I pulled the cam out, was checking out my stuff and find that the thrust plate seems to have gouged itself pretty bad.

what did this? can i use it like this?

 

think i'd just buy another one from gm parts or a bone yard

 

But im worried, it did this in less than 100 miles! what cause it?

 

How much oil pump/distributor load do you have? Are you running 140W gear oil?

Seriously, are you using a HV oil pump under higher pressure? I'd get a replacement and take a good look at the front of the cam for burrs, galling, etc. That baby is trying to auger itself in there pretty hard. That reminds me - gotta go!

 

No its 90W but its synthestic thats better right?


J/k

its 10W-50 oil, I have a HV pump YES, but I also have a gear drive... Im wondering if its because of the gear drive? The cam and gear drive all look ok...


I DID notice that the "dual idler gear" was spinning up against my timing cover and creating swirls and gouges in it. thats bad too huh?

 

The cam should not be putting that much force on the plate. Definitely get a new one before proceeding. Two other things: Not sure if you were kidding, but 10W50 is pretty thick. Second, if you're running the knock sensor, that idler timing set is going to really screw with it.

 

well too late i put it back in like it is. i swapped it around to the other side was presented to the block. oh well.
no there is no knock sensor.

 

Since you have a "fresh" side exposed, it's probably as good as a new one. Did you get a look at the rear of the front cam journal?

You might want to try a 10W-30 or straight 20W to break in the engine (light loads, of course). Unless you plan on severe heat, you probably don't need the 10W50.

 

<b>Did you get a look at the rear of the front cam journal? </b>

yes in fact i have a picture of it. It is very rough, not exactly what i would call "100 miles old"

 

Cam bearing wear: You just HAD to have a gear drive, right? Now live with the consequences. That's what's tearing up the front bearing. Either that or the cam bearing is too tight a fit around the front cam journal (bad cam bearing set, or .001" undersized and you didn't know it- nobody EVER checks cam bearing clearance even if they are super **** about bottom end clearances).

Torn up thrust bearing: why is it only torn up on the inner tiny fraction of an inch?? Am I seeing that right? I thought they were supposed to contact over the entire face area of the bearing. Maybe it's different with your gear drive, but that don't look right.

Is your front cam bearing installed all the way into the block and STRAIGHT? That could certainly tear up both the bearing and the thrust bearing. Is there a sharp lip on the back of the gear drive cam gear maybe?

 

you are seeing correctly, the thrust plate is only half mangled.

i took it out again because i want to be sure from this point out.
yes i had to have the gear drive!

when i put it around the gear drive (cam gear) it has a little lip where the thrust plate sits. when i put it in (the cam) it stays on that lip, but only half of the thrust plate comes in contact around the bearings. its weird. i can feel around the back of the (cam drive gear) and feel the thrust plate on the top half, but cannot feel it on the bottom half.

obviouselly, this is how it was made. the thrust plate sits on that designated LIP on the (cam drive gear) and doesnt move off of it.

I suppose it may be eating the bearing... but that indicates what? too much oil pressure? too much cam "thrust"?

Is there a way to fix it (without ditching the gear drive) or do i just keep replacing thrust plates about once every 1000 miles?

and it seems to have "worn in" to a point where it doesnt want to WEAR any further. I have a feeling if i put it back in the way it came out, it wont wear any more.

 

I'd call the manufacturer of the gear drive and see if that's normal. They might have a bad batch of gear drives or some sort of known problem situation that you'll never know about without calling them.

If the answer is "that's normal" then I'd reinstall the thrust bearing the same way it came out. It sounds like it's just going to dig into the bearing in that same location again if you flip it over. If it's already "clearanced" itself as far as it's going to then why make it do it twice, throwing more metal into the oil?

My expereince with gear drives is very limited (one, actually) and it wasn't on my car.

I doubt your oil pressure or excessive cam thrust has much to do with this. Cam thrust with a flat tappet cam is always going to happen since it's designed that way- it's always trying to pull the cam further into the block.

 

Well that thrust plate obviously can't be re-used for anything, it's totally fornicated from where somebody whacked the edge of it with a screwdriver or something. Go get a new one.

Unless it's part of the gear drive itself, a 010 block like that one doesn't require a thrust plate.

That block has some hellacious core shift.... the cam bore is cast easily 1/8" too low and over toward the driver's side. Typical sloppy 70s quality control. Don't be too surprised if you have other "mystery" issues with it; these might include The Starter Problem, the problem where lifter bores don't point directly at the cam and it eats the same cam lobe every time you put a new one in, etc. etc.

Take out the 2 oil plugs on either side of the cam (NOT the one above the cam) and drill a hole in them to oil that gear drive POS, about .015"-.020" diameter. A #70 drill is about perfect. That will help a chain live almost indefinitely, so it should help the gear drive make it at least a few hundred more miles before it inevitably needs replacement. The common-sense thing to do would be to lose that garbage entirely and get a high-quality chain, the $60 kind not the $20 kind; since there's no advantage whatsoever to those street gear drives, they're just for people who want some monkey-spank action from the noise. You won't lose any actual real perfrmance from going to a chain, may even pick up a few HP.

 

<b> .015"-.020" </b>

So i drill that size hole, 1 in each of those little plugs above the cams (not the one above though).

<b>so it should help the gear drive make it at least a few hundred more miles before it inevitably needs replacement.</b>

The Gear drive shows NO signs of wear at ALL. not even a little bit of wear.

and its REALLY quiet. doesnt make a peep. can barelly hear it.
the blower is the loudest thing on the car.

<b>the cam bore is cast easily 1/8" too low and over toward the driver's side</b>

How can you tell? I had it checked and everything from a machine shop not even 4 months ago. Want me to take more pictures for you to look at and tell me for sure? I dont want to use my $2000 rotating assembly in a block with massive core shift.