Re: Small Block or Big Block
Personally, Id probably be using that big block. Granted, you will need to spend a bit of money to make the swap work, but the big block will be durned easy to build especially with the parts you got. With the factory 402, no questions asked Id run the stock crank and rods(With good ARP bolts) up to 550 horses or even a little better. And with the 781 heads(Which are great factory cast big block heads), Id mill them down a bit and use the right dome piston for around 10:1 comp or a tad more. You will have to CC the heads to find out what the chambers are. Usually, they check in around 119-122 and the typical oval port big block head will lose 1cc per .005 taken off(flat mill). Meaning, youd get roughly an 8cc reduction by flat milling them .040. Even with the 2.06 and 1.72 valves it will still do well. Bowl work could help a lot. And if you wanted to go all the way, bigger valves can help as well....they just may not be necessary depending on how much power you actually want.
From there, an rpm aluminum intake, 750 carb and the right camshaft will really bring this thing to life. You could use a lunati voodoo 276 camshaft and have a motor thats easily capable of 12's and descent street manners. If you wanted something a little more on the wicked side, their 402A3 solid is a nice cam. Its numbers are 243/251 at .050 110lsa and .586/.600 lift. This cam could definitely benefit from larger valves and 11's is definitely doable. It will be a little bit of a handfull. If you wanted a tamer solid cam, the 402A2 will be a fair bit tamer and still make plenty of power. Its 238/248 at .050 with a wider 112LSA.
If you want to equal that power in a small block, you would definitely be best to buy a whole new rotating assembly for durability purposes cause the small block stuff wont hold like the factory big block stuff. And if your buildin a 383, youve got to anyways. And of course, your not going to find a stock casting small block head that will compete with some of the better big block heads. Heck, a real well done port job on those 781's could net you around 315cfm worth of airflow......some of the top notch big dollar small block standard 23 degree heads make 280ish. Like the AFR heads and Race rite heads....both top of the line standard small block heads, but youve got to pay 1200 dollars or more for a set. And then of course they still dont always compete as well with your ported stock big block heads........and that can work out to be a good bit cheaper(working on the big chevy heads you already have). And a mild job on the 781 heads(nothing too crazy) should net similar numbers to these small block aftermarket heads...and since you already got em, depending on where you look you could have your heads set up for less than the cost of those small block heads.
Whatever you do, come up with a realistic goal(power and street manners) and from there you can have an idea of how youd really need to build either motor. And once you know that, you can do some pricing. You can often save money building the big block in some situations cause you can use so much of the stock stuff.....whereas much of the small block stuff has to go. Plus, there aint nothing like a big block under the hood. Hehe. Dont get me wrong, I like small blocks a lot too...a whole lot, but if I had the options right there in front of me to go one way or another, Id have a hard time passing on the big motor. Its a little different if you have to find a core to start with and find heads. Then the big block could easily cost more, but with both options readily available, a lot of times they cost pretty similar.
One final note, I might be overestimating your goals. If all you want is something thats say capable of low 13's or as fast as mid 12's...the small block would probably be the winner pricewise. You could go with one of those 900 some dollar vortec packages with the modified heads and manifold, cast crank(stock if you keep it a 350) cheap aftermarket rods and hyper pistons with a 268 degree cam(like a voodoo 268) and have a good driver that would probably make a 12.80 motor from a 383. Easy low 13's assuming proper gearing and converter. So keep your goals in mind when you do all your combo figuring and pricing.
Last edited by greg moreira; Dec 15th, 05 at 10:11 PM.