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Author Topic: 1967 Z28 questions  (Read 3411 times)
j-rho
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« on: March 24, 2010, 02:09:35 PM »

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.pdf

The 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
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Marty
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« Reply #1 on: March 24, 2010, 05:38:56 PM »

You mention smog. Not all Z28's had smog in 67. California sold cars might have been the only ones. So build it without smog. If you started with a NOR body it wouldn't have smog.

DZ was for 69 Z/28 only.

Martin
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Martin Foltz
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68 Van Nuys Camaro
j-rho
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« Reply #2 on: March 24, 2010, 07:18:24 PM »

Hi Marty,
Yep, that is part of the reasoning for wanting to do a '67 - it was the only year of the three you could get one without the AIR/smog stuff.

You're right, I forget the 302 wasn't called/stamped a DZ before '69.  If I've read it right, the '67 block was a normal small-journal 327 block but with a 3" stroke crank.  Of all the engine components, I think one of those cranks will be hardest to find; I think it'd be a lot easier to piece together a DZ, but my view may be biased based on what I'm able to find on eBay...
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RAfbody
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« Reply #3 on: March 24, 2010, 08:31:36 PM »

Actually it should be easy to find a crank for a 67 302.  The 822 casting was widely used in 283's as well and had the notch like the 302.  The only real difference is the 302 crank was tuffrided and the 283 cranks were not.  All 283 cranks were 3" stroke and will bolt up in the small journal 327 block.
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Russ
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« Reply #4 on: March 24, 2010, 08:46:17 PM »

sounds like a plan but will a 2900-3000lb car with say about 400 hp be a competitive combo?327 block 283 crank =302 cid and 2 bolts mains are just as good as 4 bolts .i never seen a crank fall out of sbc and jerry m says he shifts his at 8600 rpms with stock crank and rods with good bolts.your carb size should be 780 cfm so you can go to holley for the jet sizes and tuning.its comes down to hp versus lbs i have a matching number 68 rsss 396 but it will get smoked and dusted if a srt4 neon 4 banger pulled beside me at a stop light
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j-rho
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« Reply #5 on: March 24, 2010, 10:12:33 PM »

The car's power to weight ratio will be its strong suit.  Our speeds in autocross are very low, the fastest we usually get going is mid 60's mph.  With a 3.73 rear and 25" tires, the car should be good for close to 70mph in first gear.  However, the emphasis in autocross is on the car's handling, which will not be the Camaro's strong suit, but since it'll be close to the same weight as its competition, on the same size tires, so I think I can get it close in that department.
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JohnZ
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« Reply #6 on: March 25, 2010, 09:54:22 AM »

The '67 Z/28 was released late, and its engine and tune-up specs never made it into the '67 Chassis Service Manual or the '67 Chassis Overhaul Manual; they probably got to the dealers via a Service Letter that was a supplement to the shop manuals. They were, however, supplied to the NHRA for their stock-class rule book; Jerry MacNeish can probably help you with that - I don't know if it's accessible on-line.
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dutch
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« Reply #7 on: March 25, 2010, 10:11:18 AM »


Yep, that is part of the reasoning for wanting to do a '67 - it was the only year of the three you could get one without the AIR/smog stuff.


Z models from Norwood shipped to Canada were KD-1 smog system exempt in '68 - if that helps... possibly a loop hole to allow use of '68 body/parts like the different crank, better rods and bolt size, and rear axle spring/ shock config. Being a Donohue fan you must know many of the '68 changes were ones he promoted after his thrashing with the first year models.
Maybe you can get around the '67 only smog thing if they only need you to prove that smog exemption was available on a set model and year. Its hard to imagine they would ask for delivery proof for a given car?
ie: Could the existence of a proper tag allow an exemption for a 'N' car (as a possible CDN variant) to make the smog free option and other/more possibly better parts work?  - Randy
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j-rho
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« Reply #8 on: March 25, 2010, 12:09:59 PM »

Hi Dutch,
Unfortunately in the SCCA, we are limited to campaigning US-spec cars only.  If there was some way to get a '68 without AIR in the US, that would be great, but I would need to be able to show such a thing was possible.

