[396chevelle]

Looks like I may be picking up a 427 this weekend, but I want to check it out first. I was wondering if anyone could tell me what the stock bore size is and also the size for 30, 40, 60 over? What are some things to look for to make sure I"m getting a good motor? He say's it ran 40 to 60psi oil pressure for a year and then it driopped to around 10psi. The motor is together minus the intake. should I just check the cylinders and bearings? He says he thinks it spun a bearing. but I would think it would have been knocking. Maybe I can get lucky and it was a bad oil gauge lol.

[cobalt327]

The nominal dimensions of a BBC 427 are 4.250" bore x 3.760" stroke. Add for overbore. More HERE.

Use the casting number and date code along w/the suffix if it's there to determine what the block was, originally. More on casting numbers HERE.

The deal here is, you can sometimes get away w/making a 427 out of a 396/402- but the bore will be maxed out. If the engine block is cast as a 427 there will be room to overbore it, w/o risk of running out of wall thickness.

You can also make a BBC 427 out of a 454 block by using a 396/402/427 (3.76" stroke) crank.

Lastly, be sure the engine isn't a tall deck truck engine (decks are +0.400" taller than passenger car block. 9.8" vs. 10.2")- unless you're OK w/that.

To tell a passenger car block from a TD block, check how much room's above the water pump holes- the pass. block has the top water pump mounting holes very close to the deck, the TD block's holes are ~ 0.500" down from the deck, IIRC.

[396chevelle]

Ok im going to get the castings tonight for the block and heads he says he looked them up and it is a 427, but it is a tall deck truck motor. Is there any major diff in the 2? What kinda hp can i get from this if done right?

[396chevelle]

Ok im going to get the castings tonight for the block and heads he says he looked them up and it is a 427, but it is a tall deck truck motor. Is there any major diff in the 2? What kinda hp can i get from this if done right?

[nofearengineer]

I think the truck blocks are superior, from a geometry standpoint (can use a longer rod if you can get an appropriate piston), but have their share of new problems, like less hood clearance, and requiring a different intake, longer pushrods, etc. This can mean more $$$.

[396chevelle]

I would be putting it in a chevelle with a 2" cowl, so hope it would fit there. I was gonna get it and build it over a period of time. My main concern is can part be readily avalible through summit and such?

[396chevelle]

I would be putting it in a chevelle with a 2" cowl, so hope it would fit there. I was gonna get it and build it over a period of time. My main concern is can part be readily avalible through summit and such?

[396chevelle]

Ok im going to get the castings tonight for the block and heads he says he looked them up and it is a 427, but it is a tall deck truck motor. Is there any major diff in the 2? What kinda hp can i get from this if done right?

[396chevelle]

OK, I need some opinions on this. I'm basically makeing a trade for something I have that I don't use anymore for this 427 motor complete minus intake, 2 x trubo 350's 1 short shaft one long shaft / one stock converter-one 2400 stall converter, 750 eldebrock carb and a black max electric fan. The main thing I was wondering is with this 427 tall deck is it easily able to build over 500hp? Are parts easy to find? Will it fit easy into a 69 Chevelle with headers on it? Please someone tell me the in's and out's for this motor. I don't have the money to just go purchase a motor like I would like, so doing some horse trading is right up my alley, but at the same time I don't want to trade for a head ache. I have a 402 in the car now, but was going to have the 427 rebuilt for a spare. I was planning on trading my 92 883 hugger that needs minor work. It has been sitting for 10yrs with a crank here and there, but I hate to see it go to waste when I'm looking for spare motors and parts my bike is only worth about 1,300 to me. Anyway opinions? and In's and Out's please. Need to make up my mind and let this guy know.

Thanks Guy's,

[Deuce]

I ran a truck block for a few years. The main issue is that the deck height is .440 higher ... which messes up a lot of things. You will need spacers plates to go in between the heads and the intake. The push rods need to be longer. The distributor will not reach all the way down to the camshaft without modification to the distributor and the intake.

I used the stock length rods and bought a new " stroker " crankshaft ... to push the pistons all the way to the top of the deck. My block was .030 over so I had a BIG cubic inch engine ( for the time ). It was 484 ci . This was over 35 years ago. Way before GM came out with the 502's and 572's

Now you can buy the intake spacers and push rods already made for the tall deck block. I had to make the spacers back then. I ordered a set of special push rods. I was a tool and die maker so figuring it all out and making it was not a issue for me at the time.

.

[396chevelle]

Ok im going to get the castings tonight for the block and heads he says he looked them up and it is a 427, but it is a tall deck truck motor. Is there any major diff in the 2? What kinda hp can i get from this if done right?

[Torque454]

454's and 427's share the same block with eight 4.250" bores. You wont be able to tell what oversize the bore is without special tools. If the heads are off you can look at the piston to see what size is stamped on it and that will tell you if its standard size or oversize. Otherwise, a ruler or tape measure should get you close. If you roughly measure a 3 and 3/4" stroke and a 4 1/4" bore then it is a 427. If the stroke measures right at 4.00" then its a 454.

Like i said you wont measure an overbore with anything less than, i believe a dial caliper? (sorry not sure if thats the right name or not, cant call it right off hand I just know what it is)

.030 overbore would make the bore 4.280". A .040 overbore would be 4.290" bore. A .060 overbore would be 4.310".

[Overdriv]

A tall deck block is a very desirable item to a racer as they are made of good alloy and can be stroked and bored to give a variaty of engine sizes. Today, pushrods are readily available as are intakes made for the TD that have a recessed distributor mounting hole so you can use a regular length distributor. Just remember, raising the heads .400" will mean regular off the shelf headers may or may not fit your Chevelle. Also the engine will be a bit taller and wider than a standard deck BBC.

If it were me, if it has never had a rebore, I'd make the trade and then decide after researching the cost of machine work and parts, make the decision whether to use it or sell it and get a regular block.

A TD BBC is good trading material at the very least.

[matts37chev]

there is a lot more tall deck stuff available now, but it is more expensive and race orientated, its a lot more work to build a street motor (lower rpm)