please help me decode my big block - The 1947 - Present Chevrolet & GMC Truck Message Board Network

coggonobrien · 08-20-2008, 08:57 PM

supposed to be out of a 69 caprice, I haven't pulled the pan yet but here's what i've got:

passenger cylinder head from rear to front:
19/8
M Truck
GM4T
This one is tough to read but looks like 3933148

Intake manifold, 4 barrel cast
K16
This one is tough to read but looks like 3883848
GM1
T

Block
3955272

red69ss · 08-20-2008, 09:23 PM

1969 396 go to nastyz28.com to run your #'s ,search for nastyz28 engine decoding

72 CustomCamper · 08-20-2008, 11:31 PM

The block numbers come back as 3955272....396.......69......2 or 4 bolt

The cylinder head number come back as 3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber

Chuck

coggonobrien · 08-21-2008, 06:05 AM

performance wise are the heads going to be worth using?

1968SWBBigBlock · 08-22-2008, 02:20 PM

I have a set of 148 heads and they seemed to be great heads - not a 781 but really nice for a street motor
Most folks will bad mouth them since they say Truck -
They are not peanut port heads by any stretch
I say use em

70rs/ss · 08-25-2008, 03:51 PM

112cc is about as small as you can get without using a closed chamber 98cc head or getting a set of GENIV Vortec 100cc's. All of that means you can get a better compression ratio without a pop-up or at least a smaller pop-up which saves some $$$. Oval ports without peanut ports are all good heads. Heck, peanuts work great if using it to pull (like as in a truck being used as a truck) since under 4500-5000 they produce great velocity and that helps power down low. If for a hot rod, then no, cause they tend to fall flat on their face at 4500ish rpm. Use them, they are as good as any early BBC casting, bigger valves, bowl blend, back cutting the valves, etc are all little tricks to get more out of them and shouldn't cost too much, or do it yourself, lots of books/videos out there for help.

coggonobrien · 08-25-2008, 04:38 PM

can someone post a pic of a peanut port heads? just wanna see what they look like. thanks

70rs/ss · 08-26-2008, 06:10 PM

Here is the best I could find, the intake ports are the small ports (peanut) the exhaust are the same as any other oval port head. Basically two figers would have a hard time fitting into them.

joeys66pickup · 08-26-2008, 07:55 PM

are all BBC heads with PASS cast into them Peanut Ports?

70rs/ss · 08-27-2008, 02:02 PM

Nope, pass is a foundry code I think. Most BBC have hi perf cast into them as well, no biggy and not any indication of what it is.

BTW if this is all 69 stuff (heads should have a casting date in them as well, usually looks like this: A 12 9, not that exact number but a letter, two numbers, then one, the letter is a month code A=Jan, 2+Feb, etc, then the two middle numbers are the day cast and the last number is the year so a 9 would be 1969. If 69 then not peanut ports, since they didn't come around till late 80's aerly 90's. they are good heads, just buy a pop-up piston to bump comp to about 9:1 and you'll be golden.

08-20-2008, 08:57 PM	#1
coggonobrien Registered User Join Date: Mar 2008 Location: Coggon, IA Posts: 580	please help me decode my big block supposed to be out of a 69 caprice, I haven't pulled the pan yet but here's what i've got: passenger cylinder head from rear to front: 19/8 M Truck GM4T This one is tough to read but looks like 3933148 Intake manifold, 4 barrel cast K16 This one is tough to read but looks like 3883848 GM1 T Block 3955272

08-20-2008, 09:23 PM	#2
red69ss Burnouts are therapeutic Join Date: Jun 2007 Location: lancaster, south carolina Posts: 852	Re: please help me decode my big block 1969 396 go to nastyz28.com to run your #'s ,search for nastyz28 engine decoding __________________ 1969 CHEVELLE SS 1972 C10 ALMOST DAILY DRIVER 1968 C10 RUSTBUCKET (MISSION IMPOSSIBLE) 1972 PONTIAC LEMANS CONVERTIBLE (WIFE'S CAR) "My wife and I were happy for twenty years. Then we met." - Rodney Dangerfield "The difference between genius and stupidity is that genius has its limits." - Einstein

08-20-2008, 11:31 PM	#3
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,369	Re: please help me decode my big block The block numbers come back as 3955272....396.......69......2 or 4 bolt The cylinder head number come back as 3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!"

