Hot Rod Forum banner
1 - 20 of 43 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
Has anyone experienced a problem where only 2 lifters got chewed up and ruined those cam lobes? It was number 7 exhaust and number 4 intake. Car was broken in properly with oil additive and lube used on everything. An oil pump primer was also run for 8 minutes turning the engine every minute. This is a stock rebuild of a 327. We are trying to avoid this happening again. The oil pressure remained normal. The car was run in the garage for a total of around 35 minutes
 

Attachments

·
Race it, Don't rice it!
Joined
·
8,277 Posts
Lots of reasons this happens.
Soft cam
Soft lifters
Lobe taper
Lifter radius
Lifter bore indexing
Spring stiffness
Seal, retainer, guide or valve-piston clearances.
Cam thrust

What cam/lifter/springs?
 

·
Administrator
Joined
·
8,300 Posts
X2 with johnsongrass on the valve springs.
Maybe shoulda run break in springs.
 

·
Registered
Joined
·
14,572 Posts
Whose cam and lifters, what is the spring pressure?


How long was the break-in period and what RPM?


Is there a windage tray, blocked off top end oil returns or reduced top end oil supply?



Did you 'grease the shaft and lifter feet before installation? By grease the shaft I mean like using Isky Rev Lube lovingly rubbed in not just smeared on?


Had you checked lifter to their bore clearance? Too much quickly gets trouble going.


Bogie
 

·
Registered
Joined
·
17,613 Posts
I wrote this initially several years ago when we began experiencing failure of flat tappet cams due to the removal of extreme pressure lubricants from "off the shelf" motor oils. It has been improved by other writers down through the years and I would now call it the "Bible" of how to make a flat tappet cam work with today's lubricants.
https://www.crankshaftcoalition.com/wiki/Camshaft_install_tips_and_tricks
 

·
Registered
Joined
·
4,379 Posts
Those pictures make the case for retro roller lifter cam with link bar lifters. More money up front, but not when you see pictures of the likes posted by the OP.
 

·
Registered
Joined
·
5,756 Posts
Rebuilt 327, eh!
Like in torn down, thoroughly cleaned hot tank style and then assembled or just new stuff in an assumed clean block.
Likely the latter!
 

·
Registered
Joined
·
4,203 Posts
Too much valve spring pressure especially during the camshaft break in period is the usual culprit for cam lobes going flat.

Examples:
I like SB Chevrolet stock or stock reproduction camshafts with the GM “Soft Touch” cam lobes (valve acceleration ramps). All SB Chevrolet factory and reproduction factory camshafts use 85 seat pressure and less than 300 lb open pressure. Those GM engineers are not stupid and they hate warranty problems.

My 1962 Chevrolet Bel Air has a 1968 350 CI engine with a GM 3863151 camshaft (L-79) and GM 3911068 valve springs (Z-28, 30-30, etc.) and the engine has about 62,000 miles on it and about 170 psi compression on every cylinder.

The Chevrolet 427 (L-88) engine used a camshaft with .560” valve lift and valve springs with 116 lb seat pressure at 1.880” and 310 lb open pressure at 1.320” . That old motor ran pretty good.

I used those valve spring on my 1969 Pontiac Firebird 400 with Ram Air IV valves and a Crane solid lifter camshaft with .525” valve lift at 298 lb open pressure.
 

·
Registered
Joined
·
1,417 Posts
My first cam must have survived by the grace of god. The builder used white lithium grease brushed on every moving surface in the motor. Sat for about 15 years. Primed motor with zinc additive in oil. Dribbled Crane assembly lube on the cam lobes the best I could. Ran motor as suggested but certainly had a few moments here and there when it idled for a few seconds. Springs weren't too strong, but strong enough in time to destroy the exhaust valve rotators that the builder left in, also strong enough to take out the stock exhaust rockers/valve tips.

I actually sold the cam, lifters, and flat top/beveled pistons on Craigslist. Always wondered if it survived in a different block.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #11 ·
3 10 minute segments of break in at 2000-2500 rpm
No windage tray or blocked off oil passages
Greased the cylinder walls, oiled the piston rings and used generous amounts of assembly lube on everything including cam lobes and lifter bases
Did not check lifter to bore clearance but all went in easily
Engine was completely torn down, hot tanked, machined, honed, magnafluxed, bored new cam bearings, freeeze plugs, galley plugs...the full works
 

·
True Hotrodder
Joined
·
1,894 Posts
Greased cylinder walls is certainly not a hot trick to do but that has nothing to do with the cam and lifter failure.


