[joes455]

So im in the process of priming engine while assistant is diring eng obet by hand.(Eng is on stand and all spark plugs are out)During spinning of motor there is a sudden release of pressure.Dropped pan just enough to peek inside while priming and noticed oil pouring out at the forward cam bearing (new bearings)but only at top dead center ,spin crank just a little bit and oil pressure builds back up.What going on?

[joes455]

I dont remember if it was tdc on compression or intake stroke.It would only loose pressure at one of those two position

[joes455]

I think i figured it out,looks like the timing chain feed hole at the cam journal is lining up with the front lifter valley holes.Is it ok to restrick that hole in the cam journel when suppling oil from the front oil plugs to lube chain?

[74Grandville]

never heard of anyone drilling the plugs in the front of the block to lube chain. why modify what the factory did?

[Dragncar]

Originally Posted by 74Grandville

never heard of anyone drilling the plugs in the front of the block to lube chain. why modify what the factory did?

I put a .023 hole in mine along with the .030 hole in front of the distributor gear and the factory did not put one there either.
My BOP composite gear looks new after a dozen years of roller cam use.

[formula kid]

In drilling the inner plug on the back of the block which is in front of the distributor is a way to be shure that you are getting lubrication on the Distributor gear. If you look through old Pontiac parts books to about 1973-1973 it was listed for Ram Air engines.

[hurryinhoosier62]

Originally Posted by 74Grandville

never heard of anyone drilling the plugs in the front of the block to lube chain. why modify what the factory did?

X 2! If you have ever washed a Pontiac block you have seen precisely how much fluid emits from the timing chain oil port; it is tremendous! Why add an additional oil port that is only going to lubricate the back of the cam timing gear?

[joes455]

Thanks dragon car you totally took my post from timing chains lubing circut to distributor lubing modification and how good your composition gear looks.Who gaf.Thanks for the info hurringhoosie62,I would not have notice how much oil is passing out that cam journal when lined up with that cam bearing hole.I agree no need to drill front plugs,and to add never never open up the front cam bearing lube hole,it also will ruin oil pressure to the drivers side lifter journels everytime cam rotates and holes line up.I have cam in and valvetrain components installed and adjusted,so will be looking at ways to restrict the flow from the discharge port at the journal. ANY IDEARS ARE WELCOMED

[mgarblik]

As mentioned, Pontiac has lubrication to the front of the engine, thrust plate, timing chain and sprockets covered and then some. Think how long the plastic camshaft sprocket would have lasted without all that oil? After 150K miles that fairly thin thrust plate rarely wears much with constant forward load applied. Possibly, the best feature of their oiling scheme. How important is that front lube? Found out the hard way. By mistake I blocked that front feed on the first roller cam bearing Pontiac I built. Heard a screeching noise on the dyno after just 1/2 hour of break in. Thrust plate was wiped out badly. Lesson learned.

[joes455]

Thanks mgarblik,been and playing around with the front cam journal diameter ,restricted it down to .110 with a rollpin from the original .185, still wasn't happy with the discharge amount ,installed another smaller rollpin brought that down to .070 and now I have I believe the correct amount of oil.The pushrods are spitting lube on the rockers now.