Camshaft Question

[Mr Clean]

I agree with HRPC, on they are still useable. but cam bearings are not very expensive, and while you have it apart, and it seems you have a doubt about them, replace them.

 

[davbell22602]

Its fine. Its cam bearings for a rering motor, not a new rebuild or reman engine. IF it were down to the bronze colored babbit, I'd say have them changed, but looks fine in the pic and your desicription, I say they are usuable for a rering motor and you'd get full life out of them.

Even with a new cam?

All my main cap bearing came to .0015 with plastagage. The desired spec is .0005-.0015and max is .0025.

 

[bucket]

Even with a new cam?

All my main cap bearing came to .0015 with plastagage. The desired spec is .0005-.0015and max is .0025.

I'm no pro, but I would run those cam bearings too.

Is that just the main bearings? How about the rods?

 

[davbell22602]

I'm no pro, but I would run those cam bearings too.

Is that just the main bearings? How about the rods?

Thats just main bearings. I'm replacing rod bearings. Just found out today that I have to replace my valve springs after testing them with a valve spring tester. I'm supposed to get 90 pounds with when the valve is closed and only getting 60-64 pounds.

 

[HotRodPC]

I agree with Clean too, that they are cheap, but the most expensive part of the cam bearings is the install, and the hassle of dropping off the block at the machine shop, then waiting to get it done and go pick it up. That does sound OK on the mains. Its right in the middle and actually, .0005 seems a bit tight for old school motor IMO, so I'd say .0015 is real good if .0025 is max. But then again, just depends on the motor model itself. Newer model motors, like Ford Modular motors and LS motors are much tighter spec and also why they run thinner oil, 5w-30 instead of 10w-40. But, You can change main bearings yourself without a machine shop, and they aren't that much either. Also, Main bearings are critical for good oil pressure, so you might consider doing at least the mains. I'd do the mains long before I'd consider the hassle of cam bearings. And what about rear main? I'd replace that too while it out and apart.

 

[crazy4offroad]

Is it 0.015 or 0.0015??? It should be 0.015" or fifteen thousandths of an inch. Fifteen hundred-thousandths of an inch just dont sound right lol. Keep in mind the expansion of heated parts, that 0.015 may go closer to 0.010" in a warmed up engine.

 

[HotRodPC]

Is it 0.015 or 0.0015??? It should be 0.015" or fifteen thousandths of an inch. Fifteen hundred-thousandths of an inch just dont sound right lol. Keep in mind the expansion of heated parts, that 0.015 may go closer to 0.010" in a warmed up engine.

Good Catch C4, I am sure its it's 3 digit. .

 

[davbell22602]

.0015 is what the HP How to Rebuild Your Big Block Ford Book has for the spec. Its on page 123 on top paragraph center column on text if someone else has same book it check it also.

 

[crazy4offroad]

Now that I think about it you may be right Dave, it's been a while since I plastigauged bearings.

 

[Mr Clean]

I agree with Clean too, that they are cheap, but the most expensive part of the cam bearings is the install, and the hassle of dropping off the block at the machine shop, then waiting to get it done and go pick it up. That does sound OK on the mains. Its right in the middle and actually, .0005 seems a bit tight for old school motor IMO, so I'd say .0015 is real good if .0025 is max. But then again, just depends on the motor model itself. Newer model motors, like Ford Modular motors and LS motors are much tighter spec and also why they run thinner oil, 5w-30 instead of 10w-40. But, You can change main bearings yourself without a machine shop, and they aren't that much either. Also, Main bearings are critical for good oil pressure, so you might consider doing at least the mains. I'd do the mains long before I'd consider the hassle of cam bearings. And what about rear main? I'd replace that too while it out and apart.

I thought I read in the past Dave had or was going to get a Cam Bearing install tool? I thought he was replacing the Cam Bearings, not a Shop.

 

[Mr Clean]

Thats just main bearings. I'm replacing rod bearings. Just found out today that I have to replace my valve springs after testing them with a valve spring tester. I'm supposed to get 90 pounds with when the valve is closed and only getting 60-64 pounds.

If you are replacing your Cam with a new Cam, you should replace your valve springs to mach the Cam anyway. That is one of the reasons they sell a Cam kit, with springs, keepers, seals, and new lifters, so it's all new and matched.

I don't know maybe I build a motor different from other people, I replace most "wear" parts while I have it apart, sure it costs a little more, but a little piece of mind goes a long way.

 

[davbell22602]

If you are replacing your Cam with a new Cam, you should replace your valve springs to mach the Cam anyway. That is one of the reasons they sell a Cam kit, with springs, keepers, seals, and new lifters, so it's all new and matched.

I don't know maybe I build a motor different from other people, I replace most "wear" parts while I have it apart, sure it costs a little more, but a little piece of mind goes a long way.

Out of all the parts I have to replace on this 390 the bill at rockauto is up $675 on when adding everything in the shopping cart.

 

[HotRodPC]

Out of all the parts I have to replace on this 390 the bill at rockauto is up $675 on when adding everything in the shopping cart.

And, that's not even a full rebuild. That's a fuggin rering job. I can rebuild a small block Chevy 350 for that. ANd you're still not done. When you get going, the nickel and dime other items will add up too. But, that's why Chevy is what it is. Cheap and Easy to keep. In the old school variety anyway.

 

[davbell22602]

And, that's not even a full rebuild. That's a fuggin rering job. I can rebuild a small block Chevy 350 for that. ANd you're still not done. When you get going, the nickel and dime other items will add up too. But, that's why Chevy is what it is. Cheap and Easy to keep. In the old school variety anyway.

Here's what I gotta replace: engine gasket set, .030 moly piston ring set, intake valves, exhuast valves, valve springs, valve seals, timing set, rod bearings, camshaft, lifters, and camshaft bearings(optional).

 

[HotRodPC]

Here's what I gotta replace: engine gasket set, .030 moly piston ring set, intake valves, exhuast valves, valve springs, valve seals, timing set, rod bearings, camshaft, lifters, and camshaft bearings(optional).

I wouldn't use moly rings for a rering motor. Its hard enough as it is to get Moly rings to seat in a new fresh bore with a good Sunnen hone job, and going to be even harder yet with a ball hone job and the rings fitting a hair looser. What makes you think you need moly rings in this motor? You running nitrous or a turbo on it? HI compression? Sure moly lasts longer, IF you can get them to seat and find a good home in the cylinder. Chrome Moly rings are even harder yet, and ductile iron or plasma moly even harder there yet. I'd likely just go with some standard cast rings, or quick seat rings. You're not expecting a million miles out of a re ring motor I'd hope. 80-100K is about all you shoud be expecting on a rering old school motor IMO. And again,you're there, I'd replace the main bearings too just because and I woudln't worry about the cam bearings.