[54nomore]

You'd have to turn it down .100" to get .050" clearance, just sayin'. ;D

[scott70]

Years ago I pulled the 455 out of my car I raced for a freshening and found one of the ears broke off the oil pump shaft where it goes in the distributor. I figured I dodged a bullet there before a major failure.

[t money]

I was on Amazon the other day and checked out M54DS and IS54A and it said Country of origin China. I hope Melling not making this stuff oversea now. ?? But if your worry about running a oil pump drive rod get it Cryogenic Paul Carter has a price list on his web site it’s $3 a couple years ago (maybe 5-7 dollars now today) but cheap insurance.. also most engine builder can tell you a local place that will cryogenic freeze your part

[AG]

I think there is a place in Worcester, MA. I am going to get the internals of my TKO done there.

[Formulajones]

Originally Posted by scott70

Years ago I pulled the 455 out of my car I raced for a freshening and found one of the ears broke off the oil pump shaft where it goes in the distributor. I figured I dodged a bullet there before a major failure.

Yep, that's how dad's last 455 got smoked. Broke the ears off one of those aftermarket shafts after 4-5 years of use. Just one of those odd deals.

[scott70]

Originally Posted by Formulajones

Yep, that's how dad's last 455 got smoked. Broke the ears off one of those aftermarket shafts after 4-5 years of use. Just one of those odd deals.

Engines dont like it when theres no oil pressure. Mine was a GM factory piece.

https://forums.maxperformanceinc.com...d.php?t=553318

[taff2]

Originally Posted by hurryinhoosier62

You guys really need to study metallurgy and heat treating. As long as the base alloy isn’t brought past its quench point( very unlikely in a normal lathe cutting operation) turning .050 off of it isn’t a cause for alarm. If it makes you sleep better at night, re-heat treat the shaft. .

I fully understand the principle of a torsional shaft- we use more than a few in the trans we build - however,that turned down shaft has 90 degree sharp edges where the turned down section meets the original diameter, no one with any inkling of performance sense would turn a load bearing shaft to that form. It's building in a potential failure.
Yeah ,it's not as easy to turn a tapered section at each end of the cut, but good engine building isn't about 'easy' . Each to their own I suppose.

[taff2]

ps, turning down an oil pump driveshaft by .050" means taking a .025" cut, that's .025" off each side - not .050" off each side!

[Tom Vaught]

Originally Posted by 54nomore

You'd have to turn it down .100" to get .050" clearance, just sayin'. ;D

Originally Posted by taff2

ps, turning down an oil pump driveshaft by .050" means taking a .025" cut, that's .025" off each side - not .050" off each side!

Both of you are saying the same thing basically.

If .025" will get you the clearance you need from the crankshaft then the smallest portion of the oil pump intermediate shaft will be .050 smaller.

Both saying the same thing but using different numbers for the clearance to the crankshaft.

I have to agree that unless you have the right radiused cutter to add a fillet to both sides of the cut, you made the oil pump drive piece much weaker. Then when the piece fails, as been mentioned above, you can replace the rotating pieces with a crank that has been checked for oil pump shaft to counter-weight and reduce the diameter of the counter-weight before balancing the crank. Now you can run a proper diameter oil pump drive part that has been heat treated.....

Not that hard to remove a crank on a engine stand, even if you left the rods and pistons in the block.

Tom V.

[steve25]

Just like reworking any type of metallurgy so cracks can not form, I always polish and slightly round off the drive ears on the shafts .
It makes me wonder if this simple process would have kept you folks who have experienced this type of failure from having such even if the shaft was made off shore?

[adynes]

(double post)

[adynes]

Originally Posted by taff2

I fully understand the principle of a torsional shaft- we use more than a few in the trans we build - however,that turned down shaft has 90 degree sharp edges where the turned down section meets the original diameter, no one with any inkling of performance sense would turn a load bearing shaft to that form. It's building in a potential failure.
Yeah ,it's not as easy to turn a tapered section at each end of the cut, but good engine building isn't about 'easy' . Each to their own I suppose.

