OK, We finally got the 350 dropped in and wired in place of the 4.3 in my '93 Silverado. Went to fire it and nothing. Did find the timing was off. After it fired it runs like crap. Valves are all set, all vacuum appears to be hooked up. All sensors hooked up. The only thing is right at the moment I don't have an EGR valve due to the throttle body and intake. I had to do a lot of searching to find an adapter for the EGR. Would not having one cause it to run terrible. I do have a cover plate and gasket in place of the EGR for the time being. The engine is a '74 Vette motor but all of the sending units were swapped ou. I did change the sensors from the 6 to the 8 and all wires appear to be hooked correctly. The main thing is after it starts, you can smell where it is running rich. Also the TB sound like it is sucking a mass amount of air. We went all over it looking for a vacuum leak and found none. It kind of sounds like a Hoover thru the throttle body. I was told by a few different people that the V6 computer will work fine with the V8. Also it is a Holley throttle body and a Holley Pro-jection intake. I know some don't like Holley and says they are junk, but with the way the truck is running I really don't think it has anything to do with a junk TB that some don't like. I feel that there is something simple that is being overlooked, or something that I have definately missed and am searching for some ideas. Will or will not the 350 run correctly with the V6 ECM? And can someone explain why or why not it will or won't with the current ECM and PROM. I am desperate here guys.

Thanks,
Kevin

Change the computer. A v6 computer is programed for a v6 and a v8 is programed for a v8. All the sensors will have different readings from v6 to v8. Especially(sp?) the pcmtiming, Its trying to read v6 timing when there is 8 cylinders.

So all I need is a computer from a '93 with a V-8 and it should be plug and play? And if so...now all I gotta do is find one. :( Thanks for the reply. I have heard everything from it is a direct swap to it will run on the V6 computer, to it's a real pain. I am believing the latter. :banghead:

The ECM form a 4.3 to a 5.7 is different. So are the PROM's make sure that the prom that you get in side of the ECM is set up for your emmision levels to, otherwise you might waste a whole bunch of time trying to chase a miss that is ECM related. If you find a ECM used for a 305 it is the same. Also make sure that the ECM is also set up for the same trans as what you are running.
Good Luck!

I double checked on what I had posted on Sun. I was wrong there a couple of ECM that are interchangable from V8 to V6, however there are many ECM's available for that year that are not interchangable. None of the PROM's inside of the ECM are though.
If you can hook up a scantool and get me the ECM and PROM identification I can lead you in the right direction of what you are going to need to solve that issue.

Did this solve the issues for you?

What I did was pick up another ECM witha PROM but it was out of a '94. It fired right off and idled. I have a few other issues I need to get cleared up on the truck before I proceed any further though. Now that I have it running and movable, I need to get another EGR as the one from the V6 does not fit. The bolt pattern is different. Then what I need to do is swap ECM's. The '93 ECM is dedicated to that year only. The '94 ECM is different from the '93, so I need to put the '93 ECM back in then swap out PROMS. Then there is getting the timing set and I need to get the exhaust straightened out.Top priority was just getting it fired though. We'll get the rest straightened out this weekend. I know I'll have some more questions but for the moment I am just glad I could drive it around the block. Thanks all for your responses. Without them it would still be sitting.

Kevin

Let us know if you need anything else. I might be able to help you out, who knows.