counterbalanced crankshaft

I have an A motor with a C (Ford Factory counterweighted) crank ground to standard A shell mains and AER B rods--Smoothest motor I have driven.
 
As someone who has used both (-and suffered failures from one), I now realize why there is a reason why one is more expensive than the other. If for no other reason, look at the warranty difference. I now prefer to use the US manufactured one by a company that has been around a long time.
 
My first crank that I used, the flywheel flange was running out .005. That would make a very bad vibration. I had to fix it before using it. At the time one was cast iron the other was the good material 4140. The cast crank was the bad one.
 
I ran a Burlington crank in a competition engine with dipper oiling on shells with performance rods. Under a bit of pressure the crank broke at no 3 big end and took the block, rods etc with it. Ive heard of another similar incident also in a competition engine, so I think they are fine for normal road use but maybe check carefully for a hot engine. Pressure oil feed might help.
 
No dog in this hunt, just a couple observations;
The "A" crank journal sizes are not up to spec for a Hot motor, definitely not a competition motor. Cross drilling the crank to oil the rods makes the situation even worst, you are removing up to about 9% of the cross section on a journal that is too small already.

Personally not seen a broken Burlington crank, after seeing one up close I declined to attempt for a customer's hot motor. I have seen the aftermath of two broken SCAT cranks, they were stroked with "A" rod throw diameters and cross drilled. Both broke along the oiling hole on the #4 rod.

It really depends on the application and the loose nut behind the steering wheel.

J
 
johnneilson said:
No dog in this hunt, just a couple observations;
The "A" crank journal sizes are not up to spec for a Hot motor, definitely not a competition motor. Cross drilling the crank to oil the rods makes the situation even worst, you are removing up to about 9% of the cross section on a journal that is too small already.

Personally not seen a broken Burlington crank, after seeing one up close I declined to attempt for a customer's hot motor. I have seen the aftermath of two broken SCAT cranks, they were stroked with "A" rod throw diameters and cross drilled. Both broke along the oiling hole on the #4 rod.

It really depends on the application and the loose nut behind the steering wheel.

J
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While I definitely will yield to your wisdom regarding not up to specs, surely you would agree that many, and I mean MANY were subjected to competition and racing without failure, so how do you argue that point? Additionally, many AA trucks were outfitted with OHV heads that often doubled the original horsepower. These trucks were subjected to much more intense loads, -often at the same RPMs as a racing engine, and they lived.

I am curious on the SCAT cranks that failed, was the drilling for pressure done by SCAT during the manufacturing process, or by the engine rebuilder?
 
I wouldn't drill an A crank for oil to the rods. If the motor is stock you don't need too, if it hopped up you will likely break the crank at #4 rod throw. That is the weak link.
 
A cross-drilled hole in a shaft will introduce a stress riser of 3 or more times the nominal stress--see any machine design textbook. You better know what you are doing. The shaft is subject to not only bending but torsional loads. The combined stress plus the stress riser will promote a crack to form. If the shaft looks like it cracked on a 45 degree angle it was primarily a torsional failure, probably aggravated by bending stress. You have to know where to drill, how much section you need, the expected loading, and know the capability of the crank material.
 
BRENT in 10-uh-C said:
While I definitely will yield to your wisdom regarding not up to specs, surely you would agree that many, and I mean MANY were subjected to competition and racing without failure, so how do you argue that point? Additionally, many AA trucks were outfitted with OHV heads that often doubled the original horsepower. These trucks were subjected to much more intense loads, -often at the same RPMs as a racing engine, and they lived.

I am curious on the SCAT cranks that failed, was the drilling for pressure done by SCAT during the manufacturing process, or by the engine rebuilder?
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Brent,

I would guess that the "double HP figure" would be 80-100 HP. And you are right, many lived at those power levels. By today's standards, this would be a hot street motor, not a competition motor. To fully understand what a competition motor is capable of you need to look towards Bonneville as the speeds are averaged over a mile run so not only does it have to make power, it has to stay there for awhile. My run this last year was under 21 seconds for the final mile, at about 6500 rpm.

The "C" crank besides the counterweights has approximately 1.6 times the cross section on the rod journals. This in itself is a huge difference in strength, not to mention drilling for oil feed. There are a few shortcomings in the "C" crank, with proper work can be used to make ~200 HP.

The two broken SCAT cranks were strokers, "A" rod journals and yes, drilled at factory. I know that one let go about 6000 rpm, the other probably close to that, one block survived. I have no idea why.

John
 
I have a Burlington in a fairly hot hillclimb engine, stock oil except pressure center main, 3 years no problems. The supplier recommends against drilling the Burlington.
 
Unless things have changed in the last few years, the SCAT crankshafts are made from an offshore forging that can be machined and ground to make either a 4 cyl Chevy, Model A, or Model B crankshaft.
Unfortunately for the Model B crankshaft, there is not enough material on the forging to allow machining to Model B connecting rod diameters.
Tom Leib is the owner of SCAT, and very personable. I am sure that he will answer any questions.
 
bob keenan said:
thoughts on a scat vs. burlington crank,also well made connecting rods
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This subject, i.e.- crankshafts, including the ones that you name, has been discussed any number of times in the past here. If you can 'search' files for these discussions, IMO you will find a lot of input to your crank question.

As to rod use, a well known racer , a member of this forum, has said that he has used Ford's B rods in his race (B-ville) engines....and NEVER had a failure of these rods ! Enough said to use properly prepared Ford B rods with confidence, I'd say !

I've spoken to Tom Lieb of Scat a number of times regarding his crankshafts for our A/B engines. He does not make a full sized B crank and will not, he said.

You will get biased opinion on this subject, if giver is a crank rep, in my experience.

If you use an A block with drilled A sized crank, you will not be happy if and when if snaps. If may last a long time , if not drilled and not raced..your choice.

Years ago, I kept a file of pictures of snapped cranks. Mostly drilled A sized / puny rod throws. Most were raced, but not all. Everytime discussed, there was 'blowback' from crank reps, that they used them all the time without any such breakage. Seems that that has changed somewhat with experience ?

Good luck to you. You are doing the right thing by asking these questions before making expensive decisions.
 
Interesting thread, sounds like it comes down to you-get-what-you-pay-for as in most things in life work out that way.

And it has been said before that Model A Ford people are some of the 'cheapest' around:D
 
BRENT in 10-uh-C said:
Bob, this post has drifted some, so if you don't mind me asking, -is this crankshaft you are asking about intended for use in your Tudor or is this for a competition engine??
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Brent,

This should have been the first question back to OP.
When asked to put together a motor, it usually starts with 5 main bearing and how much?

My first question back is "what is the intended use for this motor?"

Most applications do not require the amount of investment of 5 mains, just an ego thing I guess.

J
 
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