Guest 77vegasz Posted February 13, 2005 Share Posted February 13, 2005 I am starting up my new motor, a 389, 350 block .060 over with 3.75 stroke. the compression is 12:1, I am using World Motown 220 heads, and a Comp Cams solid lifter cam, 247 254 duration @.050 with .504/.498 lift. A Weiand single plane intake and a Holley 750 Double Pumper with vacuum secondaries. And a new HEI ignition system. I have degreed the cam so I know it is right on. The problem is that I need to put in too much initial timing to start the motor and keep it ideling at 1100 rpm. I am talking around 25-30 degrees. Once warmed up, I can set the timing at 12 degrees, but when I shut it down, I cannot restart the motor, and will get a backfire up through the carb. And yes the distributor is in right. Any ideas? Jon Quote Link to comment Share on other sites More sharing options...
jt1 Posted February 13, 2005 Share Posted February 13, 2005 Did you verify the mark on the balancer and the timing pointer are correct at TDC? That seems a likely suspect. John Quote Link to comment Share on other sites More sharing options...
Guest 77vegasz Posted February 14, 2005 Share Posted February 14, 2005 The mark is dead on, I set it up with a dial indicator and adjustable pointer when the heads were off. I can tell it has way too much advance as it will detonate badly under throttle. Jon Quote Link to comment Share on other sites More sharing options...
jt1 Posted February 14, 2005 Share Posted February 14, 2005 You might check your timing light against a known good one, esp. if it's a dial back. It really sounds like cam timing to me. Are you certain you were on the intake lobe (2nd lifter) and not the exhaust lobe (1st lifter)? We won't discuss why that one comes to mind. John Quote Link to comment Share on other sites More sharing options...
Guest 77vegasz Posted February 14, 2005 Share Posted February 14, 2005 I built the motor. I set up TDC right off of the top of #1 cylinder prior to placing the heads on. I am begining to believe that it is a fuel delivery issue. I have an old 750 Holley on it. I hooked up an air fuel monitor to the exhaust, and the mix is varrying lean to Ok. It stumbles and idle slows when lean. I went up on the primary jets from 70 to 74s but that made no real difference. I am going to beg a loaner carb off of a friend to test the theory this week. Jon Quote Link to comment Share on other sites More sharing options...
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