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Peter Wilson
03-27-2011, 11:37:24 AM
I need Opinions ! I am in the process of converting my '71 Z/28 from a racecar into a street car , the car has 11,000 original miles and was tubbed in '72 and run as a Legal SS/IA racecar from '72 to '84 , then was converted to a modified production car with a roller cammed LS-6 454 . the engine was hurt in '89 and the car sat in a garage since then . the damaged LS-6 was sold out of the car around 2005 , I bought the car in 2006 and have been collecting parts ever since . my intentions were always to go back bigblock . what would be the best all around street crate engine for this car , the GMPP 427 , 454 , or 502 . I have always loved screamers , but torque monsters are good too . I just dont want to tear the car apart with a torque monster . I have been leaning towards the 427 , but the 502 seems to have a better crank and heads , ( GMPP catalog states the 502 crank is cross-drilled , heads are basically the same except the 427 has 2.19 intakes compared to the 502 having 2.25s ). This car has a turbo 400 and 9" Ford rear with drag axles and spool . Iam changing the axles to street axles , a 4.11 gear and a detroit locker , the auto transmission might stay for the first summer , but I have rebuilt an M-22 to go in the car eventually . The turbo 400 has an L-88 convertor , I took out the "as-raced " Turbo 400 w/manual valve body and 5500 stall converter and sold it off as it would never be used by me anyway as I dont think this car will ever see the track again . I need opinions on what would be the best engine . the 502 and the 427 are real close , price wise , the 454 is a bit cheaper . I also want to have an engine with "room to grow " in case I want to go more radical later

03-27-2011, 12:26:58 PM
Stay away from any of these "low tension piston rings" engines from GM, they are prone to excessive oil consumption, if I'm out for a big block, I would start with a stout short block and start from there, picking the best pieces that suite my budget.

03-27-2011, 12:56:54 PM
Can't say what the best for you, and your style and conditions that you drive in, but for me, I like my 427/4L80 Makes lots of power for street use, and I would never consider a non-overdrive trans.

03-27-2011, 01:27:27 PM
i put a zz502 in my dads car, does go through a little oil... doesn't smoke or anything though.

took awile to tune it well with the carb that came with it, but the car now runs great and can be driven daily. we have and do drive it two hours to the drag strip and two hours back.

with bad 60' times it ran a 11.70, full weight 1980 camaro (all steal body panels, full interior). with 125 shot of nitrous it ran an 11.22 @122 with a bad 60' time and running out of gear well before the finish.

03-27-2011, 04:59:40 PM
The 502 is externally the same dimensions as the smaller motors- it's not a tall-deck or anything that would require custom parts to get the exhaust to fit. I say go for the cubes if you're laying down the kinda bucks they are asking for any of those motors. If you're going 454 or smaller I say just buy a used engine and rebuild it to your specs- the old Mark IV motors are still plentiful and cheap in rebuildable condition.

03-27-2011, 05:05:06 PM
I have a 454 HO and love it...Doesn't burn a bunch of oil at all...Massive torque and great power...Has boss for manual fuel pump...For the money, I like it better than the zz engines

old zeder
03-27-2011, 10:06:58 PM
Buy the best with cash you have, the zz502 will give you the torque you need and then some

03-27-2011, 10:28:45 PM
427 would be cool - I'd love to build one.

Its ok to give up some cubes, just give it plenty of compression and spin it up:bowtie:

03-27-2011, 10:53:18 PM
Why not buy a motor from an aftermarket builder with better materials inside and more powerful power numbers


Peter Wilson
03-28-2011, 07:13:28 AM
The Big draw to me on the GMPP crate engines is they can be ordered at the local GM dealership , No freight ,and they can have it in a couple days . also how many performance motors have a 2 year warranty . where-as I live in Canada , if I buy from one of the name brand builders in the US , I have to pay shipping duty and taxes to get it here , if there is an issue or warranty concern , it goes downhill from there , dealing across border can be a pain , too many gov. agencies with their hands out trying their best to get ya for everything they can $$$$$$$

03-28-2011, 04:42:11 PM
Okay.. so for Canada I can see your point. As for The United States there are alot of builders that actually give three year warranties.

As for the GMPP motor the warranty is only valid if installed by an authorized installer.


old zeder
03-28-2011, 06:43:44 PM
Peter it's a good deal for us Canadians to get the GM crate engine from a locale dealer, no worries, no hasel, and you know the cost up front and what you are getting.
I went south to Ohio and bought my crate from Jim Pace Motors was able to negotiate the cost and get all the extra items I needed, saved a few bucks and brought it home with me, the CDN dollar is high at the moment so it will be a good time to make a deal.
If you can swing the deal get the zz motor it comes with some good parts and aluminum heads so later on you don't have a set of steel heads to sell when you upgrade.
Just something to think about

03-29-2011, 04:06:47 AM

03-29-2011, 07:38:31 AM
Read those crate engine warranties very close...most say that if it's ever used in competition, warranty is void, this includes GM.
I vote ZZ502, only because you don't have a bigger one listed :D

Peter Wilson
03-29-2011, 08:17:06 AM
Dont want to go any bigger as that would mean tall block , iam going to have enough trouble fitting this engine under the stock hood , I dont want to go to a scoop or cowl . I like the looks of the stock hood with Z stripes too much . otherwise I would probably go into debt and buy the 572 /620 .... if it would fit , but not a chance....

03-29-2011, 09:47:43 AM
the 572 wont fit..
4" cowl and 16" air cleaner w/ a 2" drop base.