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View Full Version : 90 sc auto drop in 4.2 block



deathvenom
06-21-2009, 12:20 AM
i have a 90 sc auto. stock but all new parts minus the block. i got it running and then i lost a ring #2 piston. now hears my idea: buy low mileage 4.2L from lkq $275 "u-pull it" put my new heads, intake, brackets, m90, and sensors "stock ecc and efi". i know there will be harmonic balancer issues. and i have a hypertech chip. what am i missing? will the heads and intake fit? i plan on keeping the 4.2 block internals all stock and keeping the 4.2 fly wheel. will it mount to my trans? :confused:

deathvenom
06-27-2009, 10:05 PM
o.k. started to swap my bad 3.8 block for a 4.2 here is some pitchers of day one oh and it was 109F 30% humidity and the concrete was 126F
<a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18109896"><img src="http://hotlink.myspacecdn.com/images02/80/93e3451cfc88447585bf99929da1ddfd/m.jpg" alt="Stock 3.8 SC some parts off" /></a>
<a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18109899"><img src="http://hotlink.myspacecdn.com/images02/90/fad4fe9a5a3b4d04ac79d904a8d63f2c/m.jpg" alt="M90 super charger" /></a>
<a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18109901"><img src="http://hotlink.myspacecdn.com/images02/65/f1ab769a3ff4497ba2f05ef2ac7a9683/m.jpg" alt="custom short ram air k for an gm diesel" /></a>
<a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18109904"><img src="http://hotlink.myspacecdn.com/images02/65/787c3ecd14d44191a133df75964b629c/m.jpg" alt="ford blue and aluminum colors" /></a>
<a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18109905"><img src="http://hotlink.myspacecdn.com/images02/108/92a45239dfc2406ca8273395e87ad771/m.jpg" alt="pipe from sc to inter cooler. going to repaint it" /></a>

that's a hypertech chip under the intake tube :D

scxr7
06-28-2009, 10:56 AM
The flywheel will be alright. You will have to put your s/c balancer on the 4.2 engine. both the s/c and 4.2 are internally balanced. it will bolt directly up to your stock transmission. I don't know if your transmission is an auto or manual, but if its a manual you will have to install a thrust bearing on the back of the block I think. unless the 4.2 was manual also. If the 4.2 had an auto behind it, then just double check to make sure the converter bolts line up on the flexplate.

The single port heads will bolt up to the 4.2l. you're alright there. the ONLY issue I can think of would be the oil pan. It might interfere with your K-member. I know the v6 mustang guys have to swap oil pans, but I'm not sure if the s/c guys need to swap oil pans for the 4.2 to fit.

deathvenom
06-28-2009, 01:05 PM
I'm using stock AOD, 3.8sc's heads intake sc timing cover and balancer. using the flex plate that comes on the 4.2 and the 3.8sc's oil pan. i also planed on using the 3.8sc's sensors and computer. not shore witch cam to use tho :confused:.

Ddubb
06-28-2009, 01:50 PM
You might do a little searching on these forums for the swap. I thought it had been attempted a couple times.
I know a local guy named Kevin was having the swap done on his SC. His father in law, Tom Battles runs a shop here in Campbell, Ca. - Sprint Mechanics. He built up a 4.2 and had to custom build something to make it work. I thought it was the timing cover needed modifying. Might be worth a few minutes to do some searching, or give Tom a call and ask him exactly what needs to be done. I thought he was trying to sell the whole 4.2 swap set at one point in time - they blew a piston ring I think and scrapped the project. Its been a while.

- Dan

deathvenom
06-28-2009, 02:59 PM
i found a guy that dropped in the 4.2 all 4.2 parts i know the heads will fit and the oil pan if the timing cove dose not fit i will have to make a bracket for the crank position sensor. not that big of a deal but I'm not shore what cam would be better the 4.2's or the 3.8sc's

