Big Block Upgrade

[cudabob496]

On a 1977 Vette that I am considering buying, its in great shape, but the engine is an original with about 100,000 miles on it. How easy is it to drop in a crate 502 motor? Anyone done that? Is there a book on it?
Thanks
(PS, please don't ask why do you want to do that. I don't like being embarrassed by little rice rockets!)

 

[Crimson Thunder]

It will drop right in.Corvettes came with big blocks until 1974 so the parts are all avaliable.Hood clearance will be your only issue.

 

[cudabob496]

But what other mods are necessary? Will everything else fit easily, or do you have to buy other accessories? ie power steering, power brakes, A/C, headers, etc? Thanks

 

[vette427]

On a 1977 Vette that I am considering buying, its in great shape, but the engine is an original with about 100,000 miles on it. How easy is it to drop in a crate 502 motor? Anyone done that? Is there a book on it?
Thanks
(PS, please don't ask why do you want to do that. I don't like being embarrassed by little rice rockets!)

You can rebuild and build that motor for about the same price as a crate motor, get near the same power and maintain a "numbers matching" car. there won't be many rice rockets that will touch it if you do it or get it done right. I hate to see original cars dismembered, but that's just my opinion. Its your car, its your choice...good luck...regards...

 

[Evolution1980]

It's highly unlikely that the market for a matching numbers 1977 Corvette is going to skyrocket anytime soon. Unless he's going for a survivor award, I wouldn't bother keeping it original. As I like to say, "Are you keeping the car for you or for the next owner?"

Do some more checking first. The last year for the big block option was 1974. And there were differences between the SB and BB builds. I'm pretty sure such differences included heavier front springs due to more weight of engine, a larger radiator, and I think the BB had different mounting points or engine mounts in general?

You're also going to need to replace/redo pretty much everything from the transmission back. The TH350 (if you have an automatic) is not going to handle a 502 BB, even a mild one. You'll also likely need heavier duty shafts, u-joints, etc.

So even if the engine is a 'direct bolt in', there are other costs that will have to be included. The stock '77 drivetrain (and with 100K miles!) wasn't created to handle that much power.

 

[Ed's 1970]

I am going to be putting in a 540 solid roller in my 1970 and have done a ton of research so far. Most of it has to do with the drivetrain, the motor is the easy part. The 502 is very similar to my engine, with a shorter stoke of 4.0", it will be a very nice engine in your corvette. If u run an auto trans, this will help the stock rearend parts live. Since my car is a manual already, I am keeping it this way, it will shock the rearend more. The biggest challenge is the transmission and rear-end parts selection. Right now I am leaning towards keeping it a 4 spd since this is a direct bolt in and will cut down on mods. My other option is the Richmond super street 5 spd, this will take a lot of mods to the crossmember. Rearend will have much stronger axles, spindles, and spider gears, but essentially remain in the stock configuration. Rearend gearing will probably be a 3.08. You will for sure need a big radiator, preferably aluminum and a high flow water pump. A built turbo 350 may be able to handle it, but a turbo 400 most guys will recommend with a big block.

 

[73shark]

You'll need all of the accessory brackets, exhaust manifolds (unless you're using headers), big radiator (elec. fan(s) would be good), new hood unless you're going w/ the stock low rise manifold. That's just what I can think of off top of my head. I know that the folks that have done this say you never foresee all of the different things you need. Good luck.

 

[Koop]

With all of the assorted crap you gotta do with the BB conversion my tech convinced me to go with the ZZ383 out of the GM catalog. Big Block power, Small Block weight with none of the hassle.

What ever you do, it's yours so make yourself happy!

 

[cudabob496]

Thanks for the info. Maybe the ZZ383 is smarter, though on the street I know that torque rules! Aren't there small block 427s as well?

 

[Evolution1980]

Aren't there small block 427s as well?

Yeah, for a ton more money. The LS7 is technically a small block.

 

[Koop]

Thanks for the info. Maybe the ZZ383 is smarter, though on the street I know that torque rules! Aren't there small block 427s as well?

The ZZ383 is no barn burner, but 425HP/460Torque does make my 40 year old chevy a handful for the ricers. The tech even convinced me to keep the 3.08 rear diff, I wanted to put in 3.73's. It may not be the quickest car off the line, but it sure does wake me up! TThe motor makes enough vacuum to keep everything working, it just dropped right in with no mods.

I like it, but more power is always better!

 

[Ed's 1970]

Thanks for the info. Maybe the ZZ383 is smarter, though on the street I know that torque rules! Aren't there small block 427s as well?

Yep, torque does rule, thats why I wanted a big motor..
I say if your going with a 427 or larger, build a big block engine. The parts are way more heavy duty and will last longer.
The 2 big disadvantages are weight and miles per gallon....but mgp could be improved with some tuning.
I know with the 350 in this car, it had to be revved to the moon to make any power, very little low end torque.

 

[Koop]

I don't know if I would agree that a big block gets worse MPG than my 383, I get crap for MPG. It makes BB power and it uses BB amounts of fuel!

Also consider with the 383 you have aluminum heads, pistons, intake and headers. A bit of weight shaved off the old horse.

I don't think the '77 rear end is going to handle a BB power without improvements, I suspect the stroker might be to much for it. Put in more power, if the ass end blows build it better! :bash

 

[Kid_Again]

Intersting post, all I know is C2s but I am dropping a new engine into the '65 and storing the #match 327. My '66 has a zz440 and my buddy VNV has a 502/502 in his '65.

I could have easily gone to a bb in the '65 and just decided not to. I fell in love with the 383 ("No Replacement for Displacement") and dropped the idea after I saw the numbers on Engine Analyzer software. I'm not like most guys who will drop their 401k's into an engine -uh, basically, I'm cheap.

I've learned through lots of reading and expert advice that since the sbc is valve-constrained, you have to spend a LOT of money to make big mouse motors work well. Good wishes if you have the money.

Go for the bb and don't look back.

My sb is the best compromise that I could envision and afford. 355ci, Vortech blower, Comp Cam with RR's and optimized for the blower, JEGS .205 intake heads (made by Canfield apparantly). The iron is optimized for the low end and blower takes care of the high end - which for me is ~5500 rpm since this is a street engine.

Good luck and buy a hood that'll fit, rather than restrict the engine