mjl1977

Ok so I brought my block to the shop the bearings I brought were wrong according to machinist, so he used clevites.
I picked up block got home saw big scratches in the rear bearing and middle and cracking on the front.
So I returned it and today picked it up and they are replaced but they look as if someone has sanded or honed them is this a normal practice?
It test fit my stock cam not the one I'm using and it fits well he test fit a cam aswell.
Its a 4.8 we had bored 3.800 and lunati rods and wieseco pistons balanced and crank balanced too. Figured I would add that if anyone was curious as to what I'm working on. I'm just really picky and mildy concerned about my cam bearings of all things.
Also he suggested I use a hi pressure oil pump is that wise?

pdsq98gt

Without a pic it's hard to tell. But even stock bearings look like they've been sanded and have copper showing.

brandon6.0

iTrader: (32)

yea I think that's normal. usually cam bearings get a lil dinged up when installing them. but the machine shop has the tools to clean them up. which sounds like that's what they did.

slogo

Theres so many things wrong here.
My opinion is if you get bearings back from a machinist and they look like they have been
sanded or honed, then they tell you to use a high pressure oil pump, I would start over with a different machinist. Im not going to say what my opinion is of post # 2 and 3.
Good luck

Taxman20

iTrader: (11)

Bearings that are new and never been ran should never show any signs of wear. Period. Yes, period means the end and no other answer is a good answer. There is no such thing as honing bearings.

Paul Bell

iTrader: (9)

Very often, cam bearings need to be "adjusted" to get the cam to fit. This is why they need your cam to do bearings.

How experienced is the machinist with LS engines? LS engines have more internal leakage than other engines, a little more oil pressure is rarely a bad thing.

zraffz

iTrader: (1)

When I dropped off my LQ9 my machine shop for cam bearings and some othere work, my guy wanted my cam too.

This was new to me so I asked him why and he explained sometimes the cam clearances on these LS motors are out of whack. Which as backwards as it sounds to me, it means it's probably acceptable practice to hone the bearings. He did not have to do anything to my durabond bearings though.

Taxman20

iTrader: (11)

If they are that bad then they should line hone the block and not the bearings. I'm new to LS engines myself, but honing a bearing is asinine.

Quick Ranger

iTrader: (2)

What is it with the LS blocks and cam bearings? I've drove in tons of cam bearings myself on old SBC and BBC, never had a single issue. I'm worried to do them on the LS block, and it looks like most machine shops can't get it right either.

brandon6.0

iTrader: (32)

well for one u cant get oversized bearings for the ls motors. I have a 6.0 block that spun a cam bearing and only needs oversize bearings to fix it. problem is there are none.

Taxman20

iTrader: (11)

Well that sucks. I would have thought they made oversized bearings since this is apparently an issue that's been around a long time from what I have researched. You would think someone would produce a new bearing to fix this issue.

KCS

iTrader: (20)

On the Gen III blocks, the cam tunnel ID's should be:
2.3260-2.3280" for 1 & 5
2.3161-2.3181" for 2 & 4
2.3063-2.3083" for 3

I haven't had to repair a block for a spun cam bearing yet, but if I needed to, I would just probably try honing them all to 2.3270" and putting in cam bearings for 1 & 5 in all 5 holes. If 1 or 5 is damaged, the Gen IV blocks have an even larger ID at 1 & 5.

I wouldn't worry too much about scratches in the cam bearings. They're not like rod or main bearings where they are gently laid in their caps/saddles and gently clamped onto the journal. They are beaten into their bores with a large hammer and the cam is slid in from the front of the block and each journal and lobe passes across each bearing. If the cam bearings do not have scratches fresh from the machine shop, then they probably didn't test fit a cam.

Taxman20

iTrader: (11)

Good idea.

mjl1977

He did test fit a cam but it was a stock one, he would not used my durabond coated bearing he said they were wrong.
He said if my cam is to tight he will polish it down for clearance.
The hi pressure oil pump recommendation was his idea based on the how long the oil travels thru the block he thinks this will help premature lifter failure. Me I don't know but I spent a lot on the machine work and if I knew exactly what part number for the cam bearings I would put them in myself.

Exidous

iTrader: (11)

This is not correct. Durabond makes oversized bearings. Check out their parts catalog.

They make +.010" and +.020" types.

CHP-8R1 is an example.

5FOX3

Well for whats its worth I honed my cam bearings to take out a couple small high spots.