New motor – No start

I’ll try to be brief,
I swapped motors in my 97 4door Lumina, put a 1996 3.1 with 47,000 mi. in. The only diff was the back side manifold had to be swapped.
Gave it a complete tune up.
I also changed the intake manifold while I had it on the stand.

Now it wont start. Sounds like it wants to start but gives up only a little murmur.
Sprayed either in the throttle body and it dident help.
Has spark at the plugs.
Plugs are plenty wet (almost to much).
Compression test found 180 – 200 psi in cylinders 1,2,3,& 4, but only 60 psi in cyl’s 5 & 6.
Only thing I can think is maybe I got the push rod mixed up on those 2 cylinders? But would that effect it this way?
I put a little oil in the # 6 cyl and it added 10 lbs to the compression test (70).
Had some problems with the shifter and thought the park neutral safety switch but I have spark and it turns over so I eliminated it.

Any suggestions or thoughts??????

Yes, if you put a long push rod where a short one goes it will not allow the valve to completely close, causing low compression. Hopefully, you didn't smack a valve, as these engines have pretty tight clearances.

could that be my starting problem?

I’ll try to be brief,
I swapped motors in my 97 4door Lumina, put a 1996 3.1 with 47,000 mi. in. The only diff was the back side manifold had to be swapped.
Gave it a complete tune up.
I also changed the intake manifold while I had it on the stand.

Now it wont start. Sounds like it wants to start but gives up only a little murmur.
Sprayed either in the throttle body and it dident help.
Has spark at the plugs.
Plugs are plenty wet (almost to much).
Compression test found 180 – 200 psi in cylinders 1,2,3,& 4, but only 60 psi in cyl’s 5 & 6.
Only thing I can think is maybe I got the push rod mixed up on those 2 cylinders? But would that effect it this way?
I put a little oil in the # 6 cyl and it added 10 lbs to the compression test (70).
Had some problems with the shifter and thought the park neutral safety switch but I have spark and it turns over so I eliminated it.

Any suggestions or thoughts??????

It doies sound like you have valves stuck open in 5+6, that's the only way to explain a reading that low, unless there's a big hole through the pistons, and I'm assuming we can count that out, but I'm suprised it's not backfiring through it...

Did you put the different style intake on? Why change it?

Same intake, new gasket. The thought was, its commonly known around here the intake gaskets are time bombs on these motors so while i had it on the stand, change the gaskets (rather than 20,000 mi down the road and change it under the hood). Sound right by your experiance??

Also, thanks for the responce, i plan on checking the rods tonight, hopefully there wont be any damage done from improper placement.

You were spot on changing that intake gasket while you had it out :thumbsup: . It's much easier to do on the bench than in the car.

50 bucks - 2 hrs labor