Chevy & GMC Vans

I am not sure I have seen this tip for anyone's engine build.Really I had forgot it myself.

http://www.holley.com/data/Products/Tec ... 9R9971.pdf

Slot the dist housing for oiling of gears.

Good one, Gary. I'm surprised I hadn't heard of that before. I'm curious now how the gears were oiled before that mod. I'm thinking just oil drain back.

I'm thinking you're right Skip...

Good to know. I never heard of that mod before, but it makes sense!

Goon un. Never read or seen anything on this b-4 now. Sounds like a winner.

Sounds like another crock to me, listen to Skip !!

Sounds like another crock to me, listen to Skip !!

:-k

Think I missed something,,,what was it ?

HPbyStan wrote:Sounds like another crock to me, listen to Skip !!

Stan from Wi the show me state. :-k

The link states how the gear was lubed before the slot,and the fact the gear is under addition stress after putting in a high volume or high pressure oil pump.I do remember changing dist gear for high proformance.I forgot this mod and did use it as well.Holley can only confirm the need for it.

All I know is that whenever I used a modified distributor to prime an engine the tube was always thoroughly soaked with oil when I pulled it. I would call that low rpms. Sounds like a crock to me. How much oil do they think is going to drip, cool and lubricate through a .030 slit? That is a pin hole.

First I want to say that not all of us do the same things.So given .030(think if was a bearing clearance-that's a ton)I respectfully agree to disagree with the use of this slot.I think there is some value to seeing mods are needed to save the cam gear on high volume/high pressure oil pumps.After all why then would there be a number of brass gears offered and well as "some" steel gears.The example of this is as follows from Sumit:

http://store.summitracing.com/egnsearch ... wordSearch

Lockdoc-getting back to the question of .030,well Bill that is the normal next size up in a over bore.Also .030 is the hole size to pump-up hydro lifters to keep them from collapsing.Bill,while you are free priming your engine,you are not considering how the effect of (in some cases)higher spring pressures for higher lift cams(slows the gear down some) and the effect of high volume/pressure oil pumps have on cam gear wear.Think about how much that drill motor bogs down trying to turn over that pump and that isn't with the valve train stress.There are any number of passages that are .030 that do in fact major oiling in these SBC's.I do believe that will effectly make a difference with the slot.But again I respectly agree to disagree.

Here you will see the add-on heavy duty driveshaft for oil pumps when either high pressure/high volume oil pumps or heavier oils are in use.Surely the issue of stress is apparent warrenting their use.

http://store.summitracing.com/partdetai ... toview=sku

So given the two examples I gave for changing the dist gear/driveshaft-I to believe this slot mod is valid.

I know-I know,I don't normally post on engine stuff.Well If I don't change that,nothing will ever change.Trust in the fact I forgot this mod,but I have done it before.

I started this thread not for a debate-but more to pass on a tip.Use it or not,doesn't really matter to me.When you see finnally the pics of my build,you will see it in use.

Gary, I don't think anyone is trying to start an argument. I think we just question the necessity. There are a lot of parts and pieces in the aftermarket that are just there for the sake of making someone some money. And there are a lot of mods that are not necessary on your average street motor. I personally have never had to change a distributor gear because of abnormal wear. Then I will be the first to admit that I've never built a 9000 rpm motor. Anyway, I thank you for that information. I'm always open to new info. Merry Christmas, my friend.

For the general membership on the forum referencing my threads or posts,I am the first to call into question articles from Hot Rod,Popular Hot Rod,calling them comic books selling mods that do not live up to the claims they say they do.So I am "real street" having done that,been there before.

I thought of one other thing I wanted to add.I read where Lockdoc posted on another thread awhile back the effects of larger tires/lifts have in the long term on parts.He brought to the thread that there are consequences to some of the mods done.Surely,that put a smile on my face and under my breath I was saying "that a boy". =D>

I wasn't agreeing or disagreeing with you Gary. You didn't write the article. The article states this is a fix for any engine operated for extended periods at low engine rpm's. Comparing a .030 over bore to a .030 slit is comparing apples to oranges. The bore leaves A LOT more space in the cylinder. Hence you need oversided pistons and rings. The same is true for bearing surfaces. A real comparison in that anology would be a .030 scratch\gouge in the cylinder wall, not a bore. There are not many .030 oil passages that I know of in the engine and the ones that do like the hydraulic lifters you mentioned are under PRESSURE forcing oil through them. This "slit" does not have any pressurized fluid going through it. Take a cup and poke a .030 hole in it and pour some oil in the cup. See how much drips out of it. I'm no engineer and I am frequently wrong and put in my place but the cup example is where I am coming from. I would think you would need a much larger hole if you would expect any significant oil to drain down the distributor shaft and on to the gear.

Bill, you can correct me if I'm wrong but I think that the space between the locating rings at the bottom of the distributor housing is pressurized somewhat. That is how pressurized oil gets to the right lifter galley. It may also be how the distributor gear is lubricated. Whatever leaks past and drain back. If my memory serves me correctly I remember that the early 265 engines had a distributor with a slot cut in the bottom of the distributor housing. If that slot wasn't positioned correctly then the right side lifters wouldn't get any oil. I learned that the hard way. Boy, I've been messin' with this stuff a loooong time. Any of you old timers have a similar experience?

lockdoc wrote:I wasn't agreeing or disagreeing with you Gary. You didn't write the article. The article states this is a fix for any engine operated for extended periods at low engine rpm's. Comparing a .030 over bore to a .030 slit is comparing apples to oranges. The bore leaves A LOT more space in the cylinder. Hence you need oversided pistons and rings. The same is true for bearing surfaces. A real comparison in that anology would be a .030 scratch\gouge in the cylinder wall, not a bore. There are not many .030 oil passages that I know of in the engine and the ones that do like the hydraulic lifters you mentioned are under PRESSURE forcing oil through them. This "slit" does not have any pressurized fluid going through it. Take a cup and poke a .030 hole in it and pour some oil in the cup. See how much drips out of it. I'm no engineer and I am frequently wrong and put in my place but the cup example is where I am coming from. I would think you would need a much larger hole if you would expect any significant oil to drain down the distributor shaft and on to the gear.

Honestly Bill,I am not sure why Holley said .030.Seems resonable that Holley found a problem in the field from customer complaints and their only motive to write the article was to ward off customers from trying to return cams.Holley gained nothing sales wise to suggest the mod.That .030 was enough for a solution.I'll be dammed if I can remember why I have been doing it and find any ref to it.Just that during a build,I guess once I got to that section of a engine,it would remind me as a stored summary in my head.I have the file and I know that is what it is for. #-o