I was just looking at some old posts, I found one that said actual stock ZZ502 motors actualy put out more like 600HP and 600FT.LBS, anyone else have the same info? I just installed mine and I would like to know what kind of power I have. Either way, I think my TH350 and 10 bolt will be the next items to upgrade!! :eek:

Every motor is a little different as far as tolerances go because they are all assembled by hand just like you or I would do it using parts from vendors off the shelf so there will be some variance in the specifications.

Anyway my ZZ502 cranked out over 570 horse at sea level in an air conditioned dyno room with no mufflers. I had pocket ported the heads, substituted roller rockers for the stamped steel non-adjustables (have to change the studs so I used ARPS) and was running a rev kit. I can

http://www.high-performance-engines.com/ce15-16dyno.jpg

my neibors ZZ502/502 ran 7.52 at the track in a 73 z28 with 3,500 stall and 5.13 gear with 33" rubber. He bought the complete motor carb and all.

500-530hp is what I've heard on stock 502s.
Now with a cam & intake - 600hp is no problem.

my neibors ZZ502/502 ran 7.52 at the track in a 73 z28 with 3,500 stall and 5.13 gear with 33" rubber. He bought the complete motor carb and all.

^^ That's not very impressive. Something must have been wrong. Maybe a 6.5?

^^ That's not very impressive. Something must have been wrong. Maybe a 6.5?

A 7.50 would equate to about an 11.70 quarter mile time, not real impressive but not too bad for a crate motor. A 6.5 in the 1/8 would equate to about a 10 flat in the quarter, probably out of his range. Heck, there are guys on this site with pumped up high compression 383's that can't break 11's.

Heck, there are guys on this site with pumped up high compression 383's that can't break 11's.
Come on now, I think there a guy here with a little chevy II with a very mild 383 that runs 11s:yes:

^^ That's not very impressive. Something must have been wrong. Maybe a 6.5?

No that was his real time, he said he thought cam & intake would do him wonders but he wasnt messing with it until the warranty runs out.
Hey dont want to give anyone the wrong impression when I said 5.13 and 33" dont think its a race car this car is a full weight full interior all steel street car with cage.

One more thing, what carb works best with the ZZ502 in an auto trans 3.08 gear 69? I currently am using my 750 edelbrock for now. Motor is all ZZ502 factory parts with the exeption of Edelbrock performer rpm heads, Edelbrock performer rmp air gap manifold and Comp cams magnum roller rockers. And....any recomendations for a torque convertor with the correct stall that can handle the ZZ502? :beers: "I love that beer smiley!"

HP950 or HP1000 with a 1" open spacer would be good.

Anyone have a chassis dyno specs on a Ram Jet 502?? This would be through a TH400 and tight converter.

I just purchased a ZZ502 and it's advertised to be 502hp and 567ft lbs torque. I don't have it installed yet. I'm painting the block chevy orange. That black just isn't right in my opinion... It came with a holley 850 vacumn secondary. Guess I'll try it for a while but will probably end up running a double pumper on it :D

I just purchased a ZZ502 and it's advertised to be 502hp and 567ft lbs torque. I don't have it installed yet.

Same here. EFI though. I'll Dyno this summer.

I just purchased a ZZ502 and it's advertised to be 502hp and 567ft lbs torque. I don't have it installed yet. I'm painting the block chevy orange. That black just isn't right in my opinion... It came with a holley 850 vacumn secondary. Guess I'll try it for a while but will probably end up running a double pumper on it :D

Car Craft ran a dyno test story on a ZZ502/502 crate engine back in their May '99 issue. I was just looking at this issue a few days ago. Here is what they found on the dyno, including some jetting changes they did which might help you out:

GM Crate Engine ZZ502/502:


Dyno testing was done through 1 7/8" headers exiting through 5" truck mufflers rated at 400 HP apiece.
Carb was the GM supplied 850 Holley
HEI distributer
Actual compression ratio of this engine is 9.2:1 - GM says it's 9.6:1
Engine was found to not be knock-sensitive on 92 octane pump gas no matter how much total timing was used during testing.
With the stock 850 Holley atop the GM dual plane intake using the GM-recommended 36° total timing, the 502 made 582.7 lb/ft @ 4000 RPM and 518.6 HP @ 5500 RPM. They noted the stock jetting was lean, so they bumped up the jetting from the stock #78 primary #82 secondary to #84 primary and # 86 secondary which produced the best power of all the runs at 586.3 lb/ft and 528.1 HP.


On another note, I was leafing through the leatest issue of Chevy High Performance tonight on the newsstand, and noticed Edelbrock's full-page ad about their "Top-end" kits. They have a complete kit with heads, cam, intake and carb for GM crate engine short-blocks. Up until this latest ad, it was all for small blocks, but what caught my eye is the new top-end kit for the ZZ502/502 short-block. With Edelbrock's single-plane 454-R intake, 24° heads and Performer RPM hyd. roller cam, they claim 611 HP. That's not too shabby I think. :cool:

That sounds about right to me D.R., Thanks everyone for the info!! :beers:

No problem, glad to help. :cool:

My 502 came with a pcv in the drivers side valve cover. Do I have to use it on this motor or can I just install a valve cover breather? If I hook it up on the rear of the carb, I won't have any place to hook up my brake booster?????