Thread: Change cam bearings?

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We're doing a budget rebuild/refresh on an old 1972 350 and have run into a little hitch. We weren't planning on replacing the bearings or rings or anything, just mostly all of the gaskets since it leaked oil like a faucet. I'm not sure if the engine has ever been disassembled so I thought I would check out the camshaft, and found out that one of the lobes is completely rounded so now we need a new cam and lifters. We did notice tiny metal flakes on the cam when it came out like some of the cam bearings got nicked or scratched. I ran my finger around the bearings and couldn't feel anything, and couldn't see any scratches with a flashlight.

Anyway, my question is should I replace the cam bearings just in case? I know I would need to take out the crankshaft and pistons in order to get the bearings pressed in, but that really takes the 'budget' out of our budget rebuild. Can the same main and rod bearings or piston rings be reused if they are kept in the same order that they came out? That would at least save some cash if the cam bearings needed to be replaced.

when a cam fails small ground iron gets every were. at the lest pull cam bearing pull engine apart wash clean ball hone piston bore polish crank .re ring . bearings rods . mains .cam

Ditto what Pat said -

I know you said you’re on a tight budget – but at this point any money you spend without at least prepping the block will be short lived. All that metal went "somewhere" and in all likelihood permeated every possible crevasse of the engine

Before you start, find a good local machine shop. You may already know one. Talk with the machinist that will be doing the work and tell him (or her) that you’re on a budget and would like to have an “ala-carte” approach that will allow you to pick-and-choose what you’ll have done. Work with the shop and buy the parts from them. Building a relationship with them will go along way towards a successful build.

At a minimum, I would recommend the following:

1. Take the block to a machine shop and have the block hot tanked. This gets all the glop off makes things a lot easier to work on. Having a clean base is a must for paint as well. You can have the shop measure all your clearances at this time and determine if a bore is required or if you can get by with a cylinder hone. The shop can also check the other “vitals” and determine if the mains are square as well as the deck.

2. Have the machine shop put in new cam bearings. You can decide if you able to put in new brass freeze plus and the oil galley plugs.

3. If you have a good micrometer, you can measure the crank. If you’re happy with the results, just get new standard size bearings. If not, you’ll need to have it turned and buy appropriately sized bearings. In that you’ve had this one running, you may well be able to reuse the crank “as-is” with new standard sized bearings. I’ve rebuilt engines with well over 100K miles and been able to use the crank without any work.

4. If your bores are good, inspect the pistons and if they’re decent, new rings and rod bearings will be the ticket. If not, new pistons and rings will be required. This can be a big ticket if you go fancy – Speed-Pro piston and ring kits are $250, JE and Keith Blacks can easily run $900 plus.

5. Your rods are probably okay. The stock rods are really pretty tough to hurt as long as they have good oil. If you’re using the original piston, this is a “no-brainer”, keep the stock rods too.

6. Have your heads done at the machine shop. Talk to them and decide how much you want to invest and plan a course accordingly. Again, if you want to get fancy, you can drop a ton of money here. If possible and practical, have your shop do a good valve job, replace what’s necessary and call it good.

7. Buy a good gasket set. Your machine shop probably will cut you a good deal on FelPro or similar.

8. If you’re going to stay with a stock cam profile buy it (and new lifters) from your shop or NAPA. Buy a new, true roller timing set from the same place.

The rest is really straight forward. When you get the block home, scrub it really good with hot soapy water. I like Dawn (get you own so as to not tick off your lady!) Dry the block real good with compressed air and then paint everything that shows. Lube all the inside parts with a light coating of oil or assembly lube (don’t use WD-40).

If you don’t have an engine stand, get one. You can find them cheap (I’ve seen them for $59), but I would recommend one with four casters as they are a bit more stable with heavy motors. If you don’t have an assembly manual, buy one. I would not worry about cam failure if you break it in slowly and as per any instructions that come with the cam. Use good oil and change is after a couple hours run time and look for any “tell-tale” signs, i.e, metal or water. Take your time and have fun.

Pick a part half price day . I've found good engines for $100 at a half price day at the wrecking yard, I would go in a couple days early and check the inventory. Find a car or truck that looks like it was running yesterday before someone ran into it. good clean engine, pull a valve cover, If there is still any oil that hasn't been required to be drained , quick compression check.