The use of lock nuts and short block Chevy bolts with lock nuts has been discussed here already. Now I find myself in this situation... After fitting dippers on the rods, the rod bolt nuts cannot be secured with cotter pins because the holes won’t reach the castellated portion of the nuts. I am considering using self-locking nuts on the original bolts but the 3/8"-24 connecting rod lock nuts that I need don't seem to be stocked by any of the online catalogs of the major car parts suppliers.
I finally located a grade 8 lock nut which is specified for mounting rear leaf spring shackles on early 50’s Ford pickups. In the picture 7 or 8 threads can be seen vs the 9 or 10 on the original castellated nuts. Obviously the extra threads are doing less work since half of the thread is cut away on the castellated nuts.
Am I missing anything here, or are these grade 8 lock nuts a viable solution for the Model T connecting rods?
What I have done is grind the nut the thickness of the dipper. They are still in that engine 25+ years later.
And the only reason I put the dippers on was I got about a pound of them in with a bunch of other stuff I bought. I'm not convinced they do much. The nut and the windage from the rods can't leave a puddle of oil in the trough. Model A's and Chevy's have a different thing going on down there that dippers work.
The Stover type nuts in the picture are supposed to gall the thread as they are installed. It's one time only and on perfect threads, not for bolts that are well used and drilled. Dave in Bellingham, WA
Try the nut on a rod bolt, the deformed thread may chew up the original bolt. You might better use the Chevy 350 rod bolts. You could also use a Loctite primer and Loctite and your original nuts.
In any case better take a hard look at your original bolts and their threads."
if you use the 350 bolt why not use the nut also no lock on a 350 why would you need it on a low powered t ford???? charley
Chevy rod bolts are to short by about an 1/8th inch.
The way that guys are using them you have to butcher the rod.
Use these nuts as they lock and you can put them on and off with out hurting good threads.
Charley, you have more vibration on a T Ford engine than a modern 350 Chevy.
The rebabitted rods I have used were furnished with new rod bolts which I assume were 350 Chevy bolts.
The rods were not butchered.
The ends of the dippers can be bent up along side the nuts to hold them in place.
I grind the dippers into a figure eight pattern to get them to fit better into the rod cap. Don't grind too much or the dipper scoop may not have enough material to hold it in place.
Done correctly, the dippers do a lot of good.
I know this has been around before, but I wonder if it is necessary to use dippers at all. Henry didn't!
If you use shorter bolts in a Model T rod, you have to butcher them.
By either cutting metal out of the cap so the Babbitt is not so thin as to hit steel, and weaken the cap, or change the center distance, that changes the compression in which case, neither is Acceptable, and is butchering!
Most of the time with short bolts, they make it so dippers can't be used with out more butchering.
Jim, grinding the nuts down so the the cotter keys will fit is a great idea! I do wonder about the effectiveness of the dippers as you do, since the rod nuts are creating a trough as they pass through the oil just before the dippers.
The aircraft lock nuts would be great but their locking portion will not reach the threads with he dippers installed.
My current options appear to be:
1 - grind the connecting rod nuts so the cotter keys will fit.
2 - not install the dippers at all.
It's true that Henry did not install dippers on the Model T at the factory but it's also true that driving conditions have become more aggressive as time goes on. Perhaps the dippers offer some extra lubrication?
Do we have any definitive results regarding the effectiveness of oil dippers VS no dippers?
The earliest T rods did have dippers. I had some. The early crankcases also, I believe, had deeper troughs.
I used these nuts on connecting rod caps with dippers. Right or wrong, they seemed to work fine.
Chris, thanks for that picture. Those lock nuts from Albany County Fasteners cost 1/10th what I was about to pay, same grade and size.
I've put small block chevy self-locking nuts on all the engines I have done here over the last 10 years. Used the stock T rod bolts. Have not had a single one loosen up yet. No cotter pins, I use lock washers on the mains and pan instead of those PITA cotter pins too. No problems.
I'm not at home now, but aren't the originals 19/32"s, or something like that!
Tim, I haven't been able to find the small block Chevy self-locking nuts by themselves. Where do you get them?