69 427 block (3955270) oddity - I think?

[Steve Antonucci]

Gentlemen,

I recently purchased a "good" 427 block for my L/71 engine project.
Casting number: 3955270, 4-bolt mains, Date: I-5-8 Engine code: TO1297BJ
and standard bore! Yes, the code listed is correct !

OK, here are the odd things. The block has "Hi-Perf & Pass" cast into the
block on the oil filter boss area. That's a good thing. But, on the back
side of the block ( in the bell housing area ) it also has a TRUCK designation
cast in. That's a first for me! I didn't see it until I got it home. Once I
saw the "Hi-Perf & Pass", I guess I got excited a little, so I stopped looking.
I believe that this '270 block is a passenger vehicle casting, isn't it? In
other words, it's not a tall deck truck block - right? Joe, where are you?!

Second oddity is the code I listed above. I can't find it in my reference
literature anywhere! Anybody got a clue what it came out of? By the way, if
it is a marine block, it shows absolutely no signs of any of the typical
corrosion. That's another good thing.

Lastly, is a strange one. While cleaning the block, I removed the "spin on"
oil filter mounting plate. In it, I found the typical bypass valve. I have
been told that this was put there in the event the oil filter got clogged.
Well, as we cleaned the block further, I decided to remove the NPT plug that
connects to the oil filter galley from the back of the engine. This plug is
located on the left side of the block, immediately behind the oil filter area,
in the bell housing location ( behind where the flywheel would be ). Whew -
what a mouthful! When I removed that plug, I noticed something in the hole.
So, I went back to the oil filter mounting area and immediately noticed another
of those bypass valves. However, this one was pushed into the block itself.
I probably would not have seen it if I didn't remove that NPT plug!

The machine shop owner told me that he sees these bypass valves in that location
on older style blocks that used the cannister type filter (pre 1968 ). Can any
of you validate this whole bypass valve location issue for me?

So the question is this: Would there be any reason for this 427 block to have
two bypass valves? Seems strange to me. More importantly, would this second
valve cause oil pressure problems? The prevoius owner told me that the engine
spun a rod bearing soon after assembly! Luckily, no mains were spun!

I am planning to go the whole tour on this block soon. Obvioiusly, I would like
to be sure it is correct ( other than the code ) for my L/71 build though.
I hope one or more of you can help me with this.

Thanks again for all the help over the past few years.
Steve

[Terry M.]

Re: 69 427 block (3955270) oddity - I think?

Steve,
Bevis and Butthead sure would have fun with that -- it will probably bring out all the sophomores.

The only BJ code I find in 1968 or 1969 Chevrolet applications is for a six cylinder, but I don't have marine or stationary engine applications. On the chance that the guy setting up the number stamps at Tonawanda on January 29 was celebrating new years early, there is an LJ code for 335 hp police package automatic with hydraulic lifters, also a 366 CID YJ for 60 series trucks also automatic (Allison in this case). Others will have to chime in about the differences between the 366 and 427 set-ups.

I don't think The HI-PERF PASS or TRUCK cast into the case means a lot. I have seen a lot of those markings on big blocks in all sorts of applications. I don't think it, alone, is anything to get excited about.

Someone else will have to help with the tall deck situations. I am not familiar with them.

[Joe L.]

Re: 69 427 block (3955270) oddity - I think?

Steve------

I can't find any use of a "BJ" engine suffix code for any Chevrolet model for 1969, the only model year that the 3955270 casting was used. So, if the code is correct, then I don't know what it's for. The 3955270 block is a "short" deck passenger car/light truck block only; that casting number was never used for a "tall" deck MD/HD truck block.

The valve that you found behind the NPT plug sounds like an oil cooler bypass valve. However, usually these valves are installed in the oil cooler fitting that is above the oil filter. I've never heard of one being installed in the fitting which is on the back of the block (i.e. behind the flywheel).

[Joe L.]

Re: 69 427 block (3955270) oddity - I think?

Terry-----

The 3955270 casting would not have been used for a 366 cid application, so it can't be that. It is possible that the "BJ" suffix code was used for a marine or industrial engine application. If it were marine, I would think that there would be some other "clues" found on the engine evidencing this sort of heritage.

