New intake tuning problems - Team Camaro Tech
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post #1 of 7 (permalink) Old Sep 22nd, 03, 04:15 AM Thread Starter
 
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My 69 had an original setup 350 engine. I just added headers and a Flowmaster exhaust. I also just added Crane Powermax cam (266/272 advertised duration), Edelbrock RPM airgap intake, and Edelbrock 750 manual choke carb (1407) converted to electric choke.

I am still running my stock points distributor.

When I rev up the engine in my garage it seems to run fine. My problem is that when I test drive the car it seems to be "breaking up". If I slowly apply the throttle the car runs fine but when I accelerate fast it is as if I have a misfire.

I played with the timing and it seems to run best at 10 degrees advanced but I canít get the misfire/breakup problem to go away.
I tried running the vacume advance line and the timed advanced line to the distributor but it seems to run better with the timed line.

Any ideas?

I was thinking about trying an HEI distributor but donít know if it could be a carb problem.

[ 09-22-2003, 08:14 AM: Message edited by: jrager ]
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post #2 of 7 (permalink) Old Sep 22nd, 03, 07:52 PM
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Isn't 10 kinda plain jane for advanced? I don't play the numbers with cams but I wouldn't skip out on 16 to 18 for timing. The first thing I thought seeing your add ons was oops... adding all that at one time doen't give an idea of where things went wrong. An expert of the intake might take you thru the jetting and tuning for the carbs internals. Jets aren't the only thing you might be looking at changing out with that heavy dose of intake. Not sure of edelbrock but I think there's something called an accelerator pump cam in there. It makes the size of squirt or something like that. My memory is shot right now going thru an army school.
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post #3 of 7 (permalink) Old Sep 23rd, 03, 03:27 AM Thread Starter
 
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Thanks for the reply. I will try more timing and see if it helps. I installed the cam and Intake in one shot.
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post #4 of 7 (permalink) Old Sep 23rd, 03, 07:11 AM
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How about bolting on the old carb to test?

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post #5 of 7 (permalink) Old Sep 24th, 03, 03:32 AM Thread Starter
 
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The old carb was a two barrel. I may be able to try out my father in-laws Holey 750 DB. We are in the process of installing a 350 in his car.
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post #6 of 7 (permalink) Old Sep 29th, 03, 04:11 AM Thread Starter
 
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Over the weekend I pulled my Edelbrock 750 and installed a Holey 750DP. The car ran like a drag car in that it idled like it had a cam from hell in it. I bumped the idle up and took it out for a spin. It ran very similar to the Edelbrock carb as in I was still experiencing the break up problem.
Under throttle (even partial throttle) the car misses once in a while and stutters until I get the RPM up and am at wide open throttle. Then it runs fine. It is just when I am going from idle up it is breaking up.

I have run the timing from 4 BTDC up to 14 BTDC and the problem has not gone away. If I try to go up in the timing to 16 or 18 BTDC my timing marks do not go beyond 14.
Would I need a timing advanced light with the dial on the back?

Is needing that much advance normal?
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post #7 of 7 (permalink) Old Sep 29th, 03, 05:39 AM
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Put the Edelbrock back on, time for 10-12* BTDC, and change out the secondary ignition system, most of all, the coil. Do all of this after tuning for best vacuum reading on your vacuum gauge. Now, check for intake leaks at the new gaskets.

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