Hello everyone. First post, apologize in advance for its novel length-
I am currently in the research phase for a project wherein I intend to construct something of a Z28 clone. Not to try to pass it off as real or make money or anything, but to race!
As some personal background, I am a die-hard autocrosser with the SCCA. I've been competing on the national autocross scene for about 8 years now and in that time have managed to win a couple championships. The thing about me though, is I like to put together cars nobody else thinks to try. I've beaten Mitsubishi Evos with a Lexus IS300, Honda Civics with a Nissan 240sx, and at the moment I'm the only guy campaigning a Viper against Lotus Elises and Porsche GT3s. My plan is to build a '67 Z28 to beat up on non-M 3-series BMWs and Mazda RX8's. There are some other cars that might be easier or less expensive, like a Fox Mustang or an early 90's Firebird 305, but I really like the first gen Camaros and am a ridiculously huge Mark Donohue fanboy.
Autocross has a lot of different preparation levels, or categories, from Stock, all the way to "Modifed". The prep level I'm interested in running the Camaro in is the first level up from Stock, called "Street Touring". This class allows only some very basic modifications to the car, much less than what's being carried out by the "restomod" folks. Our rulebook is here if anyone is interested:
http://www.scca.com/documents/Solo_Rules/2010_scca_solo_rules.pdfThe Street Touring category has a few classes within. The reason I'm interested in the Z28 is because there's a class (STX) explicity for 4-seat cars with engines up to 5 liters. Just like in Trans Am!
As a quick summary, in Street Touring we can change the seats to race seats, we can change the shocks and springs, but have to keep the same spring type. We can change wheels but are limited to 9" in width, and street-compound tires 265mm wide. We can change sway bars, and add a panhard or watts link. In double wishbone suspensions, we can change the upper or lower arms, but not both. We can replace the suspension and drivetrain bushings, as long as the replacements are not metal. We can upggrade the brakes to 4-wheel disc and put in a limited slip differential. On the engine side, we can do headers and a exhaust, and can change the air filters, but that's about it.
The thing about SCCA is their, "if it doesn't say you can, then you can't" rules style. So all the tricks and tweaks and subtle modifications people usually do (Guldtrand mod, gear ratio changes, porting, cam changes, etc.) aren't legal. The car would need to have a DZ302 with bone stock internals (engine can be first overbore, but not to exceed .020"). The interior would have to be stock, though we can can upgrade steering wheel and shift knob. The exterior would also have to be stock, no flaring or cutting. While the VIN plate doesn't have to specify the chassis as a Z28, everything about the car has to be just as it would have been in 1967, but for the above modifications. That's what brought me to the "originality" subforum here.
The reason I'm interested in a '67 Z28 is because it could be ordered in a way that faovors this ruleset. We are not allowed to remove smog equipment, so I'd have to run the smog pump on a '68 or '69. It also appears as though the car could be ordered without a heater in '67 only, which would be a big weight savings - yes, I am crazy, though I also live in San Diego and would trailer the car to far-away events.
I can't swap parts between years of Z28, so none of the fancy '69 parts can be used. Can't use "trunk kit" or dealer installed items either, like cowl induction or the later crossram carb setup.
So here's where I get to finally asking a couple questions-
First, while we can't swap parts between years, we can leverage factory part "supercedence". This is where the factory revises a part somewhere along the line, and specifies the new part in replacement of the old. Specifically in regards to the DZ302, does anyone here know if the later 4-bolt large-journal block was ever issued as a superceded part for the old one? For instance, if the year was 1970, and you owned a 1967 Z28 with the original motor, and blew it up while under warranty - when you took the car into the delaer, would the dealer put in another 2-bolt block, or would they give you the revised '69 unit? This stuff is all so old now, tracing parts supercedence through old parts books or fiches might be hard. The reason I ask of course, is it would be much much easier to put together a "stock" 4-bolt DZ302, as so many more were made.
Second question. I've actually purchased the factory assembly manual, chassis service manual, and the Body by Fisher manual for 1967. The thing I've found, is the service manual completely leaves out any reference to the 302 motor. My other concern is whether I will be able to tune the carb for the right mixture with the free-flowing headers and exhaust. We don't have any explicit allowances to re-jet, we can only make adjustments prescribed in the factory service manual. The manual lists jet sizes for all other motors, but not for the 302. If I am protested, I need to show that the carb setup is stock, tuned within the factory tuning range. Is there a separate manual that lists the standard jet sizes, and tuning procedures, for the 302? I suspect the '68 and '69 manuals do, but it would need to be applicable to '67.
Thanks in advance for everyone's help. This site is a great resource!
--Jason Rhoades
