302 Carb Tuning - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 4 (permalink) Old Jan 7th, 03, 03:45 PM Thread Starter
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Join Date: Mar 2002
Location: San Francisco, CA 94114
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I'm trying to get my 302 dialed in and I figured some of you guys have way more experience than me. Here's what I've got...

780 DZ carb
68/76 jets
6.5 primary power valve
8.5 secondary power valve
idle mixture at 3/4 turn
yellow secondary spring
.025 pump shooter
lowest observed idle vacuum of 7 inches
accelerator pump arm and floats properly set
nice lopey idle at 950 rpm

With this setup, the car has a rich smelling idle, a slight hesitation when going to full throttle and a chassis dyno air/fuel ratio of 11.5:1 at 4,000 rpm and 12:1 at 6,000 rpm. The plugs also read rich.

The first change I made was jetting down the carb evenly from 68/76 to 66/74. This gave the car crisper throttle response and a stronger top end charge, but I picked up a slight steady-throttle surge between 2,800 and 3,200 rpm. I'm guessing the surge is a lean condition from the new primary jetting. I richened the idle mixture 1/4 turn and then 1/2 turn, but this did not cure the surge.

As a next step, should I go back to the 68 jet in the primary to cure the surge and change the both power valves to a 4.5?

I really appreciate any thoughts you might have.

--Neil
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post #2 of 4 (permalink) Old Jan 8th, 03, 12:44 AM
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Your orig listing is as supplied when new.

My two cents would be....

Yes, I'd lower the power valves, say 4.0 front, 3.5 rear?

Open up secondary plates with screw pass side screw alittle more so primary plates can be closed alittle more for more idle mixture adjustment.

Probably move up front squirter to .028, maybe .030.

Ignition timing needs alittle more base advance? Book reads 4* [email protected]

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Everett "OBJECTS IN THE MIRROR APPEAR QUICKLY UPON RAPID DECELERATION"
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post #3 of 4 (permalink) Old Jan 8th, 03, 09:06 AM Thread Starter
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Everett,

Thanks for the tips. Should I go back to the stock jetting until I get these other issues worked out?
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post #4 of 4 (permalink) Old Jan 8th, 03, 12:39 PM
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I would and write down what you did to keep track of you've been so one may backtrack and keep a history.

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Everett "OBJECTS IN THE MIRROR APPEAR QUICKLY UPON RAPID DECELERATION"
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