Team Chevelle banner

determining a 454

15K views 19 replies 12 participants last post by  jfman 
#1 ·
i went to my local machine shop/junkyard today. i asked about buying a 454 block, he pointed me in the engine section. there are all these engines just sitting here, i cant tell whats what. beside the difference between v-6 v-8 inline 6 etc. to me i cant twll the difference between a 454 and a 350 or 302 428 etc. is there something i can look for on these blocks that will tell me its a gm 454 engine? i dot really need a specific generation as long as it is a true 454. thanks.
 
#3 ·
345014.....454.......70-86...
346236.....454.......75-76...2-bolt
359070.....454.......70-90...
361959.....454.......73-90...2 or 4 bolt
3963512....454.......70-76...2 or 4 bolt
10051107...454...............4-bolt, Bowtie, MkIV, 9.8" deck
10069286...454.......90-91...4-bolt, Mark IV, Short deck
10114182...454.......91-up...4-bolt, Gen.V
10185050...454...............4-bolt, Bowtie, Gen.V, Short deck
10237297...454.......96-up...4-bolt, Vortec 7400", "L-29" Gen.VI
12550313...454.......91-up...4-bolt, Gen.V crate motor, Gen. VI 4.25" bare block, fuel pump boss
12561357...454.......96-up...4-bolt, Gen.VI
14015443...454.......87-90...2 or 4-bolt, Mark IV, Truck, Motorhome
14015445...454.......78-90...2 or 4 bolt
24502504...454...............4-bolt, Bowtie, Gen.V, Race prep, 9.8 "short" deck height

The numbers in bold will be on the driver's side of the block, right by the bellhousing flange. There should also be a "GM" cast into the block in the same area.
 
#5 ·
small block has 4 valve cover bolts
big block has 7 valve cover bolts
there will probably be 40 small blocks to 1 big block.
once you have found a big block,look at the flywheel or harmonic balancer,there will be a weighted piece on one spot as these are external balanced,you can feel behind the balancer for this weighted casting.
note : truck engines(big truck ,school bus not pick-up): tall block: look at where the water pump bolts up ,on a truck engine there will be about a .5" between the bolt hole and the head surface.stay away from these unless you biulding something real big. good luck
 
#6 ·
Also, if for some reason you can't put them next to eachother, and can't judge sizes, and all you want to do is distinguish between a small and big block, look at the lifter valley, more specifically, the cam tunnel. A bbc will have slot where u can actually see the cam, a smallblock is solid.
 
#8 ·
tom kennedy you said stay away from the truck engines 454. is that all truck engines?good topic as i will be starting to look for a bb so i can build it up slowly as money permits, what are some cars to look for? any trucks or vans that would make a nice motor for the chevelles? i think a lot of guys could use this information. myself just never really got into motors so i have to ask a lot of questions and learn. (just a 20 year bodyman here.) thanks
 
#12 ·
There's at least one guy on here running 10 seconds with a "Truck" block. The real problem is core shift, some say truck blocks have more shift, some say that's a myth. Anyway, a truck block with less core shift is better than a passenger block with more core shift.

Unless by Truck he meant Tall Deck. But NONE of the stock application 454s came as Tall Decks, that was only the old 366/427T engines. IF you get a Tall Deck 454, then it is a Bow-Tie block and it is one of the best of the best GM blocks.
 
#15 ·
Tall deck "truck blocks" are 427 and 366 CI. They have a .4 higher deck height. They require a different intake, and a distrubutor with a longer shaft to compensate for the .4 deck height difference. You also need to get longer rods, so you can go from the 4 ring pistons to stock 3 ring pistons. Stock, these engines come with larger 4 ring pistons to reduce blow by from higher mileage engine. This is because they were mostly extreme duty engines... used in dumptrucks and cranes and what now. Most of them require custom headers, and have brake booster to valve cover clearance issues...
Oh also.... the tall decks came with steel cranks and rods... very good to rob from them if you find one.

Truck motors (ie.. suburban, and 1 ton dually motors) are fantastic donor motors. Pull them out of that old rusty truck, rebuild it with go fast goodies and you have the same thing that is in every 70 Chevelle Ls6 CLONE you see in the shows.

I hope this helps.
 
#17 ·
I have a question, I am new to engine building and I have just bought a Mark IV 454 casting #10069286. And I was wondering if I could put a set of rect port heads casting #3964291 that were made between 69-70. Or do I have to go with the Mark IV heads? Also did I go wrong with the Mark IV block?
 
#18 ·
gmg1977 said:
I have a question, I am new to engine building and I have just bought a Mark IV 454 casting #10069286. And I was wondering if I could put a set of rect port heads casting #3964291 that were made between 69-70. Or do I have to go with the Mark IV heads? Also did I go wrong with the Mark IV block?
Yes you can use the heads. 69-70 heads are actually Mark IV heads. All BBC engines from 65-90 (and some 1991) are Mark IV engines.
 
You have insufficient privileges to reply here.
Top