2 part question On some small blocks there is a bolt going thru the upper left hand corner of the cam thrust plate. This bolt has a hole thru it allowing oil to go from the lifter valley to drip on the timing chain. What size hole runs thru the bolt?

Next question I am building a 360 and putting a timing chain tennsioner on it. When I took the bolts out of the cam thrust plate none of them had holes as mentioned above and the timing chain tennsioner only has 3 holes to bolt it on 2 above the cam and one below and to the left.
With this type of set up how does the timing chain get oiled?

should be a triangle sheet metal piece that goes behind the lower bolt with a locking tab on the 4th hole to drip oil on to the chain

the hole in the bolt is early and the drip tab is a later set up

an engine oil cooler would use a hollow fuel pump bolt and spray oil directly onto the chain

the tensioner you have is for a late model engine

not sure if the tensioner is gonna use either of the oil set ups

it will get oil with out either one from splash and from the top holes in the vally part of block

maybe some one running the tensioner will chime in on the drip tab

i dont think its used with the tensioner

the drip tap is a integral part of the tensioner...

SB's have tchain longevity problems. I'd checkout the mod in the SA design SB stroker bible for the oil mod, drilling a 1/64" (.015") hole in one of the front main horizontle oil gallery mini cup plugs then a larger hole in either the drip tray or the tensioner so you get a constant SQUIRT of oil on the chain rather than a DRIP. I have one of those oe bolts and iirc the hole is 1/8 but again thats a miniscule drip

I went through the same dilemma. Then I realized what I was dealing with : A car company (like ALL the others trying to save a penny on thousands of parts).

I went with the "drilled through bolt" ( which costs $$$ to machine ) rather than the cheezy drip sheetmetal compromise for the shareholders.

Your mileage may vary...

On my tensioner plate, i drilled the 4th hole and bolted it on. The tensioner plate has an oiling tab.
I did not drill a oiling hole in the plate where the oil galley is (no problems so far), but it might help. I just would not go too large with the hole because it could reduce your oil pressure/volume going to the bearings.

In the above pic below and to the right of the top right bolt is a round raised nub. You could drill a larger ~ 3/16" or so hole in that raised area and w a pin drill, drill a 1/64" (.015") hole in the drivers side mini cup plug behind it. The only hard part would be getting the old cup plug out to then press in the new drilled one as nomally you drive them out from the other end w a long rod. This would give you a pressurized squirt to take care of the chain/gears which would not at all compromise your oil pressure in the gallery

There is an abundance of oil splash and fog in the area from engine rotational splash. The chain gets plenty of lubrication. They don't need to be submerged or flooded with oil. I have yet to see a dry chain.

No I am not going to redrill bolts.I have the tensioner and ave had since they were made available. Had no problems and no dry chains. Never had to modify an OEM set for oiling' so why start now. Only real problems was the plastic sprockets and all the oil in the world wouldn't have really helped them.

Thanks for the replies. I drilled some bolts with a .08 drill bit. Gonna put one in the upper left.

Hopefully you have the oil slinger in use with it cupped the right way (cup outward)to keep excessive oil off the front seal now that you have increased the oil flow to the front end loading the it and increaseing the protential for a front seal leak the slinger will be more nessessary.

I think the cam plate also has a slot milled on the back of the plate so oil from the front cam bearing will get oil the timing gear and chain.