SOHC into a Navajo-Smog legal

[Stic-o]

So some of you have been following my Plan B build, but I thought I would do a separate thread on the engine swap. My swap will need to be California smog legal, and I'm using multiple donors parts from different years for the build.

Why the SOHC?
I understand this is the first question asked. Simply, because I had a perfectly good complete donor, and the motor only has 103k and runs super smooth. No chain noise. Plus out of the box, it's the same hp as the V8.

We're Starting off with a 1991 Mazda Navajo (Explorer Sport).

• Stock OHV 4.0
• Manual Transmission (M5OD-R1)
  
• Auto/Electric transfer case (1354)

I'm removing all of the wiring, and I do mean all! Everything from taillights to headlights. as well as the fuel tank. The plan is to keep the Navajo dash, and try to get the donor parts to swap in. from cluster to hvac, to even the headlight switch. I'll also try to keep the original steering column.

The donor vehicle I'm using is a 2000 Explorer Sport

• Stock SOHC 4.0
• Auto Transmission 4x2 (5R55E) - this will not be used

Substitute Donor parts

• 2008 Ranger FX4 Auto Transmission 4x4 (5R55E)
• 1994 Explorer Sport Manual Transfer Case (1354)

I'll be swapping over the entire wiring harness from the 2000 Sport over to the Navajo, again taillight to headlight. Also the gas tank, cluster, and havc. Since I cut the back roof off the Navajo, I'm not 100% I'll even bother with the A/C, but heater will be important. For the SOHC to fit, I'll need to swap the entire HVAC box off the firewall. Other issues will be the steering, but that shouldn't be to big of a deal, as I try to keep the Navajo column. I'm not sure If I could use the power steering pump off the OHV on the SHOC. this would eliminate figuring out new PS hoses. The break booster and pedal assembly will also be swapped over. All smog will be swapped over and of course, everyone's favorite, as I will retain PATS. Yes PATS in a Navajo.

Everything for the most part should just bolt in. As I'm basically just swapping everything over to a newer body.

 

[boominXplorer]

I've got an entire 03 Explorer Sport engine harness/computer/column ect from a manual trans truck if you want to go that route. I also have everything from the truck manual related like exhaust manifolds, pedals and trans (it's 2wd). I'll dig the thread up as I still have everything from it and would love to get rid of it.

For Sale - 02-03 Explorer Sport / Sport Trac Manual transmission swap kit COMPLETE

Also one issue you didn't mention is the oil pan running into the crossmember. The balance shaft portion sticks out and will contact a ttb truck crossmember. You'll have to lift the engine up to get it to clear.

Kudos to going sohc over v8. You'll save weight and end up with almost the same power (minus low end torque) as the v8.

 

[CDW6212R]

Sounds like my kind of fun, I hope it turns out great.

First I suggest finding Ryan's old thread about his 1st gen truck, the one he swapped a 302 into. He did tons of work to that truck, but the part which will help you is the swap of the dash and firewall.

You will have a harder time if you try to modify the older firewall to accept the wiring and AC holes etc. Ryan made it a fairly reasonable task to replace the firewall. Then the dash and everything connected around it are plug and play. The wiring will lay into the 1st gens great with the dash. The door panels can be swapped if you'd like, but the door wiring has to go with them if it has power windows.

 

[Stic-o]

I have heard about the cross member issue, but I'll deal with it when I get to it. The ttb stuff is coming out anyway, but I'm trying to do the motor first, get it smog legal and then do the axles. Keeping it auto so the wife can drive it. Easier off-road too.

Firewall will be fun, so we'll see how that goes. Also have a roll cage to deal with that I'm trying to leave untouched.

For the doors, I'd love to convert them to manual windows. Make the wiring easier. Not sure if that is just a bolt in thing. More reliable too.

 

[boominXplorer]

I'd consider swapping to an 01+ job 2 intake manifold if you need firewall room, It's a bit more compact.

 

[Mbrooks420]

Great project! Excited to see it unfold.

 

[Stic-o]

I'd consider swapping to an 01+ job 2 intake manifold if you need firewall room, It's a bit more compact.

I hear the issue is the valve covers. The SOHC is actually wider then the V8.

 

[CDW6212R]

I hear the issue is the valve covers. The SOHC is actually wider then the V8.

It's taller, but I didn't think it was wider. The SBF is a 90 degree engine(block), while the 4.0's are a 70 degree engine. I think the deck height is about the same, the 302 has an 8.2" deck height.

 

[boominXplorer]

Well considering the ohv block and sohc block are identical things don't change there. The heads are a good bit wider with the passenger rear being the problem spot I bet.

 

[ghosttrain2]

I did this swap in 2009, and love it! Also gutted the '94 harness, and used most of the wiring from a '97 donor. I kept the electronic 4x4 from the '94, except the switch, just use a spring to center toggle for the transfer case control. I also welded in the firewall, A and B pillars from the '97, and used the stock '97 dash, and HVAC. No smog here in Nevada, but I am sure it would pass.