Wont start/ really confused

[Kyledvor61]

Just got my motor back together.

Motor is getting fuel

Has good spark, fresh plug

cams are timed perfect, valve lash etc. is all perfect

Turns over as it should

motor kicks over fine like usual. It will pop a little but thats all. When you pullstart it and dump into gear, it turns over and halfassed runs for under a second then dies. I'm really at a loss here. It has spark and fuel. Only thing I can think of is jetting is way off. The setup before was stock head and airbox. Now I have a ported head and an open intake.

Any ideas? The motor is a 426 bottom end and a 450 cylinder and head. Its in a quad frame with oil conversion if that matters

Thanks guys

[spark250]

although you said it's all good it sounds like a spark plug or timing. Does it have 450 cams?

Is it possible that the timing needs to be set differently considering a 426 crank and timing marks and 450 cam timing marks?

[Kent Rathgeber]

Check your intake system from the airbox in. The only reason that engine isn't running (assuming the cams are timed correctly, you're getting fuel and spark) is that it's not getting any oxygen.

I have heard of people leaving rags in the intake tract during rebuilds

(no, not me )

[Kyledvor61]

its a 426 bottom end, 450 cylinder and head, with 450 cams. I just assumed the timing would be the same as a 450, as thats what I set it to.

and ill check the intake tommorrow, though I highly doubt thats what it is, ill still check though

do the cams need to timed different since the bottom end is 426?

[Kyledvor61]

and the plug is brand new, just put in on reassembly. CR8ES comes to mind