i just did a head swap on my truck cause i blew a head gasket and my old head had pin holes in the exhaust ports. since then it stumbles when i drive it, almost sounds like there are bubbles in the exhaust. i have a 32/36 weber, msd ignition box (5520) replace spark plugs (ngk) and wires (napa auto parts), upped the richness on the fuel air mixture, upped the fuel pressure and checked the timing. any other ideas what could be the problem?

 

Attach a vacuum gage to any manifold vacuum port and see what you get for a reading. Vacuum can tell you a lot about how your engine is running.

 

Triple check your timing.

 

Check you have a good power supply to your ignition module and a good earth. You can also check the tower on the coil for arcing, and inside the distributor cap for carbon lines which would indicate a crack. Also the rotor if worth checking by replacement as they sometimes fail and short to ground, under load. They get a tiny pin hole which is very difficult to see.

 

Ok i figured it out. I had made a mistake. Re checked the timing and i was off about two teeth on the distributor. I marked the notches on the pulley and realized they were way off. Although my point gap was way off too

 

Glad you got it sorted out