427 or 454 which is this

trying to figure this block out here is some pics of the numbers i have found


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3963512 427/454 69-71 335-450HP 2 & 4-Bolt COPO

CE 68 to Present, Warranty replacement

H 13 8
H is the 8th letter in the alphabet. The 8th month is August.
13 is the date of that month, August 13.
8 is the year. In this case 1968. Since the new model starts halfway into the year the block was used in a 1969 vehicle.

So it would be my hunch it's a 427 as the 454 didn't come along until the 1970 model year. Did you get a crank with the engine? If so what are the casting numbers? It's a bit difficult to find a COPO block. This block is worth some bucks to someone restoring a Yenko car as well as other lines that used the COPO blocks.

always like 427's over the 454, what it gives up in cubes, it makes up for with quick rev's

If it has a flywheel or balancer on it, a clue would be to look for an externally balance part.....Balancer has a piece cut out of it on a 454

__________________
In the words of Walter Cronkite..."And that's the way it is."

Ontario Rodders

I always get a kick from those "quick rev" comments when people talk about smaller engines like 327's or 427's.

But you know it doesn't matter how fast it revs in neutral. What matters is how fast it revs in gear. And I'm sure the bigger the engine, the faster it will increase the rpms in gear. For example, a long stroke 496 will "rev quicker" than a 427 when you put the same load on it.

So, if you want to go faster then build a bigger engine. Put a 4 or 4.25" crank in that 427 block and it will rev quicker (in gear).

and I , get kicks out of those that denounce it..
tell ya what you tke your 454/496
I'll take a 427 can am engine.. and see you has the better road course times.. there is a reason chevy didn't use the 454 in can am. and it wasn't a cid limit

I hear the same thing from a couple of my friends (father and son BTW) . Has a 355, wishes he had a 327. I try to explain that it is not the rpms that make power, it is the horsepower and torque. and how easy it is to get an honest 350 hp from a 355.

will be taking it apart this week to get the crank numbers the only thing that did not come with it was the heads the intake is casting number 3933163 and dates are close to block dates with the winter snow flake on it now just need to get down to the mains to check if 2 or 4 as far as going with a 454 or 496 it was the 427 i was looking for and thanks for all the input much appreciated

If you have a short block, simply measure the stroke. Run any piston to TDC, mark the cylinder at that point with a Sharpie. Run the same piston to BDC and make a mark. Measure between the marks. 3 3/4" stroke tells you it's a 427. 4" stroke tells you it's a 454. Am I missing something here?

Years ago there was a debate on here about what dictates how fast a engine tachs. Many factors of course are in there but one that plays a major role is weight.
However the fastest taching small block I ever seen was at a drag strip I used to hang out at. There was a guy who had a '64 El Camino that he called "the farm truck" It had been worked hard and that was obvious by looking at it. Anyways, under the hood was completely worn out 350 that he had installed in the car some years before. It had over 100,000 hard miles on it too. When he decided to race it, he yanked the 350 out, installed new rod and main bearings to get the oil pressure back up along with a new oil pump. He didn't bother to hone it or replace the rings. He installed a sizeable hydraulic cam, a set of ported camel back heads, headers, single plane intake, HEI with a MSD 6AL ignition box, 250 cheater nitrous kit. 750 holley carb, 3500 stall converter, TH350 trans with a shift kit and 4.56 gears with a limited slip unit in a GM 12 bolt. He used Mickey Thompson ET Drag slicks. It was always fun to watch him make a run, because the car smoked so bad it would fog the track down in smoke, and if you were one of the guys who lined up beside him and became his victim you not only got out ran but smoked out as well.
That small block was the fastest taching engine I ever heard, the open header exhaust note didn't sound like almost every other drag car there, since it tached so fast it gave it a unique sound, kind of like a ferrari V12 running open headers. He raced it 2 whole seasons like that, and I only seen him get out run twice. He made many a big block a victim. At the end of the second season it finally gave up and when it did, it did it in grand fashion. It slung seven rods, the eight rod was still holding on to what was left of one of the crank journals and it was holding on with 1 bolt. He would tell you the secret to it taching so fast was it was worn completely out so it didn't have much friction. Another engine that tachs like lightning is the Chevy 4.3 V6. The one I have in my truck tachs really fast but that's due to it being a small block with 2 cylinders chopped off and thus the entire rotating assembly is lighter. It too gets a unique exhaust note when winding it up.

Relax, guys. The debate over the large cube versus the "small" cube (427 is NOT a small engine) has been going on since the 348 first got stomped by a 283.

For the Mark IV, the 427 certainly has it's following, and for good reason. It really isn't that it "catches revs" so quickly, it's that it can rev to the moon and live. One of my customers has a 447 CID (427 + .100" bore). He shifts it at 8,500. His 3,200 lb. '69 Chevelle runs mid 9s when it hooks (manual trans). Another had a 496 in a '65 Nomad. It was just over 3,300. 9.60s and it HOOKED! Both engines were similar in compression. The 496 had 4.10 gears vs. the 4.56s in the Chevelle. The point is, they both make about the same amount of horsepower. The 496 obviously makes more torque at a lower rev. But the 447's ability to make power over 8,000 is the "equalizer". The 496 probably could do that, too, with a lot more cylinder head, induction and camming. But that would come at a price of longevity over the smaller engine.

In 1969, I attended my first professional race. It was the Can Am race at Laguna Seca, the Monterey Grand Prix. Bruce McClaren won it and Denny Hulme finshed second. I remember the announcer talking about the big "494" Chevys in their Mk VIIIs. Later, I learned they indeed had 4.25" strokes. It was the massive torque getting those monsters "off the corner". To this day, only nitro has impressed me more than those Cam Ams. Mario Andretti even drove a Ford-powered one called the "Boss 429er"...

FWIW

Jim