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#1
09-01-2021, 10:47 PM
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Piston Eyebrows for Old Vs. New
We all know the valve angle changed in 1967. I have a '64 421 45B block with piston cut for '67 and later heads. It was built by Dan Whitmore and has only a couple of hours running time. The eyebrows are on the top side only. I know the eyebrows were closer to the center of the pistons on pre-'67 engines.
We're going to use '64 "716" heads on this engine. Is there any chance the pistons will work with those heads? The cam is a Melling version of the 068 with about .470" lift. Maybe a dumb question, but your comments will be appreciated.
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BONESTOCK GOATS '64 GTO Tripower Hardtop (Wife's Car) '64 GTO Tripower Post Coupe (My Car) '99 Bonneville SE Sedan |
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#2
09-02-2021, 12:18 AM
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I ran a 744 cam in a 421 that was bored out to a 428. I ran stock trw 428 pistons and 093 heads. It worked fine.
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#3
09-02-2021, 06:37 AM
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The valve notches moved closer to the center of the bore because of the change to a more vertical 14 degree inclination angle.
A original 068 cam with .406” to .420” lift would not be a problem, but with .470” lift I would with out fail mock assemble it with clay and without a head gasket and with light checking springs on the 4 end cylinders to see what you have . Do you know what you have for deck clearance now? Off the top of my head if I recall right if you have .020” deck clearance now then with a .039” crush head gasket, and with running .470” lift I think the exh valve was ok the last time I did a build like yours. The intake valve is the wild card ! You need a dead nuts minimum of .045” valve to piston clearance and if your forced to run things that close your valve springs better be super dam good!
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 09-02-2021 at 06:42 AM. |
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#4
09-02-2021, 02:34 PM
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Years ago I built a .060 over 389 using 400 pistons. Had a Sig Erson 480 lift cam in it and used the stock 093 heads. Not an issue. But check, with clay, as stated. You should be just fine.
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Jeff 
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#5
09-02-2021, 02:55 PM
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Note that the point of least clearance is not at TDC so just to reiterate, you need to check with the cam in, a lifter pumped up all the way and with very light checking springs so as to not pump down the lifter.
You can find such springs at most well stocked hardware stores.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#6
09-03-2021, 12:44 PM
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Thanks for the help. We will proceed with caution.
The rear main seal is a BOP assy. To change that involves removing the rod caps, taking the crank out, etc. Debating on whether to take a chance. This engine was last run quite a few years ago.
__________________
BONESTOCK GOATS '64 GTO Tripower Hardtop (Wife's Car) '64 GTO Tripower Post Coupe (My Car) '99 Bonneville SE Sedan |
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#7
09-03-2021, 03:34 PM
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Since the heads will be off it will be easy to check deck height. If Dan built the engine there's a really good chance he decked the block.
Good old modeling clay or even a Tootsie Roll would work sitting on top of the piston with hand cranking the mocked up assembly with the head in place and valve train for one cylinder. It takes more time, but a set of checking springs on a pair of intake and exhaust valves and plotting the clearances on each side of TDC would be better.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
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