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  #1  
Old 08-08-03, 04:59
Bob Carriere Bob Carriere is offline
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Default David Hayward...need your help...

Bonjour Monsieur Hayward

Been working on my C15 Cab 11 .... finally removed the nose piece and can now send you numbers found on the replacement engine in that truck.

If you recall it is a GMC that appears bigger than a 216.... migth it be an elusive 270 c.i.....

Starting from the top..... head has the following casting numbers

....... BK.........J64................ 2136477

On the block behing the exhaust pipe.......

GMC 2 6107328

and on a same silver(aluminum?) plate

GMC Truck & Coach Div.
General Motors Corporation
Pontiac Michigan
Serial NO
(hand stamped) G 5502 (same # appears next to dist.)

Bore Stroke Cyl

3 23/32 3 13/16 6
Made in USA

Now what have I got??????



While you got your nose in the books.....

.... I have a parts ex water truck.... only the power train/ frame but it has the (maybe) original 216.... my first one....

....number on the pad near dist. 193587

..... does that number make any sense???? engine has a shallow oil pan...6 blade fan....tranny is std GM 590474 similar to my Cab 11 but has the power takeoff for the pump I presume ... but no pump.


...and another techy question.... in my search for rebuilding a 1958 Chev truck 261 ... it was suggested that I locate the heads with the following last 3 digit in the casting numbers....
- - - 848 .... which apparently have somewhat smaller combustion chambers and may raise my compression ratio......

...well it seems that I have two of them on the re-engined parts trucks I have acquired.... one is Block number GM 764476 with the Captain's bar behind the starter..making it a 261??
the full head casting # is 3836848.

What pearl of wisdom can you share about these heads????

As usual your precious help and experience will be greatly appreciated.
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C15a Cab 11
Hammond, Ontario
Canada
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  #2  
Old 08-08-03, 14:58
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David_Hayward (RIP) David_Hayward (RIP) is offline
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Default Phew!

B'jour! Well it's hot here today, 32 C plus and now a problem to heat my brain up even more.

1. My information has suggested that the GMC engine is a US built 1954 Model 228 cu in GMC, from the block casting number. The head casting could be a date code J-6-4 for October 4 1954 which would make it a very late 1954 Model or perhaps a 1955 Model. # 2316477 is not known to me. The engine # appears to be # G 5502. "G" prefixes were used by GM of C during the war on GMC-built GMC 248 cu in engines. I am assuming here that GMC carried on post-war with G prefixes...I will see if I have a bore/stroke list to check.

2. # 193587 sounds like a car engine, lhd, but which year? It could be a Candian unit from 1948 but we really need the block casting number.

3. The 1958 TRUCK namely Jobmaster Six unit [261 cu in] had a lower compression ratio than the equivalent Pontiac Astro-Six 1958 unit and thus lost a few bhp, which went to 152 I think in '58 for the cars. I have no idea whether this was because they used a head with smaller combustion chambers in the car unit, or whether the head was planed to increase it. # 3836848 is a 1955 and 1956 Model 235 Head ...now I know of at least one Canadian engine that now runs a 1955 235 Head on a 1955 261 Block...no just found another known to me so that combo evidently works. I can't find a casting # 764476 so is it an engine # please? It could be a 1953 or perhaps a 1954 Canadian unit but we need the casting number again.
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Old 12-08-03, 02:41
Bob Carriere Bob Carriere is offline
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Default Found the bore & stroke...

Hi David

Found and old copy of Motor's Truck Repair manual....which I had sitting in my Power wagon library..... it is listing a GMC 248 from 1952 to 1955 with a engine model 248 A, C, and D .... all with the same B & S I had given you... which comes up to 248.5 compression 7.5 to 1 ........ HP from 100 to 130 on various RPM.

Now this book has little else in serial numbers etc.

Now the other engine number should have been 3764476 which makes it a 235 and the heads are the elusive 3836848 and that is on a re-engined C60.

On the Cab 13 frame in the field it has Captains bar ( assuming ) 261... can't read the casting number the engine cover support is in the way..... and it has the same head number 3836848.

The 216 with serial number 193587 stamped near the distributor has the block casting number of # 3835124...... does that make it the car engine you referred to ????

Now on the GMC engine in my cab 11 the casting number checks out on inliner international as a 1953-54 248 GMC....... now how would that explain the G 5502 serial number that sounds like wartime production ..????

In comaparing the 248 to the 216.... they seemed to have used the same water pump as the 216 and the 6 blade fan... and the 216 carburator....wonder how much was original 248 or how much got grafted from the donor 216 when it was re-engined????

Strangely the 216 and the 248 seem to share the same bellhousing bolt patttern and the similar front engine mount plate.... yet the rest of the block is very different.... for example the 248 has a T- fitting on the front of the oil gallery... just behind the fan.... one side of the T fitting feeds the oil pressure gauge the other side feeds a small oil line that is connected behind the water pump into the front of the head.... lubricating what???

