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Author Topic: 69 cowl induction rarity  (Read 12099 times)
black69
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« on: January 06, 2008, 06:22:44 PM »

I needed someone to check my logic on the fresh air hood. If there were 10K hoods produced on cars in 69, and the pace cars took up around 3700 of them, and the copos took up the remaining 700, would that mean roughly 5600 hoods were left to go towards the remaining SS cars (pace cars are ss cars) and Z28s?
That's my current logic. To me it is fairly rare to have a real cowl induction hood on a 69 if you look at the 5600 vs the total z28s + SS cars totals (around 55K?). Its like a 10% chance you would run across a real one.
Am I missing something?
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JohnZ
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« Reply #1 on: January 06, 2008, 07:34:53 PM »

It also missed the first four months of production.
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william
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« Reply #2 on: January 06, 2008, 07:40:28 PM »

COPOs may not be included in that total. The ducted hood was not listed on documentation as it was included with 9560 & 9561.

Don't forget Z10s-another 500 or so where ZL2 was a required option.

Otherwise, yes. A factory ducted hood 69 is rare. Most Z/28s were not built with one.
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black69
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« Reply #3 on: January 07, 2008, 06:57:40 PM »

thanks. I do wonder how much difference in peformance a fresh air hood provides over the standard hood. I wonder if a L78 with the hood would be any worse off against an L89 without the hood. Would the weight savings get canceled by the heated air coming through the radiator..just a question I had...

I know my 65 L78 425hp vette runs fairly different once it starts seeing more hot air feeding it and becomes sluggish, but with cold air it is just a blast to drive. The L78 camaro with the fresh air hood runs fine all the time and I have let it get pretty hot (210).
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JohnZ
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« Reply #4 on: January 08, 2008, 12:07:47 PM »

The standard rule of thumb is that there's a 1% power gain for every 10*F reduction in intake air temperature.
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black69
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« Reply #5 on: January 08, 2008, 02:19:43 PM »

was there any pressure added as the air drafted off the base of the windshield with that hood? . And if so, are their horsepower rule of thumb numbers for that?

I am thinking with underhood temps brewing pretty high at a head to head drag, a L89 ss hood car would be closer than you think with a ZL2 L78 when the pedals went to the floor.
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jdv69z
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« Reply #6 on: January 09, 2008, 02:59:48 PM »

COPOs may not be included in that total. The ducted hood was not listed on documentation as it was included with 9560 & 9561.

Don't forget Z10s-another 500 or so where ZL2 was a required option.

Otherwise, yes. A factory ducted hood 69 is rare. Most Z/28s were not built with one.

I'm wondering if maybe Chevrolet sold more of these hoods over the counter than as original equipment??
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Jimmy V.
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« Reply #7 on: January 10, 2008, 09:22:52 AM »

was there any pressure added as the air drafted off the base of the windshield with that hood? . And if so, are their horsepower rule of thumb numbers for that?

Probably zero net effect from that; even forward-facing hood scoops didn't really do anything, as they're in stagnant boundary layer airflow. That's why the scoop on a Pro Stocker has the intake 18" above the normal hood surface.
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« Reply #8 on: January 10, 2008, 11:52:13 PM »

I heard from a Chevelle guru, that the ZL2 hood was worth about 10hp.  I thinks it's anyone's guess.
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68Z28
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« Reply #9 on: January 11, 2008, 10:39:01 PM »

How can we know if we have an original hood or not? Huh
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no69x-44
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« Reply #10 on: January 12, 2008, 12:13:59 AM »

How can we know if we have an original hood or not? Huh

The orginal hoods had "notch" on the side edges of the hood up near the hoods meet the windshield.  The Repro hoods do not have that little notched out area and are smooth on the side edges. 
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duntov3030
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« Reply #11 on: January 12, 2008, 11:00:53 AM »

How can we know if we have an original hood or not? Huh

The orginal hoods had "notch" on the side edges of the hood up near the hoods meet the windshield.  The Repro hoods do not have that little notched out area and are smooth on the side edges. 
Can someone post a pic of this notch?  Thanks.
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« Reply #12 on: January 12, 2008, 06:54:43 PM »

Photos below - the hood with a straight line in the side flange at the rear is the repro, and the hood where that line is a "notch" is the GM hood.
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« Reply #13 on: January 12, 2008, 09:11:46 PM »

Thanks

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68Zproject
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« Reply #14 on: January 14, 2008, 11:45:34 PM »

Is there any way to date an original hood?
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68Z28
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« Reply #15 on: January 15, 2008, 10:29:39 AM »

Is there any way to date an original hood?

There should be a Chevrolet "run number" on it somewhere, like there is on the fenders and header panel, but I haven't found one yet.
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« Reply #16 on: January 15, 2008, 07:48:40 PM »

Thx.  It looks like I have a GM hood.  Too bad it's on a 68, but I like it.
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68Z28
black69
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« Reply #17 on: January 15, 2008, 11:38:56 PM »

Below, I hope is a nice run number reference. I have a 20 (car is built first week of june). original paint, sharp stamp number. Nice find tonight...

http://albums.photo.epson.com/j/ViewPhoto?u=3010288&a=32237566&p=76094361
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wtexz10
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« Reply #18 on: January 16, 2008, 06:46:38 PM »

I have an 18.  Car built the first week of May.

Kris
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« Reply #19 on: January 17, 2008, 11:09:38 PM »

I have a 6.  That means what?
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68Z28
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« Reply #20 on: January 18, 2008, 03:02:59 PM »

I have a 6.  That means what?