<object width="368" height="500" classid="clsid:D<param name="movie" value="http://videos.streetfire.net/flash/SPlayer.swf" type="application/x-shockwave-flash" /><param name="allowScriptAccess" value="always" /><param name="wmode" value="transparent" /><param name="allowfullscreen" value="true" /><param name="FlashVars" value="&video=397fd8f0-ae78-49de-bbc9-e4d5ff4c62b0&servicecfg=386" /><embed src="http://videos.streetfire.net/flash/SPlayer.swf" flashvars="video=397fd8f0-ae78-49de-bbc9-e4d5ff4c62b0&servicecfg=386" allowfullscreen="true" wmode="transparent" width="428" height="352" allowscriptaccess="always" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" /><br/><a href="http://videos.streetfire.net/video/1996-Thunderbird-42L-V6_40296.htm">1996 Thunderbird 4.2L V6 Stroker</a></object>

deathvenom
07-01-2009, 01:47 AM
This is what i got done to day

<a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18250915"><img src="http://hotlink.myspacecdn.com/images02/65/db2ecff15aea40c8a4fd0909f6fbb7cb/m.jpg" alt="" /></a><a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18250919"><img src="http://hotlink.myspacecdn.com/images02/109/f8afc43d0e1b442180e673e1c4690e5f/m.jpg" alt="" /></a><a href="http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=411268935&albumID=1402217&imageID=18250923"><img src="http://hotlink.myspacecdn.com/images02/76/b778e3c7cbd2405388fabca45c4ebc0b/m.jpg" alt="" /></a>:rolleyes:

and i found a crack in the block. to morrow i'll clean it and get all the good parts off of it.:o

David Neibert
07-01-2009, 08:08 AM
Does the block you are installing have provisions for mounting the early model crank sensor from the 90 SC motor ?

David

old_coot
07-01-2009, 09:29 AM
I am curious to see how well the powdered iron rods do with boost....Do you know what the final compression ratio is going to be? That will determine a lot of your cam requirements. ...............Dan

deathvenom
07-01-2009, 04:31 PM
i will have to use the 3.8's timing cover. should fit same block.


i have no ideal what the compression will be. i'm going to use the 3.8sc heads.

fturner
07-01-2009, 08:44 PM
On the older cars, the block holds the crank sensor, not the timing cover.

Its not the heads that determine the compression ration, its the pistons. Your probably going to end up running the stock compression ration of that 4.2 or pretty close to it.

Fraser

old_coot
07-02-2009, 10:23 AM
On the older cars, the block holds the crank sensor, not the timing cover.

Its not the heads that determine the compression ration, its the pistons. Your probably going to end up running the stock compression ration of that 4.2 or pretty close to it.

Fraser

Yeah Fraser, thats what I am thinking too...If he keeps his original early blower and pulleys it should only make about 7.5 pounds of boost like mine did so it may live...much more than that and I would worry about the rods taking it..................Dan

S_Mazza
07-02-2009, 12:04 PM
On the older cars, the block holds the crank sensor, not the timing cover.

Its not the heads that determine the compression ration, its the pistons. Your probably going to end up running the stock compression ration of that 4.2 or pretty close to it.

Fraser

The heads do play a role based on chamber size. The splitport heads are different for sure, but I don't know how much different. The 4.2 piston dishes are a good bit smaller than the SC dishes, so the CR will probably go up from that.

However, the crank throws will make a bigger difference. 3.74" is 10% more throw than 3.39", so I would expect to get close to 10% more compression based on crank alone.

fturner
07-02-2009, 12:30 PM
I guess I should have said its not just the heads that setup compression ratio's :).

Fraser

David Neibert
07-02-2009, 01:12 PM
i will have to use the 3.8's timing cover. should fit same block.


i have no ideal what the compression will be. i'm going to use the 3.8sc heads.

On a 94/95 SC motor the crank sensor mounts to the timing cover, but an 89-93 SC motor has a different style reluctor wheel and sensor. The early model crank position sensor mounting bracket that you have, bolts to the block. If the 4.2 block doesn't have those mounting provisions, you will need to fabricate a bracket to correctly locate the crank sensor.

David

deathvenom
07-02-2009, 04:17 PM
i figured i would have to make a bracket.

deathvenom
07-11-2009, 01:56 AM
ok can't find a 4.2 but i did find 3 4.6 dohc so i will do a conversion:)

Pacman
07-11-2009, 05:33 AM
4.6 dohc FTW!

seawalkersee
07-11-2009, 05:49 PM
4.6 FTW until you mod the 3.8.

SWS

S_Mazza
07-13-2009, 12:01 PM
4.6 SOHC non-PI FTL. 4.6 DOHC PI aluminum block FTW.