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hi ive got a 351 cleveland that im trying to tune. Its got 2v head with big valves,isky 280 mega cam wiand accellator manifold and a 750 vac secondary carb. I just put the carby on it brand new and its running like a pig! Big flat spot when i take off, sounds like its missing when its idling and the seconderies are not opening. just wondering where do I start? Its got 74 and 68 jets in it I dont know what power valve is in it could that be the problem?
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G'day,have you double checked for vacume leaks?Is the PCV valve in the rocker cover working OK?What duration @50thou does the cam have?
It sounds like your down on vacume!The jetting seems about right.
Make sure the accelerator pump is adjusted prop
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I couldnt find any vacuum leaks and I went and bought a vacuum gauge the vavuum at idle is 5hg which is low its gat a 65 power valve in it im gonna try a 45. the cam has got .565 lift 280 advertised duration, 232 at 50thou and 108 lobe center. would that
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G'day,That cam pretty much is the same as the one I'm running except my lobe centre is 112.Having a tight lobe centre of 108 will bleed off vacume and make the idle a fair bit rougher.
That vacume of 5hg is way low!!! It should be more like 15-20hg,s
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the vac shold be about 18"hg at 800 rpm
check all the vac ports in the carbie are conected or blocked off
but it sounds more like the cam timing is out heaps too retarded
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