Engine Swap troubles. HELP

[jmspurgin]

Hello , I have a 99 Yukon with 5.7. The engine locked up so I decide to do a swap. I purchased a low mileage motor from a salvage yard. The new engine came out of a 96-97 Chevy truck. After I changed motors, it started up and would idle just fine, but when you would give it gas it would start missing. I did notice a few differences in the two. The exhaust manifolds and intake manifolds were different. A friend suggested swaping everything back to original. I changed intake but exhaust manifolds are different (bolt holes are not exactly the same) . I believe the only thing different, other than size, would be the smog pump hoses I Believe. My question is would the smog pump not being hooked up cause the engine to not run. I am out of ideas and don't know what to do. All suggestions would be greatly appreciated. Thanks

 

[SunlitComet]

you got any pics of this mess and no, smog pump would not cause a no run condition.

 

[kelly1]

Do you have any engine codes that have registered since you did the swap and fired it up?

 

[Trippers99hoe]

Hello , I have a 99 Yukon with 5.7. The engine locked up so I decide to do a swap. I purchased a low mileage motor from a salvage yard. The new engine came out of a 96-97 Chevy truck. After I changed motors, it started up and would idle just fine, but when you would give it gas it would start missing. I did notice a few differences in the two. The exhaust manifolds and intake manifolds were different. A friend suggested swaping everything back to original. I changed intake but exhaust manifolds are different (bolt holes are not exactly the same) . I believe the only thing different, other than size, would be the smog pump hoses I Believe. My question is would the smog pump not being hooked up cause the engine to not run. I am out of ideas and don't know what to do. All suggestions would be greatly appreciated. Thanks

The intakes were different how? The exhaust bolt pattern on SBC has been the same for like 50yrs.We need pics

 

[retorq]

The intakes were different how? The exhaust bolt pattern on SBC has been the same for like 50yrs.We need pics

LOL if they were different Vortec head swaps into older engines wouldn't work ... maybe this guy is putting them in upside down?!

 

[99 2dr]

Exhaust manifolds are most likely warped. Your local auto parts store should sell exhaust spreaders that will make them fit.