AMC Eagle Den Forum

Hey guys... I saw howell has a fuel injection kit for my 1980 258 but theres also the kit for the 4.0L Head. Is there a 4.0L head that will bolt onto my 258? I made the mistake of buying a 4.2L valve cover for it but of course it didn't work so Im wondering about switching out the head. Please help???!!

The 4.0 head will fit with some slight modifications.  The biggest issue with the swap seems to be modifying the exhaust and brackets for the front drive train to make it all fit.  Going with FI makes it even better.

My 1980 Green SW has a Howell kit on it right now. It starts up and idles perfectly with minimum complexity, it's pretty slick. I would love it if they didn't charge you three times their cost. Make sure you ditch their fuel pump and install a factory GM version inside your gas tank. It's noisy and unreliable and crazy expensive to use their pump.

Also be prepared to have trouble with your return vapor lines. With the Howell kit those need to be in perfect shape because they will now carry a steady volume of gasoline back to the tank from the fuel pressure regulator. It is a much heavier use than they ever had originally. Mine was clogged and restrictive, and it caused the pressure to spike way too high. That leads to terrible hissing, pathetic idle, and horrible gas mileage.

Your 1980 probably has the cast intake and exhaust manifold. Try to ditch that for a 1981 up style intake and exhaust manifold like I did. Get all the linkages and cables all the way to the gas pedal itself if you do.

Yes a 4.0 head will bolt on to your engine if you read the directions. Fill in the water jackets. Make a pair of alignment dowels from an old pair of 4.0 head bolt upside down with the hex head ground off. Realize that minor modifications to your brackets will be necessary to account for a slight shift in your intake location.

I think you made a mistake describing your valve cover woes. There are three types. 1980 has steel. 1981 to early 1987 has plastic that can be replaced by the common aluminum aftermarket covers. I think that's what you meant when you said you bought one already. Late 1987 is aluminum exactly like the early 4.0 covers and is interchangeable with the newer 4.0 covers readily available in junkyards.

In other words I don't think you'll be able to use the 4.2 valve cover you purchased with either your 1980 head or a 4.0 head.

The 1980 block is not lightened and will be less likely to have problems with the weeping from the 4.0 casting holes.

If you get the head, you ought to get a new camshaft to go with the head. The stock 4.0 cam will work just fine with the carter you have or any of the various aftermarket carbs and fuel injection systems sold, but the factory ones didn't have the fuel pump lobe.

Is the '80 tin cover? Those heads were slightly lightened (79-81 unless swapped) than '78 and earlier and the plastic cover ones were lightened more.

I have an '80 head and cover, but since no interest has been shown, they go next load of scrap metal. (because I'm moving soon)