1967 327/300 rear main bearing and cap

[Timothy B.]

I removed the oil pan today to repair stripped threads on the drain plug. The pan has a nut inside and not the nut plate we discussed some time ago. Can this nut be heli-coiled to repair the threads and is the size 1/2" fine thread?

Also Look at the pics of the bearing, I assume the fm means Federal Mogul and the size is .001 oversize, is this correct..

Finally, look at the pics in the next post to see what someone did to one of the dowel pins that locate the oil pump. Are there any suggestion on how to remove this damaged dowel. Looks like it was drove in to far then Bubba tried to pull it out.

All comments are appreciated, Tim

[Timothy B.]

Re: 1967 327/300 rear main bearing and cap

Pictures of damaged dowel pin..

[Mike M.]

Re: 1967 327/300 rear main bearing and cap

Pictures of damaged dowel pin..

i wouldn't remove the dowel as there are three points that the pump attaches to the main cap, hence i doubt any mis-alignment will occur. if you're hell bent on removing it, drill it out and replace it. regrads,mike

[John H.]

Re: 1967 327/300 rear main bearing and cap

Tim -

I agree with Mike - leave it alone; the pump isn't going to move when it's located by two pins and a bolt.

[Clem Z.]

Re: 1967 327/300 rear main bearing and cap

I removed the oil pan today to repair stripped threads on the drain plug. The pan has a nut inside and not the nut plate we discussed some time ago. Can this nut be heli-coiled to repair the threads and is the size 1/2" fine thread?

Also Look at the pics of the bearing, I assume the fm means Federal Mogul and the size is .001 oversize, is this correct..

Finally, look at the pics in the next post to see what someone did to one of the dowel pins that locate the oil pump. Are there any suggestion on how to remove this damaged dowel. Looks like it was drove in to far then Bubba tried to pull it out.

All comments are appreciated, Tim

if it was a undersize bearing it would have had "US" under size stamped after the .001. i believe that some corvette parts places sell a new weld in nut. don't mess around with a heli coil for this. if you can't buy one have a machine shop make one for you

[Joe L.]

Re: 1967 327/300 rear main bearing and cap

I removed the oil pan today to repair stripped threads on the drain plug. The pan has a nut inside and not the nut plate we discussed some time ago. Can this nut be heli-coiled to repair the threads and is the size 1/2" fine thread?

Also Look at the pics of the bearing, I assume the fm means Federal Mogul and the size is .001 oversize, is this correct..

Finally, look at the pics in the next post to see what someone did to one of the dowel pins that locate the oil pump. Are there any suggestion on how to remove this damaged dowel. Looks like it was drove in to far then Bubba tried to pull it out.

All comments are appreciated, Tim

Timothy-----

Yes, this is a Federal-Mogul bearing. This particular bearing is a "CP" type bearing which is a so-called "tri-metal" bearing---steel backed with a copper alloy layer and a lead-tin overplate. Original Chevrolet engines did not use this type of bearing. They used a steel backed premium aluminum bearing. This is the type I use and recommend.

This bearing looks to be in pretty good shape EXCEPT that there is some wear on the thrust surface. So, I would not re-use it.

I do not understand how someone futzed up the dowel pin like that. However, I think the oil pump should still align ok. However, make sure you use a stock-type bolt with slightly raised shoulder beneath the bolt head. Do not use a stud in this circumstance.

I think you can still get a flange plate for the drain plug from GM under GM #3723008. This plate has a tapped hole for the 1/2-20 thread size of the plug. However, the old plate can be a bear to get off while avoiding damage/distortion to the oil pan. So, I like your idea of using a thread repair. However, I think I might use a Thread-Sert as opposed to a Heli-Coil.

[Timothy B.]

Re: 1967 327/300 rear main bearing and cap

Thanks everyone for the information, keep it coming.

I was hoping to use this bearing again as I am concerned about replacing just one bearing as it's not part of a set so I am worried about similar machining.. The crankshaft looks V/G and the bearing surface to my eyes seem normal. I did not check end play but I will install and check to see if it's excessive causing this side wear.

If I install a new bearing with the engine in the chassis could I still get accurate plastic-gage reading checking clearance, (crankshaft weight down).

