CRG Discussion Forum
Welcome, Guest. Please login or register.
Did you miss your activation email?
April 24, 2014, 06:02:32 AM

Login with username, password and session length
Search:     Advanced search
Welcome to the CRG Discussion Forum!
Forum registration problems: Make sure you enter your email correctly and you check your spam box first. *Then* email KurtS2@gmail for help.
97523 Posts in 11718 Topics by 4581 Members
Latest Member: Cooper48
* Home Help Search Login Register
+  CRG Discussion Forum
|-+  Camaro Research Group Discussion
| |-+  General Discussion
| | |-+  Factory documents regarding jetting over the years?
« previous next »
Pages: [1] Print
Author Topic: Factory documents regarding jetting over the years?  (Read 907 times)
j-rho
Member
***
Posts: 28


View Profile Email
« on: January 10, 2013, 01:20:45 AM »

First, I want to thank this board for their help and wisdom, I have asked more of it than I've been able to provide in return.  Hopefully some enjoy reading the blog authored in the build of my Camaro (http://www.rhoadescamaro.com/build)

Presently I am trying to understand if Chevrolet or GM ever, since the Camaro started in 1967, provided a service manual, technical bulletin, memo, or any other kind of factory-authored document, authorizing or describing how a dealer's service department or owner, could change the metering jets (or any of the other common tuning elements like power valves, vacuum secondary springs, or accelerator pump components) in their first generation Camaro.  Specifically I'm interested in the Z28 from 1967 and its Holley, but such documents, if they exist, might be much more broad and cover the entire Camaro line.

Some situations that might have warranted changes - a dealer operating in Denver, might have wanted to sell their cars with leaner than original jets?  As leaded fuel began being phased out for unleaded, that too may have prompted some kind of manufacturer-authorized carburetor component change? 

Basically, anything from the factory saying the owner could make carburetor component changes, for purposes other than racing.  It could have been authored in the 60's, 70's, maybe even the 80's, which is ok, as long as it applies to the '67.

If something like this exists, it opens up a lot more tuning options for me, where I have to run a stock carburetor on my race car.

I've just about exhausted my Google-Fu, and in the past this place has been great at revealing info that exists nowhere else on the Internet...

Thanks so much!!
Logged

hotrod68
Member
***
Posts: 472


almost finished

rusticman48@aol
View Profile Email
« Reply #1 on: January 12, 2013, 02:59:41 AM »

  As far as I know, no such documents ever existed. As I understand it, even the COPO cars were delivered as-is and the dealer/racer was expected to do the tuning. Some of the first ZL-1 cars were delivered with the wrong carburetor (780) and Super Stock racers were in a tizzy for a bit. The Yenko cars were tuned in-house i.e. re-curved distributor etc. Even the first Z/28s came with the headers or cowl air cleaners in the trunk for the buyer to install and tune.
  With the advent of air pumps and emissions equipment surely a dealer service department wouldn't have been issued a factory directive on modifying the engine of a street car--especially after 1970 and the Clean Air Act. Mechanics on the line at a dealership go by the emissions sticker on the car as far as idle speed etc, or consult the factory specs in the book.
  On a race car you can do pretty much whatever you please internally in the carburetor depending upon class. The factory jets were usually pretty close and if anything they were lean to meet emissions standards. The beauty of the Holley carburetor is it's simple design and ease of tuning. Basically, tweak the jets, mess around with the secondary diaphragm spring and play with squirter and you're set. Unleaded fuel didn't come about until the '70s, so that wouldn't affect a '67 at all.
  Good luck and I hope this helps.
Logged

HotRod'68  1968 coupe undergoing frame-off resto/rod. 386/350/4.11s
69pace
Member
***
Posts: 364



View Profile
« Reply #2 on: January 12, 2013, 09:12:46 AM »

x2 on the above - but what you may find are collections of tune tips in the hot rod magazines over the years 69-70-71-75 and up when major changes in the clean air acts kicked in forced shade tree mechanics to over-ride and disassemble the restrictive settings and technology. You also may find a old timer in a local car club who has these all written down.
Logged

