Author Topic: Carb jetting for '67 Z/28  (Read 6723 times)

j-rho

  • Member
  • ***
  • Posts: 28
    • View Profile
Carb jetting for '67 Z/28
« on: May 05, 2011, 05:21:37 AM »
Hello,
I'm the crazy guy building a '67 Z28 clone to autocross with the SCCA (http://www.rhoadescamaro.com/build).

One thing I'm curious about, is what was the original carb jetting in the car in 1967?  I have all the factory manuals, but none of them mention it, at least not in the engine sections.

In the 1968 manual, I've seen it specify #68 primaries and #76 secondaries, same jetting as the SS396.  Does any documentation exist showing jetting for the '67 Z?

Other thing, does any of the factory documentation (not race prep guides, but service manual type stuff) prescribe any sort of jet changes?  An example, maybe for customer cars at high altitude?  Haven't seen it in the books I have but maybe I don't have all the right ones.

Thanks again to the super Camaro brain trust!!!

Jerry@CHP

  • CRG Member
  • *****
  • Posts: 1457
    • View Profile
Re: Carb jetting for '67 Z/28
« Reply #1 on: May 06, 2011, 12:02:09 PM »
68's F and 71's R were the jets used.  These were just a base line.  Engines do not work welll with this jetting.

Dyno work and reading EGT's are the best way to dial in your jetting.  That's what I have done over the years.

Jerry

j-rho

  • Member
  • ***
  • Posts: 28
    • View Profile
Re: Carb jetting for '67 Z/28
« Reply #2 on: May 06, 2011, 05:14:04 PM »
Thanks for the info Jerry!  The wacky thing I'm doing, is running this car in a class where I'm not actually allowed to change the jetting, unless there is a factory prescribed method to do so.  So, I need to find something that details what the stock jets were...and if I want to change them from there, I have to point to a factory manual or something, that describes the process.

So far I haven't had luck on either front.  Closest I've found documented is the jetting for the '68 302, the 68/76. 

Jerry, in your experience, what's the best jetting for the 302, with headers, high-flow exhaust, and a good ignition?  Car will weigh around 3000lbs. with 4.88 rear.

Thanks again!!!

Jerry@CHP

  • CRG Member
  • *****
  • Posts: 1457
    • View Profile
Re: Carb jetting for '67 Z/28
« Reply #3 on: May 07, 2011, 08:15:24 PM »
What altitude?  New 3310 Holleys are jetted 72-76's.  This works good for sea level.

Jerry


j-rho

  • Member
  • ***
  • Posts: 28
    • View Profile
Re: Carb jetting for '67 Z/28
« Reply #4 on: August 17, 2012, 04:34:47 AM »
Sorry for bringing this back up...

Jerry, curious how you know the base Z28 jets?  Just from taking them out of original cars?  And was 68F, 71R, just for 1967?  The manuals I have say the '68s were 68/76 - and the "Project Camaro" article from the back of your book (4th edition) even has the words "...and standard .076" jets in the secondaries..."

The car will be used primarily at sea level.  I can change jets, if the factory every provided documentation showing this was a standard procedure, but I haven't found anything like that.  Are there any special factory carb tuning documents that were provided to dealers?  Obviously racers know how to do this stuff on their own, but I'm in a weird class where I'm not allowed to change jets unless it was a factory authorized/documented procedure.  Also in a bit of a pickle, because I'm not 100% what the stock jets are, or if they even would have been the same between a car sold in Southern California, and one sold in Denver.