I have a person that is trying to tell me that the 68 396 engine that I have can be made into a 427. I don't know anything about these things. My thoughts are, first of all I don't know if it is possible to do that, but if it is possible, I wouldn't think it would be worth the value of a real 427 so what would be the sense? I personally wouldn't pay as much for a 396 made into a 427. what do you think?

 

The guys in the C3 forum would be better ones to ask... you have posted this in the C4 forum. I have a feeling you are correct about your assumption though. Good luck.

 

It will be worth whatever a 396 is worth I would guess. If I remember correctly a 427 is a de-stroked 454. 4.25" bore(same as the 454) with a 3.76" stroke (same as a 396)

Basically you can make one with a 454 block and a 396 crank. Even .060 over won't get a 396 block to that bore so I don't know how he is doing it.

The advantage is that it spins faster with the shorter stroke. If you are looking for a 427 for restoration reasons I am sure that you will want to find an original 427 block for numbers reasons

 

no.... A 454 with a 396 crank is a 427. It's the bore size that makes a 427. A 396 bore cannot be taken out to a 454 bore size in order to make a 427. So only the crank out of your 396 is usable to make a 427. Also, all 427 crankshafts were tuftrided. It's a super hard bearing surface made by dipping the crank in a salt bath heated to a solution. Tuftrided cranks have a gray surface color. If you are wanting to build a 427, be aware pistons are very expensive. You may not be able to find low compression 427 pistons. Pistons are 454 size diameter with a different wrist pin location. 427's are class race engines, which somehow makes the pistons expensive.

I got beat to it. There was some odd information going around that certain 396 blocks could go out to 454 bore size. With a freeze plug removed from the side of the block. If a pencil will not go though the cylinders, the cylinder walls could be thick enough. Still that's a stretch and sonic testing would need to be done to make sure some cylinder wall would be left. You would be much better off finding a 4-bolt 454 block and using it.

 

I know a 69-427 RAT owner that bored his 427 to .060, that must be a 500+ CID. He gets 7 MPG

 

He is telling stories I think...

.060 over on a 427 would give you a bore of 4.31" and with the stock crank a displacement of around 431ci or so.

Oh yeah...and I get like 7MPG

 

While thinking about this a little more. Connecting rods would be an issue. All big block connecting rods are the same length (excluding 502ci engines and up) All 396's rods had 3/8ths bolts holding the caps on. 3/8ths bolts are what small blocks connecting rods use. No big block engine should have 3/8ths connecting rod bolts. I would highly suggest going aftermarket on the connecting rods. Get some H-beam rods with 7/16 bolt caps and put connecting rod failure behind you. You also want floating wrist pins NOT pressed pins. Big blocks never really broke crankshafts. Maybe after a rod failure, the crank was damaged. People that run blowers needed the extra strength of a forged steel crank because the snout could fail with the added torsion of the blower pulling on it. Tuftrided 427 cranks are out there. I've had two setting around here in past years and sold them on ebay. If you find one and it's been turned, the tuftriding is gone and now it's just a 396 crank in value. You should be able to find a standard 427 crank with it's tuftriding in tact. you could spin a bearing on them without hurting the cranks bearing surface. Very hard and difficult to turn them down to under-size. Heads, I have a set of 109cc semi-open chambered BB heads that need redone. Had to go look and make sure, they are the 049 castings, oval port heads. Some say these 049's out flow the rectangle ports. I sold all the rectangle ports and kept these if that tells you anything. U2U me if interested or have more BB questions. I doubt I'll ever need these heads. If I ever build another big block, it'll be at least a 502 with aftermarket heads.

 

Put a 454 crank in a 396 block and you get a 427 also. Same rods in either one - different pistons.

 

With all the aftermarket support out these days, I would build a small block for anything less than 454CI. If I went big block, I would go big. 540 on up. I wouldn't do a 396 or 427 big block unless it was a numbers matching muscle car. Plus you have a couple of hundred pound weight advantage with a SBC, and easier fitment.

 

You might as well just go 454 at that point. You lose the advantage of the shorter stroke / larger bore so you would be better off with the additional cubes.

 

He might be talking about boring a 396 .030 over and adding a 454 crank into the engine. That combination would get you 427 cubic inches and it would still have casting numbers indicating a 396. My guess is you would do this if you were looking for more power but wanted to keep the numbers matching 396 block. In other words a sleeper.

 

some very early 396 blocks can be bored to 4.250 (IIRC it's the ones without guide pins for the front timing cover, been long)...recent deep price drops for ultrasound thickness testers means many auto machine shops have a good chance of success now to do this...BUTT, current racer fixation on 500+ cube rats and sour economy has now made 427/454 blocks dirt cheap, not worth "pokin" the 396.

imho, "best" combo is a "short 454"...a 427/454 block bored .125" over with a 396/427 crank...great torque, low piston speed (will live at high rpm), ez to balance (all internal)...MUST pass sonic check for core shift before boring.