MTFCA Forum

Got a knock when I decelerate so decided to take out some shims. Unable to narrow down which rod was knocking.

Got shims removed on #'s 1 and 4 and had a hell of a time getting a cotter key in the 2nd rod cap hex head on #4. Finally got the nut tight enough to reveal the cotter key hole. After removing shims on #1 I'm fairly sure that was the knocking rod as it went back together easily.

Now of course when I try to hand crank it over it is hard as hell and no way my starter (6 volt) will turn it over.

Where did I go wrong?

Did you use something like plastigage to determine which rods needed attention and by how much? It sounds like you have one or more rods too tight now.

Allan from down under

CRAP!

No I didn't use plasti gauge. Sounds Like I need a new set of shims to install.

Your thoughts?

Take the caps off one at a time and use timesaver grit to set the clearence. No measuring, no plastigage, no scraping, no tight bearings.

Timesaver works. Plastigauge works. When you take shims out, take one out from one side at a time, tighten up the nuts and see if the engine is hard to crank. If it is hard you have taken out one too many shims. Put one back and try again. Alternate the sides that you take the shims out of, first one side then the other. Taking one shim out at a time means that you reduce the clearance by half the thickness of the shim. The shims are so thin that it will not bother the rod to take one out at a time, as long as you alternate sides.

Use the yellow Timesaver. Follow the directions. Clean out the Timesaver after using it. Timesaver works best if you have the engine out of the car and can take the crank out to clean the crank and journals. I rigged an electric motor to turn the crank when I used Timesaver on my engine.

Here is my story about tight rods, told to my by my father, long deceased. He crossed the United States during the 30's like a lot of people, moving to California to find a better life. He made the trip with friends and must have been in his late teens. They were driving a 1928 Chevy. The engine developed a rod knock, probably more than once. They pulled into a junk yard and got a used rod. They tightened it up to the point where the engine could not be stared with the starter motor or hand crank. They would push the car to start it and continue on their way. The new used rod would eventually break in and they could start the car in the normal way. They made it to California from New Jersey. My father went on to become a successful attorney in San Diego.

You have to get the shimming right first, using time-saver on a engine that you can't turn over will do diddly-squat!

Just in case you do not know the shims peel apart a thousand and a half every layer, you need to take a razor blade to get them started.

Something that irritates me is the lack of shims to do the job. I love Plastigauge, as it give me an idea of where I'm at. However, ready made shims in .001,.002" would be nice. I've always had to make my own, and it's a pain. I like Timesaver too, but I wish I could buy 60 or 80 grit from Langs. The 100 grit takes too long. I set my bearings at .0015.

If you keep the shims you peel off, you will have some one thousandth shims to use in the future. Also it helps to do one rod at a time and it will be just a little snug but you should be able to turn it with the crank. Then loosen the nuts and do another rod same way until you get all 4 adjusted. Then tighten the nuts and install the cotter pins. You might need to pull start the car the first time, but after it runs for a few minutes, it should start with starter or crank.
Norm

Thanks for all the advice. Ironically, when I did this to another car I must have gotten lucky because it came out fine. THIS time however that is not the case.

While I think plasigauge is great for steel backed insert bearings, I stopped using it a long time ago on poured babbitt bearings because I wasn't getting a consistent reading. I have been using the aluminum foil method. Re the nut; if the holes don't line up at 30-35FP, I swap the nuts around or file/sand a little off the bottom till they do. Being very close or almost able to get cotter pin in, maybe ok but more then that, I do as suggested above. Using the correct wrench for the rods should yield approx that torque reading. Repeated over tightening of bolt can lead to pulled or stripped thread and replaced bolt/nuts.

Mark Gregush wrote: ↑

Sat Sep 12, 2020 2:15 pm

While I think plasigauge is great for steel backed insert bearings, I stopped using it a long time ago on poured babbitt bearings because I wasn't getting a consistent reading. I have been using the aluminum foil method. Re the nut; if the holes don't line up at 30-35FP, I swap the nuts around or file/sand a little off the bottom till they do. Being very close or almost able to get cotter pin in, maybe ok but more then that, I do as suggested above. Using the correct wrench for the rods should yield approx that torque reading. Repeated over tightening of bolt can lead to pulled or stripped thread and replaced bolt/nuts.

What bothers me is I removed a couple of shims and NOW the rod bolt is too "short" to reveal the cotter key hole without tightening the nut MUCH more than it was before.

I would have thought that removing shims would expose more threads. It did not but rather "appeared" to shorten the the bolt. I KNOW that didn't happen but something did (operator error).

John, The only way removing shims could shorten the bolt would be if the bolt is turned in the rod. There is a flat spot on one side of the bolt, and that side should be placed against the rod and the bolt will drop into place. If that flat spot is turned in a different direction, the bolt will not drop all the way into place and will appear to be too short, but could give you problems if it should turn to the proper position while running the engine.
Norm

What Norman said^.

I use small block Chevy rod bolts and nuts. They almost drop in and if the nuts don't loosen up in them, I seriously doubt they will in a T engine. JMHO, YMMV. Dave