Does Federal Mogul make a bearing set that is premium aluminum like original. If I decide to change these I should roll a new set of rod bearings also as I assume they are the same..(see where this is going)

Joe, can you expand on the thread-sert idea, where to purchase etc. I purchased the GM flange plate some time ago knowing I wanted to repair this problem. This nut inside the pan bottom is thick and stocky that's why I threw out the heli-core idea. Major work to remove and install the plate..

I will post some pics of the engine bottom later today for everyone to inspect, Thanks again, Tim

[Larry M.]

Re: 1967 327/300 rear main bearing and cap

Tim:

Two thoughts on the pan nut: Take your time and use a Dremel grinder to remove the old nut weld, concentrating on grinding the nut metal and not the pan metal. Or, have an experienced TIG (heli-arc) welder weld up the stripped threads and then have a machine shop re-drill and tap. A good machine shop should be able to do both the welding and the tapping.

Larry

[Clem Z.]

Re: 1967 327/300 rear main bearing and cap

i would NOT change the bearing as it will last a long time with that little bit of wear. don't start the engine with the clutch pushed in because till the oil pressure comes up you have a dry start there. always start in neutral with your foot off of the clutch. car that are not driven often have the oil on parts like the thrust side dry up and get no lube till the oil pressure come up.

[Terry M.]

Re: 1967 327/300 rear main bearing and cap

i would NOT change the bearing as it will last a long time with that little bit of wear. don't start the engine with the clutch pushed in because till the oil pressure comes up you have a dry start there. always start in neutral with your foot off of the clutch. car that are not driven often have the oil on parts like the thrust side dry up and get no lube till the oil pressure come up.

[Timothy B.]

Re: 1967 327/300 rear main bearing and cap

Read some info about a time-sert for repairing the stripped oil plug threads. Drill the hole and countersink the top, tap the hole then install this time-sert bushing in what looks like another tap and thread into the hole and the final three threads are supposed to lock into the time-sert bushing somehow.

I am checking further as I may install from the inside so the countersink will prohibit the bushing from coming out. I will let everyone know what method I use because if this works it's much easier than trying to remove the nut or nut flange..

[Clem Z.]

Re: 1967 327/300 rear main bearing and cap

The “start in neutral” works for 1967 and earlier, but Chevrolet screwed those of us with C3s and some newer Corvettes. There is an interlock that prevents cranking the starter unless the clutch is depressed. OH! I am so depressed.

just disconnect the wire and put a jumper between the 2 contact on the wire. problem solved. we had a problem here in the snow belt with the salt on our shoes corroding the switch contacts so we just bypassed it.

[Terry M.]

Re: 1967 327/300 rear main bearing and cap

The Time-sert has the advantage of being able to seal liquids whereas a Heli-coil is a spring like device that will not seal liquids. Google time-sert to see what it looks like and how it works. Time-sert needs more material around the hole to work, so there are places where it will not be effective.

[Joe L.]

Re: 1967 327/300 rear main bearing and cap

Thanks everyone for the information, keep it coming.

I was hoping to use this bearing again as I am concerned about replacing just one bearing as it's not part of a set so I am worried about similar machining.. The crankshaft looks V/G and the bearing surface to my eyes seem normal. I did not check end play but I will install and check to see if it's excessive causing this side wear.

If I install a new bearing with the engine in the chassis could I still get accurate plastic-gage reading checking clearance, (crankshaft weight down).

Does Federal Mogul make a bearing set that is premium aluminum like original. If I decide to change these I should roll a new set of rod bearings also as I assume they are the same..(see where this is going)

Joe, can you expand on the thread-sert idea, where to purchase etc. I purchased the GM flange plate some time ago knowing I wanted to repair this problem. This nut inside the pan bottom is thick and stocky that's why I threw out the heli-core idea. Major work to remove and install the plate..

I will post some pics of the engine bottom later today for everyone to inspect, Thanks again, Tim

Tim-----

Federal-Mogul does make a premium aluminum bearing. In fact, they are the one that currently makes the GM bearings. The Federal-Mogul premium aluminum bearings are kind of hard to find, though, in the aftermarket. They are called "AP" bearings.

I think you could just replace the one bearing without causing any sort of problem. In fact, GM has always sold bearings individually and not as a set just for this reason. However, the last part number I have for a .001" undersize GM rear bearing, GM #12329791, is discontinued. There may or may not be a new part number. If clem feels that the bearing is OK, you could probably just go back with it.

Thread Serts can be purchased from McMaster-Carr.