Installed BLP Blocks on 4150 HP - Won't Idle, Super Rich

[jmarkaudio]

Try a .036 idle feed, sounds lean.

[ojh]

I'd check the idle feed to see if the gasket is letting raw fuel into the vacuum port down low, just adjacent. I think you'll find the metering blocks were intended for use on race throttle bodies and they don't have that vacuum port (on the stock Holley it supplied the 'ported' vacuum high up on the side of the original metering block). The raw fuel will be going into the engine below the closed throttle blades and you wouldn't see it.

[Dohctor_32V]

The IFR jets received with the blocks were too long, causing them to be plugged by the gasket. BLP sent the correct ones, and it is running fine. Thanks for the replies.