[unruhjonny]

So I am slowly but surely continuing to sell off my now dwindling supply of spare/extra parts.

I have a spare 350 that I received a year or two ago as payment for storing a bunch of other parts for several years.
The main reason why I accepted it, was that it's a runner.
It was pulled from a 1977 Trans Am my brother bought - so I can attest to it having run.
Now lets take pause, I am not saying it was a strong runner, but simply that it ran.
It's a 1973 post-EGR revisions engine, that I received with a 1969 four barrel intake manifold. -that intake was the other reason why I accepted this engine.

I recently sold my spare 400, and as a result, I am shuffling things around and decided to clean up this 73-350 before putting it away again.
I noticed that some lifters were getting stuck in their bores, so I took the time to remove the rockers and pushrods one at a time, pull the lifter, and clean pushrod, lifter bore and the lifter of old gunky oil.
My other 350(a 77 with the light crank) was pulled and put aside after a rod bearing span, and I learned the hard way that you need to be on top of things, or like that engine, things can seem to seize on you.
During my cleaning of this 73-350 I noticed that one of the cam lobes is nearly flat - it does ever so slightly still open and close the valve, but not a whole lot.

It might be worth noting that this is the first engine I have ever seen to retain the original composite cam gear.

Here's my crazy idea that I'd appreciate an honest opinion on:

I have an "A" cam that I pulled from my 70-400 back in 1998;
I was wondering if it might be feasible to pull this worn '555' cam, and simply replace it with this "A" cam;
And to be clear, I am meaning to leave the original to this engine (now thoroughly hardened) lifters in their original bores.
I would pull the timing set, and replace with another better (but used) set, sufficiently lube everything, and button it back up.
My thoughts are that since the cam and lifters have both seen ample heat cycles, that nothing should be liable to failure due to lack of heat cycles.
(Or maybe I am totally off my rocker?)

I don't imagine that this will ever be any thing more than a spare motor, cleaned up, and in running condition.
I know that right now everything is matched up, and even though that one lobe is worn badly, it would (hopefully) run quietly should I need or want to put it into service. I am concerned that doing this might make it run less reliably, or exponentially noisier.

Am I chancing things going awry by leaving the lifters from this '555'(?) cam, and using them on an "A" cam?

I'd appreciate thoughts.

[leeklm]

No personal experience doing it myself, but have always understood mixing a set of used lifters with a different cam is a big no-no. If you still have the original lifters from "cam A" marked from the appropriate positions, that may be a workable option.

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[unruhjonny]

Originally Posted by leeklm

... (I) have always understood mixing a set of used lifters with a different cam is a big no-no. ...

I have had this understanding too;
I also understood that this was a thing for engines which early on had cam failures, and that the nearly new lifters on a new cam caused mishap.
Or maybe it was purely a matter of "new" with "used"...?

Either way, if figured this was worth asking, especially in the context of what it is.

["QUICK-SILVER"]

The lifter off the worn lobe is guranteed to eat any lobe it can get on.

Spring for new lifters and do it
Clay

[unruhjonny]

hmm.
ok.

I was hoping that I might find a solution which didn't need a break in period.

I guess I'll leave it as-is for now then.

[Sirrotica]

With standard springs that are probably way down on pressure, lack of a break in isn't going to kill the cam and lifters. It's been done thousands of times in dealerships for decades. Now I'm talking a new set of lifters on a used, but in good shape cam, or a new cam and lifters. Not a cam that is already almost flat. The case hardening is gone, and nothing will save that scenario.

Usually the cam and lifters would get a liberal coating of GM EOS (engine oil supplement) and the rest would go in the engine, along with fresh oil, and filter.

If anyone is as naïve to think a new flat tappet cam, and lifters is broken in by the factory, or in a dealership when a cam and lifters is changed, you're living in a fantasy world.

In a dealership, the car is started, timing set, and a quick check to make sure nothing is leaking. There could be a road test, but not likely. Car gets sent to the bull pen until customer pays their bill, and down the road it goes.

[steve25]

If your taking about a darn near fully rounded off cam lobe then before using the motor again I would want to pull the pan to see what some of the bearings look like from all the cast iron grit that got in the motor, also while in there you will want to change out the 40 psi 5/8” pick up tube oil pump over to the standard 60 psi 3/4” pick up tube pump which also has the needed thick gear cover to stop pressure loss.

[A.W.Dille]

A good friend of mine and I were discussing reusing cams and lifters many years ago. Both of us were running Ford products at the time and with him being in the machine tool trade got to talking about parts and wear patterns. That's when he told me that each lobe will develop its own pattern and any old part (lifter) would not produce the same pattern, resulting in quick and excessive wear on the cam lobe. Reusing lifters that were on the same lobe with the cam you're wanting to use should be fine or new lifters on the replacement cam and break in just as you would a new cam.
Just my .02.

[unruhjonny]

Originally Posted by Sirrotica

With standard springs that are probably way down on pressure, lack of a break in isn't going to kill the cam and lifters. It's been done thousands of times in dealerships for decades. Now I'm talking a new set of lifters on a used, but in good shape cam, or a new cam and lifters. Not a cam that is already almost flat. The case hardening is gone, and nothing will save that scenario.

Usually the cam and lifters would get a liberal coating of GM EOS (engine oil supplement) and the rest would go in the engine, along with fresh oil, and filter.

If anyone is as naïve to think a new flat tappet cam, and lifters is broken in by the factory, or in a dealership when a cam and lifters is changed, you're living in a fantasy world.

In a dealership, the car is started, timing set, and a quick check to make sure nothing is leaking. There could be a road test, but not likely. Car gets sent to the bull pen until customer pays their bill, and down the road it goes.

this is a perspective that hadn't occured to me.

Thanks for taking the time to reply!

[Sirrotica]

Originally Posted by unruhjonny

this is a perspective that hadn't occured to me.

Thanks for taking the time to reply!

Since I've worked in many dealerships, as well as independent garages, and owned my own business, breaking in camshafts, and lifters on stock engines happens seldom, if ever. We all know it didn't happen when the car was produced new.....

The main difference is spring pressures are much higher on performance cams, and the ramps are more aggressive. Stock pressures and moderate ramps make the break in of less aggressive cams way less important. The importance of new convex lifters is what makes them turn as the slid along the lobes, so a flat lifter or worse yet a concave surface is when they quit rotating, setting up the wear cycle.