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New Eng. Rough-In Tuning Help

547 Views 5 Replies 4 Participants Last post by  boss351
Fired up my new roller 302 today, yippie!! I haven't driven it (except up and down the driveway). It's real shakey at idle and when I put it in gear (just in gear, not talking about driving) it falls on it's face, the rpms really come down, I have to bump the throttle up a bit. Above idle (in gear or not) it's very smooth and sounds good. Here's some vitals:
Edelbrock 289 Perfomer intake
Edelbrock 1406 carb
E-303 cam
Duraspark II dizzy and box, I have it set at 15*BTDC right now
Tri-Y headers, no exhaust system yet (that's the very next thing scheduled)
I tried various idle mixture settings, but to no avail.
My driveway's long enough to tell that she'll take off o.k., but this idle stinks. Any suggestings, tips, maybe I'm overlooking something obivious.
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· Registered
566 Posts
Make sure that you have your distributor hooked up to the correct vacuum port on the 1406 (assuming that you have a single advance distributor...just disregard this if it isn't). I believe you want it to be on the ported vacuum fitting (should be the one on the left).


· Registered
10,537 Posts
If the engine runs OK under power when launching down the driveway *G* (I used to launch the race car up the driveway into the garage...), then likely you have a vacuum leak which is destroying your idle and low-rpm torque, but once the engine starts getting fuel from the main jets and the vacuum drops, like under load, things mellow out...

Check out your hose connections and for obvious gasket vacuum leaks.

Since you're running the E303 roller cam, which has 220 degrees duration @ .050" lifter rise, some idle reversion is to be expected. This could be the cause of the symptoms you describe. Depending on your CR and trans choice, idle quality could be problematical. Often, a secondary idle circuit helps this but is not possible on an Edelbrock, to my knowledge...

Describe the engine CR, trans type and converter stall speed, if auto...

Get back to us..
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