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Old 01-19-2003, 08:04 AM   #1
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What is the potential of a 402 BBC??

I have the opportunity to pick up one of these engines and do not know mych about it other than the fact that it is a BBC.
Does anyone know what these came in originally ? Were there hi performance models ? Not even sure what year it is...
I have been looking for a 427, which is hard to find. would this be a substitute ??

Thank's Guy's (and Gal's) !!!
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Old 01-19-2003, 08:28 AM   #2
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They are 396s with a factory bore. Friend has one in his 1969 Chevelle SS. I believe they can iin 68-72 models or somewhere around there. Chevelles, maybe trucks as well. Some came with what they called the 375 horse heads, overall pretty good engines. I believe they can be made into a 427, but I'm not sure. Not real familiar with big blocks, but I'm sure someone else will tell you before long.
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Old 01-19-2003, 09:00 AM   #3
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Certain year 396's were really 402's , but still badged as 396. Think it was 1970 or so.....pretty good motor.....still can use most big block parts as far as I know...also some came with factory alum.heads
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Old 01-19-2003, 09:15 AM   #4
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The 402 was available from 1969 to 1972

The 402 was a 396 that the factory bored out +.030". It was usually in trucks but some cars also received them and were badged as a 400 but that was confusing since there was also a 400 SBC. Shortly after that is was rebadged as a 402.

You can't make a 402 into a 427. At least not in the traditional way. The 402 uses the same small bore and stroke as a 396. A 427 uses the larger bore of the 454.

You can make a 427 by installing a 396/402 crank into a 454 block.
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Old 01-19-2003, 10:51 AM   #5
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Well, the 402 has the same bore 4.125 and a tiny bit longer stroke 3.76 vs. 3.75 than the small block 400.
And since typically, big block parts are more expensive than small block parts ... Am I better off with a small block 400 and a 6" rod for trying to build some torque (I realize the 402 has a 6.135" rod)
Or is there some other design characteristic that allows the big blocks to build more torque ??

Thank's for the feedback !!
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Old 01-19-2003, 11:13 AM   #6
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If you go with the Big Block , you can use anything from any BBC , except the bore is different. The stroke is 3.76 for the 396,402, and 427 , the rods are the same at 6.135. The 454 has a 4.25" bore , same as a 427 but has a 4.00 stroke. In other words , if you already have the motor , you can interchange alot of parts. My father restored several SS Chevelles , and pretty much any SS 396 from 1969 till 1972 is really a 402 from the factory. Chevy left it like that because the 396 was very respected , and people dont like change. Also alot of trucks,El Caminos got them too. Go with the Big Block if you can...would be sweet !!!

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Old 01-19-2003, 12:17 PM   #7
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Stock BBC heads flow about as much as a set of good aftermarket SBC heads so getting more air into the engine is easier and cheaper. More air = more power.
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Old 01-19-2003, 12:18 PM   #8
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A 402 based big block will make a little more horsepower and torque than a simular build 400 based small block.

It is a more durable motor too.
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Old 01-19-2003, 12:40 PM   #9
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I have a 402 in my garage, would this be better to place in my car than say rebuilding my 350 as a 383? The heads are casting number 3999280. What entails a big block swap? Am I gonna just need to use headers and play with the exhaust? It may be a possibility to do this summer, but it is it gonna be a pain? Also, think it would run under a CCC setup at all? I dont want to fiddle with torque converter lock up myself? How much is handling compromised with this motor?
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Old 01-19-2003, 02:14 PM   #10
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Are you sure those aren't "820" castings, not "280"?

If so, the 820 is one of the best castings for a mild street-type big block. They have moderate ports, open chambers, with the "squish" area that 396 heads lack, but with small enough chambers to get reasonable CR without huge domes, which cause other issues. Nearly all big block applications require domed pistons, but the smaller of a dome you can use, the easier it is to get it to run on pump gas.

With the right cam, you could probably coax it into working with a CC Q-Jet.

I can't answer whether it's better than a small block; each has its own advantages and disadvantages. Personally I'd rather build a big small block for one of these cars rather than a small big block; if I was working on a Chevelle, the answer I'd give might be different. If I was going to go to the trouble of putting a big block in one of these I'd at least use a 454.
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Old 01-19-2003, 05:46 PM   #11
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Im looking for more power, and the motor is in my garage just waiting for a home. It needs a rebuild as it is, and Im thinking a swap entail merely doing headers and custom exhaust. Am I wrong to assume just this? I could use the extra cubes and torque with the car, and could have the equivalent after a home port job and bigger valves of a bargain 400 small block with really sweet aftermarkets on it. Plus the bad *** factor of a big block sitting under the hood is a big plus.

This is also coming from someone with minimal mechanical experience. My father is very good with swaps. I also worry about eating my 700R4, but I have a TH350 I could build to put in when the other one goes. If I could get the car a solid 13 flat performer with the big block Id do it, but I dont know if the expense of working the big block justifies it over building a small block.
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Old 01-19-2003, 05:46 PM
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