6th week of the year - mid-February.
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« Reply #21 on: January 18, 2008, 03:04:06 PM »

Thanks again JZ.
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68Z28
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« Reply #22 on: January 26, 2008, 11:06:27 PM »

Below, I hope is a nice run number reference. I have a 20 (car is built first week of june). original paint, sharp stamp number. Nice find tonight...

http://albums.photo.epson.com/j/ViewPhoto?u=3010288&a=32237566&p=76094361
I have a 06A Z28 with the factory cowl hood option and docs to prove it. I have the original hood and will be looking for this number on mine tomorrow. The problem with my original hood, is previous owner installed hood pins. Would you guys try and have this fixed to keep the original hood, or buy another GM hood? Thanks!
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Travis
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« Reply #23 on: January 27, 2008, 08:47:47 AM »

fix it!
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69yellowz
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« Reply #24 on: January 27, 2008, 09:41:53 AM »

fix it!

 Thanks for the reply Kevin.  I was concerned about repairing it due to heat warping it.  They did not do the neatest job when drilling the holes either. It looks like when they first drilled they were about a half of a hole off and then had to enlarge the hole, this was all covered by the hood pin chrome ring of course. The inner structure is a little messed up as well. I am going to drive out to where my car is stored and  look for this run number on the hood, I know its a little thing but I'm kinda excited to see if its there.  God bless!   Travis
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Travis
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« Reply #25 on: January 27, 2008, 12:51:29 PM »

Below, I hope is a nice run number reference. I have a 20 (car is built first week of june). original paint, sharp stamp number. Nice find tonight...

http://albums.photo.epson.com/j/ViewPhoto?u=3010288&a=32237566&p=76094361
I have a 06A Z28 with the factory cowl hood option and docs to prove it. I have the original hood and will be looking for this number on mine tomorrow. The problem with my original hood, is previous owner installed hood pins. Would you guys try and have this fixed to keep the original hood, or buy another GM hood? Thanks!

 I just returned from looking at my hood and cant believe it!, I have a 20 stamped in mine as well.  Thats is so cool!! I will be trying to find a way to repair it.
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Travis
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« Reply #26 on: January 31, 2008, 06:21:58 PM »

Mine has a number 12 on my 04A SS.  I never knew about this number until I read it in this thread!
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« Reply #27 on: January 31, 2008, 06:48:24 PM »

Quote
I just returned from looking at my hood and cant believe it!, I have a 20 stamped in mine as well.  Thats is so cool!! I will be trying to find a way to repair it.

Find someone who can TIG weld the holes, TIG can dial down the heat and not warp the metal.
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m22mike
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« Reply #28 on: February 01, 2008, 03:08:14 PM »

I bought a SS hood this year off E Pay, not sure of the year of the hood. It's is going on my 69 SS X66 car. I am tired of the cowl hood thing on every first gen you see these days. Roll Eyes I am also ditching
 the rear spolier !
 Any way, my hood find has "AA" stamped on it.
Comments ?

                   Mike



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1968RSZ28
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« Reply #29 on: February 01, 2008, 06:43:17 PM »

Any way, my hood find has "AA" stamped on it.
Comments ?

"Acme Aftermarket"     Huh     Grin

Paul
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m22mike
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« Reply #30 on: February 01, 2008, 10:33:33 PM »

 Roll Eyes

 Mike
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« Reply #31 on: February 18, 2008, 12:00:32 AM »

My Hood has the notch in it as is indicated to be a GM Hood. But it does not have any stamping in the location you guys have stamps. Does this still make it a GM NOS hood? Can this difference between GM and repro be confirmed by anyone else as I guess there are several manufacturers of these repro hoods now. Please let me know what you all think. Thanks in advance
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JohnZ
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« Reply #32 on: February 18, 2008, 02:08:02 PM »

My Hood has the notch in it as is indicated to be a GM Hood. But it does not have any stamping in the location you guys have stamps. Does this still make it a GM NOS hood? Can this difference between GM and repro be confirmed by anyone else as I guess there are several manufacturers of these repro hoods now. Please let me know what you all think. Thanks in advance

My GM ZL2 hood doesn't have a number stamped there either.
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« Reply #33 on: February 21, 2008, 01:19:23 AM »

John - Thanks for the reply. I was also hoping others might have been able to look at their known repro hoods to see if any of the repro manufacturers had now manufactured any so that they now looked like the original GM in the same area as the pics show or if my hood was in fact 100% sure an original NOS GM.... Grin
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black69
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« Reply #34 on: February 22, 2008, 07:27:32 PM »

my friend with a white 69 copo (yenko) was surprized that I found where this number was located,  and went and found a number on his original hood! even new guys can contribute
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« Reply #35 on: March 09, 2008, 10:16:22 AM »

Just thought I'd throw this out. When I was ordering my 69 396-375 the salesman asked if I wanted a fresh air hood. I didn't know what it was , but said ok. It cost 79 dollars!
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« Reply #36 on: March 09, 2008, 05:40:34 PM »

My GM hood purchased from Classic Industries in the mid '90s.
No numbers or letters.

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« Reply #37 on: March 09, 2008, 11:29:53 PM »

Just thought I'd throw this out. When I was ordering my 69 396-375 the salesman asked if I wanted a fresh air hood. I didn't know what it was , but said ok. It cost 79 dollars!

For that price I hope you ordered a couple of spares!!     Grin

Paul
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« Reply #38 on: October 16, 2009, 02:38:32 AM »

i have read that the ZL 2 cowl induction gave 10 HP. i believe thats in the "camaro untold secrets" book. all Z/28 options were engineered by GM for trans am racing. the spoilers also were engineered so that they worked.
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« Reply #39 on: November 11, 2009, 04:37:19 PM »

MY CAR IS A JUNE 69 BUILD VIN #661XXX, AND THE COWL HOOD IS STAMPED 23.
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