Thread: is it valve float or timing

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hello i just built a nd put a 402 in my chevelle and runs great pulls great until4700 rpm then it acts like it has a rev limiter and falls on its face. its not just one cylinder but all and as soon as it goes below that rpm range it runs fine please help

If your're floating the valves at 4700, would have to be some real trash for valve springs! What kind of ignition do you have, what about timing and carburation?

its a stock hei 12 degrees timing 750 cfm elderbrock carb and distributor ran fine on my small block but built this one and this is what happens like i said it runs real good untill then its 30 over lunati cam 578 int 582 ext could it be the modgual in the dist thank you