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Messages - COPOZ/28

#1
Originality / Fastener Needing Identification
July 29, 2026, 07:33:44 PM
I found this one, loose, hex head screw wedged between the upper rounded edge of the washer reservoir and the  radiator closure panel on my '69 Z28.  It's 1/4"-20, non-full thread, 7/16" hex head, 13/16" long with a small hole drilled through each flat on the hex and a larger dia. blind hole, about 1/8" deep, in the center of the head.  Anyone recognize it as a legit Camaro fastener?

At first blush, it resembles the two fasteners that attach the left side radiator support to the radiator closure panel, into well-nuts, but the those screws have a flange head and do not have their hex flats thru-drilled, per the AMK website -- unless I'm wrong about that.

Thanks for the help.

#2
Thank you!

That's one less thing to do (three times!) for my trip to and from the Camaro Nat's in Morgantown, PA, next week, with a side trip on the way home to Jerry MacNeish's shop in Maryland for an appraisal/certification.
#3
I will be trailering my '69 Z28 in an enclosed trailer very soon.  Although I am an experienced trailer user (boats, 5th wheels, utility, etc.), this will be my first time using an enclosed car hauling trailer.  The trailer has an electric winch to pull the car into the trailer, rather than having to drive the car in.  I plan to attach the winch cable to an axle strap looped around the center of the front suspension crossmember and then pull the car up the ramp with the winch.  I'm hoping others have determined if it is advisable to remove the front spoiler and support rods before loading the car into the trailer. 

If I don't remove the spoiler and support rods, is it possible these parts would contact the loading ramp's surface as the car begins to make its way up the ramp?

Thanks for your help.
#4
Thanks Jim.
#5
Originality / Adjusting Nut Front Park Brake Cable
June 20, 2026, 03:47:50 PM
Does anyone know the hex size and thickness of the pair of 5/16"-18 adjusting nuts (GM #9417954) on the front parking brake cable?

Are they the standard 1/2" hex for a 5/16"-18 nut or are they the oversize 9/16" hex?

They could also be thicker than a standard nut to permit an open end wrench to hold the one nut (the nut that is against the cable guide) while the 2nd (locking) nut is tightened.

Also, I've found conflicting info on whether these nuts are phos/oil coated or zinc plated.

Thanks for the help.
#6
Restoration / Speedometer Cable Clips
April 26, 2026, 06:18:08 PM
Like many before me, the correct speedo cable clip is a difficult part to find.  Some cars have 2 holes in the tunnel and use 2 clips in the tunnel area, while others have one hole in the tunnel.  In addition, there is a hole behind the ignition coil on all cars for another clip, close to the cable's grommet, just before where the cable enters inside the car.

One restoration parts supplier offers two versions of this clip p/n 3772324, one of which is described as "assembly line correct" at a higher price.  I've tried installing this "assembly line correct" clip and find that one of the short locking fingers breaks off when trying to get it into the sheet metal hole and/or when expanding the locking fingers.  This happened with two of these clips.  Reviewing posts from others on these clips, it is apparent no one is making a workable version of it.

In the meantime, I've found another style clip that does a great job of supporting the speedo cable, in any of the 2 or 3 locations for a speedo clip and securely fits into the existing approx 5/16" drilled hole in the sheet metal.  The clip I found is actually a MoPar brake line clip for use with armored brake tubing (measures approx. 5/16" dia. over the armor/spring material).  It was used extensively on 1960's and early 70's MoPar cars.  This clip not only fits the existing sheet metal hole nicely, but also gives a secure fit to the Camaro's speedo cable.

Until such time as I can find the correct style Chevy clip that actually installs, expands the locking fingers properly without them breaking off, and stays put, this MoPar clip is going to be used to keep the speedo cable properly routed.  They are available from any of the MoPar restoration parts suppliers.
#7
Garage Talk / Re: fuel additive for winter storage?
April 17, 2026, 07:32:36 PM
I have also used Sta-Bil for a few decades with good results.  About 10 years ago, I switched over to the ACES IV stabilizer and octane enhancement product from BND Automotive.  It equals the performance of Sta-Bil when it comes to keeping fuel fresh over long periods of storage.  But the ACES IV product has other other significant advantages over Sta-Bil.  It does a very good job of enhancing the octane level of unleaded gas, something Sta-Bil does not do.  It also reduces ring/bore wear.  Both of these advantages have been documented by Automotive Engineer/Racer/Tech Writer, David Vizard, in extensive A/B dyno tests he has run.
#8
I was rooting around in the trunk of my 05E Norwood '69 Z28 recently and I discovered this small pad tucked up close to the rear seat back.  Does anyone recognize what this may be, assuming it came with the car?  If it did, could it be a protective pad to prevent the bumper jack from scratching the chrome on the bumper?
#9
April 2026 Update:

Good news!  A fellow CRG member, known to many of us, has volunteered to offer their original '67 Z28's List #3910 Holley carb for me to gather needed information that will help me to complete a forthcoming database of fixed and changeable tuning orifice diameters, and other features, on 1st Gen Z28 carbs.

I will be visiting this volunteer in July, 2026 and complete the List #3910 portion of the database later that month.  This will leave the very low volume List #3911 carb, used exclusively on California bound '67 Z28's with the K19 A.I.R. smog control system, as the only missing data.  I suspect my chances of having anyone step forward with one of these List #3911 carbs, complete and in its original unmodified condition, are about nil as only fraction of the 602 total '67 Z28's were delivered to California.

There is a possibilty that the List #3910 & #3911 carbs were identical as far as certain drilled orifice dia's are concerned, but whether this is true or not is unknown to me at this time.

The primary metering block used on the List #3911 carb is stamped with the ident no.: 5462 on its top surface.  Does anyone have one of these 5462 metering blocks they would allow me to measure various hole dia's, or agree to let me send various size numbered drill bits to you for you to measure these few holes?

