3.8 SC shortblock in non-SC Cougar?

BLOWNXR7

Registered User
Hello,
I have a 1990 Cougar LS w/ a lower end knock. I also have a spare SC shortblock from a 1990 XR-7 (automatic) that I would like to swap. The LS is my winter vehicle and I'd rather not spend the money on a yard motor if I don't have to. Does anyone know if this is a simple swap or will I be wasting my time. Thanks in advance for any assistance.

David M.
1989 XR-7 5-speed
1990 LS "knocker"
 
nope dont think its gonna work the coolant passages are different in the sc block and heads, plus some extra sensors anyone back me up on this
 
Just slap the short block in. There is no difference other then the lower compresion it will now have. The mustang people put SC 3.8 short blocks with split port heads and stang heads all the time.
 
rzimmerl said:
nope dont think its gonna work the coolant passages are different in the sc block and heads, plus some extra sensors anyone back me up on this

I agree on the issue of the coolant passages. Here is a picture of a 89-95 N/A head.

singleport%20heads.jpg


Now here is a picture of a 99+ splitport head, which shares the same coolant passage design as the SC heads.

splitport%20heads.jpg


Notice the difference in the coolant passages. You'll either need to use 96-98 N/A heads or 89-95 SC heads on your LS with the SC shortblock.

-Rod
 
Hello,
Thanks for the info. I do have a set of SC heads that go w/ the SC shortblock. I am assuming I would use the SC head gaskets? I have an upper gasket set for both motors. Am I going to end up with a gutless engine? Low compression + natural aspiration = no power? It doesn't matter that much as long as I can save my XR-7 from the saltoholics that keep the roads "clear" in the winter.

David M.
 
i hate the salt gods they are rotting away at my lx that is in great shape except for the damn rust thats slowly eating it away
 
Did the 90 N/a have the balance shaft?

You will also need the neutral balance flexplate and balancer from the SC.
 
The N/A 3.8 does not have a balance shaft. I think only the late 4.2 does.

There is a slight difference in thickness of the cylinder wall and hence placement of some of the water passages. Either way it's not enough of a difference to matter. The dramatic differences in the photo above are not translated to the block. In other words, the blocks from both motors are very similar in placement and # of passages. I don't think it will matter which gasket you use.
 
Hello,
I appreciate all the response. Has anyone tried this before. I have a complete SC engine and a complete NA engine w/ warped heads and a worn bottom end. I can probably piece everything together but I would like to have some idea what I am going to end up with. Any consensus?

David M.
 
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