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sd4 engine

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shredeagle:
I came across a pontiac sd4 complete running engine  I was thinking of putting in my 81 sx4. im just not sure what such an animal would be worth . any input would be helpful . thanks.........

captspillane:
The Pontiac Super Duty Iron Duke's were usually 1980 and newer, which means that they will not bolt to your Eagle transmission bellhousing. The newer ones can only use light duty "60 degree" GM transmissions. I like that our Eagles can use heavy duty cheap SBC transmissions like the 700R4. The Pontiac engines were only called "Super Duty" because of how much bigger and stiffer the crank was in comparison to a normal Iron Duke. It was an expensive upgrade at the time but I wouldn't pay much for one now because of how commonly available those super duty cranks are. Every single Mercruiser Marine Engine has the same crank. I've got 3 Mercruiser motors so far for $300 total. They're very common and very cheap once the boat rots out from around them.

I also prefer to use the Mercruiser blocks because they have a factory overbore available. The first Merc Iron Dukes were 2.5L but eventually they offered a factory 3.0L stroker version too.

The biggest problem with the Merc blocks is partially an advantage. I like the non-cross flow head. It opens up the crammed passenger side and makes the Iron Duke much easier to maintain and work on. You lose a small amount of flow advantage to the cross flow heads, but I think it is worth it to me. I'm using factory manifolds from a '77 or '78 Iron Duke and it wouldn't be hard to make your own headers if you couldn't find a set.

Alternatively you could rebuild the Eagle engine with the internals from a 2.5L Mercruiser engine to make your own Super Duty Eagle engine. The donor engine will probably cost about $100, so you'll probably have more in the rebuild kit then the Super Duty hardware itself. If you get the Pontiac Super Duty motor for less than $200 you'd probably be best to move those parts over to the Eagle block anyway, so it's about the same deal.

shredeagle:
thanks so much for the info. I was led to believe the sd4 was a bolt in replacement. the guy wanted 3000 bucks for it. I would like to talk to you more about the mercruiser options if that's ok with you ? thanks again..........

captspillane:
I've actually written alot of the information down in this thread, here in the same section of this forum. There is even a side by side picture of a Mercruiser crank next to the stock Eagle crank. It is visually obvious that it is stronger.

http://forums.amceaglesden.com/index.php?topic=38412.0

carnuck:
You CAN use the 904 off the AMC 4 cyl  (909 if it's lockup) from '83 Up Eagle and '84 up Cherokee/Comanche 4 cyl or 2.8 V6 or AX-5 from the std trans ones. The flexplate/flywheel is another issue as well as exhaust, mounts, etc, but the bell pattern is 60 degree GM.

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