Moly paste lube needs to be rubbed into each and every lobe of the camshaft. And then as you put it in, you can pre-oil the bearing surfaces of the cam with a regular engine assembly oil but you should also give the lobes one more coating of the moly lube. The bottoms of the lifters need to be checked for any type of damage or scars plus if you put them on a sheet of glass they should not sit perfectly flat. They should have just a hint of wobble and this convex surface is what allows them to rotate. And you of course have honed the lifter bores lightly and all of the engine block has been cleaned extremely well prior to assembly? Lube the lifter holes with 30 wt and make sure the bottoms of the lifters are moly coated. I normally prefer to soak the lifters in 30 wt overnight if possible but it's not required if the lifters are solids however I always soak rollers. I also use a hot plate and heat some oil up to 200 degrees and let the timing chain assembly soak in it for at least 30 minutes. Cylinder walls can be cleaned with ATF and paper towels, keep wiping the cylinders until the towels come out CLEAN. Prior to putting the pistons in the holes, use a good 30 wt motor oil to lube the walls and piston rings, skirts.


Only the outer springs of your valve springs should be used for the break-in period. Fresh oil and filter ( I normally dump an extra quart or two in depending on the pan size - it helps with getting oil splash on the cam and lifters) , a bottle of ZDDP that is premixed with a quart of the oil. I do not, never have and never will use oils that are branded "Break-in Oils". The engine needs to be set to fire immediately, brought to 2500 and then rolled a few hundred RPM up and down for at least 30 minutes. If you think the engine might over heat then put window fan(s) in front of the radiator to help cool it. Shut it off, let it cool down some, drain oil and cut the filter open. Once the engine is cold, re-torque the heads unless gasket maker has expressly stated not to do so.
 

·
******* Professional
Joined
·
1,321 Posts
Elgin .45/46 lift gm style cam
elgin lifters
? springs...thinking this is the problem
If you bought a set of modern aluminum heads..... know that they typically come with valve springs for a hydraulic roller cam. Let's discuss exactly what your springs are. All the moly lube in the world won't do you any good if the spring pressure is too high for a flat tappet cam.

Bogie already asked you this once aready, but you didn't answer him.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #14 ·
They are not aluminum heads. I don’t what the spring pressure is. I am expecting that was the problem. Waiting for my valve spring pressure tester to arrive tomorrow.
 

·
Registered
Joined
·
4,203 Posts
The 1963 Pontiac 421 Super Duty factory race cars came with standard “low tension” break in valve springs on the engine with the “high tension” racing valve springs in a box that was placed in the trunk at the factory.

The car owner was instructed to change valve springs after break in and before race day.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #16 ·
Thanks Chasracer; very helpful information.
Like the idea of adding an extra Qt or 2 on startup. Using hydraulic lifters and have read pros and cons to pre-soaking them. They pump up quickly on startup so I only coated them with assembly lube.
The cylinder walls were scrubbed many times with clean motor oil until spotless.

I think the cause may be that all I could find local for the cam was assembly lube by Lucas. I did extensive reading on the product b/c I've always only ever used moly paste but this product says safe for breaking in new cam, lifters, and valve train (contains moly and zinc), so everything got a generous application during assembly. I applied red grease and assembly lube to the cam journals and this lube also to the lifters and cam lobes.
Had the timing close enough to fire up quickly for break-in.
Appreciate all of the responses to this issue!
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #17 ·
Only running single springs with dampers. I have a spring pressure tester on order, so may know more in a day or two. Thanks
 

·
Registered
Joined
·
14,572 Posts
3 10 minute segments of break in at 2000-2500 rpm


Did not check lifter to bore clearance but all went in easily



Break in should be about 30 minutes with no interruptions.


I was thinking of lifters being too loose in their bores rather than too tight. When the bores are worn out the lifter oscillates, wobbles, or orbits about as it rotates causing scraping motions at the interface.



None of this dismisses a materials problem with the cam or lifters.


Bogie
 

·
Registered
Joined
·
3 Posts
alanco

I think you got a bad cam. Engine oils today do not have zinc in them due to smog laws. Use a good cam lube, put a zinc additive or oil with zinc in it for a flat tappet cam. It is always smart to degree a cam just to make sure it was indexed correctly but this has nothing to do with wear but it has a lot to do with the engine starting and running correctly right away.
 

·
True Hotrodder
Joined
·
1,894 Posts
They are not aluminum heads. I don’t what the spring pressure is. I am expecting that was the problem. Waiting for my valve spring pressure tester to arrive tomorrow.

Uhhh, a complete cam and kit is really the way to go on a flat tappet cam. That way all of the components will be matched and you have a better chance of success. I just assumed that you had the right springs for your installation.
 
1 - 20 of 43 Posts
Top