[Steve Antonucci]

Re: 69 427 block (3955270) oddity - I think?

Joe,

I knew that would get confusing when I wrote it. I only saw the very edge
of the bypass valve when I removed the NPT plug. To gain access to it, I
had to go back to the oil passages underneath the oil filter mounting
plate. Then, I simply pulled it out.

The location of the valve in question that you mentioned: "installed in the oil cooler fitting that is above the oil filter" - are you referring to the very
large center NPT thread/plugged hole in the center location right above the
oil filter?

So, expanding upon this, is this second valve only needed if the external oil
cooling provision was used? If so, sould it remain out of the block?

Lastly, I will send you some images of the block in question as I don't have
a way to post images here yet.

Steve

Steve

[Clem Z.]

Re: 69 427 block (3955270) oddity - I think?

that oil filter by pass valve was used when the BBC was equipted with a external oil cooler.they used this valve in case the oil cooler got plugged you would still get oil to the engine bearings. myself i use a expansion plug in this area when i used a remote oil cooler.

[Joe L.]

Re: 69 427 block (3955270) oddity - I think?

Steve----

I looked at the pictures you e-mailed. The fitting with the square head pipe plug is the one that I'm talking about. That's the one that I think the by-pass valve is installed in. As far as I know, this valve is not required if the engine does not have an external oil cooler. This pipe plug does not look like a factory installed piece to me so, perhaps, this engine once had an oil cooler.

The engine stamp pad shows only the engine ID number and no VIN derivative. This almost certainly means that the engine was never installed in a passenger car or light truck. By 1969 I believe that VIN derivatives were being stamped on most all engines installed in vehicles. This likely means that the engine was a marine or industrial unit; I seriously doubt that it was a crate SERVICE engine for automotive use. In fact, if I recall correctly, the color of the engine looks like the color that Mercruiser used many years ago for their engines. So, I'd say that it's likely that this engine was originally installed in a boat.

What its origin is is actually pretty meaningless, though. For you, it sounds like it's just a core that you're going to use to rebuild.

[Steve Antonucci]

Re: 69 427 block (3955270) oddity - I think?

Clem,

So as I'm not using any other oiling provision other than the stock setup,
I assume I can leave this valve out of the block. Just finding it was an
unexpected event.

Lastly, would the existence of this valve in my 427 block be a strong
indication that the engine did have external oil cooling, or that it
was "preped" for that provision. Who would have used the external oil
cooling anyway? Road racers, or drag racers?

BTW, Joe, did you get my images?

Steve

[Clem Z.]

Re: 69 427 block (3955270) oddity - I think?

if you do not use a external oil cooler just leave the valve out. all types of racing except drag racing could have used a external air to oil cooler,also marine use engines will use a external water to oil cooler. go to google and type in "3955270 block" and you will find some interesting stuff

[Steve Antonucci]

Re: 69 427 block (3955270) oddity - I think?

Joe,

All good points!

Far be it from me to disagree with you, but I have seen several documented 1969
cars that do not have VIN's stamped on the engine pad or left rear of block
for that matter. I own one such 69 SS 396 Camaro.

I contacted the previous owner (last night) of the engine and he could not
verify the existence of the valve in question. He did mention that he bought
the block from a "Corvette Guy" in the mid-west. This guy was into L/88's and
such, so perhaps this was a racing block. BTW, I saw no signs what so ever of
orange paint anywhere on the block. So, it could have been tanked at some
point in its previous life, or originally painted black - who knows!

I agree with you about its possible marine heritage. My thoughts all along.
And, as you noted, this block is destined for that L/71 build! It will have
to be decked anyway, so the point is moot. If the code had checked-out, I
would have gone to the ends of the earth to save it though.

One fast poser to you: Where can one find marine appl. code break-downs?
Does anyone know, or care for that matter?

Thanks to all for the helpful insight. The little valve threw me for a loop
and I just needed some reassurance. You guys gave it to me. THANKS!

Steve