08-21-2008, 06:05 AM	#4
coggonobrien Registered User Join Date: Mar 2008 Location: Coggon, IA Posts: 580	Re: please help me decode my big block performance wise are the heads going to be worth using?

08-22-2008, 02:20 PM	#5
1968SWBBigBlock Active Member Join Date: Oct 2006 Location: Ohio Posts: 1,643	Re: please help me decode my big block I have a set of 148 heads and they seemed to be great heads - not a 781 but really nice for a street motor Most folks will bad mouth them since they say Truck - They are not peanut port heads by any stretch I say use em __________________ 1968 SWB 454 + .040, 490HP x 540 FT pounds of Torque 10-1 Kb Forged pistons, recon rods w/ ARP wave loc bolts 781 heads Ported with 2.19/1.88 SSTvalves Lunati 60204 cam, Micro Trol lifters, Ported Edelbrock Performer Rpm manifold armor coated, Pertronix Triple Strike Ignition Holley 770 Street Avenger carb,Headers armor coated Built by Watson Ruppel Performance in Sarahsville Ohio. Hardshift Tranny Built Turbo 350,TSI 10" 3000 stall 12 Bolt Eaton Posi 4.10 Richmond Gears moser axles 18.5" x 31" Hoosier Pro Street Radials ET Classic 5 Wheels - polished Power Steering, Power Brakes,Disc Brakes,Tach & Gauge Dash, Tilt,Factory Air (gone) Custom Paint & Body Work Special thanks to my wife, my son and my money tree

08-25-2008, 03:51 PM	#6
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: please help me decode my big block 112cc is about as small as you can get without using a closed chamber 98cc head or getting a set of GENIV Vortec 100cc's. All of that means you can get a better compression ratio without a pop-up or at least a smaller pop-up which saves some $$$. Oval ports without peanut ports are all good heads. Heck, peanuts work great if using it to pull (like as in a truck being used as a truck) since under 4500-5000 they produce great velocity and that helps power down low. If for a hot rod, then no, cause they tend to fall flat on their face at 4500ish rpm. Use them, they are as good as any early BBC casting, bigger valves, bowl blend, back cutting the valves, etc are all little tricks to get more out of them and shouldn't cost too much, or do it yourself, lots of books/videos out there for help.

08-25-2008, 04:38 PM	#7
coggonobrien Registered User Join Date: Mar 2008 Location: Coggon, IA Posts: 580	Re: please help me decode my big block can someone post a pic of a peanut port heads? just wanna see what they look like. thanks

08-26-2008, 06:10 PM	#8
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: please help me decode my big block Here is the best I could find, the intake ports are the small ports (peanut) the exhaust are the same as any other oval port head. Basically two figers would have a hard time fitting into them. Attached Images

08-26-2008, 07:55 PM	#9
joeys66pickup Dr. Frankenstein Join Date: Feb 2008 Location: beaverton,Or Posts: 458	Re: please help me decode my big block are all BBC heads with PASS cast into them Peanut Ports? __________________ I Wanna Go Fast!!

08-27-2008, 02:02 PM	#10
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: please help me decode my big block Nope, pass is a foundry code I think. Most BBC have hi perf cast into them as well, no biggy and not any indication of what it is. BTW if this is all 69 stuff (heads should have a casting date in them as well, usually looks like this: A 12 9, not that exact number but a letter, two numbers, then one, the letter is a month code A=Jan, 2+Feb, etc, then the two middle numbers are the day cast and the last number is the year so a 9 would be 1969. If 69 then not peanut ports, since they didn't come around till late 80's aerly 90's. they are good heads, just buy a pop-up piston to bump comp to about 9:1 and you'll be golden.



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