'69 302 Holley - Team Camaro Tech
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post #1 of 9 (permalink) Old Jun 15th, 15, 06:31 PM Thread Starter
Hans
 
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'69 302 Holley

Greetings from a new poster.

I am going to be working on a '69 Z-28 with a factory 302 ci engine and the original Holley for a local shop. I have seen the car, but have not heard it run yet. Very clean, all correct as far as I can tell (AIR pump, etc.). The customer complaint is of a stumble off idle, then it goes great, with an occasional miss-fire. Carb was rebuilt by a local carb shop (I was going to handle this but ended up incapacitated for two weeks), and the stumble is still there.

I'll check the whole system out from scratch (timing, advance (vacuum, mechanical & total), accel. pump, cam, etc. Before I go over tomorrow, I'd like to know which power valve they had stock and the primary jet size of the stock Holley. I have more research to do tonight with an extensive library and I may find this, but it's unlikely.

I have 40+ years experience with performance automobiles incl. Drag Racing, SCCA trans am ('81-'84) & F-5000 and currently own a BOSS 302 and a '69 L-68 Corvette, so I've seen a few problems, I'm just trying to save a bit of time up front. Any help is appreciated, thanks in advance,

Hans
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post #2 of 9 (permalink) Old Jun 15th, 15, 06:47 PM
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Re: '69 302 Holley

Check the vacuum advance first to make sure it's not losing vacuum from a bad diaphragm. I say this because I've had this same problem and that was the cause. Good luck.

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post #3 of 9 (permalink) Old Jun 15th, 15, 06:49 PM
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Re: '69 302 Holley

Going from memory it was 72/76 and 6.5 pv front and rear.

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post #4 of 9 (permalink) Old Jun 15th, 15, 08:53 PM
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Re: '69 302 Holley

Hans first make sure you are working on a list 4053 carb.

Jets are 68 P - 76 S
Primary Power valve is a 6.5 and an 8.5 sec PV.

Also the sec throttle stop was adjusted to 1/2 turn open from the factory.

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post #5 of 9 (permalink) Old Jun 19th, 15, 02:23 PM
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Re: '69 302 Holley

After tuning my 4053 DZ carb. several times on my Original 69Z 302 I still have ,it runs very smooth and best w/74 front-78 rear jets ,6.5 PV, block off the vaccum advance and set total timing to 37 degrees all in, don't worry about the idle advance it will run great.
Install a 160 thermostat to keep it cool.
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post #6 of 9 (permalink) Old Jun 19th, 15, 06:52 PM
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Re: '69 302 Holley

It does sound like the accelerator pump on the carb, but you said you checked that. Maybe it has the wrong accel pump cam or it is just slightly out of sync, or the pump diaphragm has a crack in it. Can you duplicate it with the air cleaner off and look down the carb and see how the squirt is. Maybe you did that already idk.
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post #7 of 9 (permalink) Old Jun 26th, 15, 01:45 PM Thread Starter
Hans
 
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Re: '69 302 Holley

OK, got to take a look, and its very slight, a sort of 'stutter' rather than a real stumble. I've narrowed it down to the metering block. I have another Factory Holley off of a '70 LT-1 (list 4555, p.n.# 3972121) and I substituted the metering block and it works perfect.

My Holley parts list shows a N/S part, any guess where I might find one? He's using mine for now, but I want it back! Wrong part # anyway. Anyone have success pulling the well tubes and plugs? Dang old parts!

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post #8 of 9 (permalink) Old Jun 29th, 15, 06:06 PM
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Re: '69 302 Holley

I had the same issue on my 70 Z28 List 4555 780 Holley. Once it was the .015 accel pump setting at full throttle and the 2nd time was the power valve.

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post #9 of 9 (permalink) Old Jun 29th, 15, 06:15 PM
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Re: '69 302 Holley

Check with Eric at Vintage Musclecar Parts.
I don't know for sure if he sells just carb parts.

http://www.vintagemusclecarparts.com/

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