tazmo65

iTrader: (3)

I just installed a set of durabond chp-23 cam bearings in an ls2 block and I am getting anywhere from .0036 to.0055 clearance measured with bore gauge. I called the local speed shop and they told me to feel glad! He says most guys have problems with them being to tight. The specs I found call for .0009 to .0038. I feel what I have is a little to much? I want to get this right because I have been chasing valve train noise issuses.

KCS

iTrader: (20)

Yeah, I'd run that. The Durabonds are usually tight. I had as little as .0005" clearance so I had to turn my cam down about .002" to get enough clearance.

tazmo65

iTrader: (3)

The front and rear bearings are both at .005. You don't think that will cause pressure issues? I tore back into this engine after only 2000 miles after rebuild because of lifter noise on drivers side only when warm. The machine shop initially installed a set of clevite cam bearings that had up to .006 clearance. On a side note, I am going to tighten up the clearances on the bottom end. I currently have .003 on rods and .0025 on mains. I am going to shoot for .002 across the board.

KCS

iTrader: (20)

It might lower pressure a little but I wouldn't call that an issue really. It just means more oil can flow around the cam keeping it cooler and better lubricated. Just run a high volume pump, like a Melling 10296 or 10355 if you're worried about the pressure.

tazmo65

iTrader: (3)

That is the pump I am currently running along with 20w50 valvoline racing oil. I guess I will tighten up the bottom end with that setup and see what happens.

KiwiKid

Hi Taz,

I am also using the Dura-Bond [Teflon coated] and we are shooting for .002-.0025" on the cam bearing's on our big bore 400ci engine, the same as we run on the mains and big-end's on all our Ls7 road racing engines using coated bearing's. In the Ls7 the mains receive the oil first and they are the more critical of the two, least IMO. We run 60lbs hot using a 3 stage Dailey dry sump pump and pan, and never less than a 20-50 multigrade oil.

Cheers,

Mark.

tazmo65

iTrader: (3)

So how much do you figure I could tighten up my cam clearanceso by going with a coated bearing instead of using a plain bearing.

KiwiKid

.002" would be safe.

tazmo65

iTrader: (3)

How thick is the coating on a set of coated durabond cam bearings?