Impalas.net banner

ZZ502 Questions

6K views 19 replies 4 participants last post by  Big Dave 
#1 ·
I just bought a lightly used ZZ502 and over the next year or so will piece together all of the parts I need to drop this in my 67 Impala. This basically is a long block with the stock intake, first thing I noticed was the half open port on the heads. There is no intake gasket so I'm sure it will look fine when I get to that point, but isn't there a concern for water to get in?



This also came with Comp Cams roller rockers, the lash feels fine but should the needle bearings be this loose when the valves are closed? If one of the valves is open or has tension on the springs its rock solid.

https://goo.gl/photos/m2z3vvuRiD8U3RUk8
 
See less See more
1
#7 ·
That is a blind cavity formed with green sand when they cast the head. It is to top half of the heat cross-over passage. There is a similar cavity below the heat cross-over tube that fills with engine oil. The intake gasket seals that area and is held in place by the intake manifold gasket. Most aftermarket heads do not include a heat cross-over as they are fair weather heads. People rarely spread salt and plow a drag strip to race in the winter. As such there is no need for a heat cross-over as no one is stipping at the tree waiting for the motor to warm up and the choke to finally turn itself off.


These heads were cast by Edelbrock and are the equivalent casting of their Performer RPM "roval" heads. GMMP bought the heads as raw castings and have port matched the heads and CNC'd the chambers. They also performed a three angle valve job and installed larger Manley stainless steel 2.30 intakes and stainless 1.88 exhaust valves that are not used on the Edelbrock heads. The intake ports are 290 cc in size and are square instead of round. (the stock oval port heads have a 265 cc intake port. "Peanut Port" heads started out at 230cc but shrank down to only 190 cc in the later years.)


There is no need for concern; like the poster says Stay Calm, and carry on.


Big Dave
 
#9 ·
No I didn't look at the video. The heads use pre set stamped steel rocker arms (non-adjustable). Once the rocker arms are run down they rest on a shoulder on the stud and can not be further tightened or loosened (which is a problem as I run a solid roller cam) .


I replaced those rocker arm studs with ARP ones and used CompCams chrome-moly steel alloy roller rockers. Also I normally toss the push rod guides at the same time I have the rocker arm studs off the heads as I use 7/16 inch diameter chrome-moly push rods instead of the smaller 3/8th inch diameter ones used by the factory.


The factory cam is a hydraulic roller which makes a truck load of bottom and mid range torque (a true tire smoker). You can usually find a higher lift cam for sale used out of a ZZ 572 as people are never happy with the factory grinds. Neither hydraulic roller cam will spin past 6,400 RPM as you hit valve float at 6,200 RPM and the motor will nose over.


I still have the ZZ502 I bought back in 1999, but it is currently installed in the 87 K20 four wheel drive Suburban I have parked out in the back yard. I replaced the ZZ502 as it wasn't making enough power for my desired level of performance (it is a disease that no one has found a cure for), and I built a standard deck height 582 BBC to replace it using brand new 402 decals on the valve covers.


That combination allowed me to put my '85 Impala on it's back bumper with a set of 10.5 inch wrinkle wall slicks and well prepped track. Best of 9.39 in the quarter mile at Bradenton (a NHRA sanctioned track) which isn't bad for a four door taxi cab.


Big Dave
 
#11 ·
Thanks again for the info.

The 502 I bought has the rockers replaced with Comp Cam roller ones too. In the video it just seems like the rocker arm bearings has a ton of play.

You can not just swap the rocker arms you have to also remove the non-adjustable rocker arm suds as well or you will have a ton of play in them. Look at the top of the rocker arm stud. IF it says ARP on the top of the stud then you know that they were replaced when the roller rockers were installed. Problem is Mr. Gasket as well as other sell adjustable rocker arm studs that are not marked.





Above is the non-adjustable Gen V and Gen VI engine rocker arm studs compared to the aftermarket and Mark IV originals.


Big Dave
 
#13 ·
Truck oil pan holds five quarts but it won't clear your front cross-member unless you take a torch to it (and weld back in lower down a piece of metal to reinforce the area where you just cut out a big chunk.

I run a Moroso seven quart side kick out pan with full baffles and trap doors to control oil sloshing around, along with a windage tray and oil scrapers. Back in the good old days the racing community was smaller and once you got your foot in the door you could be introduced to all of the names in the car mags so I used to talk to Dick Moroso.

I had Don Garlits for a next door neighbor and his best pal was Art Malone who owned an electrical motor and generator shop on N Nebaska Ave in Tampa (and was the only place that sold Holley carbs). Art ran a top fueler back then and frequently blew Garlits doors off (or would have if diggers had doors).

