JimStC]

I would try ported first since it's proven. If that doesn't work for you, you can always unport them later.

Great idea! Is that what they mean by exporting? Selling them to the Chinese since you screwed them up. I am learning so much.
Thanks for all the advice. 14.9 second quarter mile here I come. Heck someone needs to be last.
Sarcasm aside, thanks Jason for the clarification. That 25 lbs means a need for a few more ponies.

[Dave Patti]

GT40's can port? GT40's can port? Did I hear right????

Well, it was worth a try... Carry on...