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#1
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Factory machining
I just for the second time watched the video titled “ 455 casting and machining in production of 1970” and I was very impressed by a fact that I missed the first time watching it,
Pontiac during production did a ruff balance of the crank and then once the short block was assembled they spun it up to do the final balance. This was done to a tolerance of 1/2” ounce which is to me amazing since the average balance job done by a machine shop is 3” once , Does anyone know what the other GM divisions did and used in there balancing jobs?
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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! |
#2
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#3
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I have built a `70 Buick 455, a `71 Ford Cleveland, `71 Mopar 340, `78 Mopar 440, and a few sbc`s. Pontiac factory machining and tolerances are pretty damned good for factory "crap".
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#4
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I recognize someone in the video
Look at the Pontiac employee at 9:56
Sure looks like the guy from Article in 1981 Car Exchange |
#5
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I think you are right!
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
#6
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Guy probably took pride in what he did everyday.
Kids now have no work ethic.
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66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#7
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Too bad that precision didn’t carry over into their grinding of crankshafts. The “best” one I have seen was only .005 under stroke. The worst was .020 under stroke.
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#8
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The 1970 455 with 71 HO heads that has a bazillion runs on it has the factory line bore and deck job. Mains studs too, never align honed. ( 4 bolt)
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#9
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Your judging that difference in stroke ground into the Crank without having the original Rods and Pistons and there tolerance's that where related to it all during production I bet, so you can't judge what the actual final deck height was on any given cylinder just by looking at the Crank!
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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! |
#10
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Quote:
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#11
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I'm with Hoosier. Don't know why anyone would be googly eye'd over any factory machined mass produced engine. I've never had a virgin engine rebuilt in any brand that had nice tolerances. Cranks with shorter than advertised strokes, uneven deck heights all over the place, and don't even get others here started on Pontiac cam tunnels.
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The Following User Says Thank You to Formulajones For This Useful Post: | ||
#12
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The Following User Says Thank You to mgarblik For This Useful Post: | ||
#13
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I am sorry about starting this thread talking about factory balancing, when you guys want to talk about other tolerance's , lol!
__________________
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! |
#14
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The Following User Says Thank You to racegto65 For This Useful Post: | ||
#15
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#16
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Quote:
__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#17
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left 0.41 grams right 0.44 grams This was a re-balance from another shop I thought was questionable. It started out as initial unbalance left 28.5 grams right 22.2 grams Going to Lewis was a good decision. |
#18
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Quote:
Makes me wonder about Pontiac spec when they talk about "half-ounce" but no distance measure. Quote:
Then the torsional damper is neutral-balanced but with a series of holes drilled in the outer ring. The factory spins up the engine, and then pounds steel pins into the torsional damper--or punches holes in the flexplate--or both, to suit each individual engine that comes down the assembly line. If an aftermarket shop hacked-up the flexplate or screwed with the damper, I'd call them butchers. Buick does it as a matter of course. As a result, replacement flexplates have to be match-balanced to the original, and you'd need to have the original steel pins removed from the factory damper, and pounded into the replacement (in the same relative positions). Quote:
1/2 ounce = 14 grams. I didn't have a good concept of how much a gram was. My wife tells me that 1 gram = 1 raisin (more or less.) Last edited by Schurkey; 05-18-2021 at 08:33 PM. |
#19
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Here's a screen shot of the balance job Paul did for me on the last 455 Pontiac and what I've come to know as the normal quality I get from him, and why I don't like to use anyone else. Factory stuff doesn't even come close.
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