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Calling all SOHC Experts - Differences and Headers

Fredness

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I have a 1998 Explorer Sport.
Anyone with an early SOHC, learns one thing quickly - if it isn't a '99-'03, there is nothing for it.

But why?
I presume it is because the '99 is the first year of the "improved" SOHC (timing chain cassette mods) and the year after the "death" of the OHC engine in the Explorer. This makes sense for parts makers since "obviously" anything that is a 4.0L before '99 is not an SOHC.

We've seen the same issues with the 3.0L in the Ranger being listed as a completely different engine that the Taurus, which we now know is not true.

Also, I've gotten the same mis-information from parts makers: "Oh, you have a '98? That's an OHV engine" - Sorry Mr. Aftermarket parts maker, I know the difference, I HAVE an SOHC. We also know that the '97 was a mixed SOHC/OHV year as well.

So, before my '99-'03 SOHC Explorer headers get here, prove they will or will not fit...
 



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Jakee

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Can you take a couple of pics of the engine bay?
 






Fredness

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Silver X

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I didn't think the timing chain tensioner/guides were improved until '02 or '03. My '01 still had the junk parts on it and had to be replaced under recall.

As far as the exhaust manifolds on the earlier SOHC engines, I'm guessing there might be a difference between EGR positions compared to the new headers. Or maybe they really will work, but people don't realize it, lol.
 






CDW6212R

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Yes, internally the SOHC are all identical until 2002(not counting 4WD balance shaft).

FYI, the OHV didn't die in 98 or 99, it was later than that.

Are you looking at OBX headers? I noticed the EGR differences in the two part numbers which they carried. I'd bet it has to do with the EGR system. Good luck,
 






Fredness

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Yes, they have two EGR's, "Right" and "Left" - I compared the pictures and I have the "Left" system witht he EGR on the lower union of the driver side exhaust manifold with an ~3/4" round threaded connection.

As far as I've seen, the OHV died in the Explorer in 1998 - but checking Ford PN's, I see the OHC was carried in the Explorers until 2000 (as VIN "X"). So, there goes that portion of my theory.

But this fails to explain the separation of the 1997-1998 SOHC from the rest of the family.

Here are pics as promised:
Left (Drivers) manifold

DSEhxStock.jpg


Right (Passengers) manifold

PSEhxStock.jpg


Here is what is inbound...

11125.jpg
 






CDW6212R

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Let me know what you think, and what else have you done to the truck? Please change only that at one time, don't make multiple changes at once. I saw them last month but I doubt that they would help gas mileage, low speed efficiency. Regards,
 






Fredness

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I have 4 other mods in the works (Headers, Full UDP set, EFan, 70mm TB), but it is a piece by piece deal with testing runs after each, so there will be comparitive data.

To date:
Volant Intake
Custom cat-back (2.25" DI/ 2.5" SO MagnaFlow, mandrel bent)
X3 with custom tune (12.5:1 AFR @ WOT)
>20K on Plug Wires, Double Plats, O2's.
 






CDW6212R

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Well good, you are close to where I'm at. I only lack doing a couple of things to the trans again, and tuning. I have a ported stock 4.6 TB(65mm) that I haven't installed yet, maybe today. I'm only after fuel mileage for this, my 99 work vehicle, it isn't much better than a 302 now(no PCM tune). When I do finish the tuning is last, with an ExCal I. Regards,
 






jah81592

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There isn't much more for the 99 and later on with the exception of cat back systems. I offer a whole bunch of parts for all, one year not having any more than the other. '99 was supposed to be the year for the improved timing tensioners. If you go with a full pulley system you will not yield the same hp and torque as you will if you go with only the crank. BTW the cooling and charging won't be negatively affected (I live in AL-AC and cooling system function is a necessity). If you have any questions I will be happy to help. Around here I am the resident SOHC guy.;)
 






aldive

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I had to go with an overdrive alternator pulley to keep my charging up to par.
 






