is it valve float or timing

[bulldog37]

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

[Dave Severson]

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?

[bulldog37]

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