Special distrib. req'd for '67 BB cam oiling ?

[Wayne M.]

Below, I copy part of the description of an eBay auction for a 1111258 1967 L71 distributor. Is the part about requiring the partially filled oil groove on the lower shaft correct for the '67 big blocks ? Seller claims to be an NCRS Master Judge [in fact, he may be lurking here ].

description quote -------------------------------------------------------------
The early Big Block Engines (65-67) require a unique distributor housing to insure proper oiling to the "top end" of the engine (see detailed picture of the lower portion of the housing). Oil travels from the pump to the rear cam journal, but then to the lifter galleys. On the LH side from the cam journal it must go past the distributor. Although, the need for the "grooved" cam required for the 65-66 motor was eliminated in 67, all three year model blocks had a small void (opposite side to the cam) at the distributor bore that surrounds the lower groove of the distributor housing (near the oil pump gear). If the unique distributor housing shown here is not used, oil pressure/volume will "bleed off" through this void back to the oil pan, thus reducing the amount of pressure/volume delivered to the lifter galley-serious damage may result!-these engines are too expensive to take a chance; so, get the right distributor, don't make the mistake of running any other type of unit-you could be sorry.
end of quote ---------------------------------------------------

Here's the link to the auction if you want to read the whole thing:

http://cgi.ebay.com/ebaymotors/CORVETTE-67-BB-435HP-TI-Distributor_W0QQitemZ200414534336QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item2ea9a31ac0

[Steven S.]

Re: Special distrib. req'd for '67 BB cam oiling ?

I hope John doesn't mind, I did a copy and paste from another forum where he commented on this some time ago...

The "partial groove" distributors are unrelated to the rear cam bearing issue. I don't know that anyone really understands what the original rationale was for the partial groove, but it didn't last long, and GM has always shown the full-groove distributor as fully-approved for Service on all BB's back to the '65. BB and SB both use the same distributor. :thumbs:

[Rich P.]

Re: Special distrib. req'd for '67 BB cam oiling ?

Albuqurque NM. Isn't that where Bugs ***** was supposed to make a left to make it to Pimo Beach

Rich

[Clem Z.]

Re: Special distrib. req'd for '67 BB cam oiling ?

I hope John doesn't mind, I did a copy and paste from another forum where he commented on this some time ago...

early BBC were famous for internal oil leaks and i think that was tried to cut down on the internal oil leak around the distributor where it fit thru the lifter oil gallery. that way you would not have a 360 degree area for the leak to occur. JMHO most engine builders installed "O" rings in the dist housing to seal that area.

[Wayne M.]

Re: Special distrib. req'd for '67 BB cam oiling ?

early BBC were famous for internal oil leaks and i think that was tried to cut down on the internal oil leak around the distributor where it fit thru the lifter oil gallery. that way you would not have a 360 degree area for the leak to occur. JMHO most engine builders installed "O" rings in the dist housing to seal that area.

Very interesting, Clem -- I saw one on eBay a couple of months ago, and figured it must have been a mod. to achieve results similar to the partially filled annulus. Pic below (on the left) is of an NOS ball bearing distr (1111263) I have, but it's band is dated 6_J_15, which must be a service unit from 1976 or even 1986. Maybe they continued to use the lower housing molds from the earlier '67-69 era, for OTC Camaro use.

One other item; notice the reverse driven gear on the lower shaft end -- were only BB Chev engines available with reverse grind cams OTC ?

[Joe L.]

Re: Special distrib. req'd for '67 BB cam oiling ?

Very interesting, Clem -- I saw one on eBay a couple of months ago, and figured it must have been a mod. to achieve results similar to the partially filled annulus. Pic below (on the left) is of an NOS ball bearing distr (1111263) I have, but it's band is dated 6_J_15, which must be a service unit from 1976 or even 1986. Maybe they continued to use the lower housing molds from the earlier '67-69 era, for OTC Camaro use.

One other item; notice the reverse driven gear on the lower shaft end -- were only BB Chev engines available with reverse grind cams OTC ?

Wayne------


I believe that ALL of the 1111263 distributors were SERVICE units. None was ever installed in any PRODUCTION engine. Whether any were ever installed in SERVICE-only engine assemblies, I do not know.

As far as reverse-rotation (i.e gear drive) cams, none that I am aware of were ever used in a PRODUCTION small block and, as far as I know, none were ever available from GM as a SERVICE-only item for small blocks.

A big block reverse rotation camshaft was available in SERVICE but not used in PRODUCTION. Whether any of these were ever installed in SERVICE-only engine assemblies, I do not know.

[Clem Z.]

Re: Special distrib. req'd for '67 BB cam oiling ?

there were gear drive reverse rotation performance cams available for the BBC when it first came out. i figured that the gears came from a gear drive cam for BBC HD truck engines but i never checked into this.

