427-425hp w/GM 401 heads

dahkahuna · 12-06-2012, 12:38 AM

OK, I have 2 differint opinions now 1 for the 1.84 valve and 3/8 stems and another with 1.72 valve and 3/8 stems . Who is correct?

dahkahuna · 12-06-2012, 01:22 AM

I see in the NHRA blueprint specs that when you use the 401 the 1.84 exhaust valve is the legal valve to use ........Ruler you were right , thanks

RULER · 12-06-2012, 05:19 AM

The iron head uses the 1.72 exh. and the 401 alum. uses the 1.84 exh and also you run at 435hp. with the alum. head 425hp with the iron head. Thanks

Pedigo Perf · 12-06-2012, 10:02 AM

I think the 401 alum head has a standard spec for all combinations it can be used on.

2195/1845 with a 103.3 chamber volume.

Again, check the guide as always.

RULER · 12-06-2012, 11:55 PM

The 401 head can be used on the 1969 427/430 ZL1 or L88 with 2.195 1.885 valve and 114.8cc camber also.there is a different HP. rating for the ZL1 and the L88, The ZL1 gets a bigger cam. If you use an original head casting (aliuminum) then there is a HP reduction.

dahkahuna · 12-07-2012, 01:32 AM

Is there a horsepower penalty on the 396=375hp aluminum head engine if you use the original # 842 aluminum casting cylinder head or is the factored hp # for the 401 only ?

RULER · 12-07-2012, 02:30 AM

All the info you are asking for is in the classification guide. I don't think there is any difference on the 396 aluminum heads (new or old) but i could be wrong, just be careful if you call it a 402 that changes alot of small stuff.

12-06-2012, 12:38 AM	#1
dahkahuna Member Join Date: Jul 2006 Location: san dimas , calif Posts: 128 Likes: 0 Liked 5 Times in 3 Posts	Re: 427-425hp w/GM 401 heads OK, I have 2 differint opinions now 1 for the 1.84 valve and 3/8 stems and another with 1.72 valve and 3/8 stems . Who is correct?

12-06-2012, 01:22 AM	#2
dahkahuna Member Join Date: Jul 2006 Location: san dimas , calif Posts: 128 Likes: 0 Liked 5 Times in 3 Posts	Re: 427-425hp w/GM 401 heads I see in the NHRA blueprint specs that when you use the 401 the 1.84 exhaust valve is the legal valve to use ........Ruler you were right , thanks

12-06-2012, 05:19 AM	#3
RULER Member Join Date: Jan 2006 Posts: 222 Likes: 15 Liked 58 Times in 18 Posts	Re: 427-425hp w/GM 401 heads The iron head uses the 1.72 exh. and the 401 alum. uses the 1.84 exh and also you run at 435hp. with the alum. head 425hp with the iron head. Thanks

12-06-2012, 10:02 AM	#4
Pedigo Perf Member Join Date: Feb 2008 Location: Wichita Ks Posts: 383 Likes: 70 Liked 30 Times in 17 Posts	Re: 427-425hp w/GM 401 heads I think the 401 alum head has a standard spec for all combinations it can be used on. 2195/1845 with a 103.3 chamber volume. Again, check the guide as always.

12-06-2012, 11:55 PM	#5
RULER Member Join Date: Jan 2006 Posts: 222 Likes: 15 Liked 58 Times in 18 Posts	Re: 427-425hp w/GM 401 heads The 401 head can be used on the 1969 427/430 ZL1 or L88 with 2.195 1.885 valve and 114.8cc camber also.there is a different HP. rating for the ZL1 and the L88, The ZL1 gets a bigger cam. If you use an original head casting (aliuminum) then there is a HP reduction.

12-07-2012, 01:32 AM	#6
dahkahuna Member Join Date: Jul 2006 Location: san dimas , calif Posts: 128 Likes: 0 Liked 5 Times in 3 Posts	Re: 427-425hp w/GM 401 heads Is there a horsepower penalty on the 396=375hp aluminum head engine if you use the original # 842 aluminum casting cylinder head or is the factored hp # for the 401 only ?

12-07-2012, 02:30 AM	#7
RULER Member Join Date: Jan 2006 Posts: 222 Likes: 15 Liked 58 Times in 18 Posts	Re: 427-425hp w/GM 401 heads All the info you are asking for is in the classification guide. I don't think there is any difference on the 396 aluminum heads (new or old) but i could be wrong, just be careful if you call it a 402 that changes alot of small stuff.

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