Referring to your other post on the GMC engines..... what distinguishing feature would a 270 have compared to the 248 besides the casting numbers????? once in a junk yard dodging wasps and other nasty creatures a quick visual reference is often the best clue.

Hoping that you are njoying the California weather .... are you actually missing the rain and fog typical of Merry Ol' England???



I have finally stripped my Cab 11 to a bare frame/power train assembly. the 248 will be coming out next... and it will be installed on a metal frame and mothballed for the time being... I may decide to rebuild in my spare time later.... as if I had spare time...hahaha. The impressive thing about the GMC 248 is the size of the exhaust/intake manifold and the large 3 bolts exhaust pipe connector.... even larger than the stock 261...... typical of a heavy working trcuk engine with lots of breathing CFM capacity.
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  #4  
Old 12-08-03, 10:14
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David_Hayward (RIP) David_Hayward (RIP) is offline
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Default GMC 248

The GMC 248 cu in unit was produced in Canada from August 1940 for about a year in Walkerville, though all others were imported from Pontiac, MI. It was used throughout the war in GMC and some Maple Leafs. This is an extract from one of my books:

'In fact, civilian production was being discussed as early as March 1945 in THE WAR-CRAFTSMAN with a neat diagram in their March issue to remind General Motors of Canada workers how the system ran in peacetime from Dealer orders to delivery. Re-tooling was undertaken to produce new motors for the peacetime market. The 1946 2-Ton Chevrolet trucks used a new re-cast version of the 216.5 motor, to create a more-powerful 235.5 cu. in “six” used in various Chevrolet Trucks up until 1962, and as mentioned above, in higher-compression form with slight improvements, in the “small” Canadian Pontiacs until 1962, thus endowing the Pontiacs more power than their Chevrolet “sisters”. This new motor was a re-stroked version of the previous 224 in. six as used in Pontiac cars, 1937 to 1941, Maple leaf Trucks and G.M.C.’s, which now measured 3 9/16 x 3 15/16” bore / stroke. G.M.C. and Maple Leaf used either the new 235.5 Chevrolet “six” or the G.M.C. 248.4 “six” in various models at least until 1950. Pontiac Sedan deliveries sold ostensibly by G.M.C. Dealers as “G.M.C.’s” used the 235 in. six. Canadian G.M.C.’s also used the Chevrolet 216.5 cu. in. “six” from 1946, with some versions using the new 235.5 Chevrolet “six”, the G.M.C. 248.4 “six” until 1948 when they added new 269.5 and 308.2 cu. in. motors, and a new Detroit Diesel Diesel “six” of 425.4 cu. ins., depending on normal or forward-control Cab-over-motor models'. The 248 was rated at 33.19 hp...the engine debuted in 1940 and were serialled # G-1001 and up 3 9/16 x 3 12/16 in Bore & Stroke, and was the basic GMC engine before the 270. So, because the 248 originally went in where the 216 did, it should fit straight in. The other queries I'll sort out in a moment my time.
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Old 12-08-03, 21:09
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David_Hayward (RIP) David_Hayward (RIP) is offline
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Default Further reply

Sorry for the delay but the forum went kaput fore some hours and I could not post any reply.

# 3764476 is apparently a 1958-62 235 Block
# 3836848 is a 235 Head apparently from 1954-56 Calendar Years at least
# 3835124 is a CANADIAN 1947 engine, passenger car by the way

Now as regards the G-5502 serial I believe that the engine # was G-5502 and that it is a 248 cu in unit. Oh, and US, nothing to do with Canada!
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Old 13-08-03, 02:58
Bob Carriere Bob Carriere is offline
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Default So far away yet sooo good!!!!

Thanks David

I plan to remove the GMC 248 this weekend and store on a storage frame I will build with casters..... and stuff it in the attic of the barn ofr future consideration. I plan on drainning all the current motoroil/deisel fuel combination and over filling with basic motor oil. The thing is very tight and doesn't leak...... cylinders will get an idividual dose and soem poured in the carb and oil intake on the valve cover. Then will tape over all openings.

That G5502 seem to good to scrap!!!!!

Will prepare my 1958 261 for shipping to the machine shop...along with the cab 11 216 bellhousing for accurate line boring in case the dowels do not perfectly line up..... I will pull the front engine support plate from one of the spare 235 currently installed in the C60 for eventual installation on the 261 when it is rebuilt.

Let's see ..... after all inspections and measurements, rebore, linebore, new pistons, rings, etc. other parts as required... stock 1958 truck cam shaft.... probably balanced...... should run like a fine watch and I will be sitting a lot lower in my chair after my wallet gets deflated.... oh and yes.... Chev gray paint all over.....

Am I forgetting anything .... oh wise one......????

Again thanks for you help.
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C15a Cab 11
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Canada
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  #7  
Old 13-08-03, 12:15
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Default Grasshopper...

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