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#1
01-31-2008, 01:34 AM
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BHJ Tooling & Lifter Bore Angle?
We have never questioned the accuracy of our BHJ tooling fixture for doing bronze lifter bores for our Pontiac blocks. However, when putting our cam in the cam doctor, we always assumed that the Pontiac lifter bores were perpendicular to the cam lobe. I have been told this is at 45 degrees to center.
However, 1 degree would throw our cam profile off substantially. Are all Pontiac block lifter bore holes perpendicular to the cam center, or are some offset? Are the intakes the same as exhaust? Has anyone offset these for performance gains? thanks, Lynn lmc3470@aol.com |
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#2
01-31-2008, 03:46 AM
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Factory blueprints ????
I would love to get ahold of a scanned image of a set
__________________
Working on going faster (and now staying dry at the same time !!) |
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#3
01-31-2008, 12:07 PM
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Lynn, does anyone around there have a CNC machine that does probing? Guess you could answer questions about the OEM and BHJ machining that way.
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#4
01-31-2008, 03:52 PM
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45degrees would be optimal for the cam to have the most lift on the follower. any less (or more) would be cheating yourself of some lift. i would trust the
BHJ fixture more than any production tolerences of a factory block.
__________________
'78 Ford Fairmont 526ci pontiac; true 10.5 tires and stock suspension. 5.14 @140.5 w/nos; 8.86@151 all motor.8.17@172 1/4 mile w/nos |
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#5
02-01-2008, 04:12 AM
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I have also never seen a block blueprint. The time I spent machining lifter bosses of a couple of blocks gave no clue that the original lifter bores were anything other than parallel to the cylinder centerlines. Although I wasn't looking for it, it seems I would have noticed if they were inclined a degree- that would be about .025" offset from top to bottom of bore.
__________________
Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons? ... or has built a record breaking DOHC hemi four cylinder Pontiac? ... or has driven a couple laps of Nuerburgring with Tri-Power Pontiac power?(back in 1967) |
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