Anyone have a picture of this? I guess grind a groove, or flat, on the "housing" at some point to improve oil flow to the dist gear on the cam, and back lobes?

Just figured since it'd be a free mod to me now, why not? Just wanted to hit the right spot.

Thanks

 

I had a picture of it somewhere. At the base of the distributor where it's machined to fit the oil passages in the block you just file a shallow grove in the spot that's above the distributor gear when the distributor is installed and timed.

Another common mod though is to O-ring the distibutor in the same location to prevent any oil from escaping here.

 

when it's installed and timed, so it has to be at a certain spot around the circle?

o-ring it? hmm, I may skip that one...

 

Obviously O-ringing to improve sealing and grooving it to oil the distributor gear would be mutually exclusive.

The groove has to be in a spot where it'll put oil onto the distributor gear, otherwise it's just an internal oil leak that accomplishes nothing.

I don't know if I'd bother with it.

 

Conventional wisdom dictates that there is adequate clearance between the machining in the block and the machining of the distributor lower housing to permit oil leakage at a rate which is sufficient to lubricate both the cam and distributor gears and the lower distributor shaft bushing/shims. There is about the same clearance there as in a rather loose main or rod bearing, and we all understand that they sling plenty of oil up to the cam lobes and down into the sump - So much so that a windage tray is frequently installed to prevent sump foaming and capture the excess oil flying around the crankcase.

A groove certainly wouldn't hurt, so long as the oil pump has sufficient volume to maintain good pressure.

 

O-ringing won't work without modifications to the block. MSD has a description of this in their instruction manuals for their distributors.

I've heard of the groove thing for the distributor too... IIRC, all you do it just 'complete' the groove all the way around the distributor shaft housing down by the gear. Its grooved some of the way around, but all you have to do is 'finish the 'job' so to speak. Though may have been for something else, as this was an OLD rebuild book I read this in (circa 1972)

 

It requires machining the distributor too.

That's for the earliest small block chevies where the distributor used to meter oil to the mains.

 

From Crane's website:

More is not always better

If you've experienced excessive wear of a camshaft distributor drive gear, and maybe had to replace either the cam or the distributor drive gear itself, here's some good information you'll want to retain. Crane Cams roller tappet camshafts are ground on 8620 billet steel cam cores that are heat treat hardened to resist wear.

This 8620 steel billet material is wonderfully tough stuff, but it can also be very hard on distributor gears! To remedy this, Crane 8620 steel billet cams MUST use a high silicon copper alloy distributor gear, to prevent rapid wear of the camshaft's distributor drive gear. These are usually referred to as "bronze" gears.

Cast iron hydraulic or mechanical tappet cams are also susceptible to premature wear of the camshaft distributor drive gear or the distributor gear itself. This problem, when it occurs, is usually accompanied by the use of a high volume oil pump in a stock or mildly modified engine.

Cam gear or distributor gear wear is usually NOT caused by the high volume pump itself, but by insufficient internal engine running clearances.

Chevy V-8's, small block, big block, and 90? V-6 engines, all use splash lubrication to oil the distributor gear. Although higher RPM operation provides sufficient lubrication to prevent wear, low speed use can be a problem. The situation can become critical if a high volume oil pump is used. The high volume oil pump was developed for engines where bearing clearances were increased over stock. These work fine in racing engine applications, where extra clearance is provided in the short-block.

However, when a high volume oil pump is used in an engine with stock internal clearances, the increased volume of oil can't flow through the engine fast enough to relieve the back pressure created. This places an increased load on the distributor gear, and leads to accelerated wear.

Once the gear on either an 8620 steel cam or a cast iron cam is worn excessively, the cam itself must be scrapped! There is no repair for this problem, and the only option is to buy a new cam. To eliminate this annoying and expensive problem, we offer a simple, do-it-yourself way to help oil the distributor gear and reduce this accelerated wear in Chevy V-8 and 90? V-6 engines.

On these engines, the lower portion of the distributor housing drops through the oil gallery that supplies oil to the lifters on the passenger side of the engine. Two rings at the bottom of the distributor housing seal the top and bottom of this galley. Oil flows around the distributor, between the two rings.

Solving distributor gear wear is as simple as filing or machining a .030" groove in the bottom ring of the distributor housing. A three cornered file can also be used.

The distributor housing should be grooved in any engine operated for extended periods at low engine RPM. With the distributor installed in the engine - ready to run - the groove should face TOWARDS THE CAMSHAFT. This will provide a reasonable flow of oil to lubricate and cool the distributor gear and cam gear as they operate.

Remember to keep the groove facing the camshaft, and be sure to use the correct Crane high silicon, copper alloy distributor gear for best results.

 

My MSD distributor has o-rings on the top and bottom. As per a local Stock Eliminator racer (take out the o-rings)

 

Even MSD says the use of the O rings is optional on their distributors.

 

Pics diagram of mod would be very helpful. Where can I get a picture or diagram.

 

If you're not a bot, LOOK AT your distributor. There are 2 raised areas down near the gear. Those places seal off (somewhat) the passage in the block that feed lifter passages. All ya gotta do is cut a small groove or whatever (emphasis on "small") in one of them to oil something. Not hard to wrap your brain around. Kind of a no-brainer. Speaking strictly as someone who lacks a brain, so, no wrapping for me, butt since this is a no-brainer, it's right up my alley. Much tougher for someone stuuupid like me than for someone [forrestgump]smarrrrrt[/forrestgump] like you. Butt hay, I get by, in spite of myself.

If you cut a groove in the lower one, it oils the gear. Not hard to see where to put the groove for best oiling of the gear; kinda like, LOOK AT the dist, LOOK AT the block, LOOK AT the gears. Put your groove where it squirts the oil on the gears just before they mesh, taking into account of course the variation that might occur as a result of adjusting the "timing". Pretty ... self-evident. Even I, lacking a brain, can figure that out. Harrrrrrdddddd as it is, it's not insurmountable.

Not sure of any benefit to grooving the upper one.

 

I do the small groove on bottom and machine for Oring on top (if not present). I've found, it keeps from blowing out the china wall seal , especially on certain intakes that dip down into the valley, like lt1 and miniram engines.

 

True; butt MUCH HARDER to make an O-ring groove with any degree of precision, than a quick short vertical one (or a wedge, or a divot, or a whatever) in the BOTTOM boss on the dist body, that bypasses all that and oils the dist gear.

Or, just leave it all alone, and bolt it up and run, like BILLIONS of other small block Chevy builders that have gone before you, and they worked just fine. If you're not going out and trying to run with the Pro Stocks then you probably don't need to overthink it any further.

 

Here are your pics.