Question : CAM Bearings

[Tiger81269]

I am rebuilding a 1998 3.1L after it had the leaking intake gaskets and the Cam broke into 2 pieces. The CAM bearings where definately scored but did not spin.

I took the bare block into my local shop to have it hot tanked then have new CAM Bearings pressed into place. They said the OLD ones came out easier than what they are use to seeing. (this is the first 60 degree GM V6 they have ever done) They are comparing this to a typical small bock Chevy V8.

They have not tried to press in a new bearing yet. They say since the old ones came out so easily the new ones wil not stay in place. I have looked at the old bearings and I do not see any "turning" marks around the O.D. of the bearings indicating that they had spun. I only see marks in the direction of the bearing being pressed in and out of the bore.

So my questions to the Comunity .....

1: Do the cam bearings fit looser in this V6 than in the traditional V8?

2: does anyone have the SPEC on the CAM Bearing Journal Bore so I can measure the block?

[bszopi]

http://60degreev6.com/content/3100_Engine_Specifications

Scroll down to the camshaft area and the specs are there.

[Tiger81269]

Thanks.......

And from what I have been reading, everyone uses Typical SBC cam bearings but the #1 bearing is not used!

[SappySE107]

Correct, I just had the SBC cam bearings installed into a 3400 block. The largest one is not used out of the set.

[Tiger81269]

Excellent....

I'm hoping that the Cam Bores measure OK.

Not sure why the OLD guy at the shop says the old bearings came out too easy. Wondering if because the block is fully grooved so less area to hold the bearings made it seem like they were looser than typical non grooved blocks?

I'd put them in myself but I don't have a bearing tool for this engine.

[geoffinbc]

Small blocks have a groove all around too. The center galley of a small block feeds the cam bearings and then the oil goes around the outside of the bearing and down to the crank.

[Tiger81269]

Oddly enough I've never built a SBC. My experience has been the Traditional Pontiac V8 (389, 421, 400, 455, etc) and on those engines the Bore is straight and flat. The cam bearings have 3 holes of which only one is lined up at 6 O,clock. And let me tell you they are hard to get in and out and you don't have much room for error getting that hole to line up!

That's why I wonder why this old machinist said the old bearings came out too easy and that he doesn't want to put in new ones for fear they would fall out when the engine is running!

I will be meeting him tomorrow to discuss this so I need to bring ammunition. I plan on taking my bore gage to measure the bores and match the readings to the spec.

If they don't measure up right then I've got a parts car on my hands.

[geldartb]

what part number or brand are you guys using for SBC bearings. i did a search with rock auto on a 95 camaro with a 5.7. well i attached a picture to show.

just want to know if there is one that is better than the other.

[Tiger81269]

I seen a blog someplace that you need to order bearings from a pre-1990 SBC.

So 1955 - 90 would work.

I'm gonna tell that parts person 1969 Camaro 350 (only because that is the year I was born! lol)

[geldartb]

well if you click on any of the part numbers like the pic i posted from rock auto you get a wide range of years say from 1955-2007.

looking up a 69 camaro 350 it came up with all the same part numbers except this one was added in
ok it seems like we need Gen I SBC bearings.

and it seems like this is the number CLEVITE/PERFECT CIRCLE Part # SH290S

[ForcedFirebird]

I have a small block bearing press in tool and it works perfect on the 60 degree.

[Tiger81269]

Bad News fellas,

Machinist called today... Cam Bearing Bores are all oversize by .010" to .014"

Although the bearings themselves don't look like they have spun.

So to me it isn't worth the money to have it align bored.

Although I would enjoy finding a 3.1 or 3.4 short block to build up someday just for fun.

WORD to those that find this thread.... If You have had a Camshaft brake or had the Intake gaskets fail... Before buying anything new have the cam bearing bores in the block measured!

[geoffinbc]

That much oversize and the cam bearings would just fall through. Just find another block they are less than $100 around here for a complete short block.

[Tiger81269]

Yeah the bearings just fell out... literally!!

I wish I could find a short block that cheap! Heck I wish I could find a short block period!! I have ALL my contacts looking for them. It seems the CASH for CLUNKER thing that went on took a lot of those engines off the road for good!

I've got searches for a 100 mile radius from Cleveland and nobody has one (3100 - 3400) that is good enough to rebuild or sell. Only complete engine I found had 180,000 miles and they wanted $800 for it! NO WAY!!

So I'm just crossing my fingers. If I don't find one then I'll scrap what is left of the car!

[pocket-rocket]

Yeah the bearings just fell out... literally!!

I wish I could find a short block that cheap! Heck I wish I could find a short block period!! I have ALL my contacts looking for them. It seems the CASH for CLUNKER thing that went on took a lot of those engines off the road for good!

I've got searches for a 100 mile radius from Cleveland and nobody has one (3100 - 3400) that is good enough to rebuild or sell. Only complete engine I found had 180,000 miles and they wanted $800 for it! NO WAY!!

So I'm just crossing my fingers. If I don't find one then I'll scrap what is left of the car!

The Ranger guys aren't too impressed with the Cash for Clunkers program either. There was one guy parting out an 02 for a junk yard that looked cherry, but it was a victim of the C4C program... Such a waste that program is. /Yoda speak