Cam Bearing Wear/Melting

I am fully aware of the small cam bearings that BBB's are cursed with. I even had a 455 back in the '80s melt the #1 bearing, blocking off the oil to one lifter galley/rocker shaft (after a fresh rebuild). Being paranoid of this, I used TA back-grooved bearings installed per-instructions and used an old Poston Ent. lifter galley crossover line in the rear on our front engine dragster build. This winter we are upgrading/freshening the 464 with forged flat-top pistons, floating rods, TA510 cam, head porting, Dominator SP1 and a 1050, so I broke it down for inspection. All of the rod bearings and mains look MINT, which is especially good on the mains because I had used KB full-grooved units. The problem is, the camshaft turned freely, but wouldn't slide out of the bearings. After great effort, and scraping shavings of the cam bearings as it came, I was able to remove the cam, which also survived unscathed. Why are my cam bearings melted/worn so badly? I had consistent oil pressure with 10W-30 oil, no indications of any problem, just pulled it to upgrade. I have a new set of back-grooved TA bearings and some regular DuraBonds, any suggestions???

 

I only use the Teflon coated grooved, maybe cam wasn't straight, always should check that, was the tunnel honed?

Had one one time I had to get turned with Emory cloth, bearing fit too snug dry certainly wasn't no room for oil in there ha

 

Was that a single back grove or the dual grove duel feed bearing? ALso before the bearings go in, any type of edge to the first cam bearing hole will smudge the grove, which defeats the purpose of the grove.

 

Is the oil transfer groove still on the #1 journal of the cam?
I have every 350 cam I've used and V-6 Turbo cam welded closed.
Reason being, that transfer groove on the #1 journal isn't needed anymore when using TA's back grooved bearings.
Those two thin journals on the cam can still wear into the #1 bearing causing it to not wanna come out easily.

 

Was the block line honed? Are you then using a undersized timing chain and maybe too tight? Do you run a oil line to the rear oil galley? What rpm do you turn it to? I usually go 3 years before freshening mine,never seen that before..

 

I believe the bearings were dual-grooved. No special mods were done to the bores (chamfer) but I can always try that this go-round! Thanks!

 

No, the cam still has the annular groove. Maybe I just need to run the Dura Bond bearings and do the oil mods to the bore (redirect feed hole)? The new cam has the groove as well. Thanks!

 

The block was lightly line honed and I used a standard chain set. I ran the Poston crossover line which connects the two galleys at the rear, maybe I should get the oil there a different way? We have never turned the motor much over 6000, usually shifting around 5500-5800rpm. It HAD a GS105A cam in it, which supposedly maxxed-out at 6K but our setup was happy just above 5500. We will be switching to a TA510 which is much bigger and has a wider LSA so I look for it to peak higher by a good bit, especially with the ported heads and 1050 carb. Thanks!

 

I would eliminate that Postons transfer line at the rear and just use the TA grooved cam bearings.
I made my own line for the rear years ago for my 350, it didn't make any difference when using the grooved cam bearings.
I removed it, and re-installed the plugs. I noticed oil pressure came up ALOT faster on start-up.
My theory on this is with that line installed, that instead of the oil hitting that dead end and creating pressure for the mains, it continues around to the left side galley to be leaked out past the lifters, which it is already doing on the right side PLUS feeding the main bearings.

 

The funny thing is I do have the T-A dual cam bearings and the Poston bracket in the back of the block.On start ups,I have 80 pds of oil pressure instantly,this on my 70 GS 455.I use 10/40 oil ,the good stuff.Bruno.

 

Check the Cam for straightness on a surface block with Dial Indicator . You will be surprised .

 

Valve spring pressure open?

Did the cam spin freely when installed?

What kind of pre-lube was used on the cam journals"

Describe any irregularities in the initial start and break in.

 

I used dual springs with around 130# closed and just over 300# at the .520ish lift of the cam. The cam felt fine rotating on regular motor oil after installing the dual-grooved bearings (I am used to BB MoPars being *tight* but turning and have had zero problems with them so far), which was a relief. I have a pre-oiling drill attachment and pre-oiled the engine with 5W-30 oil and zinc additive for break-in. Kept the rpm up to seat everything, set the pressure regulator adjustment to 60# hot above 3000rpm with the 10W-30 we regularly run installed before racing it. We used a bronze distributor gear, and the Poston 1/8" oiler line out of paranoia with a HV pump. The bronze gear shows some wear (not scary) as you would expect but the cam gear is mint. Trust me, the main and rod bearings are cherry in this thing, and I am reusing the KB full-grooved mains but I have new rod bearings so they're going in. IDK?

 

This concerns me.

 

Using that "High Volume Pump" without closing off the front cam journal groove can cause that type of bearing damage (as per post #4). And RPM on cold oil will also cause that,... if the front journal mod hasn't been done. Just curious as to why you are using a High Volume Pump?

Larry

 

This didn't happen because of spring pressure or a little run out in the cam. If your using a High Volume pump you must not use the white and never use the red spring, in my opinion. Use a stock steel color spring with the early pump cover and start with the orange or the factory steel color spring from a late model pump cover. Install a adjustable regulator or shim the spring for desired oil pressure. I have run engines for years with a high volume pumps with no trouble, then one day on one of these engines that had been running for YEARS I decide to up the pressure and install a white spring. Within one minute the cam bearings were wiped out. Didn't even change the oil or anything, just the spring. Your failure is centered around the high volume pump and the way the rest of the engine was built. Pressure relief spring, bearing clearances etc... Install a new TA pump assembly, Coated TA1559 cam bearings. As far as the groove in the #1 cam journal, I have simply roughed it up and filled it with JB Weld, machined & polished lightly and ran it. I pulled that engine down 7 years later and it looked like it did when it went together. No wear spot in the cam bearing either. Questions, your all welcome to call me.

 

Mike T
The Kenne Bell HV kit states in the instructions not to use the white spring. Were you using the TA kit:spank:

 

That's what Mike is saying to "NOT" use the white spring with the HV pump

 

Damn, JB Weld holds up thereou:
I gave that a thought years ago when I first did that mod on my 87 GN, but thought "it will chunk out and screw everything up"
Glad to know JB weld works there:TU:

 

Youhavetoread
half way about into it and Mike states he installed the white spring,