572 cu. in Crate Engines

[corvettecrazy]

interesting point...I wonder if that is true

Stallion : I agree anyone who is probably putting a blower on one of these knows what they are doing and not to mention that the motor comes in a crate so you dont have to remove it from a car to make the changes. much easier to do when the motor is new.

 

[Stallion]

Even 10:1 is still a decent CR and you couldn't put a blower on that unless you bring that down even farther.

 

[MaineShark]

Compression ratio is not the issue.

Cylinder pressure is.

With a cam that has a lot of duration, the compression ratio can be much higher, without the cylinder pressure getting high enough to cause problems (pre-ignition). With lower CR and shorter duration, the peak pressure might be greater than a high-CR, long-duration engine.

Joe

 

[JohnZ]

Exactly - that's why my 11:1 '69 Z/28 runs fine on pump premium (due to the high overlap of the OEM "30-30" cam) and other small-blocks at only 10:1 with less radical cams won't. The earlier intake and exhaust closing and reduced overlap of a less radical cam builds higher peak cylinder pressure, which increases the tendency toward detonation.

 

[67HEAVEN]

Exactly - that's why my 11:1 '69 Z/28 runs fine on pump premium (due to the high overlap of the OEM "30-30" cam) and other small-blocks at only 10:1 with less radical cams won't. The earlier intake and exhaust closing and reduced overlap of a less radical cam builds higher peak cylinder pressure, which increases the tendency toward detonation.

Hmmmmmm. Maybe I'll have to rethink my intention of tossing my ZL-1/LS-7 '180" cam after all. (in the middle of a rebuild of the complete car for those who don't know)

Although I fully recognize the insanity and "ridiculousness" of using this on the street, I'm willing to suffer the slings-and-arrows of horrible driveability and the requirement of playing with the throttle at every stop light if it can be made to work on today's gasoline. Seriously. Driveability is not an issue. I don't mind working!!! I yearn to ride-the-monster again, if only on the street.

Okay JohnZ.......your opinion please on the likelihood of popping a hole in a piston using this cam, approx. 11:1 compression, and well-ported open-chamber aluminum heads with today's pump premium.
SPECS HERE

 

[Stallion]

I understand, thanks.

 

[JohnZ]

Dunno how that combination will react to pump premium - not that familiar with open-vs.-closed chamber BB's; all my experience is with SB's.

 

[Stallion]

John, kind of a personal question, but why do you prefer SBCs over BBCs? I would honestly like to get really delved into SBCs and get knowledgable about them, to the point where I will buy an independent SBC and just work on it and mod it outside my Vette (maybe put it in with time, but no use).

TR

 

[JohnZ]

Dunno, TR - I've just always owned SB's, spent a lot of my GM career working with them and building them at home for myself and later for others. The only BB's I ever owned were new cars - a '67 Chevy Impala SS with a 396/325hp, and a '69 Caprice hardtop I bought for my wife with a 427/390hp. Just a matter of personal preference, I guess - I prefer a light car with less weight on the front end and a high-winding small-block for the street. That was Zora's favorite formula when I worked for him in the Corvette Group in '67-'68, and I guess it stuck.

 

[Stallion]

I see what you mean, John. Lemme ask you one more question...

Is it practical for me to go out and get a project SBC? Something to work on and learn from? Don't forget, I'm 17 and on a somewhat tight budget. But I think it would gobs of run and definitely extreme learning, too.

What do you think?

Thanks, John!

TR

 

[MaineShark]

Big blocks are just excessive for street use. A small-block can produce all the cubes and power that are practical for a street car.

If you're building a 1000-hp monster, then a big-block might be useful, but that's not likely to be an extremely practical street car.

You can bore and stroke a small-block to 454 cubic inches, and produce well over 600 hp. If you need more than that, then the extra weight of a big-block might be worth it. If not, then save the weight and get a small-block.

Of course, that's sort of 'Vette-oriented. If you're interested in a car that isn't exactly the king of handling, or a truck of some sort, then the ease of getting power out of a big-block might be worth the weight penalty.

