Dracula383

Hey does anyone know if this is normal? My dad has a 406 small block with a pretty radical cam (I think its around 300 degrees duration or so) and he has an off idle stumble. Vacuum gauge reads about 7 lbs at idle and then when he opens the throttle blades on the 650 barry grant it drops to 0. He is going to put a reserve canister on to see if that helps. Where is a good place to tap in for a vacuum T? It has power brakes as well. Any helps is appreciated guys, thanks James

74vetteman

Normally, stumbles or hesitations are a sign that the engine isn't getting enough fuel. Check the accelerator pumps for excessive clearance, or maybe you need larger squirters or a different cam.

Edit: By different cam, I mean the cam on the accelerator pump arm.


[Modified by 74vetteman, 11:41 PM 8/21/2003]

The Dude

I agree with the earlier poster who suggested tuning the carb's shooters and accel. pump cams. Is this a single-plane manifold? And, BTW, don'tcha think a 650 on top of a 406 with a camshaft like the one you're talking about may be something of a mismatch?