I've been pricing crate engines and I notice there's a 502 and a ZZ502. The ZZ502 puts out 500hp and 567ft*lbs of torque. The regular 502 has 450hp and 550ft*lbs of torque. There's a significant difference in price of about $1700. Is the ZZ502 with the extra hp worth the extra money? Torque amount is really close. Seems like for $1700 you could swap out the cam or something on the regular 502 and make up the differnce for less $$.

502/540hp has iron heads, plain truck-style valve covers. No frills, just thrills. drop-in and could look like your typical BBC by adding chrome valve covers

ZZ502: several choices.. One is long block, and would cost only a few hundred $$ more than 450hp 502. It is part number 12371204. Has aluminum heads, flashier valve covers, bigger intake valves
ZZ502 also comes in a complete kit (#12371171) Aluminum heads/intake/waterpump, includes starter, Holley 850 carb, HEI dist/wires/plugs, pretty much everything you need to do it, including gaskets/sealant/oil supplement. It's a pretty good deal for someone who wants a crate engine that has parts that will work well together.
All parts on both engines are new.

The ZZ502 engines come as assembled short blocks, heads are assembled, but not installed. Instructions are included, and may also be purchased as assembled units from GM for about $400 more (was option at one time, not sure if still).502/450hp is completely assembled as picture shows.

www.spoperformanceparts.com is GM Performanceparts web site.

One is what, about 150lbs lighter. I don't know if thats worth 1700.00.

You could buy the shortblock version, put on a set of RaceRites and a cam and make a lot more power for the same $$$ I suspect.

502HO & ZZ502


12496962 is "deluxe" like 72 said, carb to oil pan already put together. 12496963 is minus starter, carb, dist, etc... small stuff

there are "deluxe" and "long block" kits - come w/ short block & heads assembled, just bolt the stuff on.

there are also "502HT" and "502 retrofit", these are basically low HP big torque engines and the "retrofit" kit is for 91-93 trucks only (comes w/ exhaust, tranny upgrades, prom etc)


GMPP site below
http://www.gmgoodwrench.com/perfpartsjsp/partlist.jsp?section=ce&cat=9274