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Sluggish off the line! HELP!

5285 Views 7 Replies 5 Participants Last post by  itsa65
ok, I have a 1968 Rebuilt 289ci with 302 heads, an edelbrock performer 289 intake with an edelbrock 600cfm 4brl carb, stock dizzy with new insides (still points). I changed my plugs which were really fouled, set my spark wires accord to chilton (two were in the wrong order). Im sitting at 15in of vacuum steady, carb vacuum tuned to highest vacuum possible. Im sitting at 8BTDC on my timing(max I can go before I get ping). it idles and starts up A LOT better with the new plugs and correct spark pattern, but from a dead stop, if I gas it hard it bogs down for about 5-8 seconds then picks up, its really bothering me because when I had the stock 2brl on there I NEVER had that problem, someone please point me in the right direction.

Thank you
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What camshaft do you have? IF the stock cam then you may have a vacuum leak, 15hg is not high enough for stock. What is your rear axle ratio? What was the benefit to the 302 heads? What year are the 302 heads? If it is not backfiring through the carb when you punch it, then it is probably too rich on mixture, you need to check the float level, idle mixture screw and air bleed, accelerator pump settings. Vacuum advance should be connected to ported vacuum (this means there is not vacuum at idle), correctly connected and operating, vacuum advance will have little to do with hard acceleration. Is your dist a dual diaphragm unit, if it is, one side advances the timing the other retards it, this is for emission? Post your results. Good Luck.
That's way to high of idle speed for an stock automatic, it should be somewhere around 450-550 in drive, which would probably be around 550-650 out of gear. The way you tested the vacuum advance is how I check them, so it is okay. Have you adjusted the carb, the ones with air bleeds are a little tricky, you have to go back and forth between the air bleed and the idle mixture screws. Do you have vacuum secondaries, if not you can't floor it at idle you can only punch it far enough so the secondaries don't open until the rpms are around 2500 rpms. I wouldn't change the ignition system yet. Many give points and condensor a bad rap, I run points and condensor in my 65 fb 289 271hp which is modified and I turn it pretty high, no miss fire, in fact we've been stranded by more electronic ignitions failures than any of the cars with points and condensor. You could have a vacuum leak on the pcv connection or a bad pcv valve (it should rattle when the engine is off, and cause about a 200rpm drop if you plug it with a finger at idle), power brake connections if you have it. IF the heads are 71 or newer they will be lower compression heads, fyi. IF the car is out of gear and you punch it, does it rev up okay or does it bog down. IF you are driving (not at idle) and you punch it, does it take off or does it bog down. Post your results. Good Luck.
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