1967 belvedere claimed as a gtx.

melvin wellman · 10-02-2022, 03:27 PM

Can you claim a 1967 belvedere as a gtx to use the 440? Also, this motor uses the 915 ( closed chamber) head. But the engine specs guide offer the 906 ( open chamber) head to be used also. Would you shave the 906 head to make it a closed chamber head? Or is there a different way to go about this? Thanks in advance for any explanation, I really don't know who else to ask about this stuff.

Paul Precht · 10-02-2022, 03:43 PM

The 906 can be milled to 915 spec and both heads have basically the same ports. You may have to mill the 906 more but not much. The 915 head requires a .0062 cut per CC and the 906 is .0042 per CC. There are currently some 67 Belvedere's running as GTXs in Stock.

GTX JOHN · 10-02-2022, 05:06 PM

Is there any benefit to running the 906 head
over the 915?

Frank Castros · 10-02-2022, 05:29 PM

At one time way back when the 906 specs approved by NHRA Tech were considered bogus. Kent Ritter was rumored to be responsible for that. I'm sure nobody will refute this.

1347 · 10-02-2022, 08:33 PM

not sure how much you have to take off a 906 head to turn it into a closed chamber head, but won't that effect piston to valve?

melvin wellman · 10-02-2022, 08:35 PM

I have some open chamber heads, but no 915's. thanks for the help , its much appreciated.

melvin wellman · 10-02-2022, 08:39 PM

Good point about valve clearance, I did not consider that.

Paul Precht · 10-02-2022, 09:33 PM

A 915 head never milled is frequently about 84 CCs, theoretically a .062" cut would bring it to 74CCs. A 906 head never milled is frequently about 88 CCs, theoretically a .058" cut would bring it to 74 CCs so your valve to piston clearance would be similar but could go either way depending on the casting. A nice set of 915 heads will cost 500 and up, 906 heads are like grass, they are everywhere and can be had for nothing sometimes.

melvin wellman · 10-02-2022, 09:53 PM

Quote:

Originally Posted by Paul Precht

A 915 head never milled is frequently about 84 CCs, theoretically a .062" cut would bring it to 74CCs. A 906 head never milled is frequently about 88 CCs, theoretically a .058" cut would bring it to 74 CCs so your valve to piston clearance would be similar but could go either way depending on the casting. A nice set of 915 heads will cost 500 and up, 906 heads are like grass, they are everywhere and can be had for nothing sometimes.

Thanks for that information, this sounds like it may work.

GTX JOHN · 10-03-2022, 02:17 AM

Quote:

Originally Posted by 1347

not sure how much you have to take off a 906 head to turn it into a closed chamber head, but won't that effect piston to valve?

Absolute it will!

I sold two nice sets 915 that were nice Pairs this week = $400 pr.

10-02-2022, 03:27 PM	#1
melvin wellman Junior Member Join Date: Jan 2015 Location: boulder, mt Posts: 14 Likes: 0 Liked 2 Times in 2 Posts	1967 belvedere claimed as a gtx. Can you claim a 1967 belvedere as a gtx to use the 440? Also, this motor uses the 915 ( closed chamber) head. But the engine specs guide offer the 906 ( open chamber) head to be used also. Would you shave the 906 head to make it a closed chamber head? Or is there a different way to go about this? Thanks in advance for any explanation, I really don't know who else to ask about this stuff.

10-02-2022, 03:43 PM	#2
Paul Precht Senior Member Join Date: Dec 2001 Location: Elysburg, Pa Posts: 731 Likes: 355 Liked 319 Times in 119 Posts	Re: 1967 belvedere claimed as a gtx. The 906 can be milled to 915 spec and both heads have basically the same ports. You may have to mill the 906 more but not much. The 915 head requires a .0062 cut per CC and the 906 is .0042 per CC. There are currently some 67 Belvedere's running as GTXs in Stock.

10-02-2022, 05:06 PM	#3
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,732 Likes: 2,798 Liked 2,482 Times in 697 Posts	Re: 1967 belvedere claimed as a gtx. Is there any benefit to running the 906 head over the 915? __________________ John Irving 741 Stock 741 Super Stock

10-02-2022, 05:29 PM	#4
Frank Castros VIP Member Join Date: Nov 2001 Location: The Lowcountry. Posts: 2,969 Likes: 2,584 Liked 2,717 Times in 957 Posts	Re: 1967 belvedere claimed as a gtx. At one time way back when the 906 specs approved by NHRA Tech were considered bogus. Kent Ritter was rumored to be responsible for that. I'm sure nobody will refute this.

10-02-2022, 08:33 PM	#5
1347 Senior Member Join Date: Aug 2007 Location: Monroe Twp NJ Posts: 503 Likes: 1,032 Liked 990 Times in 274 Posts	Re: 1967 belvedere claimed as a gtx. not sure how much you have to take off a 906 head to turn it into a closed chamber head, but won't that effect piston to valve? __________________ Duane Hoven 1342 SS/GT

10-02-2022, 08:35 PM	#6
melvin wellman Junior Member Join Date: Jan 2015 Location: boulder, mt Posts: 14 Likes: 0 Liked 2 Times in 2 Posts	Re: 1967 belvedere claimed as a gtx. I have some open chamber heads, but no 915's. thanks for the help , its much appreciated.

10-02-2022, 08:39 PM	#7
melvin wellman Junior Member Join Date: Jan 2015 Location: boulder, mt Posts: 14 Likes: 0 Liked 2 Times in 2 Posts	Re: 1967 belvedere claimed as a gtx. Good point about valve clearance, I did not consider that.

10-02-2022, 09:33 PM	#8
Paul Precht Senior Member Join Date: Dec 2001 Location: Elysburg, Pa Posts: 731 Likes: 355 Liked 319 Times in 119 Posts	Re: 1967 belvedere claimed as a gtx. A 915 head never milled is frequently about 84 CCs, theoretically a .062" cut would bring it to 74CCs. A 906 head never milled is frequently about 88 CCs, theoretically a .058" cut would bring it to 74 CCs so your valve to piston clearance would be similar but could go either way depending on the casting. A nice set of 915 heads will cost 500 and up, 906 heads are like grass, they are everywhere and can be had for nothing sometimes.