B.B. ID'ing - The 1947 - Present Chevrolet & GMC Truck Message Board Network

racerface · 09-02-2012, 06:51 PM

SCORE!!!(maybe) yesterday i got a 427 BB that came out of a C-75 chevy, early to mid 70's I was told. Problem is I need to find out if its a tall block or not and if someone could tell me the differents between the two I would greatly appreciate the help. the stamped number in the block is T0404AHT. Thanks, Pat

7dee2 · 09-02-2012, 07:12 PM

Pretty easy to tell with a glance. Look at the upper water pump mounting in relation to the top of the deck. Standard height is pretty close tall deck is not so. If engine is original to the C-75 you probably have a tall deck.

Good luck.

wilbilt · 09-02-2012, 07:17 PM

Tonawanda plant, built April 4 1973. 427 truck engine for manual trans. 230 HP. Application: L-43 60.

Almost certainly a tall block. As I recall, the tall blocks used 4-ring pistons.

clinebarger · 09-02-2012, 07:23 PM

On a "standard" deck BBC the water pump "legs" will be flush with the deck, On a tall deck there will be a space.

A STD deck in will have HI PERF PASS cast in the block.
A tall deck will have TRUCK cast in the block.

Standard deck
Tall deck

racerface · 09-02-2012, 07:47 PM

THANK YOU GUYS!!! the guy was going to scrap the engine and I couldn't let him do it so he let me have it for a small price(far below scrap value) . now I have to ask myself what the heck to do with it?

clinebarger · 09-02-2012, 08:26 PM

Quote:

Originally Posted by racerface

THANK YOU GUYS!!! the guy was going to scrap the engine and I couldn't let him do it so he let me have it for a small price(far below scrap value) . now I have to ask myself what the heck to do with it?

They are worth scrap value for the forged steel crank & miscellaneous bolts & hardware. The block/heads/Intake are junk.

davepl · 09-02-2012, 08:40 PM

I've never understood why these motors aren't more sought after: you'd think they'd be ideal for building a stroker motor, given the tall deck.

They're the same bore as a passenger 427 and 454. I'd think you could ditch the extra ring without problem, so a new crank rod and pistons should net you a big displacement, tall-deck big block.

Maybe they're too hard to clearance for stroker cranks?

wilbilt · 09-02-2012, 08:55 PM

Extra ring means longer piston, hence the reason for being of a tall block. I wouldn't call it "junk", though. It is an engine designed to withstand hard duty usage.

It seems like an excellent choice for a work truck or tow rig.

Tinkermc · 09-02-2012, 09:14 PM

I would think value would be smal a 5.7 350 also comes 290hp

PanelDeland · 09-02-2012, 10:51 PM

It's not about the HP for a tll deck.They're built for torque and long life.

69GWC · 09-02-2012, 10:54 PM

Yeah it would be nice to know the torque numbers on one.

It would be a great motor to put in a C30 with a 4 or 5sp .
Posted via Mobile Device

**WIDESIDE72** · 09-02-2012, 11:04 PM

Quote:

Originally Posted by 69GWC

Yeah it would be nice to know the torque numbers on one.

It would be a great motor to put in a C30 with a 4 or 5sp .
Posted via Mobile Device

My Dax brothers and I built a tall deck 427 for his 80 GMC c30 welding truck to replace the worn out 454 that was already bores to the max. It ran great but would not have been good for a high speed drag motor. We had to run intake spacers in order to run alow deck manifold and we had trouble finding a distributor that was long enough. We came across a lot of magnetos but few dists.
Posted via Mobile Device

rollinhard · 09-03-2012, 09:53 PM

The tall deck blocks are perfect for making big inch stroker motors. My motor for my project is a tall deck 427. Getting bored out .100 and 6.7 rod, 4.25" crank netting 505 cubic inches. All the manufacturers make tall deck aluminum intakes now so no spacers required. The stock cranks in them are 3.76" forged factory gm which are the same as the big horse power 396 and they r desirable.