Fredness

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I have the UDP (Crank), UD Waterpump (larger), OD Alternator (smaller) and standard idler (replaceable bearing).
Standard tensioner (grooved) and PS pulleys are in the process - not for HP, just for uniformity and Bling :D.

jah81592, I will yield higher numbers due to the reduced WP drag, but that should cancel out the increased alternator drag. I see it as a win/win.

Now, back to the headers:
Any ideas why they are '99'-03? and not '97-'03?
 






CDW6212R

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I haven't seen very many pictures of the first years of the SOHC, or have others speak of it. There were a bunch of Explorer upgrades in 1998, and a few in late 97. For 1999 very little changed except for the returnless fuel systems, and an under hood wire harness change. Because of you picture of your truck, I'd bet that they will work. Let us know, more information is always good.

All of the SOHC timing cassette part numbers are now 2002 parts, those are the weak link, and were upgraded in 2002. The 99 change was for the little timing chain tensioners, which still aren't good enough to last 75k miles. I got the impression that they created a great design, but didn't work out the engineering details of the tensioners and chain guides until late in production. I have had many conversations about it with a Ford tech, who was the shop foreman for many years. He supervised countless repairs/recalls of these engines. I trust what he has told me. If I had known about it before I bought my SOHC wreck, I would have done the 302/AWD instead. Regards,
 






Fredness

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Parts arrived today, we'll see how it goes...
 






Jakee

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Your stock manifolds look exactly like mine did. (If that helps) Don't think you're alone with the battle for the right parts. I've got the wrong parts for my 01 more than once (Not me, was given the wrong one from the dealer) It took 3 times to get the PCV valve, and it still wasn't right.

And for the UD pulleys....I also had to finally install the alt pulley I had sitting around. The volt gauge started to read really low when idling. After the overdrive alt pulley was installed, the problem went away.

Those new headers of yours look pretty cool. I've never heard of them but they look almost like JBA's
 






jah81592

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I have the UDP (Crank), UD Waterpump (larger), OD Alternator (smaller) and standard idler (replaceable bearing).
Standard tensioner (grooved) and PS pulleys are in the process - not for HP, just for uniformity and Bling :D.

jah81592, I will yield higher numbers due to the reduced WP drag, but that should cancel out the increased alternator drag. I see it as a win/win.

Now, back to the headers:
Any ideas why they are '99'-03? and not '97-'03?

It is for 1997- 2007. Your 1998 should have a drivers side egr. There are a few exceptions to a pass egr (Sport Tracs) other wise it will always be a driver side egr under most circumstances. My JBA dealer manual states part#1674s-1 is a stainless shorty header,drivers egr,model year 1997-2007, Ford Ranger/Explorer SOHC.
BTW, if you underdrive everything the entire accessory drive is underdriven. You will make more power with just a crank pulley. If your vehicle idles at 650-700 then yes you will see around 12.-12.4v depending on the amps being drawn at the time. I have never seen mine drop below that. Remember this u/d pulley is full charge at 950 rpm. Raise your idle just a little 125rpms and you shouldn't have any charging problems. Even though I have seen as little as 12.1 volts at idle the batt light won't come on. How long do you idle anyway? If you want to make power there is always a trade off. Unfortunately when you start modifying you will lose some driveability. There is no way around it.
 






Fredness

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I see what you are saying, but I physically have a UD Crank, UD WP and an OD Alt.
The Water pump has a special larger pulley for MORE reduction and the Alt pulley is smaller to regain the lost rpm's from the UD crank pulley.
 






Jakee

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Technically, with the UD water pump pulley, you should have less drag than with just the crank pulley. The crank pulley slows all the acc. down by a percentage, and the UD water pump pulley slows the water pump down just a bit more. The only pulley that will "Increase" drag is the OD alt pulley. But guys, were talking about very small differences here. I bet you don't even pick the difference up on a dyno, and if you do, it's going to be very small.
 






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