[Clem Z.]

Re: Special distrib. req'd for '67 BB cam oiling ?

Very interesting, Clem -- I saw one on eBay a couple of months ago, and figured it must have been a mod. to achieve results similar to the partially filled annulus. Pic below (on the left) is of an NOS ball bearing distr (1111263) I have, but it's band is dated 6_J_15, which must be a service unit from 1976 or even 1986. Maybe they continued to use the lower housing molds from the earlier '67-69 era, for OTC Camaro use.

One other item; notice the reverse driven gear on the lower shaft end -- were only BB Chev engines available with reverse grind cams OTC ?

from the pictures you can see there would be less chance of a internal oil leak if the oil was not supplied all the way around the dist housing.

[Philip C.]

Re: Special distrib. req'd for '67 BB cam oiling ?

They used those 263 dists on the race series cars because they used two gears to drive the cam, with that set up, the cam turns backward, so they used a reverse drive gear on the dist. to make it turn the oil pump, tac the the right way, That dist also doesnt have a vacuum advance so it was used on the cross ram camaro (dealer install) with the regular drive gear. That dist was $1500. otc back in the day Phil 8063

[Bill M.]

Re: Special distrib. req'd for '67 BB cam oiling ?

Here's my guess:

They went to the full groove in 1967 (my '67 L78 distributor has the full groove) because if you installed the partial groove incorrectly, you could block oil flow to the one lifter gallery.

[Clem Z.]

Re: Special distrib. req'd for '67 BB cam oiling ?

Here's my guess:

They went to the full groove in 1967 (my '67 L78 distributor has the full groove) because if you installed the partial groove incorrectly, you could block oil flow to the one lifter gallery.

that was easy to do when there was no vacuum advance on the dist. these dist were early NASCAR stuff to go with the gear drive cam.

[Wayne M.]

Re: Special distrib. req'd for '67 BB cam oiling ?

. ......That dist was $1500. otc back in the day Phil 8063

Here's a must-read article for anyone with TI. GM price for the 1111263 was $ 1700 in 1991.

Scroll down the page about 20% to the section on distrib's. Oiling is discussed.

http://www.camaros.org/trans_ign.shtml

[Clem Z.]

Re: Special distrib. req'd for '67 BB cam oiling ?

with the gear drive reverse rotation cam the thrust on the dist shaft was downward that is why they needed this ball bearing dist. the std rotation cam forces the dist gear upward against the dist housing. i found this out when i tried to used a std dist with just a change of the gear and it ate the top of the top dist bushing away. i had to make a thrust bearing to installed in the top of the dist to make it work

[Mike Z.]

Re: Special distrib. req'd for '67 BB cam oiling ?

Wayne-
Interesting you quote my E-Bay listing-I stand by it. The requirement from my research of Delco blueprints and several original distributors with ID tags indicates; the unique housing is required on all 65-67 blocks for the reasons I indicated. I agree and indicated the "grooved" cam was a 65-66 deal only, as the 67 block was grooved. However, not until 68 was the dist lower boss, which feeds the LH lifter galley, completely enclosed-similar to a SB, which all SB distributors are fully grooved. If you can get a 65-66 block next to a 67 block, next to a 68 block, you will see the changes I refer to. I firmly believe all 65-67 blocks require this unique distributor housing. I also believe it untrue, that if you install one of these distributor in a later block, you would have a problem-if the distributor is installed in the correct location (per shop manual), the blocked area would not "cover" the oil galleys.
Now, for your #263: these were over-the-counter out of the "Performance Catalog" during the late 60's, early 70's. These ball bearing vs. bushing, fully mechanical, no vac canister units were available with and/or without the blocked lower housing with either the standard or reverse rotation (just a footnote-internal parts, including TI parts are not interchangeable with line units which all had vac canisters, including L-88). The intended application for the reverse unit was the gear drive cam L-88 (primarily intended for CANAM racing; GM, through Roger Penske, was heavily involved with at the time), but also Marine applications-think twin motors. Your date of 6 J 15-to me would be September 15, 1966-just right for a 67 or earlier block. I do not believe these units were available as late as 76 or 86 as you thought. By the way, I really am a Master Judge, with a Duntov Mark of Excellence and a National Top Flight to my name.
Mike Zamora
#12455

[Clem Z.]

Re: Special distrib. req'd for '67 BB cam oiling ?

i stand by my post #4 as for the reason for the partial groove in the early dist. i think GM later tighten up the tolerance on the bore in the block and the outside diameter of the dist housing so a internal oil leak was not as bad there anymore. also when they changed the oil passage for the lifter galleries from the groove in the cam to the groove in the block this also cut down on the internal oil leaks because there is a big clearance between the cam journal and the cam bearing,about .004/.005 and there was a lot of oil lost there that did not make it to the lifter galleries to feed the valve train.