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#1
05-31-2021, 04:36 AM
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Crank clearance q
Friend has just fired up his 469 and the crank counter weight has hit the oil pump shaft and broken it. It's an Eagle stroker crank. Should it have been clearanced before assembly or is it the shaft? The shaft is a Melling 1 piece.
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69 Firebird 472, Bullet SFT, KRE 85cc, Victor, 850xp, TH400, TSP 9.5" 4800, 3.90 10 bolt, Viking DA rears, QA1 single fronts, 3558lbs. best to date 11.14@120 |
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#2
05-31-2021, 06:17 AM
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Well I have heard of that happening, but it should not have happened in terms of the crank being made right.
Then again with a max of .009” of allowed thrust crank clearance this issue should have been seen with a mock assembly long before the motor even had its oil pan bolted on no less fired up! I will refrain from asking who built the motor. I have seen some stock oil pump drive rods bent a little bit, but even so that should not make for contact even if you factor in the max ,009” thrust clearance.
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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! |
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#3
05-31-2021, 06:33 AM
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Thanks Steve I will let him know
__________________
69 Firebird 472, Bullet SFT, KRE 85cc, Victor, 850xp, TH400, TSP 9.5" 4800, 3.90 10 bolt, Viking DA rears, QA1 single fronts, 3558lbs. best to date 11.14@120 |
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#4
05-31-2021, 07:15 AM
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He says the thrust clearance was .003" so does this point to the crank being the problem?
__________________
69 Firebird 472, Bullet SFT, KRE 85cc, Victor, 850xp, TH400, TSP 9.5" 4800, 3.90 10 bolt, Viking DA rears, QA1 single fronts, 3558lbs. best to date 11.14@120 |
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#5
05-31-2021, 07:26 AM
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Is it an old Eagle crank or a recent one? A lot of the early Eagle cranks and rods were rubbish -tolerances all over the place. Typical Chinese made pieces, you have to check everything. I would aim for a minimum .050 - .060" thou clearance on anything that is close to the crank.
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#6
05-31-2021, 10:33 AM
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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 |
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#7
05-31-2021, 11:25 AM
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Luckily I had a spare pump shaft and have fitted it and run the motor again. No issues this time. Fingers crossed.
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#8
05-31-2021, 12:31 PM
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Your playing with fire again if the motor has more then 55 psi of oil pressure and the other pump drive shaft you put in is not a heavy duty one, no less if your crank end play is only .003”!
__________________
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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#9
05-31-2021, 02:22 PM
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Crank end play is 0.005" . I never measured the clearance between the crank and the pump drive. It was very small though.
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#10
05-31-2021, 11:42 PM
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Quote:
__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
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#11
06-01-2021, 01:41 AM
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Sorry for the delay in replies but, Im in UK so the time difference means I don't see your replies until the following morning.
Quite honestly I don't know if the driveshaft was correctly installed as I wasn't there during the initial installation but, I really can't see how it can be installed wrongly. It slips over the oil pump drive and drops into the hole in the block. Its impossible to fit it upside down as theres a hole drilled down the centre so that the oil pump drive pin fits into it. |
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