Something that's different about SCCA autocross vs. road racing, is our legality is competitor policed vs. tech-inspector policed.  Since the Camaro is a lot older and uncommon, my competitors aren't going to be in a good position to know what to protest or why.  If I am protested for an illegal cam or conrod or steering box or something, the "burden of proof" falls on me to show, using factory documentation, that the parts are indeed legal.  Whether I am protested or not, the more important underlying thing is that it's important to me to build the car as legally as I can - the effort of putting together something really different and unique is pointless, if I have to cheat to make it competitive.  I don't begrudge racers in other forms of motorsports for doing what "bending" of the rules is necessary to remain competitive, but in autocross, a totally amateur motorsport, that isn't really the spirit of things.

For sure, the Penske team had quite an influence!  The shock mounting point change for '68 is a big one.  By '69 the floodgates had really opened, though again, I wouldn't be able to leverage the special-order dealer-installed stuff like the crossram.

JohnZ, I didn't know of Jerry MacNeish before finding this site, but since then have seen his name come up quite a bit, and I've caught several of his impressive 10-second Youtube videos.   When I'm ready to put together a motor he's definitely someone whose ear I'll be seeking!  In the meantime I'll see what sort of Service Letters and other bulletins I can find relating to the Z28.

Thanks again everyone!
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dutch
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« Reply #9 on: March 25, 2010, 02:45:54 PM »


Jason -

 I didn't suggesting cheating or even bending the rules - just commenting that they did make emission system exempt cars for the '68 year at the Norwood facility and that is a well known fact. That they were delivered to Canada or elsewhere was just an aside...
Seems also to me there were more than few different forms of what constituted smog systems in early '68 on many different Camaro models being drivetrain and destination dependant, so since I'm not all that well versed on what a US car like mine would have been fitted for as delivered to California, verses the rest of the US.
I can't comment more than to say possibly there could be variants within the model and its build duration, that could end up more being beneficial for your needs... you bend the rules if there are, as need be!
I do know that from many of the reports of how poorly many original smog systems actually operated on cars especially with high reving engines (esp those with pumps), many if not most of the cars you would see driven today, as well as even most that you might view at shows or some of the pricier cars auctioned or sold, would have tampered with systems - rendered inoperable and on the cars for appearences only.

Randy
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j-rho
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« Reply #10 on: March 25, 2010, 07:11:20 PM »

Hi Randy,
No worries, I didn't take your post as suggesting I cheat.  The project sure would be a lot easier with some corners cut!  I am fortunate for the community dedicated to the preservation of these cars, the great knowledge and documentation present will be a big help.
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CNorton
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« Reply #11 on: March 25, 2010, 07:51:41 PM »

Jason,

This is the link to the NHRA blueprint specs:  <http://www.nhra.com/competition/blueprints.aspx>

When you arrive at that page, scroll down to Chevrolet, and choose the correct year.  The page that downloads is created as a Word document but it will contain all the specs for all the engines available in that model year.  You'll need to sort through and delete the data that does not pertain to your specific combination.  There are some parts that NHRA has accepted over the years that might be a problem within your sanctioning body.  I wouldn't assume that the NHRA data is the end-all, be-all.  It's just a guide.

c
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KurtS
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« Reply #12 on: March 26, 2010, 07:44:25 AM »

I'm not convinced that the advantages of the suspension changes outweigh the smog pump.  But all US-spec 68-9 Z's had smog.
Don't forget the 67-8 shifter is not great either....

You should talk with David Pozzi, he autocrossed his 67 from new.....
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Kurt S
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« Reply #13 on: March 26, 2010, 10:06:41 AM »

You are making it waaaay harder than you need to. I autocrossed my 67 extensively in the mid eighties, and no one back then new enough about the car to protest part numbers on obscure models. I would just about guarantee no one will care now. I'm not suggesting you build a cheater, but the superseded / service part rule is a loophole big enough to drive a truck through.  The rule book says:

Quote
Where a car is out of production and the manufacturer is either out of
business, stocks no parts or no longer has a required part, a part of any
origin but as similar as possible to the original may be substituted

I would read this to mean you don't have to a particular part number on anything, only to show it is not a performance improvement, ie any 4" bore block, most any factory head, and any factory intake. By the same reasoning, most any holley 4150 series carb with any jetting, and any rear gear would probably be legal. Can't buy that muncie shifter anymore either, so the hurst would be ok too. It's been a long time since I autocrossed, but I can't see anyone requiring a teardown to check cam specs at anything short of the national championships.

 Good luck.
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jonboy1216
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« Reply #14 on: March 26, 2010, 10:50:50 AM »

sounds like the sky is the limit with that rule Smiley Grin
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