I'm doing a stock rebuild of the 230 out of my '57 Plymouth.

The problem is that the crank becomes difficult to turn when the rear main cap is torqued down. After eliminating the bearings and seal, I removed the side seals (even though I was sure they couldn't cause the problem) and torqued the cap. Problem eliminated! What?!?

With no side seals installed, the crank takes about 5-10 ft-lb to get it moving. With the side seals (from a Felpro set) in place, it took approx. 40 ft-lb! I remembered that side seals also came with my Best Gasket rear main seal, so I dug those out to compare. They are shaped pretty much the same, but shorter overall than the Felpros. I put them in and the breakaway torque was 25-30 ft-lb. A definite improvement, but still too high, I believe.

I have tried repositioning them, but that doesn't change much. I can move them out (away from the crank) a tiny bit, but not much, or they won't seat properly in the recess where the rear edge of the cap fits down into the block. Besides, I'm still not exactly sure why they are even causing an issue.

Has anyone run into this, and how did you solve it? Thanks for any help with this!

Is this your first really old engine? they weren't know for easy turning.

Not sure if you have an FSM or not, but here's a page that might help, I don't have a 57 FSM.

Thanks for the reply. Yes, it's the oldest engine I've rebuilt. As far as Mopars, it's been small blocks and slant 6, but never a flathead. (Honestly though, quite a few years have gone by since I've rebuilt any engine!) I always thought the reason the older engines turned over harder was because of using rope rear main seals. Is that true or no? Mine has a regular rubber seal (like the one in Fig 19 of your FSM). I do have a FSM, but thanks for including that pic.

Like I said, I really can't see why those side seals would cause the problem, unless they are pressing (from behind) on the rear main seal, pushing it against the crank. However, the rear main seal is pretty rigid, so that doesn't seem likely.

Thanks again...any thoughts/suggestions are most welcome!

It has been a very long time since I farted about with flatheads, but I do remember they started out with iron pistons and 4 rings per. Last one I messed with was a 38 so it had all the old school stuff.

One thing I do remember is that you should replace the water distribution tube in the block. They tend to rot out and cause funny cooling issues.

As for eth side seals, any chance of just using RTV? Not a real fan of that stuff generally but sometimes it does the trick.

By '57 they had progressed to Al pistons, but still looong and 4 rings per! I've got a new water tube ready to go.

I had the same thought about using RTV. I normally hate to do something like that, but in this case, it might be a good plan. I'll take a closer look. Thanks again!