Author Topic: My 69 Z/28 "building find"!  (Read 20679 times)

Z28Project

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Re: My 69 Z/28 "building find"!
« Reply #75 on: January 06, 2017, 02:57:26 AM »
Yeah James.  And combine all of that with the 5.86 rear that was in it and I'm sure it was a wild ride! :)
John

69 Z/28 NOR 12B X33 H.O. 'Ex-Racer'

firstgenaddict

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Re: My 69 Z/28 "building find"!
« Reply #76 on: January 06, 2017, 03:52:04 AM »
wow set up for the 1/8 mile... aluminum rods set below the deck... to allow for stretch... oh I know too well those drag engines.
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://plus.google.com/photos/112392262205377424364/albums?banner=pwa

jdv69z

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Re: My 69 Z/28 "building find"!
« Reply #77 on: January 06, 2017, 01:53:35 PM »
So, why aluminum Rods?
Jimmy V.

Z28Project

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Re: My 69 Z/28 "building find"!
« Reply #78 on: January 06, 2017, 04:18:12 PM »
I believe the lower reciprocating weight allowed the engine to rev high and rev quick, so they were used in all-out performance builds.  The downside is the properties of aluminum only allow so many high rpm stress cycles, so after so many 1/4 mile runs you were supposed to change the rods.  From what I understand that makes it not a good choice for a long term street engine.

In todays engines, they do it with titanium connecting rods which allow the very low reciprocation weight and long term durability, at a fairly high cost! $$$   The C6 Corvette LS9 and LS7 (also in 5th Gen Z28) use titanium connecting rods.
John

69 Z/28 NOR 12B X33 H.O. 'Ex-Racer'

firstgenaddict

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Re: My 69 Z/28 "building find"!
« Reply #79 on: January 06, 2017, 06:14:35 PM »
I believe the lower reciprocating weight allowed the engine to rev high and rev quick, so they were used in all-out performance builds.  The downside is the properties of aluminum only allow so many high rpm stress cycles, so after so many 1/4 mile runs you were supposed to change the rods.  From what I understand that makes it not a good choice for a long term street engine.

In todays engines, they do it with titanium connecting rods which allow the very low reciprocation weight and long term durability, at a fairly high cost! $$$   The C6 Corvette LS9 and LS7 (also in 5th Gen Z28) use titanium connecting rods.


Not only reciprocating but also rotating mass (big end of the rod)

removing a few ounces of weight from the rotating and reciprocating masses will yield a larger improvement in lap times than removing a few hundred pounds in vehicle weight... why? a few ounces accelerated through the RPM range many times per lap takes more horse power than one could imagine.
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://plus.google.com/photos/112392262205377424364/albums?banner=pwa

Z28Project

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Re: My 69 Z/28 "building find"!
« Reply #80 on: March 10, 2017, 06:02:45 PM »
I had decided from the get-go that I wouldn't service the front drum brakes if there were any issues, and one of the wheel cylinders started leaking, so off with the drums and on with a front disc swap kit.  Not an upgrade, just getting the car back to where it once was.  :)

Front drum brakes:




Off the car:






New discs going on:






Some fresh wheels and tires coming next!

John

69 Z/28 NOR 12B X33 H.O. 'Ex-Racer'

BULLITT65

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Re: My 69 Z/28 "building find"!
« Reply #81 on: March 10, 2017, 08:08:24 PM »
I am surprised anyone would go through the trouble of putting drum on a disc car. I have heard that because the disc pads slightly drag, that drum are faster, but geez I gotta think the extra weight would negate any small gain like that.
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

Z28Project

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Re: My 69 Z/28 "building find"!
« Reply #82 on: March 10, 2017, 08:24:29 PM »
Agreed!  I asked him about that a long time ago.  He said he thought it would be quicker with drums.

Probably something he read at the time, or heard from somebody else.
John

69 Z/28 NOR 12B X33 H.O. 'Ex-Racer'

69Z28-RS

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Re: My 69 Z/28 "building find"!
« Reply #83 on: March 10, 2017, 09:09:13 PM »
I don't think there is any doubt that for DRAG RACING, it's better to have drum brakes than disks...   In the late sixties, when one could order disk brakes or use the drums (on most performance cars), if one was intending to to use it for 'acceleration testing'.. :)...  They always went with the drums, and then back off a little on the adjustment so the wheels rolled very easily... :)
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Z28Project

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Re: My 69 Z/28 "building find"!
« Reply #84 on: March 10, 2017, 09:33:15 PM »
That makes sense!  I forgot about backing the adjustment off a little.
John

69 Z/28 NOR 12B X33 H.O. 'Ex-Racer'

BULLITT65

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Re: My 69 Z/28 "building find"!
« Reply #85 on: March 10, 2017, 10:16:54 PM »
Gary, I have doubts...
Maybe in the late 60's there were no doubts?
 
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

ZLP955

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Re: My 69 Z/28 "building find"!
« Reply #86 on: March 11, 2017, 12:58:02 AM »
Very common to see serious racers swap out front disc brakes for drums back then. Mine had it done too, looked like the original owner knocked the disc assembly out of the ball joints and pulled a complete '68 drum/spindle setup, including the drum master, from the junkyard to replace it.
Tim in Australia.
1969 04A Van Nuys Z/28. Cortez Silver, Dark Blue interior, VE3 bumper, Z21, Z23, D55/U17, D80, flat hood.
Sold at Clippinger Chevrolet in Covina, CA. Ex-E/MP at Lions Dragstrip in Long Beach.

69Z28-RS

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Re: My 69 Z/28 "building find"!
« Reply #87 on: March 11, 2017, 06:20:49 AM »
Gary, I have doubts...
Maybe in the late 60's there were no doubts?
 

Austin...  to prove it to yourself, go PUSH a car wtih disk brakes vs a car with drum brakes!  :)
that will convince you.... :)
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

ZLP955

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Re: My 69 Z/28 "building find"!
« Reply #88 on: March 11, 2017, 12:53:46 PM »
John where did you source the two-piece rotors from? I know there are several suppliers who offer US-made and imported reproductions, but interested in opinions on quality, fit, finish etc from anyone who has used them. I have my original take-off parts, but the rotors are close to minimum spec and have a few pits.
Tim in Australia.
1969 04A Van Nuys Z/28. Cortez Silver, Dark Blue interior, VE3 bumper, Z21, Z23, D55/U17, D80, flat hood.
Sold at Clippinger Chevrolet in Covina, CA. Ex-E/MP at Lions Dragstrip in Long Beach.

ban617

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Re: My 69 Z/28 "building find"!
« Reply #89 on: March 11, 2017, 02:06:37 PM »
I think with the drum brakes will hold the car better when doing a burn out vs using manual stock disc brakes.