09-02-2012, 06:51 PM	#1
racerface Registered User Join Date: Dec 2008 Location: wellington ohio Posts: 55	B.B. ID'ing SCORE!!!(maybe) yesterday i got a 427 BB that came out of a C-75 chevy, early to mid 70's I was told. Problem is I need to find out if its a tall block or not and if someone could tell me the differents between the two I would greatly appreciate the help. the stamped number in the block is T0404AHT. Thanks, Pat

09-02-2012, 07:12 PM	#2
7dee2 Registered User Join Date: May 2011 Location: Syracuse, Utah Posts: 1,921	Re: B.B. ID'ing Pretty easy to tell with a glance. Look at the upper water pump mounting in relation to the top of the deck. Standard height is pretty close tall deck is not so. If engine is original to the C-75 you probably have a tall deck. Good luck. __________________ Brett 67 Camaro SS Build:http://67-72chevytrucks.com/vboard/s...d.php?t=751594 72 Cheyenne/10 Super 115" Fleetside (Waiting it's turn.) 72 Cheyenne/K30 Super 133" DRW SOLD Build:http://67-72chevytrucks.com/vboard/s...d.php?t=645614 YouTube: https://www.youtube.com/@6dee7-7dee2

09-02-2012, 07:17 PM	#3
wilbilt Registered User Join Date: Aug 2011 Location: Northern California Posts: 189	Re: B.B. ID'ing Tonawanda plant, built April 4 1973. 427 truck engine for manual trans. 230 HP. Application: L-43 60. Almost certainly a tall block. As I recall, the tall blocks used 4-ring pistons. __________________ 1971 GMC C2500 Custom Camper - Second Owner. 350/TH350, Dana 60 Rear.

09-02-2012, 07:23 PM	#4
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: B.B. ID'ing On a "standard" deck BBC the water pump "legs" will be flush with the deck, On a tall deck there will be a space. A STD deck in will have HI PERF PASS cast in the block. A tall deck will have TRUCK cast in the block. Standard deck Tall deck Attached Images

09-02-2012, 07:47 PM	#5
racerface Registered User Join Date: Dec 2008 Location: wellington ohio Posts: 55	Re: B.B. ID'ing THANK YOU GUYS!!! the guy was going to scrap the engine and I couldn't let him do it so he let me have it for a small price(far below scrap value) . now I have to ask myself what the heck to do with it?

09-02-2012, 08:40 PM	#7
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: B.B. ID'ing I've never understood why these motors aren't more sought after: you'd think they'd be ideal for building a stroker motor, given the tall deck. They're the same bore as a passenger 427 and 454. I'd think you could ditch the extra ring without problem, so a new crank rod and pistons should net you a big displacement, tall-deck big block. Maybe they're too hard to clearance for stroker cranks? __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

09-02-2012, 08:55 PM	#8
wilbilt Registered User Join Date: Aug 2011 Location: Northern California Posts: 189	Re: B.B. ID'ing Extra ring means longer piston, hence the reason for being of a tall block. I wouldn't call it "junk", though. It is an engine designed to withstand hard duty usage. It seems like an excellent choice for a work truck or tow rig. __________________ 1971 GMC C2500 Custom Camper - Second Owner. 350/TH350, Dana 60 Rear.

09-02-2012, 09:14 PM	#9
Tinkermc Registered User Join Date: Jul 2011 Location: Farmville, Va Posts: 3,026	Re: B.B. ID'ing I would think value would be smal a 5.7 350 also comes 290hp

09-02-2012, 10:51 PM	#10
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: B.B. ID'ing It's not about the HP for a tll deck.They're built for torque and long life. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

09-02-2012, 10:54 PM	#11
69GWC Registered User Join Date: Jun 2012 Posts: 1,089	Re: B.B. ID'ing Yeah it would be nice to know the torque numbers on one. It would be a great motor to put in a C30 with a 4 or 5sp . Posted via Mobile Device

09-03-2012, 09:53 PM	#13
rollinhard Registered User Join Date: Jun 2010 Location: British Columbia Posts: 192	Re: B.B. ID'ing The tall deck blocks are perfect for making big inch stroker motors. My motor for my project is a tall deck 427. Getting bored out .100 and 6.7 rod, 4.25" crank netting 505 cubic inches. All the manufacturers make tall deck aluminum intakes now so no spacers required. The stock cranks in them are 3.76" forged factory gm which are the same as the big horse power 396 and they r desirable. __________________ If you can't impress them with your inteligence, dazzle'm with your stupidity 1969 GMC lwb 2wheel drive can you say big stroker motor to come hehe



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