AMC Eagle Den Forum

The Mighty 258 => The Engine => Topic started by: mach1mustang351 on March 29, 2013, 11:24:12 PM

Title: Engine Ideas
Post by: mach1mustang351 on March 29, 2013, 11:24:12 PM
Okay.  I don't really have a question and I don't really know my direction here but I was day dreaming and had some thoughts.

This spring I would like to put together a fresh engine for big eagle.  The 4.0 is leaking from everywhere and it was from unknown history when installed 5 or so years ago.  I had planned to rob my 258 of its guts to make the 4.6 stroker out of a spare 4.0. 

I got to thinking about the plan for the SX4.  My original thought was to freshen the 4.0 from the big eagle and have a 4.0 SX4.  Then I got to thinking about doing something different.  I thought about putting the 4.0 crank into the 258 block and using my extra 4.0HO head on the block.  This would give me 226 cubic inches (3.7L).  The compression ratio would be low, around 8.2 to 1.  This would allow use of an aggressive cam and the short stroke would make for a fast reving engine. 

I did a bit of digging to see if this is something people do and apparently not. 

Just wondering if this would be neat, unique, different, stupid.  Any thoughts welcome
Title: Re: Engine Ideas
Post by: jonb8 on March 30, 2013, 08:52:05 AM
Destroking was popular for awhile, there was some guy's putting 350 cranks in 400 blocks to make 377's. I heard alot of good things about them but I never heard of them being stronger or better than stroking a 350 to a 383, You would loose torque and that's what gets the tires rolling...my only worry would be your building a RPM motor out of a block that doesn't like RPM's. Now that being said I think it should be built because we'll never know till someone does it, might be a little power house. ;D
Title: Re: Engine Ideas
Post by: mudkicker715 on March 30, 2013, 09:09:34 AM
I had thought about it. especially when that was almost a necessity for me once. but never did it.
Title: Re: Engine Ideas
Post by: eaglefreek on March 30, 2013, 09:18:43 AM
I haven't done the math, but I would think you would need either custom rods or pistons to use the 4.0L crank in the 258 block. Does a 4.0L crank and rods with 258 pistons work out? You don't want the piston done in the cylinder too far when it's at TDC. You need proper squish.
Title: Re: Engine Ideas
Post by: Amc1320 on March 30, 2013, 02:01:33 PM
Ive always wondered what could be done with a 232 and some 4.0 parts, I have a 232 in a gremmie and it has some pretty good power once I upgraded the intake and carb

I know it will peel tires as long as you want it to and rev much higher than my 258

I don't know all the math but it's one of those things to make me think if there is some combo possible

Of course a 232 block wouldn't have the right mounts for an eagle