4.0L SOHC to 4.0L OHV Pushrod Swap?

[swshawaii]

Has anyone seen this swap done successfully? After consulting with koda2000, the short blocks are the same and the existing 5R55 may bolt right up. Seems it would be a lot less work than the more desirable 5.0L Windsor V8 conversion.
I believe the OHV may be an econonmical and viable option for those with blown SOHC's. Sure, you're giving up 50 HP, but gaining time proven and long term reliability. Opinions?

 

[J_C]

I'd consider it, but then again if pulling the engine before it's trashed, putting in new chain, tensioners and cassettes for another dozen + years life expectancy isn't a bad trade off.

What model year and how many miles on it? Swapping in what OHV, low mile pull, rebuilt? I mean say you were swapping in a used OHV with 150K mi. on it already, and yours isn't much higher than that, then the engine might be worn out by the time a new set of chains, tensioners and cassettes wore out on what you have.

I wouldn't bother with a V8 conversion on a 2nd gen unless there's a lot of extra value put into the vehicle from conversions. They're not worth much money at this point, to just start over with one that came stock with a V8 then bring the rest up to par if you don't have exotic aftermarket (suspension) on it.

 

[swshawaii]

Definitely not in my plans, at least right now. My Trac only has 78,000 easily driven miles and is overly maintained IMO. In fact, I only change oil once a year because I drive less than 5000 miles annually. I posted this only because I continually read about 302 conversions, yet have never heard of anyone replacing their grenaded SOHC with the OHV. If I drove a lot, I'd give up 50 HP in a heartbeat for the proven reliability of the OHV instead of the known time bomb the SOHC is. Thanks for the feedback.

 

[imp]

Definitely not in my plans, at least right now. My Trac only has 78,000 easily driven miles and is overly maintained IMO. In fact, I only change oil once a year because I drive less than 5000 miles annually. I posted this only because I continually read about 302 conversions, yet have never heard of anyone replacing their grenaded SOHC with the OHV. If I drove a lot, I'd give up 50 HP in a heartbeat for the proven reliability of the OHV instead of the known time bomb the SOHC is. Thanks for the feedback.

@swshawaii
IMO, I would do it, for reasons you stated. However, first get rid of the 5R55S "may" fit question mark. What about PCM differences, advance curve, etc. Firing order same? Not important, but is the crank position determined in a similar way w/OHV? Did OHV have any kind of camshaft sensor? imp

 

[roscoe 0202]

later than 92 had a cam position sensor in old dist hole should be compatible
roscoe

 

[koda2000]

@swshawaii
IMO, I would do it, for reasons you stated. However, first get rid of the 5R55S "may" fit question mark. What about PCM differences, advance curve, etc. Firing order same? Not important, but is the crank position determined in a similar way w/OHV? Did OHV have any kind of camshaft sensor? imp

The PCM and engine harness would definately need to be changed.

 

[Tech By Trade]

I dont think they had the knock sensor either. you would probably have to change the cluster as well.

 

[MrQ]

Its a direct swap. 4.0 sohc computer will run a 4.0 ohv. Everything is the same minus the engine harness. The 5r55e will bolt right up.

Question is: why do it? The SOHC is the superior motor. It would be better just to replace the timing chain guides if you are going to go through all that trouble. Geez, the paranoia over that engine is just insane.

They actually do last a LONG time.

 

[Robman]

it's only the superior motor until it isn't.... The OHV just goes and goes, easier on fuel too.

( I have a 194k km 2000 sohc sport in my collection with the start up rattle which doesn't exactly exude confidence)

oh and a 400 000km ohv .... no rattle

 

[MrQ]

it's only the superior motor until it isn't.... The OHV just goes and goes, easier on fuel too.

( I have a 194k km 2000 sohc sport in my collection with the start up rattle which doesn't exactly exude confidence)

Actually it's not, they are about the same when it comes to gas mileage. The OHV is known for rear main seal leaks and blowing head gaskets. Each engine has its own issues. The cost of replacing head gaskets can be about the same as the timing guides.

 

[MrQ]

But for that trade off you make quite a bit more horsepower and torque.

 

[J_C]

Yeah it's a bit different than choosing which engine if the rest of the vehicle were new again. I'd sooner put new timing components on my SOHC than switch to a 4L OHV, wouldn't wear those out again before something else caused me to scrap it.

Guess it would depend on the mileage of the OHV since it doesn't seem likely to find a used one with low miles at this late date.

 

[roscoe 0202]

I've had two 99 explorer sports 1 with ohv and 1 with sohc both got 19 never 20 and never under 19 this was out on the road and around town but sohc had much better power. I think thesohc gets bad rap from some members here all engines have their problems.
roscoe

 

[Robman]

-I'm not sure 13 more lb of torque can be considered "a lot."
-More revs = more fuel used.

I've owned 5 2nd gen explorers and I prefer the OHV for reliability.
They're all dogs when it comes to making power, and don't get me started on that sorry excuse of a transmission they bolt to the 4 liters

 

[MrQ]

Maybe, but if it takes less time at a higher rev to get you up to speed than lower revs and a longer time it equals out.

 

[RangerX]

Manual transmissions behind the sohc have one more bolt than the manual transmission behind the ohv, would that be the same with the auto trans?
Mentioning this only because the OP mentions putting a 5r55e behind a ohv 4.0...maybe I misunderstood.

 

[MrQ]

The 5r55e transmission will work behind either. The OHV switched to the 5r55e after the introduction of the SOHC in '97. I wasn't aware that there was a one bolt difference between the two, however the bolt pattern on the engine will still match the transmission.

I am not sure about the manuals. I know the only change there was M5OD to the M5OD R2 which was stronger behind the SOHC.

 

[swshawaii]

-I'm not sure 13 more lb of torque can be considered "a lot."
-More revs = more fuel used.

I've owned 5 2nd gen explorers and I prefer the OHV for reliability.
They're all dogs when it comes to making power, and don't get me started on that sorry excuse of a transmission they bolt to the 4 liters

Robman, thanks for the dyno graph comparison. Looking at the HP/Torque curves, they appear dead even up to about 2200 revs. Depending on gearing and tire diameter, 2200 RPM would be over 65 MPH for most. Unless accelerating hard, how many drive over 60-65 MPH often?

 

[J_C]

^ While I don't accelerate much past 3000RPM often, I do often accelerate over 2200RPM, half the time I get going from stopped if there isn't traffic in front of me.

I'm not saying that's much difference, but I just don't see the argument for switching to a 4L OHV unless it has fewer miles on it since new timing components should outlast the rest of the vehicle unless you're dead set on owning it for life and doing whatever it takes to get there.

Suppose you do want to sell it some day. I for one wouldn't buy a used vehicle with a different engine than came stock because the owner told me he DIY because it's more reliable, unless I knew the guy well and had a lot of confidence in his conversion skills. and it was dirt cheap.

 

[roscoe 0202]

explorer never got m50r2 this trans fits 4.9 six and 302-351 engine the sohc got a m50r1hd. the bolt hole was moved to miss cam timing components but 1 less bolt shouldn't make that much difference.
roscoe