Thread: Block id??

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I need help identifying a block. It is said to be a 400 pulled out of a 78 3/4 ton truck. But when I ran casting numbers it said 350. It is a 4 bolt.
BLOCK #:
3956618
ENGINE VIN #:
V0425WI

It would be great if you could tell me what motor this is. I beleive it is a 400 but i may be wrong.

Just look for the steam holes between the cylinders, if it has the heads off. If not, check the vibration damper for a balance weight, or the ring gear for a weight. The 400 is the only externally-balanced SBC.

According to morte, considered the bible of chevy casting numbers to some. It is a 1969 302, or 350, with the 4 bolt main caps. Link # 1 is the block casting #s. Link # 2 shows how to find the block casting date on your motor for the year it was made. The 2nd link is titled casting # locations, but also in the first paragraph it gives the date location along with the casting location.

casting #s
http://www.mortec.com/castnum.htm

casting date
http://www.mortec.com/location.htm

It had a factory q-jet on it if that matters. I will check the date code.

Casting number 3956618 was used for the following engine blocks: 1969 - 302 used in the Z28, 1969 – 327 used in full size, and 1969 – 350 cars and trucks.

V = Flint
04 = April
25 = 25th day
WI was used for 1967 – 283 used in 4 wheel drive trucks (K-10 to K-25), 1968 – 307 used in 4 wheel drive trucks (K-10 to K-25), and 1969 – 350 GMC ¾ and 1 ton pickups with 4 bolt mains.

My guess is that you have a 350 from a GMC pickup

Regards,
Glenn

Are those 350's externally balanced because I beleive that this motor is?

Are those 350's externally balanced because I beleive that this motor is?
Did they run bigger balancers/dampers back then??

only the 400 and 454 were externally balanced.

All small block Chevy's are internally balanced with the exception of the 400 which is externally balanced on the flex plate and also require a correct “harmonic balancer”. The 400 is the only small block that actually uses a harmonic balancer which, in conjunction with the flex plate or flywheel “balances” the engine. A more accurate description for this component on all other Chevy small blocks is a “harmonic damper” or “torsional vibration damper”.

454/502 Big Block Chevy engines also use an externally balanced crankshaft.

Regards,
Glenn

Additional information:

GM used different widths, different weights and different timing positions, for a combination of seven different dampers, depending on what the engine is used for. The 350 used four different ones –
Part Number 6272221 is 6-¾”
Part Number 6272222 is an 8”
Part Number 3947708 is also an 8” referred to as “Special High Performance” and no longer carried by Chevrolet dealers (also used on the 302 motor).
Part Number 364709 is an 8” and specified for “Off Rod Racing”

GM trucks used a 7-1/4” OD damper for 265-350 trucks, 409 (trucks) an the 194-292 Inline-6 cylinder

305CI times at 12:00 o’clock position
350CI times at 1:30 o’clock

When in doubt – bring number 1 piston to TDC an install the correct timing pointer.

The date number is
C198
or
C199
I bought this in the 80's. It was a 1978 3/4 ton pickup. The guy says it was a stock 400 But everything I look for says its a 69 350. It doesnt really matter but I would like to know. So if it was in 1978 the date number woul match up.

Casting Date Example: E038 - (E = Month, 03 = Day, 8 = Last digit of model year (1978)).

Month: A = Jan, B = Feb, C = Mar, D = Apr, E = May, F = Jun, G = July, H = Aug, I = Sep, J = Oct, K = Nov, L = Dec

Is it possible that the casting date is “C108” which would be March 10, 1978?

It might have been so do you guys think it is a 400 or 350 by the numebrs I have given you I think it might be a 400.

Look at the Balancer . If it Looks Like this you have a 400 SB . Also the 400 4-Bolt main Blocks had 3 Water Plugs . Some of the 400 2-Bolt Mains had 2 but had the Boss in the Casting were the 3rd would go . All and All if the casting # On the Back off that Block show's it to be a 4" Bore L/J that's what it is . Truck that year Had 4-bolt Blocks . Most had cast Cranks and the Weaker White Iron Caps .

Just measure the bore and stroke. The numbers don't always mean much without knowing the history of the block and what sort of work has been done to it or what parts were put into it.....