I have an original matching numbers 71 coupe 4spd small block. Thinking of yanking it and putting in big block or small block with 5sp. Is big block worth xtra money of pulleys and what not. With aluminum heads not much difference in weight.Just curious. I don't want to hurt original engine hopping it up. Thanks for suggestions.

 

Let the games begin.

 

That's good thinking about keeping your SB original. Store it in the crate your new engine arrives in.
Annnnd...post pics in this thread once you begin a BB or SB swap

 

Just wondering, is this to preserve your original matching numbers engine and transmission?

 

I can build a small block with all of the horsepower I could ever want (or need),but I still want a big block someday.

 

Tough decision. I already bought a direct fit small aluminum radiator and vintage ac brackets and pulleys would have to be changed out.GM performance 383 and the ho 454 aint much different in price until I start buying the accessorie brackets and pulleys and another 500 radiator. I just rebuilt the 4spd with all American made parts but a a new 5spd would be nice.I would like to drive on hwy Trying to take care of parents and keep two houses up takes a lot of time. If I bought the eng an trans it would probably sit for a while before I had time to put it in.Like the 6.2 LS but I just put put brand new factory gages in I the car not to long ago.I just like the older engines for looks.Have to think about it a while.Dose have a big block hood on it already. Lol

 

Build a 400+ cubic inches SB with aluminum cylinder heads that can feed 400+ cubes like AFR 225 and re use all your bracketry belts and accessories

 

OK. I’ll stoke the fire. Ain’t nothing like a BB for torque (grunt) or looks. Man those valve covers knock it out of the park. Gee I wish I had a sbc instead of this Big Block, said no one ever.

 

Gee, I wish I had a sbc instead of this Big Block.

I should have bought this:



Instead of this:

 

I love big blocks but small blocks can make big power too and easier to work on why change all your stuff around. I would go with a 434 stroker motor or the blue print 396 or 427 crate motor .

 

you want a truck engine over a car engine

 

For all the extra screwing around needed for the BB to work in a corvette, and the limits it creates (search for what intakes fit under a non-L88 hood) and cost differences in stuff like aluminum heads, I'd stick with a SB
I love the BB but if mine ever grenades, I'll go SB (LS would hard not to look at these days)
M

 

I did everything you descibed, multiple different small blocks, toasted my originall small block so it needs machining now and installed a big block.

It will fit easily and you can reuse the starter, brake booster, distributor, alternator, carb, tranny, motor/ tranny mounts, clutch if its rated for hi horsepower/ torque and power steering pump (need appropriate pulley) if you have it. THats about it unless you are using a big block/ automatic radiator already. I had the aluminum Dewitts big block radiator for the HIPO small block I had in it, nothing beats good cooling.

So you will be swapping the intake, headers, radiator, fan shroud it you dont go to an electric fans with a new shroud..(.i would/ did), the accessory drive mounts, all the pulleys, and you need a big block or L88 hood. Maybe some stiffer front springs depending on your spring condition but the aluminum heads would lighten it up signfiicantly. Speaking of aluminum heads you cant find a good deal on the internet for the cheap chinese heads. They all use big valves that wont fit in the cylinders without machining the top valve relief wider. THe best I have found are Brodix RaceRite oval heads but you need $2K for those with a 100cc chamber. THe 396 came with a small dome if they are original pistons. If you are lucky the PO put in bigger dome heads but I doubt it if they have cast heads on there. It can get expensove if you need it all right away and dont do some shopping for good prices. I was buying parts up fr a couple of years before I did my swap. You dont have to wait that long if you look hard enough and ask here in the for sale section.

IS it worth it...hell ya!!!!!! . what is the best thing you can do for either motor...5 speed. That makes it soooo much better on performance and fuel mileage

 

Already got factory big block hood. I just replaced the radiator support with 26in small block support and installed a small block DeWitt aluminum radiator about 4 years ago. Just didn't to reinvent the wheel to swap in bb.

 

Can't beat a big block, looks and sounds great. I definitely need to hop mine up a bit though, it's a bit of a pooch stock.

 

depending on what comes with your big block kit..brackets,pulleys, belts, exhaust headers/manifolds mate to existing exhaust?.. probably not,,, throttle, carb re-jet, radiator hoses, water pump, shroud, hood, starter, heavier battery to crank a big block, fuel pump, carb, heavier springs, thicker sway bars, ignition shield kit, probably a couple of minor harness changes, then the 'while its out' consisting of heavier clutch, U-joints, spruce up the engine bay.. etc...

then add about 25 things I can't think of right away...

 

Are you wanting MEGA-power so you can beat the cr@p out of it? Or do you just want nice power level to have better exhilaration than with present SB?

If going for big power, pull and save the SB; then install whatever you want. If you like your car being in "stock" configuration, I would suggest staying with a SB engine, but with a modern LS unit or bored/stroked 400. You can make good HP with a SB unit and not need to change all the peripheral hardware. The SB engine in your car will keep it handling better than any BB build.

 

Big Block is my vote.
I'm pulling my 454 and replacing it with a new 496.
More grunt, more power.
Maybe to much of both.
Just keep in mind that the stock drive train will easily handle 450-500 hp/tq.
Any more than that and you are heading down the abyss of upgrading everything from the flywheel back to the rear wheels.
I know because I found the bottom of the abyss and the ticket back to the top was expensive.

 

I've been toying with the idea of pulling the LS5 out of my car and installing a 540ci aluminum block LS6 clone. It would make 675hp, on pump gas, pretty easy. My turbo 400 is built for that kind of power, but I wonder what kind of work the rear end and half shafts would need at that power level?

 

If you leave the skinny tires on it you will be ok but you’ll never find traction. If you put some sticky tires on it you’ll be building rear ends and 1/2 shafts.