Lock Nut or Castellated?

[1955cj5]

I was going to use these lock nuts instead of the castellated nuts on the rod cap studs...

Seems like a good idea...no need to align the cotter pin hole....more accurate torque...

[redmodelt]

I used those on a Model T with no issues. They are a one use nut so use regular nut when fitting the rods then use those for final fit up. They are very snug when putting on so can affect the torque. Because of how tight they went on I did go back to castellated nuts when I took up the bearings. 35-40 foot pounds is what I use for both T and A.

[PC/SR]

I use a similiar lock nut on the rods with no problems. As RedmodelT says, fit them up with the castle nuts. I use 40 lbs torque because of the tightness.

[Pete]

I would not use either.
I would use Marsden nuts. They are self locking but can be reused.
Most modern engines use them.

[1955cj5]

Thanks Pete,

where might you find Marsden nuts?

[Pete]

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Originally Posted by 1955cj5

Thanks Pete,

where might you find Marsden nuts?

Try an auto parts store.

[Boston Bruce]

Originally Posted by 1955cj5

where might you find Marsden nuts?

Google can be you friend...

[1955cj5]

No luck so far, but still googling..

[1955cj5]

OK found them....$30 for a pack of 50..I need 8....maybe I'll stick with the cotter pins..

http://www.amkproducts.com/bulk3.asp?part=B-10060

[m4banger]

1955cj5

Check out Aircraft Spruce P/N AN363- just add your dash number ie 7/16-20 is a dash 720
AN363-720 $1.39 each

Mike

[Chuck Sea/Tac]

I know a guy who uses regular nuts, with pal nuts most of his engines have upwards of 40,000 miles, nothing has come loose. That includes mine at 27,000 and no overdrive.

[Pete]

Originally Posted by Chuck Sea/Tac

I know a guy who uses regular nuts, with pal nuts most of his engines have upwards of 40,000 miles, nothing has come loose. That includes mine at 27,000 and no overdrive.

One of his came loose on an engine I had and caused a super blowup. Parts all over the street.
He didn't build the engine for me though. I got it second hand.

[Chuck Sea/Tac]

Yah Pete, but I know you. How many rpm were you turning?

[1955cj5]

I've called Tacoma Screw, Fastenal and Napa auto..I did not think it was worth calling O'reillys...no one has them or knows where I might find them...

Might Marsden nuts be known by another name?

Flex-Loc maybe?

McMaster-Carr does not have them, nor Grainger....

[J Witt]

The lock nuts you showed in your original post should work fine. Those work by punching the sides of the nut and slightly distorting to top threads to create friction.

If the nuts are correctly torqued, they likely would never come loose anyway.

The cotter pins just keep the nut from rattling around in the crankcase while the loose rod cap pounds itself to pieces.

Many modern cars use a one-time stretch bolt and correct torque, with no locking system at all. To make that work, however, the fasteners are part of a designed system that includes the material of the rod and cap. I wouldn't do this on a Model A with a stack of shims between the cap and the rod.


John

[Kohnke Rebabbitting]

These are 3/8's size, but they should still make the 7/16's size for Model A's.

Pioneer brand.

Any GOOD machine shop should either have them, or can order them.

Herm.

[1955cj5]

Originally Posted by m4banger

1955cj5

Check out Aircraft Spruce P/N AN363- just add your dash number ie 7/16-20 is a dash 720
AN363-720 $1.39 each

Mike

Mike,

I looked at aircraft spruce but did not see the size, but I will look again.

It seems there are lots of options....the Marsden being sort of elusive..

[Kohnke Rebabbitting]

If you want to ruin threads, use the punched nuts.

There is nothing wrong with Castall nuts, and keys. They will never come loose if done right, as long as the threads on the bolt, and nuts are in good condition.

Torque to 40 Foot Pounds, and then align Key hole if need be.



Herm.

[1955cj5]

Originally Posted by Kohnke Rebabbitting

If you want to ruin threads, use the punched nuts.

There is nothing wrong with Castall nuts, and keys. They will never come loose if done right, as long as the threads on the bolt, and nuts are in good condition.



Herm.

So I guess that answers the original question, castellated or lock...

I'll used the castellated........

Aircraft spruce has the others, but for 8 rod nuts and 6 main bearing plus shipping it's nearly $30...

[CarlG]

O'Riley's has the nuts that Herm was showing above (#16)