Too much bearing thickness?

[Falcon62]

I have this 4-main 200 sitting in my shop and my son's car needs an engine, so I thought I'd reassemble it and toss it in. The block is .030 over, and the crank has been turned .010 under on the mains, but .040 under on the rods.

I miked all the journals (each in several places) and the rods are all 2.0835 (except #3 which was 2.0832) and the mains were #1 - 2.2835, #2 2.2830, #3 - 2.2832, and #4 2.2835. I don't have a set of bearings, but assuming correct size for rods and mains, I end up with about .001" for clearances. I don't have set of bearings to measure for actual clearance, nor do I have any snap gauges to check thrust width.

My personal preference is -.010, and nothing under -.020, but 4-main 200 cranks aren't exactly easy to find.

Intended use will be occasional weekend drives, cruises, and so on. I want it to be reliable enough that I don't have to worry about how the car is driven, and my son does have a heavy foot.

I need to know just how much bearing thickness is too much. At what point does it become a gamble for spinning a rod bearing? I already know the standard rules of thumb, so, should I just junk this block/crank and find another later 200?

 

[MustangSix]

I have used cranks that were turned 30-30 with no problems.

Actually, some racers deliberately turn their cranks pretty small to reduce surface bearing speed.

 

[wsa111]

Phil, i don't think bearings come in over .030 under. the best bet would get a crank kit from your local parts supplier which will come with matching bearings for the crank. If you can find a standard crank, do like CZLN6 does and have it offset ground to improove your deck height. :idea: william- Don't forget if your application uses an auto trans & they give you a crank for a stick, remove the pilot bearing or you could possibly destroy your front pump in the trans.

 

[MustangSix]

Phil the packrat that I am, I have three sets of brand new Michigan main bearings for a 4 main engine in std, .002, and .020, if you need any of them.

Probably not made for our sixes, Bill, but they do make main bearings up to .060" under for Chevy and Ford V8's. That would have to be one heck of a scratch......

 

[Falcon62]

Thanks for the offer Jack, I'll keep that in mind while I search for rod bearings. When the mains miked out at -.010, I had hoped the rods would too, but no such luck.

Guess I'll search for rod bearings and see what I can come up with. Wonder why a shop turned them that size if bearings don't exist? Maybe I should have kept the old ones for reference purposes.

Bill - A crank kit would be the best option, but I doubt I'd have any luck finding a 4-main 200 crank. The 4-main 200s were only produced a couple years (63/64), so availability is sure to be limited to non-existent.

 

[Anonymous]

A friend of mine had a Pontiac 400 with the rod journals turned .040 under. I think they do make them, they're just not quite as common as .010, .020, .030 since most people probably scrap the cranks after they get too bad.

Might be a little hard finding them for a 200, but ya never know.

 

[godheadcustoms]

From napaonline.com: try part # CEBCB583P

They're listed for a 144/170, but I think the earlies all used the same rods?

 

[godheadcustoms]

Also try FSPP, Mike lists them up to .060(?) in rod bearings.

 

[Falcon62]

Hate to resurrect such an old topic, but I wanted to provide an update.

I bought a set of .010" under mains (for a 7-main, but I just used 4 ) for my 200. Spent the afternoon cleaning things up and plastigaged the mains. All four came in right at .002". Ideal clearance is .0005 - .0015, with a max of .0022, so the crank is on the outside limit at .010" under. That would be fine if I was going to be spinning it hard, but this thing won't be used that way. Sooo, I guess I could have the mains turned to .020" (still have a set of .020" mains Jack?) and use the crank. At least that way I would be assured of good oil pressure.

I'm still concerned about using .040" rod bearings, but I suppose it will be ok based on what others have said here. Seems like too much bearing to me. BTW, I checked and Mike does have undersize rod bearings to .060" for the small sixes.

 

[Nathan289]

Hey Phil,
I'll loan you my 7 main 200 if you want
you can rebuild it for me and drop it your sons car till mine is ready :roll:
Well it was worth a try
Nathan

 

[Falcon62]

Hey Phil,
I'll loan you my 7 main 200 if you want
you can rebuild it for me and drop it your sons car till mine is ready :roll:
Well it was worth a try
Nathan

I already have another 7-main 200, but I had intended to use it for a future build-up for my car. If I can make the 4-main run reliably (good oil pressure, no spun bearings, etc.), it's going in the 61 Futura.

 

[Anonymous]

Sometimes a crank is ground and then the journals are chrome plated.
You might want to look into this possibility if finding a crank becomes that difficult.
That cost would probably be more than offset however with the price of a real good 7 main 200.
I picked up a real good engine from a local yard which had just been rebuilt and put into the car before it was wrecked.
Got it for $150 and it had been equipped with AC so got a rebuildable compressor as well.
Also over size bearing are available on e-Bay all the time.
If you root around you may find exactly what you want or optionally contact sellers and see if they have exactly what you want.
I'm currently working on a learning/training engine and it is bored .040 over and crank ground .010-.010.
Found all the componenets on e-Bay.
mpcentral was one seller I contacted and was able to get some items not listed from. 7929594751 is auction for 4 brg set however listed is .020 over. I'd contact seller myself.
Other sellers also have 'stores' which you can visit and then question about their additional inventory.
Good luck

DaveP