Any issue here...SB distributor in BB engine

[Michael G.]

My fully rebuilt '66 427 is mounted on the engine run stand....soon to do initial start up and break in. When car was purchased and during dismantle of engine discovered it had a small block distributor. Knowing there is slight difference in distributor housings from SB to BB see any issue to using same distributor to do initial engine break in till BB distributor is purchased.

[Joe L.]

Re: Any issue here...SB distributor in BB engine

My fully rebuilt '66 427 is mounted on the engine run stand....soon to do initial start up and break in. When car was purchased and during dismantle of engine discovered it had a small block distributor. Knowing there is slight difference in distributor housings from SB to BB see any issue to using same distributor to do initial engine break in till BB distributor is purchased.

Michael-----


Some big blocks did use a distributor with "half-round" oil groove at the bottom. However, as far as I know and have been able to determine, this is not a necessary feature for big blocks, including the 65-66 variety. So, a small block distributor housing will work just fine with a big block.

As further confirmation of this is the fact that the 1965-1966 Corvette big block distributor housing, GM #1966654, which may or may not have been a "half round" configuration, was replaced by GM #1851158 in August 1971. The 1851158, which was a "full round" oiling configuration, then remained the SERVICE housing for ALL 1962-74 Corvettes, small block and big block alike, until it was discontinued without supercession. So, GM says that a "full round" configuration is fine for all engines.

[Mike Z.]

Re: Any issue here...SB distributor in BB engine

Michael-the 65-67 BB was unique to later BB blocks in the rear cam bearing journal area-GM actually used a grooved rear journal on the camshaft itself, which allowed oil from the cam journal (between the bearing and the cam) to the lifter gallies and on to the "top end" of the motor. Starting in 68, the block was altered to include a groove in the block rear cam journal, thus eleminating the need for the grooved camshaft-allowing oil to flow between the block and the bearing. Note: it is fatal to use a non-grooved cam or a hybrid grooved bearing in an early block-oil can not get to the lifter gallies. Along with the unique cam journal, GM used in all early BB (65-67) a unique distributor housing, required to adaquitly provide the oil presure to the lifter gallies. You can check out some of my many E-Bay listings under Michaelz505. These listings of restored original early BB distributors (I deal only in TI units) show and talk about the unique distributor housing. Although, there are those who have run their motors using a small block or later BB distributor (without the groove restriction)-I do not believe after study of the oil galley diagrams, one would choose to take a chance of improper oiling of their very valuable early BB motor.

[John H.]

Re: Any issue here...SB distributor in BB engine

Starting in 68, the block was altered to include a groove in the block rear cam journal, thus eleminating the need for the grooved camshaft-

Mike -

I think you'll find that the change in the rear cam bearing bore in the block (and in the bearing and camshaft rear journal) was implemented for the 1967 model year.

[Michael G.]

Re: Any issue here...SB distributor in BB engine

John,

That was my understanding when I was researching the rebuild of the engine that 1965/66 were unique in their oiling system. This all changed in 1967 as you've stated. The engine/car originally came with a TI distributor however was not in the engine when purchased and as stated had a SB distributor. Intial start up and break in was going to occur on an engine stand makes it challenging to wire up a TI distributor which happens to be a BB distributor. Didn't want to incur any damage using a SB distributor and so as Joe stated I was good to go.

All went good last Sunday as engine was started and run 45 to 50 minutes with minimal amount of "heart burn"! I'm the proud pappa on the left.

[Tom P.]

Re: Any issue here...SB distributor in BB engine

Just for additional info, all SB and BB (but NOT W-motors) distributors are totally interchangeable. NO, they're not exactly the same---------------they're interchangeable!
Also, for the most part, what distinguishes one distributor from another is the advance curve which is accomplished by the difference in weights, weight springs and vac can.
Thus, if you have a good dist core, you can "build" whatever you need for your engine specifics from any SB or BB distributor.

[Ridge K.]

Re: Any issue here...SB distributor in BB engine

Michael, as Tom pointed out, the distributors are totally interchangeable in 1967s.
My '67 L68 427 had a dual point distribuor with an original band stamped for a '67 vintage L79 in it. It's original TI distributor was removed during it's drag racing career. Ran perfectly, and no oiling problems with the small block distributor.
Ridge.

[Michael G.]

Re: Any issue here...SB distributor in BB engine

Thanks Ridge however my engine is a '66 with the unique 65/66 oiling system.

[Clem Z.]

Re: Any issue here...SB distributor in BB engine

Thanks Ridge however my engine is a '66 with the unique 65/66 oiling system.

the oiling system on your 66 is only different BEFORE the oil get to the lifter gallery where the distributor fit thru. it has nothing to do with the distributor. my guess the original idea behind the half groove dist was to cut down on the internal oil leak around the dist base where it went thru the lifter gallery and they found out it did not make a difference

[John H.]

Re: Any issue here...SB distributor in BB engine

Thanks Ridge however my engine is a '66 with the unique 65/66 oiling system.

Michael -

Makes no difference - the only thing unique about the '65-'66 oiling system is the rear cam journal/bearing/bore; the distributor isn't involved.

[Bill M.]

Re: Any issue here...SB distributor in BB engine

the oiling system on your 66 is only different BEFORE the oil get to the lifter gallery where the distributor fit thru. it has nothing to do with the distributor. my guess the original idea behind the half groove dist was to cut down on the internal oil leak around the dist base where it went thru the lifter gallery and they found out it did not make a difference

And maybe they found out that if you installed the half groove distributor incorrectly, you blocked oil flow to that overhead oil gallery...

[Clem Z.]

Re: Any issue here...SB distributor in BB engine

And maybe they found out that if you installed the half groove distributor incorrectly, you blocked oil flow to that overhead oil gallery...

if you would put it in 90 degrees off it could block the oil flow to that side.

[Richard M.]

Re: Any issue here...SB distributor in BB engine

For future reference of SB/BB oiling see photos in this post...

https://www.forums.ncrs.org/showthrea...230#post778230