Big Block Intake Bolt Spacing - Anyone know What it is?
#2087471
06/07/16 12:31 AM
06/07/16 12:31 AM
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Morrow, OH
markz528
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Does anyone know what the intake bolt spacing is on a big block?
I need to helicoil some of the bolt holes and need to make a jig to locate them correctly. One in particular is severely oversized and damaged.
I can measure another head but was hoping someone already has the information.
67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......
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Re: Big Block Intake Bolt Spacing - Anyone know What it is?
[Re: markz528]
#2088109
06/08/16 12:56 AM
06/08/16 12:56 AM
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State of confusion
Thumperdart
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I get roughly 4 3/4 on the ft. and rear two and a tad less on the inners......
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Big Block Intake Bolt Spacing - Anyone know What it is?
[Re: Thumperdart]
#2089941
06/11/16 12:53 AM
06/11/16 12:53 AM
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Morrow, OH
markz528
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I get roughly 4 3/4 on the ft. and rear two and a tad less on the inners...... Thanks! I took, the effort and measured today. I measured two heads and the biggest difference between the two was 0.004" so I have high confidence in the numbers.......
67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......
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Re: Big Block Intake Bolt Spacing - Anyone know What it is?
[Re: AndyF]
#2090741
06/12/16 05:24 PM
06/12/16 05:24 PM
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Morrow, OH
markz528
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That could be correct. My guess is that Mopar engineers use fractions since this stuff was designed on a drawing board back in the 50's. So the dimensions are probably 4.75 and 4.625 but I don't really know.
On the intake stuff that I make I use 4.740 and 4.640 as the dimensions and everything fits but I don't know what the real dimensions are.
Only folks who know for sure have the original blueprints. I can't disagree with any of this. Going in I would have expected standard spacing but the difference was just too great for my liking. I kept the dimensions pretty tight and the jig works pretty good on 3 heads. However I would expect manufacturing tolerances to be pretty loosey goosey. Like you said, only those with the blueprints really know.....
67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......
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Re: Big Block Intake Bolt Spacing - Anyone know What it is?
[Re: markz528]
#2090756
06/12/16 05:58 PM
06/12/16 05:58 PM
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Posts: 25,754
Rio Linda, CA
John_Kunkel
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Rio Linda, CA
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Couldn't be 118mm and 120mm and 359mm. Nah.
The INTERNET, the MISinformation superhighway
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Re: Big Block Intake Bolt Spacing - Anyone know What it is?
[Re: MR_P_BODY]
#2090768
06/12/16 06:28 PM
06/12/16 06:28 PM
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Morrow, OH
markz528
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What are you building?..... naa... we didnt play with millimeters back then  I did a quick job on a set of 906 heads for a board member for his 505 build. Did some bowl porting, intake gasket matching, put in n old set of larger valves and ground the seats. One of the heads had bad intake bolt threads. One was so bad that the 3/8 bolt would just slide in. I like to build jigs when I helicoil threads like this so that he holes are properly located and are square. Hence the jig.
67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......
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Re: Big Block Intake Bolt Spacing - Anyone know What it is?
[Re: markz528]
#2090776
06/12/16 06:42 PM
06/12/16 06:42 PM
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Romeo MI
MR_P_BODY
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What are you building?..... naa... we didnt play with millimeters back then I did a quick job on a set of 906 heads for a board member for his 505 build. Did some bowl porting, intake gasket matching, put in n old set of larger valves and ground the seats. One of the heads had bad intake bolt threads. One was so bad that the 3/8 bolt would just slide in. I like to build jigs when I helicoil threads like this so that he holes are properly located and are square. Hence the jig. I hear ya there.. I jig up a lot of stuff.. takes time but is worth it... the mill helps a lot but ya have to know where to put the hole
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Re: Big Block Intake Bolt Spacing - Anyone know What it is?
[Re: MR_P_BODY]
#2091247
06/13/16 03:36 PM
06/13/16 03:36 PM
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Joined: Jan 2003
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Rio Linda, CA
John_Kunkel
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Rio Linda, CA
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What are you building?..... naa... we didnt play with millimeters back then Engineers did.
The INTERNET, the MISinformation superhighway
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