At least, that's my opinion...

Joe

 

[67HEAVEN]

Never blipped the throttle on a SHP or HD big block, Joe?????



Horsepower sells cars........torque hauls.

 

[MaineShark]

Yeah, but you can bore and stroke a small-block to match the bore/stroke ratio of a 454 big block. You can even go to a longer stroke and smaller bore, get the same displacement and more torque

True, a really big BBC might have more torque, but how much torque can you have, before you can't drive without spinning the tires? How much torque can you really put into a 'Vette drivetrain, without blasting it to pieces?

Of course, if you have a truck, then it's a different story, because you can actually put that extra torque to use, and the weight of super-heavy-duty driveline components is not as large a fraction of the total weight of the vehicle.

Joe

 

[67HEAVEN]

Like I said, "Never blipped the throttle on a SHP or HD big block, Joe?????"



If you think they're similar in experience to driving a truck, you might want to try one out.

I've raced small blocks and big blocks. I street-driven both. I'm not trading mine........just making it b-i-g-g-e-r.

 

[JohnZ]

Buying a junkyard SBC and setting it up on an engine stand would be a good start to a learning experience; you'd learn a lot tearing it down, and you could rebuild it as your time and budget permitted. Once you get past the machine shop work, you could do it at your leisure. Nothing like "hands-on" for good learning.

 

[Stallion]

John, I think I want to do this. How much would it cost for me to pick up a "junkyard" 350 SBC? This would be fun.

Thanks!

TR

 

[MaineShark]

Like I said, "Never blipped the throttle on a SHP or HD big block, Joe?????"

Factory engines hold very little interest for me...

If you think they're similar in experience to driving a truck, you might want to try one out.

I've raced small blocks and big blocks. I street-driven both. I'm not trading mine........just making it b-i-g-g-e-r.

I don't think that the high-performance big-blocks are similar to truck engines. I just think that there is no need to go with the larger block, when you can get similar power (and torque) from the smaller block, unless money is a limiting factory, or unless weight isn't (as in the case of a truck, which is already heavy).

You can extract more power and torque from a small-block than you could ever use on the street. You could extract enough to shred the drivetrain of a 'Vette. So why would you need more than you could use? I'd rather have better handling

Joe

 

[MaineShark]

John, I think I want to do this. How much would it cost for me to pick up a "junkyard" 350 SBC? This would be fun.

Thanks!

TR

A couple hundred bucks.

Do you have some sort of magazine devoted to classified ads? Up here, we have "The Want Ads" and "Uncle Henry's", both of which are basically a weekly magazine printed on newsprint, filled with classified ads.

In the auto parts section, or sometimes in the racing accessories section (or sometimes mis-filed in other sections), there are always plenty of SBC's. A decent, running, 4-bolt engine should be easy to find for two or three portraits of Ben Franklin. Heck, there have been engines out of F-bodies, complete with the whole TPI system and wiring, for $400 or so.

Joe

 

[Stallion]

It doesn't have to be in any pretty shape. This will be a project engine to work on and learn from. And then get some pretty nice numbers out of, too.

Hmm...I don't really know of any add mags or anything.

TR

 

[MaineShark]

You've gotta have something similar to that, down there. Try some gas stations, and convenience stores. That's where you usually find them.

Also, don't just get the cheapest core you can find, since you don't want to start a build-up with some engine that has been totally trashed, and may be cracked or require such extensive machining that the end cost becomes higher. 350's are cheap enough that you can spend an extra couple bucks and get one that is in reasonable shape.

I know a guy in central Mass who has one for sale, but that might be a little far, and it will definitely require the cylinders to be honed, because they are already bored .060-over, and it has a little rust on the walls of the rear two.

You should be able to find better, easily. You might also check with some local junkyards and see what they have. You're basically looking for an easily-rebuildable "core" with four-bolt mains. (unless you plan on getting fancy with your rebuild, and want to machine it for splayed mains, in which case you want a two-bolt core)

Joe