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Old 10-02-2022, 03:27 PM   #1
melvin wellman
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Default 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.
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Old 10-02-2022, 03:43 PM   #2
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Default 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.
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Old 10-02-2022, 05:06 PM   #3
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Default Re: 1967 belvedere claimed as a gtx.

Is there any benefit to running the 906 head
over the 915?
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Old 10-02-2022, 05:29 PM   #4
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Default 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.
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Old 10-02-2022, 08:33 PM   #5
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Default 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?
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Old 10-02-2022, 08:35 PM   #6
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Default Re: 1967 belvedere claimed as a gtx.

I have some open chamber heads, but no 915's. thanks for the help , its much appreciated.
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Old 10-02-2022, 08:39 PM   #7
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Default Re: 1967 belvedere claimed as a gtx.

Good point about valve clearance, I did not consider that.
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Old 10-02-2022, 09:33 PM   #8
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Default 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.
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Old 10-02-2022, 09:53 PM   #9
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Default Re: 1967 belvedere claimed as a gtx.

Quote:
Originally Posted by Paul Precht View Post
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.
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Old 10-03-2022, 02:17 AM   #10
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Default Re: 1967 belvedere claimed as a gtx.

Quote:
Originally Posted by 1347 View Post
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.
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