Why are they so weak? Are they cammed really conservatively or something? I figure you should be getting 50-100 more HP out of their 502 engines

 

Because all of these engines are warrentied by G.M. They have to stand behind them and the more power increases the chances of something breaking.

:cheers:

 

So the potential is there? A camshaft change and some minor tweaking and things should be good right?

will a ZZ502 fit under the hood? with a dropbase cleaner?


[Modified by Guru_4_hire, 3:27 PM 8/24/2003]

 

Guru, for the $$ you are allways better off getting the locals to build you an engine, just make sure you start with a late 80's up truck block, 4 bolt mains, and you get the roller lifter setup....toss the cam, and insert what you like with dbl roller chain, get the heads reworked and install after the shortblock is in the car....
I find doing the heads in the car makes getting at bellhousing bolts, and the like much easier, not to mention visible....less to handle...easier to spin over....for clutch/torque converter hookups....
too boot you save a ton on $$$.....most local shops will give a 4k mile warrenty, no sweat, it lasts that long, it's good....

another thing is.....I don't trust the source of the later GM OTC castings...far as I know, the OEM stuff from a car is still NA made...not mexico or some such place....

GENE

 

Yes a simple cam change and tweaking the cab can get you another 50-60 out of a ZZ502. :yesnod:

A 502 is the same size physically as a 427 or 454. A 502 or even a 540 will fit in a C3 without much hassle.


:cheers:

 

I want do something with this setup on a BB -- a think a bunch of lil chrome stacks sticking out of the hood would look tight on my 73.

But I could run the ZZ502 till I could come up with the 4K for the weber set-up

 

These guys are right. #1...if you really want to build a hi-po motor, then you go aftermarket, and not with a factory assembled block. I have to say though, that with my vast experience with SB Fords, GM gives you a better block than Ford does (at least the bottom-end). #2...the camming and compression of these motors is weak/mild. My 454 HO (which was in the car when I bought it, and was next to new) was rated @ 425hp/500tq (gross ratings) and it put down 334rwhp/384rwtq. I wasn't surprised nor disappointed with those numbers.

However, putting on some better heads, a bit bigger cam (but still a very mild hyd. roller grind), and a hi-rise intake netted me 100rwhp gain. In my book, you're not doing bad if you hit 1rwhp/ci and the car is 100% streetable, no bucking surging, vacuum powered brakes work, etc.

I honestly think the bottom-end (shortblock) of the crate engines is good. It's not high-$$ forged stuff, but nevertheless you get forged crank, rods, pistons and a 4-bolt block. It's the heads, cam and compression where they fall short, so building one yourself from scratch may be more expensive, but you'll go faster. :) I've seen several ZZ502s make ~370-380rwhp in stock form. Nothing horrible, but better induction and camming would seriously wake it up.

 

the ZZ502 is 9.6 compression I believe. but I figure for 7K that is a decent engine to run till the warranty is up and recam it.

 

Yes, and the bottom end will handle the extra power with no problem. I'm a late-model hot-rodder, so most of my experience is with hyd. roller valvetrain and I love it. No maintenance, and if you're not trying to build some high-rpm screamer, you can still make really good power with them with excellent driveability.

My 454 HO only had 8.75 CR, so that hurt it, plus the cam was _really_ small. That ZZ502 is small, too. 224/234 is tiny for a 502. The new cam I put in my 454 is a 230/230 and that is still considered small.

I do not know enough about the GM alum. heads to know how much work they might need to benefit from a healthier cam, so that's something to consider when you eventually swap the cam out. Another thing is that the power ratings on these motors are derived with headers and a hi-rise intake. If you're running a stock BB hood, you will lose some HP with a low-rise intake.

Have fun!

 

I have a 73 w/ SB -- I didnt think there was a BB hood -- they looked the same to me...... I very well may be wrong.

the 454HO sounds like the perfect base for a blower.

 

The 73 used the same hood for the small block and the big block. But to run a big block, and still fit under the hood, you will need a lowrise intake manifold.

tom...

 

Thats what I thought it was

 

Yes, this crossed my mind as well. In the end, making the blower fit under _any_ hood was just not going to work. I even looked hard at the centrifugals b/c I've run those for a decade on SBFs. Just not much room in the Vette's engine compartment. :( I know it could be custom-fabbed, but in the end a set of heads,cam, intake put me in the 510+ hp (flywheel) range and if I get the urge I can easily run a little blue bottle. :lol:

I'm sorry if I was confusing about the hoods. I am not that familiar with the 73. I know the '68-71 cars had a different hood for SB and BB.

But as was mentioned, no matter you will have to find a low-rise intake that will work with those heads, unless you want to run a cowl-induction hood.

 

If your gonna run a blower might as well cut a hole in the hood.

Hopefully with a good drop base cleaner it will fit under the hood. If not I can get the low profile Dual Quad setup from Edelbrock. Of course they make a 8.75 compression 502 and might make a good blower base too.

I figure for the buck of a zz502 I cant really go wrong -- its a few years off before I can afford to retrofit all kinds of stuff in the car for that kind fun and games.