1969 Z-11 350/300 with 4 Speed
firstgenaddict
Hero Member
*****
Posts: 1092



View Profile WWW
« Reply #3 on: January 12, 2013, 02:18:28 PM »

I took a look at your page...correct me if I am wrong however, the carb appears to have the small accelerator pump on the front bowl. If this is the case, the first order of operation is to get the carb back to a base line with stock components, it would be best if you had access to a chassis dyno in order to tune the engine optimally. If you decide to go this route, have your jet sets, distributor weights lined up to minimize your change out times... you will probably find optimal power if you tune the car to about a 10-11:1 air fuel ratio.  
If you are autocrossing use jet extenders in the carb to prevent starving the engine and leaning it out...
Logged

James
Collectin' Camaro's since "Only Rednecks drove them"
 
Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
https://picasaweb.google.com/112392262205377424364/1969_Z28_Restoration
j-rho
Member
***
Posts: 28


View Profile Email
« Reply #4 on: January 13, 2013, 02:27:21 PM »

I took a look at your page...correct me if I am wrong however, the carb appears to have the small accelerator pump on the front bowl. If this is the case, the first order of operation is to get the carb back to a base line with stock components, it would be best if you had access to a chassis dyno in order to tune the engine optimally. If you decide to go this route, have your jet sets, distributor weights lined up to minimize your change out times... you will probably find optimal power if you tune the car to about a 10-11:1 air fuel ratio. 
If you are autocrossing use jet extenders in the carb to prevent starving the engine and leaning it out...
Hi James,
The accelerator pump is stock for that model.  The class I race in, only allows factory-specified tuning changes, so unless I can find documents stating otherwise, have to stick with the factory jets, accelerator pump components, and vacuum secondary spring.  What I'm seeking to find out, is if there was ever a factory document of any kind, that specified or authorized a jet or other internal carb change, for any reason.
Logged

firstgenaddict
Hero Member
*****
Posts: 1092



View Profile WWW
« Reply #5 on: January 13, 2013, 03:20:59 PM »

What appears on the carb looks to be the wrong one, it should be the larger one.
Are your metering blocks the correct number?
Must you run stock jet sizes?
Are you required to run a stock distributor, advance cam, and weights at the stock timing settings with stock heat range non resistor plugs?
   
Take note **Any computer controlled engine will automatically adjust it's timing(weights and advance cams) and or fuel mixture (jetsizes) for the altitude, air fuel ratio etc, if you are not allowed in kind tuning I am seriously surprised, unless factored it puts you at a SERIOUS dis-advantage.
Logged

James
Collectin' Camaro's since "Only Rednecks drove them"
 
Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
https://picasaweb.google.com/112392262205377424364/1969_Z28_Restoration
firstgenaddict
Hero Member
*****
Posts: 1092



View Profile WWW
« Reply #6 on: January 13, 2013, 03:33:16 PM »

Here you go RHO... Get over to the T/A forum moderated by Jon Mello, he is an EXPERT on 67 Z's and especially the racing side.
To get you started!
Camaro Chassis Prep http://www.camaros.org/forum/index.php?topic=8578.0
factory 67 rear sway bar http://www.camaros.org/forum/index.php?topic=8091.0
Factory generated Chassis Docs http://www.camaros.org/forum/index.php?topic=7863.0
1967 FIA Homologation Papers listing all specs http://www.camaros.org/forum/index.php?topic=7896.0
allowed/required modifications http://www.camaros.org/forum/index.php?topic=7834.0
Logged

James
Collectin' Camaro's since "Only Rednecks drove them"
 
Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
https://picasaweb.google.com/112392262205377424364/1969_Z28_Restoration
Pages: [1] Print 
« previous next »
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!
Page created in 0.078 seconds with 18 queries.