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Maintenance / Re: ideal 4053 jetting for stock 302/30-30/manifolds
« Last post by X33RS on August 18, 2018, 08:40:11 PM »
Stock jetting is 68 front and 76 rear with 6.5 power valves front and back.

A lot of this is going to depend where you live, the altitude, and more importantly the DA the car is regularly driven in.
 
I'll assume you're also running the stock DZ intake.  In which case stagger jetting will give you best results if you're really picky.  Mine made best power by stagger jetting, up on the driver side front and rear 2 sizes bigger than the passenger side of the carb.   I also get better idle quality by staggering the idle mixture screws slightly.  Driver side front barrel feeds #2 and #3 primarily and I could blacken those plugs with too much idle mixture.   Mine is much like yours, my idle mixture screws are out between 1/4 to maybe 3/8 of a turn, which gives me a nice 14:1 AFR while idling where the engine seems to be happy.  If I go out much more than a 1/2 turn the AFR goes pig rich.   My mixture screws are very active, which is good.

I do all my final tuning with a wide band.   Up here at 5,000 ft elevation I find the stock 68 front jetting to be "okay" on AFR readings when running the stock manifolds and original exhaust system.   I eventually switched to headers, and a better flowing 2 1/2" mandrel bent transverse exhaust system.   My car responds best to a 70 jet front passenger side, 72 jet front driver side, and 76 rear passenger side, 78 rear driver side.   It also likes the 6.5 PV's front and rear.   It cruises with an AFR of about 13:1, which works nicely at 5,000 feet, so when driven to sea level it's not going dangerously lean.  Runs closer to 14:1 cruising near sea level, and with a steady cruise of 65 mph, knocks down 17 mpg.

Up here at 5,000 ft my engine is making between 9 and 10 inches of vacuum idling at 1,000 rpm.  So those power valves work fine for me.  If I take more power valve out of it, say 4.5's, it just creates an aggravating stumble off idle that won't go away even with hours of squirter and pump cam changes.   It just likes 6.5's and I have no need to go higher.   Also works fine when I drive the car down to sea level, where the engine makes just over 13" of vacuum.

Keep in mind that if your running todays 10% ethanol pump gas (which I do) stoich is no longer 14.7:1.   Stoich for 10% ethanol is .7 richer at 14:1
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Maintenance / ideal 4053 jetting for stock 302/30-30/manifolds
« Last post by aaronz28 on August 18, 2018, 08:05:42 PM »
getting my stock DZ302 back on the road this week -  and have a few questions.

i'm getting a high rpm break up - but i think i know where/what that is - as for the carb...
i know 68-72 was stock jetting - but i also know that is WAY lean.

the motor is true 11:1, installed a NOS 3849346 cam with factory - 0-stamped rockers. - lash is set and checked at 30/30 -
ignition is 38wot, with initial around 18 -  car fires up beautifully, and I have no issues with idle at 950.
its got 70-76, with a 6.5 and 8.5 and a yellow spring - and its pretty doggy - even for a gutless 302 with manifolds lol.

one thing that seems odd - idle mixtures are only 1/4 to 1/2 turn from bottomed out with about 10"Hg at idle... so i'm slightly concerned about the mixmatch of new/old Holley parts.

the carb is an old 4053 with original metering blocks, on newer 4053 baseplate -   i still have the rest of the repop 4053 which might get put back together tonight if I can't sort this original out.

something just doesn't seem right about the way it runs - its rather sluggish to get off the line, seems ok mid-range wise - but never really pulls hard.

Years ago, I borrowed a buddy's o2 -A/F tailpipe rig and I got the best readings with 72-76 with the stock manifolds... does that sound right to you tinkerers?

Thanks
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Steve Shauger and I both have Orange/Black (exterior and interior) cars; ours are Z28s, and we refer to them as 'halloween cars'..

The chambered exhaust were std on all Z28's at the beginning of the model year (and optional on others?)  After a few months of some states giving owners hassles (who referred the states to GM), then the chambered were relegated to an *option*, that lasted a few months til around May/June '69, then the chambered exhaust were discontinued totally.  Simultaneously, GM went first to the transverse muffler by itself as std for Z28, but then when the chambered was totally discontinued (June?), they added a pair of resonators in front of the transverse muffler as 'std'...

Not sure what happened with the big block cars, but I suspect something similar after the chambered was discontinued in May/June...
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Decoding/Numbers / Re: 7029204 FF carburetor
« Last post by bertfam on August 18, 2018, 02:43:11 PM »
After 50 years, it's probably been rebuilt several times and the base plate has been replaced. I've seen this a lot over the years. Not much you can do about it now.

Ed
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Decoding/Numbers / Re: 7029204 FF carburetor
« Last post by bcmiller on August 18, 2018, 12:20:01 PM »
Could be a service replacement.
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Yeah the owner is a bodyman, and has been painting cars for years and years.  When he rebuilt her he painted it that way...how he wanted it.  Were the hugger orange cars called Halloween cars? And the exhaust.  I thought in mid 69 they introduced the NC8 chambered?  So what should be the proper stock SS exhaust on an 11A? 

Pics of what I have are sent to Kurt. 

Thanks again all!!
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General Discussion / Re: '69 Camaro pre production prototypes & pilot cars ?
« Last post by william on August 18, 2018, 11:58:09 AM »
Same car!

It's in good hands.
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Decoding/Numbers / Re: 7029204 FF carburetor
« Last post by Danzo on August 18, 2018, 10:39:35 AM »
I did which is why I am asking.
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Restoration / Re: A-Pillar Pads - Cleaning and Protecting
« Last post by ZLP955 on August 18, 2018, 05:11:00 AM »
Following on from the above post, an observation I hadn't appreciated before today, is the difference in shape at the bottom of these original pillar post covers between passenger and driver sides. See 2 additional pictures below. Reproductions seem to be mirrored exactly from left to right, perhaps one of the reasons they don't fit like the General made them?
Fearing somehow I'd managed to buy a mis-matched set (as there are differences between '67, '68 and '69, as well as coupe versus convertible!), I had to go and check the originals still fitted on the car, and to my relief, those have the same differences as the spare set. Phew!
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General Discussion / Re: New to these forums
« Last post by topcomp on August 18, 2018, 05:10:57 AM »
I haven't checked the serial numbers to see what motor it was born with.
It was originally gold & currently it's Lemans blue with white race stripes.
Eventually I will paint it Azure blue with the same white stripes.
The paint on it doesn't look bad at all, it has some striping & mottling in the metallic, but overall it look ok so paint will come a bit later. I also have a 70 split bumper drag car I am finishing up. Just painted it Pewter silver with black stripes.
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