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#1
03-08-2015, 12:33 PM
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'69 #48 heads on 1978 W72
48s on these .30 over pistons - block has been shaved 8-thousandths...compression ratio ballpark? pump gas or high octane?
lemme know - thanks in advance. |
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#2
03-08-2015, 01:18 PM
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Suggestion: post and ask same Q in the "Pontiac - Street" tech section
http://forums.maxperformanceinc.com/...play.php?f=418 |
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#3
03-19-2015, 12:49 PM
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Those heads on a stock 69 RAIII were 10.5CR. You have a little more dish volume in your piston with the 8 valve reliefs but you have shaved your block a skosh. My educated guess would be around 10.25, which to me is too high for todays gasoline. It would need to be cammed perfectly.
__________________
Bob Woodard Brighton, MI 2012 SRT8 Charger - 12.70 @ 111mph |
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#4
03-20-2015, 10:34 AM
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Heads probably not drilled for the alternator bolt if you are using 78 brackets.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#5
03-20-2015, 11:18 AM
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Been there done that.
You will need the 69/70 GTO bracket set-up to work on those heads. Kind of a pain to get it all to work on a Trans Am.
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White/Blue 71 455 HO T/A Auto Blue/Blue 71 455 HO T/A 4 Sp White/Sandalwood 71 455 HO T/A 4 Sp White/Black 70 RAIII T/A M21/373 (stripper) Carousel Red/Black 69 GTO Judge 4 Sp 2002 Firehawk Red/Black 6Sp |
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#6
03-20-2015, 03:12 PM
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Quote:
__________________
Bob Woodard Brighton, MI 2012 SRT8 Charger - 12.70 @ 111mph |
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#7
03-21-2015, 11:07 AM
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My SR 614s had the boss there to drill that extra hole, I don't think the originals did. I had one set of 16s a guy had drilled into the valve cover area but not straight. You could make a template for the holes off a late model head(or an E head) and then use a drill press/mill to get it straight and use some teflon sealer on the threads.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#8
03-21-2015, 12:00 PM
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As I recall.....1970 455 heads (cast#15) have the perfect chamber volume for healthy pump gas 400......
__________________
 Eye Candy......garage band? https://www.youtube.com/watch?v=QUPcHxHRx3s Go full screen & turn it UP! |
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#9
03-21-2015, 05:36 PM
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It looks like your pistons have the chamfer around the perimeter, which would lower your compression a bit. I run 12 heads which about the same as 48 heads on a .030 over 400 with flat tops on 92 octane with no issues.
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1978 Black & Gold T/A [complete 70 Ram Air III (carb to pan) PQ and 12 bolt], fully loaded, deluxe, WS6, T-Top car - 1972 Formula 455HO Ram Air numbers matching Julep Green - 1971 T/A 455, 320 CFM Eheads, RP cam, Doug's headers, Fuel injection, TKX 5 Spd. 12 Bolt 3.73, 4 wheel disc. All A/C cars |
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#10
03-21-2015, 06:01 PM
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1971 96's are workin' great on our '79 PWH
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