What head is on your 240? If it's an N42 or N47 the a PO must have swapped engines. In that case you probably put a 280 manifold on a 280.

My '73 originally had an N33 intake/balance tube with an EGR valve. I have since replaced the intake/balance tube with an E46 from a '71. It does not have the EGR valve. The first attached photo is of the N33. The second shows the E46. Hope this helps!

well that makes perfect sense. My 240 was a late 72 so it probably had some of the 73 features

The 280 setup is considerably different. This is for a 78 but a 76 would be similar in that it is fuel injected rather than carbed.

Yes i notice the difference in the manifolds.. I think im going to put the 280 manifold back on or fabricate the heat shield so i dont have to go through all that trouble again.. As for it running bad it seems perfectly fine. I havent even adjusted the timing yet since i got it. Once i get everthing tuned right ill see if i need to swap the old manifold back on.

ZMan,

Check your fusible links... there is one within the fusible links block for EFI... there is also one that is part of the battery cable. Check both. I had some "finnicky" fusible links that would provide continuity one second, then none the next. I would check these... they could render your whole EFI system inoperable if the fusible link is not connected.

Good luck!!!

zman, if you'll go back to my above post (#28), you'll see that I have inserted an attachment. In that attachment notice all the potential leaks is the egr is not hooked up.

No, you're not missing anything. Some people go with sequential injection when they go to a system like a MegaSquirt.

wait. now im confused. you say you could have sequential injection with a megasquirt. did some searching at hybridz and Mobys "MegaSquirt'nSpark MSS/MSnS installation guide" (heres the link) http://forums.hybridz.org/showthread.php?t=88246&highlight=sequential+injection says MS does not support sequential fuel injection. maybe theres a version that supports SFI? someone want to help explain to me?