[scouthead]

was reading about something and came across this thread:

http://forums.hybridz.org/showthread.php?t=83821


About half way down in a post from Grumpyvette there is some info about filing the lower part of the distributor housing to allow pressurized oil to spray onto the distributor drive gear... sounds like a good Idea to me... maybe...

Anyone ever do this? I have not been able to turn up any more info on doing it(only interested in this for use on a 350)
I have a couple of related questions that could probably be answered with a good diagram, but don't have one in front of me, so:

1) The part of the distributor housing that would be getting pressurized oil would be sharing the same oil source as the lifters right?

2)I assume doing this would tax (slightly?) the oil supply for the lifters? But I'm not sure how the drilling for crank & rod/cam oil relate to the lifters... Do the lifters have a seperate drilling circuit coming off the oil pump?

I would not want to try something like this and find out that one of the rods farthest from the pump is being starved of oil because it's all being diverted upstream...
I would also assume checking the wear and clearance between the dist. housing, and the block, would be wise... in case you were already spraying oil in this manner and didn't know...

 

[just4cuz]

If you crank over a SBC without the distributor you will not get oil to the top end.
The shoulder on the distributor housing shaft acts as a block/plug /whatever to the oil supply to run to the lifter galley and hence up the pushrods to the rockers.
If you chose to drill the shoulder to enhance lubrication to the cam gear I would restrict the size to maximum of 1/16 and if I did it I would drill a 1/32 hole on the back side of the distributor housing.
I have never had lube issues with a SBC distributor gear, so I believe it is uneeded.
I own Smokeys book and every Chevy Power Catalogue that has been printed since the late 60's, never seen mention of this.
In closing Smokey and the CPC ran all their engine tests with Valvoline 30 weight.

 

[scouthead]

I'll have to check, but i don't think there was intent to drill anything... I got the impression it was more like taking a hacksaw blade to the side of the distributor shoulder and creating a gap between the dist. body and the block itself.

 

[just4cuz]

Any shaving or cutting would equate to a loss of oil pressure to the top end IMO.

 

[tacoma73]

man I wish you'd scan all those Power Catalogs.

 

[tacoma73]

I'll have to check, but i don't think there was intent to drill anything... I got the impression it was more like taking a hacksaw blade to the side of the distributor shoulder and creating a gap between the dist. body and the block itself.

The effect is the same.

 

[just4cuz]

I probably could,but you would be better off looking on E bay and finding them. I have about 6 of them. In fact I just bought the latest one last week at the Chevy dealer for 5 bucks.
How about a 1968 Chevelle wagon with a factory 4 speed, 1975 truck 350 4 bolt with a 415/430 lift cam @112 lobe centers and a curve kit in an HEI with a 3.08 12 bolt posi that gets 21 mpg on the highway at 70 to 75 mph.
Been to the top of Pikes Peak with no real noticable loss of power.

 

[scouthead]

Didn't realize there was so much reading in that thread... Sorry.
For anyone not wanting to wade through it all, this is the part of grumpyvette's post that has caught my eye:

"BTW
> The bottom of a Chevrolet distributor housing can be modified to spray pressurized oil onto the distributor drive gear. The extra lubrication will reduce distributor gear and camshaft gear wear. This is especially important when the gear is used to drive non-standard accessories, such as a high volume oil pump, or a magneto that puts additional loads on it and the cam. <P>When the distributor is installed, the bands at the bottom of the housing are designed to complete the internal right side lifter galley on all small and big block Chevrolet V-8’s and 90° V-6 engines. If you hand file a small vertical groove .030" wide x .030"( <B>thats the diam. that crane recommends Ive always used the larger groove with no problems</B>)deep on the bottom band (above the gear), pressurized oil running between the two bands will be directed downward onto both the gear and the cam.<P>This procedure is recommended for all Chevrolet engines no matter what material gear (cast or bronze) or what type of camshaft (cast or steel) you are using.<P> <P> <B> keep in mind the groove MUST be lined up with the cam gear when the distrib. is installed"

 

[just4cuz]

Ok, lets look at the bottom of a Chevy distrubutor. If it is assembled correctly the first spacer has an opening which allows oil to drain onto the cam drive gear. I still think this is not needed. Hell even Smokey said a high volumne oil pump in a SBC is a waste of time and may cause point bounce, due to resistance. (even though points are no longer viable) is good enough for me. I mean shit dude if all you did is play with Chevy engines every day all day, would'nt his info be credible?

 

[Odin K30]

I agree.
When it comes to SBCs Smokey is the man!

 

[Warpig58]

SBC has one of the best oiling systems ever designed, IMO. The rings and bearings will wear out long before the dizzy drive will. If you are running a stock top end I would definately not recommend this mod.

 

[49willys]

The only time I could see this usefull is when running a bronze gear as they wear pretty quick on a billet roller cam. But since comp came out with the composite ones, I couldn't see using a bronze gear anymore.

 

[Grumpy_old_fart]

The only time I could see this usefull is when running a bronze gear as they wear pretty quick on a billet roller cam. But since comp came out with the composite ones, I couldn't see using a bronze gear anymore.

out of ignorance, whats the lifespan of the composite gear?

im very tempted to get one realy soon...

 

[Triaged]

...This is especially important when the gear is used to drive non-standard accessories, such as a high volume oil pump, or a magneto...

Then don't run a high volume oil pump or a magneto:shaking:

 

[DennisTA15]

I think this dizzy mod is mainly for the vortec motors. All vortec motors whether 4.3 5.7 or 454 have a tendency to eat dizzy gears. Vortec dizzys use an uncommon size shaft for the gear (.467 I believe). Not much after market support there, only for the more common .491 and .500. I replaced my dizzy with the billet Accel unit which uses a .491 gear, so if this one fails I can upgrade. I actually did this, this past weekend. Here are the pics of the two. My truck was running with this gear in it. I only had a slight miss at cruise speed.








Hope this helps some

 

[just4cuz]

I do not think that dizzy gear wears due to lack of lubrication. It is probably more like the cam drive gears are harder than the dizzy gear and wear them. I am not sure how much harder the roller cams are than the flat tappet ones from the factory but I would guess that would be the problem. I still can't believe the whole distributor body on a Vortec engine is composite. My son tighten one of his dizzy cap screws too tight and stripped his. Had to buy another one. A lesson learned by a 22 year old about how tight is tight!

 

[DennisTA15]

I still can't believe the whole distributor body on a Vortec engine is composite. My son tighten one of his dizzy cap screws too tight and stripped his. Had to buy another one. A lesson learned by a 22 year old about how tight is tight!

yeah me neither

This was another reason I got the billet Accel dizzy, it's built to last longer than the factory plastic unit.

 

[49willys]

Grumpy, Sorry haven't been on here lately to catch the question. Mine only has 60 runs on itso far, but my bud has went 2 seasons (400 or so runs) and it looked good enough to keep for a spare. Oil looks a lot better with out the bronze.

EDIT: for reference my bronze gears were junk in 100-150 runs. 540 in a drag car.