1970 3963512 Block Strange One

[3macs1]

Just when you think you have a grip on the GM numbers bang you get hit with this. Probally 20 years ago I pulled an original 454 engine complete out of a 70 impala. I knew the entire history of the car since it was purchased in the family new until the day I sent it to the junk yard.
About a month ago someone finally convinced me to sell the 454 since it would make his 70 chevelle closer to original. We agreed on a price and off he went.
This motor was never apart. He called today to ask me if I knew this was a 3963512 4 bolt main block with a steel crank.Of course now he is looking for ls-6 heads, etc.
Has anyone ever heard of GM doing this. This engine was 100% oval port, 3963512 2 bolt 70 Impala as far as I http://www.yenko.net/ubbthreads/images/graemlins/stupid.gif was concerned.
Last motor I leave the pan on before sale that is for sure. Boy did he get a deal. I never even looked at the side for oil filler plugs, etc.

[BARRY]

HI WHEN GM BOUGHT OUT THE 454 WITH THE LONGER STROKE THE FIRST BATCH ALL HAD 4 BOLT MAINS??? I HAVE SEEN THIS BLOCK BOTH WAYS

[3macs1]

Never knew that Barry. Wish I did. Been around these big blocks since my first chevelle in 76 and worked on dozens of them when I worked in the service station. Never before did I see a 4 bolt block on a factory oval port other than the tall 366 and 427 truck blocks.There probally was not that many in the initial run of 70 454's.
Any idea Rick or Mr.70 how many oval port 512's may have been sold with 4 bolt mains and steel cranks. Rods and pistons were oval port gear.

[370454s]

The one I have in my 70 Chevelle is a 4 Bolt Steel Crank 390 HP,454. Motor came out of a 70 Caprice that was sold new in Oct 69.

[Hotrodpaul]

Probably a supply or engineering decision based on the new large displacement engine. GM may have done it for warranty prevention reasons. I presume the steel crank was non Tufftrided and non Crossdrilled.

Paul

[nuch_ss396]

Joe,

The use of a 4-bolt block in place of a 2-bolt block is
one thing. However, I'd like to know if this engine in
question had a '6223 crank, dimpled rods, etc.. Also, of
particular interest would be the piston domes. Rectangular
port heads have larger combustion chamber volumes than
those of the oval port heads ( 107cc's vs. 101cc's ).
SHP piston domes are considerably higher, so I suspect they
wouldn't fit in the oval port heads properly. Can you find
out more about the rods & pistons? I'd like to know
more. http://www.yenko.net/ubbthreads/images/graemlins/hmmm.gif

Knowing what we know today, I'm not at all surprised at a
finding like this. If they needed a block to make production
and a 2-bolt version wasn't available, they took what they
could find. http://www.yenko.net/ubbthreads/images/graemlins/rolleyes.gif

[nuch_ss396]

Come to think of it, I remember seeing something in the past
about the 1966 big blocks. I believe some 360hp 396 engines
used 4-bolt blocks in some cases and GM sent a service bulletin
to dealers alerting them to the fact that the piston domes
were different and that care should be taken when replacing
the short block assemblies as the SHP pistons would interfere
with the oval port top ends.

Anybody remember this? It may have been in Colvin's books. http://www.yenko.net/ubbthreads/images/graemlins/hmmm.gif

[69L72RS]

What date range was the first batch of engines (454 CID) made.
I have a 454 2-bolt block coded T0806CGV.
Just curious.
Eric

[Mr70]

The CGV was a 345HP engine.
I've not seen any 345HP's w/4 bolts yet,so far only 2-bolt mains.
The only EARLY casted 1970 non LS-6 coded 512 4-bolt blocks I've seen so far were 390HP engines slated for Impala-Police & Taxi useage.

[olredalert]

------A couple of years ago I pulled two oval-port 351 67 dated complete engines out of a completely dry-rotted Pacemaker boat. They were both 4-bolt main along with the oval-port, but one was reverse rotation. Both were very low hour, beautiful standard-bore pieces, and, although low compression had the good rods and crank. Both the blocks are sitting in restored 67 Corvettes today........Bill S

[nuch_ss396]

Bill,

Were the piston domes on these marine engines the standard 10.25:1 design? With oval ports, I would expect so.

[3macs1]

Steve:
I am not sure if it had a 6223 crank. I asked specifically on the dimpled rods and pistons and he told me the shop that is rebuilding it told him they were just standard oval port but the crank did not have to be cut and was forged.
Also the air cleaner never had a 345 hp or 390 hp decal on it, just 454 and that was original. It was a fully loaded impala that my grandmother remembers was a salemans demo with 2000 miles on it when they purchased it in early january of 70. So it was a early production.They wanted the big engine to pull a camper.
The car was loaded with air, ps,PDB, tilt, PS, PW, PL, rear defrost,8t,posi, fender skirts, delux belts,remote mirrors, etc.

[olredalert]

------You have me there, Steve. I dont remember what the pistons looked like probably because they were going to a dumpster anyway......Bill S

[nuch_ss396]

OK - high or low domes?

[nuch_ss396]

[ QUOTE ]
.....They wanted the big engine to pull a camper.... .