Barry Grant worked as a power pole climbing line man for Florida power in Clearwater (an hours drive across Tampa Bay) and tuned Holley carbs as a way of paying for his race car for all comers (I learned how to tune Holleys from him). But then so did Bo Laws (tuned carbs not climbed power poles) in Orlando who had one of the first speed shops in Florida.

Last names I will drop are Harvey Crane and Smokey Yunik: both had shops in Daytona Beach which was an a hour and half drive from my house. I visited them both frequently and to body surf off Daytona beach. Smokey was always friendly, unlike Harvey, who only talked to you if you had money in hand to buy another grind (I used to buy five or six cams at time back then to see which worked best in my combination).

Everybody is dead now (except for Don, and Barry) which is the price you pay for growing old.

Big Dave
 
#15 ·
I'm in the process of pulling my 327 and getting this 502 installed over the winter. I have a few more questions before I drop another chunk of cash on parts.

* Any advice for a pulley system to run the power steering, alternator and water pump? I won't spend the top dollar for a full March setup, but their low end kit doesn't look too bad. Or can you just go with a stock setup? This again is for a 1967. Also will my current power steering pump fit with a BBC? A short or long water pump will depend on the pulley setup I get. I bought a set of the Sanderson headers which seem to hug the block and I hope avoid the issues with other header setups.

March Performance - Chevy Big Block : Long Water Pump Extra High Mid-Mount Ultra

* I decided to try out a Holley EFI setup and had to use the 65-66 fuel tank since there isn't a stamped EFI setup for a 1967. This will be a work in progress that I hope turns out OK. I do need to get a new starter and alternator and looked at the Powermaster ones. Any experience with them? I want to get a 100-150 amp alternator and I assume sticking with the 3 wire is the best option.

* I also looked at getting some tall valve covers since it looks like I might have a rocker arm ticking the stock 502's. Will the GM ones not have room with the large brake booster? I might wait until the engine is in before I buy or just use the current ones and get a 3/8" spacer and see how it looks and seals.

* I can't swing buying a new tranny so the 700R4 will get put back in and hope it holds up for a summer. I have looked around for a new torque converter too since I'm guessing the old one was an inexpensive aftermarket setup with a sub 2000 rpm stall. Why does GM recommend such a high stall with the zz502? I have read about this a lot and it seems like everyone has their opinion. Seems like there are so many different variables with the car, engine, engine specs and needs. I then to think GM knows what to put in their catalog, but I would hate to buy a 4L85e next year with the 3000-3400 stall and hate the buy.
 
#18 ·
I used a TCI Street Fighter torque converter with the same specs in my 4L80e and it was driven without an issue on the street for years. Prior to that I used a Corvette TH400 (non'lock up) converter (because everyone said a lock-up won't work), but didn't like the performance. The Corvette converter had a 2,400 RPM stall speed.

The lock-up feature only broke once when I was running some really sticky 14x33 inch slicks. TCI gave me a brand new converter under warranty without a question asked (maybe with a name of Street Fighter they suspect the car it is installed in is used for more than running to the store for milk and beer).

As to the lock up speed that is the point at which if the wheels do not rotate the engine will stall (hence the name stall speed). Your wheels will rotate on the street and aside from your tach bouncing up rapidly on leaving a stop sign you won't even know you have a higher than stock converter installed. You will need to install the biggest transmission oil cooler you can find to keep from burning up the tranny though as a loose converter generates a lot more heat. I used two 10,000 GVW tranny coolers in series on my car to verify it was chilling the fluid. Here is a product similar to the one I used:

https://www.summitracing.com/int/pa..._-shopping-_-srese1-_-derale-cooling-products

By the way no one can predict accurately the stall speed unless they know the engine (cam mostly as the torque generated is the biggest factor, gearing, and weight of the total vehicle including a trailer if towing). Those figures are a guestimate.

As they say at the bottom of your EPA sticker your mileage may vary because it always does.


Which Holley EFI did you try the TBI self learning unit, or the 550-500 race ready version with port injection and is fully programmable?

As to tall valve covers I can not tell you if they will interfere or not as I have never put a BBC in that year vehicle with tall valve covers.

Big Dave
 
#20 ·
Any thoughts on the pulley and brackets for the 502?
I pulled a five rib serpentine front drive system off of a 1989 454 one ton truck engine that I bought from a scrap yard (it was a U-pull). I used a reverse rotation Edelbrock aluminum pump and a newer CS one wire alternator instead of the stock Chevy pieces that the pick-up used (as well as a brand new Goodyear gator back belt). Never had a slipping belt or thrown belt in seven years of hard driving. Can not recall what I paid but I believe it was around $35 for the used stuff.

Big Dave
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top