Agree. Sharp inside corners create a stress concentration that is bad at resisting fatigue cracking. It would probably be worse in a street car than a drag car, as the street car would see way more hours and number of stress cycles. Would make me nervous, but the weakest part might still be the tang drive

[Formulajones]

The tang drive worries me the most. Out of all the pump shaft failures I've seen it's always been the tangs that fail.

That turn down shaft doesn't really bother me. Like I said, millions of 400 SBC's built using a shaft that looks just like that, and GM didn't bother to radius them or taper the cuts either. Haven't seen an aftermarket one done for that application that way either. Not that it isn't a bad idea, certainly treating it to a radius will only strengthen it, but the factory never bothered to do it :shrug:

If it survived a 1000hp race engine turning over 8000rpm and setting world records, and came out looking that good, I'm sure it'll be fine.

[hurryinhoosier62]

Originally Posted by taff2

I fully understand the principle of a torsional shaft- we use more than a few in the trans we build - however,that turned down shaft has 90 degree sharp edges where the turned down section meets the original diameter, no one with any inkling of performance sense would turn a load bearing shaft to that form. It's building in a potential failure.
Yeah ,it's not as easy to turn a tapered section at each end of the cut, but good engine building isn't about 'easy' . Each to their own I suppose.

taff2, are you a machinist? I am. Cuts like this are used all the time and they don’t fail. Paul K stated that this oil pump drive shaft has seen hundreds of 1,000+ hp runs, yet it has not failed.

[Tom Vaught]

I have to smile when I read about hundreds of 1,000+ HP 1/4th mile runs without a failure.

As posted in the past, run the engine at max power plus 10% for hours at a time for over 400 engine hours and then you can brag about the durability of engine parts.

Just saying.

Tom V.

[PAUL K]

This thread reminds me of the one a few years ago when all the "Internet" experts explained how "wrong" it was to build an engine with pressed in rocker arm studs.

[Formulajones]

Wouldn't GM have done that already before putting millions of 400 SBC's in production?
Doesn't the millions of them on the road in passenger cars, and millions of them in truck applications since 1970 account for some level of durability?

I think the whole process is being overthought and too many people on this forum live a sheltered life.

[PAUL K]

Originally Posted by Formulajones

Wouldn't GM have done that already before putting millions of 400 SBC's in production?
Doesn't the millions of them on the road in passenger cars, and millions of them in truck applications since 1970 account for some level of durability?

I think the whole process is being overthought and too many people on this forum live a sheltered life.

What does GM know? They made billions of cars with pressed in rocker arm studs.

Just trying to help the OP out. Sometimes the worst thing you can do is ask for advice on the Internet. I'm no oil pump drive shaft expert, but posted the first hand information I had to help the OP. At the end of the day he has to do what he needs to do so he can sleep at night. "He" also has to deal with the consequences of his decision.

It's real easy to sit behind the key board and preach how everything needs to be done text book perfect but a whole bunch harder to get off the sofa and get something done.

You ever notice how the guys with the shortest list of first hand accomplishments know the best way to get the job done!

[Formulajones]

Originally Posted by PAUL K

What does GM know? They made billions of cars with pressed in rocker arm studs.

Just trying to help the OP out. Sometimes the worst thing you can do is ask for advice on the Internet. I'm no oil pump drive shaft expert, but posted the first hand information I had to help the OP. At the end of the day he has to do what he needs to do so he can sleep at night. "He" also has to deal with the consequences of his decision.

It's real easy to sit behind the key board and preach how everything needs to be done text book perfect but a whole bunch harder to get off the sofa and get something done.

You ever notice how the guys with the shortest list of first hand accomplishments know the best way to get the job done!

Agree 100%

[PAUL K]

Originally Posted by Tom Vaught

I have to smile when I read about hundreds of 1,000+ HP 1/4th mile runs without a failure.

As posted in the past, run the engine at max power plus 10% for hours at a time for over 400 engine hours and then you can brag about the durability of engine parts.

Just saying.

Tom V.

Hi Tom, not sure if you are referring to my post but if you are that engine peaked about 7800 rpm. So you think to test the durability of oil pump drive shaft we should pull the engine 10% above peak power for four hundred hours (approximately 8580 rpm) then we would "know" we have a good oil pump drive shaft if it survives the test?