Maybe someone out there has a List #3911 main body that would yield the air bleed hole dia's?

Thanks for your help.  It is still my desire to have the CRG publish the data on the website when it is completed.

Again, if anyone with a List #4053 carb (used on all '68 & '69 Z28's) would like to confirm the dia's of any tuning holes in their carb have been drilled out or not, please send me a PM and I will respond.

Chuck B.
#10
April 2026 Update:

Good news!  A fellow CRG member, known to many of us, has volunteered to offer their original '67 Z28's List #3910 Holley carb for me to gather needed information that will help me to complete a forthcoming database of fixed and changeable tuning orifice diameters, and other features, on 1st Gen Z28 carbs.

I will be visiting this volunteer in July, 2026 and complete the List #3910 portion of the database later that month.  This will leave the very low volume List #3911 carb, used exclusively on California bound '67 Z28's with the K19 A.I.R. smog control system, as the only missing data.  I suspect my chances of having anyone step forward with one of these List #3911 carbs, complete and in its original unmodified condition, are about nil as only fraction of the 602 total '67 Z28's were delivered to California.

There is a possibilty that the List #3910 & #3911 carbs were identical as far as certain drilled orifice dia's are concerned, but whether this is true or not is unknown to me at this time.

The primary metering block used on the List #3911 carb is stamped with the ident no.: 5462 on its top surface.  Does anyone have one of these 5462 metering blocks they would allow me to measure various hole dia's, or agree to let me send various size numbered drill bits to you for you to measure these few holes?

Maybe someone out there has a List #3911 main body that would yield the air bleed hole dia's?

Thanks for your help.  It is still my desire to have the CRG publish the data on the website when it is completed.

Again, if anyone with a List #4053 carb (used on all '68 & '69 Z28's) would like to confirm the dia's of any tuning holes in their carb have been drilled out or not, please send me a PM and I will respond.

Chuck B.

#11
Originality / Speedo Cable Length With Ratio Adapter
April 04, 2026, 10:50:27 AM
My '69 Z28 was 'born' with a 4.88 axle ratio via COPO 9511CB, and therefore has the required 90 degree speedo ratio adapter, used only on 4.56 and 4.88 axle cars, in place on its original Muncie M22 trans.  My speedo cable acts like it might be starting to fail (intermittent speedometer needle vibrations).  This condition has been helped by pulling out and re-lubing the cable's inner drive core with distributor point cam lube but experience tells me this is a temporary fix.  I'd like to find the correct replacement speedo cable to purchase.  I'd also like to confirm if Z28s like mine (4.56 & 4.88 axles) with a speedo ratio adapter did or did not use any speedo cable support clips in the tunnel sheet metal.  My car has only one cable supporting clip hole in the tunnel area (not the two clip holes some have reported seeing on their car's tunnel) but there is no clip in that hole.

Would appreciate help with the following:

1. Was a speedo cable support clip(s) not used on 4.56 & 4.88 axle cars with the required 90 degree speedo ratio adapter?

2. Did 1969 Z28s originally equipped with the speedo ratio adapter use the same speedo cable length as Z28s with the 4.10 or 'taller' axles that didn't require the speedo ratio adapter?

3. If the answer to question 2 is Yes, is the 71" speedo cable offered by various parts suppliers the correct length for all 1969 cars with the Muncie 4-sp trans?  If the answer is No, would anyone know the correct length speedo cable for use with a speedo ratio adapter, and what source offers this length cable?

Thanks for helping.
#12
Jeff,

It's been about 6 months since the last post on this topic and I was just wondering if you've purchased your new exhaust system. Did you go with an aluminized system from Gardner or the Heartbeat City system?  How do you like what you wound up with?  DId it install without issues?  Quality of parts good?

Thanks for any feedback you'd be willing to share -- I'm in the process of making the same decision for my '69 Z28.
Chuck
#13
Originality / Re: Dealer Shipper - Handwritten Codes
January 29, 2026, 07:04:10 PM
The possibility that it is the dealer stock number makes good sense.  I hadn't thought of that.  Thanks Byron.
#14
Originality / Dealer Shipper - Handwritten Codes
January 29, 2026, 12:33:09 PM
Attached is a copy of my '69 Z28's Dealer Shipper.  The car is an 05E Norwood build I've owned since 1979, when I purchased it from the 1st owner.

Can anyone shed some light on the significance of the handwritten "#227" above the handwritten key codes at the bottom of the shipper?  Thanks a bunch.
#15
Originality / Re: 69 z/28 black phosphate intake bolts
November 23, 2025, 09:13:34 AM
I may be able to shed some light on this.  While I'm not familiar with this specific substitution of black phospated intake manifold bolts being used in place of the silver/zinc bolts on some small quantity of 1st Gen Z28's, I am well aware of situations in which an automotive manufacturing plant temporarily runs out of a specified part and has to use an alternate or substitute part to maintain production.  In the Big 3 auto company that I retired from after 30+ years, this was called a TSA, or Temporary Substitution Allowance, and required a buy-off from Engineering.  In fact, fasteners were the most common parts for which TSA's were approved by Engineering to keep the line running while Production Control scrambled to bring in the originally specified part.  In some TSA situations, the plant had to perform an additional activity or rework in order to make the substitution acceptable.  In the case of the black phosphated intake manifold bolts being substituted for silver/zinc bolts on Z28 intakes, it is quite feasible that the Flint Engine Plant may have been told that the swap was acceptable provided they applied silver paint to the bolt heads before the engine was shipped.  In this case, the issue was strictly appearance, not function.  TSA's, or the use of Alternate Parts were, and are today, a fact of life in any automotive manufacturing facility.