4.2L Block Questions

I'm looking at installing an aluminum 4.2L bottom end out of a F-150 in my SC, and had a couple questions. I've looked into the heads and what not, and shouldn't have any problem making that work. I was wondering about the front timing cover, and if there were any differences in the two? Thanks.

Thomas

The 4.2 is still an iron block, but does have a higher compression ratio...9.2:1 compression. THe 4.2 front cover is different and uses a different water pump. But the SC heads and front cover will bolt on.

This guy just put 462 rwhp/460 rwt on a 4.2L block.

http://www.v6power.net/forum/viewtopic.php?t=34319

Thomas A said:

I'm looking at installing an aluminum 4.2L bottom end out of a F-150 in my SC, and had a couple questions. I've looked into the heads and what not, and shouldn't have any problem making that work. I was wondering about the front timing cover, and if there were any differences in the two? Thanks.

Thomas

Click to expand...

Thanks for the reply! I'm not sure why I thought it was an aluminum block. Oh well. That sounds real good. I'm look at some Probe SRS or JE Pistons and a forged crank and rods, and will most likely spray a 100 shot along with a little boost. Steig heads and cam for sure. Should be a fun time!

Thomas

There is a few other things that SHOULD be different. The lower intake gasket on the front makes a curve on your 3.8. On the newer blocks they make a sharp turn instead of the curve. I think it carried up to the 4.2 but it is definately different on the new 3.8. The top head bolts are longer too but just use the 4.2 bolts and you should be fine. Since you will use the 3.8 heads you will need to make sure the pushrods are the correct length because of the different head heights. These are sum of the things I had to change using a 2002 block and swapping the 1989 parts over. For all of the details you could check out the tec article on TCCOA. If you can not find it search for the seawalkersee screen name.

Chris

The main difference with the 4.2L block (and ANY 3.8L block 96+) is that the short headbolts are longer with more threads in the block (one of the "fixes" ford did to cure the headgasket problems). Also I haven't noticed any difference in the lower intake gasket areas on the block which is just the front and rear rails. If you get a 98.5' or newer 4.2L it comes with a main stud girdle that bridges #2, #3, and #4 main caps and fits in the 01+ mustang 3.8l oil pan (which is required for the extra clearance). Just reuse your SC timing chain cover for proper sensor placement and bolt your SC heads on with a set of 96+ bolts or 96+ ARP studs. ALSO the pushrods shouldn't make a difference, ALL 4.2L and 3.8L block use the SAME deck height and using SC heads on a 4.2L just use the SC push rods. If there is a problem with the pushrod length then its an issue with the regrind cam, block was previously milled down, or the heads were milled.

This sounds like a cool idea. Are you guys retaining the SC lower intake and supercharger assembly with this swap? I am going to have a spare motor laying around soon and may have to concider doing this someday.

Shane