Ny-Lock Nuts

[mantta]

I have the pan off of my "A" and I am going to plastigage the rods & mains. Has any of you used Ny-Lock nuts on the rods and mains? They seem to do good on other machinery that has lots of movement and vibration.

[Pete]

Originally Posted by mantta

I have the pan off of my "A" and I am going to plastigage the rods & mains. Has any of you used Ny-Lock nuts on the rods and mains? They seem to do good on other machinery that has lots of movement and vibration.

Nylock nuts are not recommended in high heat applications.
Use Marsden nuts. These are used in most modern engines.

[dave in australia]

DON'T use nylocks. The nylon can break down in oil. Doing split pins is a supperior option, I think you call them cotter pins in the US. If you are addament about using lock nuts, search out the all metal variety, they're used on aircraft. Try 'aircraft spruce and specialty' for supplies.

[tiquer]

Originally Posted by mantta

I have the pan off of my "A" and I am going to plastigage the rods & mains. Has any of you used Ny-Lock nuts on the rods and mains? They seem to do good on other machinery that has lots of movement and vibration.

I hear where your coming from the carter pins can be a pain to put in at times . Lock nuts of the all metal veriety work great. I used them on my 30 A with high way driving and had good luck with them.

[Mike V. Florida]

Originally Posted by tiquer

I hear where your coming from the carter pins can be a pain to put in at times . Lock nuts of the all metal veriety work great. I used them on my 30 A with high way driving and had good luck with them.

Yea but really, how often do you remove those cotter pins.

[Jim Brierley]

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I use ARP, 12-point nuts. I don't like castle nuts as there are very few really good threads doing the work. I have never seen a rod nut loosen so figure the cotter pins (split-pins) aren't doing anything anyway, and I worked on truck when those nuts were commonly used.

[Bruce of MN]

I bought a bag of metal lock nuts at Fastenal, but they are taller and heavier than stock and I decided not to use them. If I still have them and anyone wants a set for the cost of postage, let me know.

[mantta]

Where can I find Marsden nuts? I havetried Fastenall and many auto parts stores and they never heard of them.

[1931 flamingo]

Granger's??
Paul in CT

[Pete]

Originally Posted by mantta

Where can I find Marsden nuts? I havetried Fastenall and many auto parts stores and they never heard of them.

Marsden nuts are standard on most modern engines.
Try Chev or Ford or Mopar parts departments.

[mantta]

I ordered them online. We don't have much choice up here in Michigan's Upper Peninsula.

[George Miller]

Originally Posted by Jim Brierley

I use ARP, 12-point nuts. I don't like castle nuts as there are very few really good threads doing the work. I have never seen a rod nut loosen so figure the cotter pins (split-pins) aren't doing anything anyway, and I worked on truck when those nuts were commonly used.

I worked on lots of engines also I have never seen rod nuts come off . But I have found a lot of cotter pins in the oil pan. I'm with Jim on my cars no castle nuts with there weak threads.

[Chris in WNC]

don't use Plastigauge.

the Mike Flanagan aluminum foil method is easier and more accurate.

full description of the process is somewhere in the Ahooga.com archives, but here's the short version:

cut a piece of doubled thickness heavy duty aluminum foil the same shape as the babbit in the cap. check with your micrometer to make certain it's .002 thick.

put the foil in the cap & snug the bolts.

if it turns with the foil in place, it's too loose, remove some shims.

if it turns without the foil but won't turn with it, clearance is OK.

[George Miller]

Originally Posted by mantta

I have the pan off of my "A" and I am going to plastigage the rods & mains. Has any of you used Ny-Lock nuts on the rods and mains? They seem to do good on other machinery that has lots of movement and vibration.

As allready said nylock nuts will not take the heat, plus they might be grade 3. I would want grade 8

[sturgis 39]

Originally Posted by George Miller

I worked on lots of engines also I have never seen rod nuts come off . But I have found a lot of cotter pins in the oil pan. I'm with Jim on my cars no castle nuts with there weak threads.

What do you mean by weak threads?

[George Miller]

Originally Posted by sturgis 39

What do you mean by weak threads?

Where the nuts are turned down for the cotter pin. There is not much to keep the nut from expanding, then stripping the thread. I will have to say the original Ford nuts were made of good material. The replacement nuts that I have seen not so good, plus the threads were a little over size.

[ScottNW/Ohio]

You want a Grade "C" lock nut - the all metal type (kind of 'coned' shaped on top)
Grainger, Fastenal, or Mc Master Carr, Lawson Products, all carry them
Stay away from the 'nylock' nylon lock nuts - these are for 'low temp' applications
Also, there are different grades of nylon lock nuts - (not many people know this) the common ones you usually find locally are only grade 5, the grade 8's will have 'notches' cut in the corners of the flats
There are also 'tall' & standard height nuts in the all metal (grade C) - just be sure that you have enough threads protruding that the lock nut can fully engage the bolt

[BobinDallas]

Remember that if you are using metal locking nuts, the lock nut damages the bolt threads, more with each use. Most bolts only will withstand about 2 removals/reinstalls before structure and threads are beyond usable limits.

Cotter pins do no damage. Use new ones each time.

[Pete]

Originally Posted by BobinDallas

Remember that if you are using metal locking nuts, the lock nut damages the bolt threads, more with each use. Most bolts only will withstand about 2 removals/reinstalls before structure and threads are beyond usable limits.

Cotter pins do no damage. Use new ones each time.

Marsden nuts do NOT damage the threads.

[mantta]

I recieved the marsden nuts today that I plan on using on the rods and mains. What makes these a locking nut and what grade are they? I don't want to find out after there is a rod sticking through the block!

[Pete]

Originally Posted by mantta

I recieved the marsden nuts today that I plan on using on the rods and mains. What makes these a locking nut and what grade are they? I don't want to find out after there is a rod sticking through the block!

There is a small inner recess in the flat that bears on the part.
When tightened the flat distorts the body like a cone and pulls the
serrations in against the thread...When not tight there is no pressure on the threads. This is why you can spin them on and off by hand and can reuse them.
Most Marsden nuts are at least grade 8.
Fastener quality is not a good place to skimp.

Question: Ever wonder why the hot shot engine builders seldom use torque wrenches?
Answer: They use the bolt stretch method which uses a dial indicator to measure the stretch of the fastener. A plain high strength nut (no locking device) will never come loose tightened this way. Checked with a torque wrench they will usually be about 10% over the NORMAL torque wrench setting.