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 :confused:

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.

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.

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

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?

Re: B.B. ID'ing
 

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

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?

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.

Re: B.B. ID'ing
 

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

Re: B.B. ID'ing
 

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

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 .
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Re: B.B. ID'ing
 

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.
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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.