Big block numbers????? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*cranknut67* · 06-18-2003, 10:29 PM

I have just acquired a big block and before I get all crazy with putting it together, I thought I'd ask you guys what you thought about the numbers and stuff.

Block #'s:
GM - T12
Casting on driver rear: 14015445
casting on motor in front pass. c9b173174
casting behind timing cover : High perf ( front and back )

casting on pistons .40
crank looks to be steel forged
crank bearings are clevite - has size of .10 on it.

casting on heads;

336781

gm73

anything that you guys can tell me will greatly help
the guy who gave it to me said it may have come out of a vette.
( yeah right )

71402BB · 06-18-2003, 10:51 PM

this is what I was able to find for ya on mortec.com

block- 14015445...454.......78-90...2 or 4 bolt

heads- 336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports

breeh · 06-18-2003, 11:00 PM

Those are great heads to have reworked with bigger valves and a pocket port.

jays68yak · 06-18-2003, 11:38 PM

Mmm I just got the same motor.

ratfreak888 · 06-19-2003, 12:16 AM

i looked up your numbers in motorbooks international. it says its a 4 bolt main(hell yeah!!!). you have the same number heads as me, they have the small valves (2.06/1.72) and relatively small intake runners with a 113cc combustion chamber. they could benefit from a good port job and larger valves but i'm making just under 500 hp with mine with nothing more than having them overhauled. it all depends on where you want the powerband. hope this helps. keep on truck'n

ratfreak888 · 06-19-2003, 12:25 AM

i looked in motorbooks international and found it is a 4 bolt main as for the heads you have the same numbers as me they are supposed to be semi open chamber at 113cc with relatively small runners and small(2.06/1.72) valves. you could benefit from larger valves and a port job but i'm making just under 500 hp and all i did was have them overhauled

*cranknut67* · 06-19-2003, 12:39 PM

I looked at the main caps and they are only 2 bolt
but the block still says "high perf" on it. I just hope it is worth rebuilding.

do the numbers .40 on the pistons represent the fact that is has been bored .40 over?
what would that make the motor then? a 460 something?
I took a measurement from the heads and they came out 118cc

so overall - this thing worth working??-

breeh · 06-19-2003, 03:06 PM

Almost all BBC have "Hi Perf" cast into them. A 2-bolt block is plenty beefy unless you are talking 800+ HP. If you are concerned, then put a main stud kit into it. .040 does mean it is 40 over and I think that your guess is pretty close. I don't have my book with me now. 60 over is a 468 so 460 sounds reasonable. As far as those heads, I have seen listings that put the chamber at anywhere from 110-119cc. How did you measure them? Anyway, I would say that it is a keeper unless you want to give it to me!

06-18-2003, 10:29 PM	#1
cranknut67 Account Suspended Join Date: Jun 2003 Posts: 139	Big block numbers????? I have just acquired a big block and before I get all crazy with putting it together, I thought I'd ask you guys what you thought about the numbers and stuff. Block #'s: GM - T12 Casting on driver rear: 14015445 casting on motor in front pass. c9b173174 casting behind timing cover : High perf ( front and back ) casting on pistons .40 crank looks to be steel forged crank bearings are clevite - has size of .10 on it. casting on heads; 336781 gm73 anything that you guys can tell me will greatly help the guy who gave it to me said it may have come out of a vette. ( yeah right ) Last edited by cranknut67; 06-18-2003 at 11:40 PM.

06-18-2003, 10:51 PM	#2
71402BB now thats a true COON DOG Join Date: Nov 2000 Location: Franconia, NH Posts: 1,977	this is what I was able to find for ya on mortec.com block- 14015445...454.......78-90...2 or 4 bolt heads- 336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports __________________ current project 67 402BB stout th350 3.08's with a locker. Plan on tubs 18.5's out back! (thanks Burnsman!) 71 SWB Stepside, was a 250, now is a 402 Big Block with 4 speed and 3.73's ( was crushed by a tree, bed sold, motor pulled) was my first truck!... oh well... 72 LWB 4x4 350 4-speed 3.08's posi wearing army olive drab green (SOLD!) 68 BURB 50TH LOOKALIKE work in progress, soon to have 250-I6 with a 3-speed on the tree 4.11's and posi ( currently sitting in back yard tarped awaiting time, $$$, and lots of love!) 67 1 TON- work truck 396 sm 420 4-speed, flat bed 4.57 gears "big red" (my first landscape truck, very rusty and crusty! but still gets the job done when needed!)

06-18-2003, 11:00 PM	#3
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	Those are great heads to have reworked with bigger valves and a pocket port. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

06-18-2003, 11:38 PM	#4
jays68yak Registered User Join Date: Oct 2002 Location: Gilroy, CA Posts: 1,454	Mmm I just got the same motor. __________________ 1969 Chevy Project SWB Fleet, 20s, 5.3, t56, in the weeds. 1970 Chevy Truck cab on a 1979 Jimmy frame-8.1 liter 496 bbc/sm465/np203-jeds doubler-np205/d60/14bff Welded/42 tsls on recentered H1s 1998 Chevy Crew Cab K3500 SAS'd with hpd60, links and swayaway coilovers. 8.1l vortec DD/towrig "I like long walks, especially when they are taken by people who annoy me. "

06-19-2003, 12:39 PM	#7
cranknut67 Account Suspended Join Date: Jun 2003 Posts: 139	454 I looked at the main caps and they are only 2 bolt but the block still says "high perf" on it. I just hope it is worth rebuilding. do the numbers .40 on the pistons represent the fact that is has been bored .40 over? what would that make the motor then? a 460 something? I took a measurement from the heads and they came out 118cc so overall - this thing worth working??-

06-19-2003, 12:16 AM	#5
ratfreak888 Registered User Join Date: Jun 2003 Posts: 104	i looked up your numbers in motorbooks international. it says its a 4 bolt main(hell yeah!!!). you have the same number heads as me, they have the small valves (2.06/1.72) and relatively small intake runners with a 113cc combustion chamber. they could benefit from a good port job and larger valves but i'm making just under 500 hp with mine with nothing more than having them overhauled. it all depends on where you want the powerband. hope this helps. keep on truck'n

06-19-2003, 12:25 AM	#6
ratfreak888 Registered User Join Date: Jun 2003 Posts: 104	i looked in motorbooks international and found it is a 4 bolt main as for the heads you have the same numbers as me they are supposed to be semi open chamber at 113cc with relatively small runners and small(2.06/1.72) valves. you could benefit from larger valves and a port job but i'm making just under 500 hp and all i did was have them overhauled

06-19-2003, 03:06 PM	#8
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	Almost all BBC have "Hi Perf" cast into them. A 2-bolt block is plenty beefy unless you are talking 800+ HP. If you are concerned, then put a main stud kit into it. .040 does mean it is 40 over and I think that your guess is pretty close. I don't have my book with me now. 60 over is a 468 so 460 sounds reasonable. As far as those heads, I have seen listings that put the chamber at anywhere from 110-119cc. How did you measure them? Anyway, I would say that it is a keeper unless you want to give it to me! __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.