[/ QUOTE ]

OK, silly question time. Did the full sized cars come with
a towing package if ordered? If so, would that possibly
incorporate a 4-bolt block? I've never heard of this before
myself, but you never know. http://www.yenko.net/ubbthreads/images/graemlins/hmmm.gif

Steve

[olredalert]

Steve,,,Definetly had low domes, if they had any domes at all. I remember thinking that a guy could run just about any gas with those pistons. Pacemaker had there own engine program of sorts. I believe they built them to have as much torque as possible while still using regular gas. These engines were painted metallic green and were prominently labelled as "Pacemaker 427s"........Bill S

[3macs1]

Steve:
The domes on the engine I just sold were 10.25 Hp pistons .
Interesting question on the towing package. The car definately had a GM installed hitch and wiring. There was a trans cooler also but I don't know if that was factory installed.
One thing for sure I will always drop the pan on any 512 block I run into in the future.

[nuch_ss396]

Joe,

No real need to drop the pan. Just look at the oil filter
boss ( side ) to see if it has the external oil cooling
attachment provision. All 4-bolt blocks had this.

Steve

[bigchevydaddy]

Are you sure this was the original engine? If it was a demo, it might have had the block replaced under warranty, and they replaced it with a 4-bolt. Years ago I lucked into a 512-casting block that came out of a "totally original" Caprice wagon. Turned out that the block had been replaced by the dealer early in its life. It had a CE stamping. All the internals were low-horse 427, but the CE block had evidently been in-stock in the parts dept. and that's what they swapped in as a replacement.

BCD

[3macs1]

Definately the original engine and it was not CE. That much I did check since I still have a bunch of big blocks and I wanted to make sure he was not getting the original 454 out of my 70 chevelle.Which is buried in the pile also.

[Kim_Howie]

I heard that alot of big wagons had 4-bolt blocks in them???

[3macs1]

Just thought I should share this info. Had a call last night from a good friend who has been working in an engine shop rebuilding motors for over 40 years. BBC his speciality.I told him what happpened with my 512 block.
He indicated that he has seen that many times over the years in the 70-454 and in 66- 396 and 427's . Most of the oval port 4 bolt's did and some didnot not have the oil filter bosses drilled for external oil cooling and dropping the pan was the only sure way to know what you have. He said if you don't beleive me colvin ????mentions it also in his book. They would fit the caps due to potential warranty issues but machining for an oil cooler was not necessary to complete the vehicle.
Sure enough I checked today and on page 57 a note is listed
In many cases, due to scheduling and parts availability, a 4 bolt block was used in a 2 bolt application.
Also stated many times during a block production run, a 2 bolt block might have been drilled for a 4 bolt application with no factory documentation of the change"
To sum it up best to drop the pan before we sell a BBC especially if it is a 66 or 70.

[nuch_ss396]

Joe,

First time I ever heard this. I will have to do some
research of my own to confirm this. http://www.yenko.net/ubbthreads/images/graemlins/hmmm.gif

My understanding was that any block machined for 4-bolt
mains got the external oil cooling modifications as well.

Colvin certainly did a hell of a lot more research than any
of us did in this area. BTW, I did find the passage in his
books regarding this, but he didn't mention anyhthing about
the oil plumbing being different. I'd still have to contend
that 4-bolt enabled blocks would have been drilled for the
external oil cooling provision. Keep in mind that when the
machining process was being performed, there was no tie-in
to the application ( SHP vs. non-SHP ). All 4-bolt blocks
would have to be assumed to be SHP, so I expect they all got
the external oil cooling modifications. If, as you contend,
some 4-bolt main blocks were used in place of 2-bolt main blocks,
I still think they would have external oil cooling provisions.
Anybody else have an opinion on this? http://www.yenko.net/ubbthreads/images/graemlins/dunno.gif

Lastly, do any of you know if 4-bolt main truck or fleet
BBC engines did not have the external oil cooling provision?

Steve

Steve

[3macs1]

Steve:
I always thought so also but there seems to be a gray area when they took a finished 2 bolt and converted it on the fly to 4 bolt. Those I could see them not bothering with the oil mods.
Another thing that makes me believe this is true is I had that engine for years and would have noticed the plugs especially when I was racing l-72's.
Let us know what you discover
Joe

[nuch_ss396]

Joe,

I brought this topic up on the NCRS technical forum and heard
from some very knowledgeable, long-time big block owners
and racers ( past & present ). I rely on these guys heavily
as many of them have been around big blocks from almost the
start of the Mark IV program.

The general consensus is that all 4-bolt main BBC engines
would also have received the external oil cooling provision
as part of this SHP feature. No members reported seeing a
4-bolt main block without the external oil cooling provision
and this jives with what we have been discussing here.

Not conclusive proof, but I have learned to trust the input
of the NCRS on all topics of an historical nature. http://www.yenko.net/ubbthreads/images/graemlins/scholar.gif

Steve

[3macs1]

Interesting Steve. I can see my friend in the engine shop possibly running into this since who knows who could have fitted the 4 bolt caps by the time he got the engine. It may not have been GM , but he was so specific and hit the years in question right on. At the same time I am not disputing the knowledge of the NCRS.
One thing that sticks in my mind is the fact these engines came out of cars that were put together in Canada. Would they do any engine machining I wonder. In the meantime I am watching the 512's.
Thanks for doing the research
Joe