TR4A motor - Need Weber tuning tips

[TommyWmson@aol.com]

My brothers TR3 is all back together now and he needs
some help tuning his Webers. This is what he has
TR4A motor (that's right it's a motor from a TR4)
Big bore kit 2187cc
headers
Mallory dual point dist
40 DCOE Webers with
       F11 emulsion
       155 air corrector
       140 main 

The motor seems to run out of power at about 4200 rpm.

What's the problem??  Need different jets? 
Any suggestions would be appreciated.

Thanks

Tommy - tommywmson@aol.com