Main bearing shim stock

[jme821]

Does anyone here have experience with shim stock applied to main bearings on their flathead six engines? I recently rebuilt a 201.3 c.i. and found out after putting the engine back together and driving down the road that it calls for shim stock between the main bearings and crankshaft. Any input would greatly appreciated. 

[Don Coatney]

The shim stock is only used to check bering clearance. It is not left in place. Today the bearing clearance can be checked using plastigauge.  

 

 

[jme821]

Thank you Mr. Coatney. That’s the best news I’ve heard all year! 

[sser2]

Exactly. What manual describes is using a piece of 0.0015 shim stock to gauge main bearing clearance. Nowadays we use plastigage for this purpose. As of manual, shims can be used to adjust a new main bearing cap. 

[jme821]

The problem lies in the car trying to reach speeds exceeding 35mph. Once it gets to that point, the car violently shutters and consequently shuts down. I just recently had the flywheel resurfaced, installed a new ring gear, clutch plate, clutch cover and pressure plate assembly. Hopefully all that fixes the problem. If not, then final place to look is the connecting rod bearing and crankshaft bearings. I want this nightmare to end.  

[Dodgeb4ya]

Did the vibration start only after the flywheel and clutch/ ring gear work?

If so there's your problem.

[jme821]

I won’t know until its all reinstalled this weekend. Thankfully oil pan gaskets are still available at Oreillys and cheap so if the flywheel and clutch doesn’t fix the problem, the pan will get dropped and the bearings will get plasticgauged. 

[kencombs]

1 hour ago, jme821 said:

The problem lies in the car trying to reach speeds exceeding 35mph. Once it gets to that point, the car violently shutters and consequently shuts down. I just recently had the flywheel resurfaced, installed a new ring gear, clutch plate, clutch cover and pressure plate assembly. Hopefully all that fixes the problem. If not, then final place to look is the connecting rod bearing and crankshaft bearings. I want this nightmare to end.  

If it stops running at the same rpm, it's highly unlikely to be an internal or balance problem.  Neither normally causes an engine to 'shut down'.  Check ignition, fuel and valve clearance in that order, IMO.

[jme821]

I would agree with you but those issues were addressed prior to the most recent tear down. The distributor was recently repacked with new grease which helped get it to 35mph. Before the top speed was about 30mph. It cuts out and shakes violently before starving itself of something. These cars P2s are supposed to top out at 45mph. 

[sser2]

These P2 cars are supposed to top out at 70+ mph in stock condition. Something is terribly wrong with your car. There are several things to look at. You could start with distributor.

 

Re-packing distributor with grease may not be enough to solve its problems. Distributor has to be taken apart to make sure that centrifugal advance mechanism and base plate are moving freely, that governor weight springs have correct tension, and that vacuum pot is functioning. Shaft bushings and points must be replaced and points adjusted. Would also be a good idea to install new cap and rotor. Correct centrifugal and vacuum advance at various engine speeds should be checked according to factory shop manual.

 

Engine will perform very poorly with bad distributor, so fix it and see if the problem goes away.  

[jme821]

Right. That’s exactly what I had done to the distributor and it did help out a little bit. I’m now wondering if the harmonic balancer and crankshaft vibration damper need rebuilt? Oldmoparts offer that service even 

 

70mph? I couldn’t imagine that car being equipped with a 3 speed manual transmission going that fast, but when it’s all said and done, every mechanical part will be new, so it’ll be fun to find out. 

[sser2]

P2 engines did not use vibration damper - it was just crank pulley - bur it would be a good idea to replace the pulley with vibration damper from later model engines.

Can your engine rev in neutral without vibration? If so, then the problem is elsewhere, e.g. bad propeller shaft.

[jme821]

It idles perfectly. Revving up to top end is another story altogether. It’ll shutter violently revving to top end. So I apologize for misinforming you all about when/where the shuttering occurs. It’s not just in third gear trying to reach top speed.

 

Hypothetically, is possible to run undersized main bearings and connecting rod bearings during all that I described above? 

[Merle Coggins]

10 hours ago, jme821 said:

It idles perfectly. Revving up to top end is another story altogether. It’ll shutter violently revving to top end. So I apologize for misinforming you all about when/where the shuttering occurs. It’s not just in third gear trying to reach top speed.

 

Hypothetically, is possible to run undersized main bearings and connecting rod bearings during all that I described above? 

 

This again confirms a possible ignition issue, not a mechanical issue inside the engine. You have mentioned the work done on the distributor, but it sounds to me that either you have a bad wire that is shorting out when the points plate moves with the advance mechanism, or you don't have the points installed correctly so that there is too little spring tension. I did this once and when the engine got over 2500 RPM the points would bounce and the engine would stumble greatly. I couldn't get over 35 MPH. A deeper investigation of the replacement points revealed that I didn't get the additional spring connected properly. Once I figured that out and got it corrected it ran great again.

I highly recommend a thorough inspection of your distributor and points again to verify that everything is correct. Also, if you have a timing light, connect it and run the RPM up until it "shutters violently" (as you state). If the timing light starts to flicker intermittently that will verify that you have a points issue. 

[P15-D24]

Agree with Merle, seriously doubt if it's something internal to the engine. I'm curious what was packed with grease in the distributor. If I remember correctly only grease called for is a very small amount of the pivots of the centrifugal advance. I would set it up to TDC on #1, pull the distributor out of the block and see what is going on. 

[sser2]

I would emphasize the importance of checking distributor shaft free play, and, if it exceeds the specs, replacing shaft bushings. I have rebuilt three distributors - all had badly worn bushings. With a lot of shaft free play, ignition cannot be set correctly! 

[jme821]

Mr. Merle, P15-D24 and sser2, it almost looks tempting enough to bypass all this by way of electronic points conversion kit? But do they make such a 6v, positive ground beast?  Although the fella that rebuilt my distributor made it much better than it was before, he didn’t make it perfect. So my options are like this, it’s either a points conversion kit, a NOS distributor or finding out who sells bushing rebuild kits? Does anyone know if a newer model distributor interchanges with 1936 Plymouth P2? 

[Merle Coggins]

Before you start planning a retrofit upgrade, open it up and inspect what you have. It may be a simple fix. 

[sser2]

12 minutes ago, jme821 said:

Mr. Merle, P15-D24 and sser2, it almost looks tempting enough to bypass all this by way of electronic points conversion kit? But do they make such a 6v, positive ground beast?  Although the fella that rebuilt my distributor made it much better than it was before, he didn’t make it perfect. So my options are like this, it’s either a points conversion kit, a NOS distributor or finding out who sells bushing rebuild kits? Does anyone know if a newer model distributor interchanges with 1936 Plymouth P2? 

Electronic conversion is not a completely new distributor - it just substitutes points for Hall effect sensor, and still relies on properly functioning centrifugal and vacuum advance mechanisms of the original distributor. Distributor is the same for years 36-38. 39 and 40 distributors will also work, but have different settings. 36-38 distributor has initial setting of 4 degrees ATDC, which allows starting engine with hand crank. From 39 on, they dispensed with hand cranking, and those distributors start at TDC exactly.

 

Bushings can be bought on eBay:

Distributor bushings