I was reading my (How to performance book) on small block chevy motors and I came across an article that recomends drilling a .030 hole through the front of the block to intersect the cam oil valley before the thrust plate area. This is to get more oil on the thrust plate and end of cam. It is recomended for roller cams running 120lbs. + of valve spring pressure.
Another mod that will oil the chain and sprocket is to drill a small hole in the top (of the three) pipe plugs in the front of the block. They do say not to do both mods unless it's a fullout race motor. I assume this is because of a loose in oil pressure?

So Is the thrust area oil hole a worthy mod?????

 

The stock LT1 has the holes you're talking about in the plugs on the two sides. When I built my 383, I replaced these with screw in plugs and had the holes drilled.

I have not heard of drilling through to the cam oil valley. Maybe they meant to the oil supply passage in this area?

 

I will have to look at my plugs they may already have them, although they were replaced at the machine shop with new ones..

(Your correct) Quote: I have not heard of drilling through to the cam oil valley. Maybe they meant to the oil supply passage in this area?

They drilled approx. 3/16" above the cam bushing/bearing.

 

For years, even before GM began dong it on the LT engines, I drilled the plugs in the front of the block for additional oiling to the chain/gears.

I've read about the 2nd hole mod but I never done both though, not even on full race engines.

Jake

 

Hi guys....could someone send me a picture or two of where you are talking about the plugs/drilling....I have my block spare block on the stand and would like to see exactly where you are talking about...plug area etc. I do not currently have the book you mentioned.
thanks...any other little tips you can provide would be helpful at this stage. use email please.
tom

 

Did you receive the photo(s) you wanted? Let us know so we can stop looking to send them.

If not, I can describe exactly where the oil galleries/plugs are.

Jake

 

Stand directly in front of the engine with the timing chain cover, chain and gears removed.

Look directly at the camshaft tunnel; the hole where the cam slides in is called the tunnel.

Above that tunnel you'll see three plugs, roughly situated at the 10 o'clock, noon and 2 o'clock positions. Some guys remove the plugs, then tap the holes for screw-in plugs, so you may have either kind - screw in or tap in.

Those are plugs for three oil galleries.

The center plug - at Noon - is one that is sometimes drilled to allow pressurized oil to spray on the back-side of the camshaft gear.

Some builders prefer to drill the two plugs - the ones at 10 o'clock and 2 o'clock - instead of the single - Noon - one.

The other place that is occasionally drilled (the one that's NOT recommended to be drilled on street engines) is actually in the BLOCK, not a plug.

To ID that location, look at the front-most cam bearing. Now look directly above that cam bearing at the Noon position ON THE BLOCK. That's called the cam gear trust face as I recall. It's there that another hole is sometimes drilled, in the block.

If the above doesn't work for you, I hope someone will post/send you a photo. Best I can do though.

Jake

 

Jake, thanks for the information....I understand so no pics are needed. I will look this weekend and get back if I have any further questions or need more detail. thanks tom

 

From the factory, the two plugs to the left and right of center are drilled. On my 383, I have threaded plugs and had the shop drill them. As mentioned, the holes are ~.030. The shop chamferred around the holes in the plugs to insure no sharp edges / chance of debris. As a result, the holes look bigger in the pic than they actually are.