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DOHC/SOHC computer stuff

2K views 19 replies 9 participants last post by  Teeps 
#1 ·
Ok, I have ran "Search" so many times and have never been able to find clear and straight forward answers. I will be picking up my 98 DOHC Mark VIII engine tomorrow. I am going to put it into storage for a couple months while I work on it and mod it.

A couple things I NEED to know, 4 cam bird, you may be able to help me....

I have a 97, has the EEC V (I think)
The engine is a 98, EEC V also ( I think)

would it be easier to just swap the computers instead of splicing the wiring?

Also....what is an average cost of swaping the engine into my car?

How much time would it take a mechanic? How much time would it take an average guy with fair auto experience to do the swap?

I hope you can help me out, it would make it so much easier.

For all of you "you should have used 'search'" I did, and it came up with HALF of the entire listings! All I need it a straight answer..

thank you!
 
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#2 ·
I know you can reprogram your factory computer to run the engine, you don't really have to swap eecs, just extend the wiring where it needs it, and run a MSD window switch for the IMRC's.

If you have to pay a mechanic to do the engine swap, it'll probably cost you triple what the engine costs at the least. Remember, the lowest mechanic's fee right now is still over $50 an hour. If you did it yourself, with general knowledge, it shouldn't take too long if you have all the parts and tools you need, I'd say a couple weekends.
 
#3 ·
:zwthstpd:

I'm using a 97 4.6L SOHC EEC to run a 4.6L DOHC in my 90 XR7, which should be running within the next couple weeks. I hate waiting for parts to arrive so I can finish a car :ztoohot:

-Rod
 
#6 ·
FoMoCoSVT said:
Another thing, how do you get it to the exhaust shop after putting new headers on since stock will not fit?


-Rod
 
#7 ·
I'm not sure how much the engine changed on the later Mark engines, but I'm swapping a '93 Mark engine into a '94 Thunderbird. I thought about using all the Mark wiring, but it would've been way too crazy (for me, anyway) to switch all the wires under the hood and everything. I took the engine harness from my old 4.6 and put it onto the new Mark engine. It was pretty simple, just about everything plugs in except like 3 connectors that you have to splice on from the Mark harness, and a couple wires need extending. My engines all wired up now, just needs to be dropped in. I think the later Mark engines have coil on plug design, so you will probably have to ditch that setup and use coil packs (if you use the Thunderbird wiring). You would use the Thunderbird computer with a reflash or chip to run the Mark engine and a RPM window switch to run the IMRC. This is just how I'm doing it. Again, I'm not sure how much the engine changed in the 2nd gen Mark VIIIs, your wiring might be totally different than what is on my '93 harness. Make sure you buy some new parts for that like the IAC, TPS, EGR valve and other stuff that likes to go bad and is a pain to change with the engine on the car (they're all towards the back of the engine). Good luck with it. I've been trying to get this done since Sept. (didn't work on it during the winter months though), I'll be putting the engine in next weekend, everyhting else is ready to go.

- Mark

BTW, I bet a shop would charge an arm and a leg for this. I called about 8 shops to do this swap and I couldn't even find anyone willing to do it. If you and a couple buddies with decent mechanic skills do this, it could probably be done in 4 days (maybe less, depending on how many hours a day you're working on it and how good you guys are). There's a bunch of tight spots and bolts and other crap that's a pain to get off, so that takes time away too (and gets you frustrated).
 
#8 ·
My guess is about 4-5 days if the timing is right at Performance enterprise in crystal river, Fl...and would run about $ 1100 exclusive of the upgraded tq converter, flex plate, new tranny seal ,bolts, Chip To run stock sohc computer, and Mk VIII headers . interested? PM me...
 
#9 ·
The IAC, TPS, etc. are not at the back of the engine on the 2nd gen Mark intakes. The throttle body is located in the middle (front to rear) on the passenger side of the engine on those. So that stuff isn't so hard to get to. I am pretty sure that is the worst DOHC 4.6L intake though. Kenny Bell makes a nice intake for it though

You may have a hood clearance issue? I dunno, be aware that you might have to cut a hole or buy a anew hood.

If you use the wiring from the 97 you will have to use the 4 post coil packs from the SOHC engine. You will also have to buy valve covers for a 1st gen Mark (will be black and very expensive) or for a 96-98 Cobra (will be silver and much, much cheaper). Plus, you would also need plug wires, which are also pretty pricey due to the nature of the spark plug end of them. The old coil packs seem to be more reliable than the coils for the coil on plug that the 98 Mark had.

Search for DOHC Swap when doing a search, if you included the sequences SOHC and DOHC in one search, yep, you would get everything on the board.

As for time to do the work, plan a day to pull it out, and a couple days for physically putting it back in, pluging everything into the proper places on the car. I don't know how much work you'll have to do with wiring so can't really say what you should expect for time to do that.

You'll need all new hoses, throttle cable from a 2nd gen Mark VIII, fuel lines...

This is probably about all I know about what you are looking to do though, it will be quite a bit different than my swap was.
 
#10 ·
As for the new Intake, how can I get in contact with Kenny Bell and about how much you think he is charging for the intake?

As for the hood clearance, it will not be a problem since I am getting the Legendary with the dual scoops before I do the swap.

So you are saying that I should use the 97 T-Bird wiring? Then put the two coil packs from the 97 on the mark engine? would they be bolt on or would I have to modify them in any way?

To cut down on time.....could I get the wiring and attach it to the engine beforehand so that it will plug in when I put it into the bird? I will have the engine in storage and will be working on just the engine for a couple months. Could I buy another harness for a 97 and integrate them while it is sitting in storage? It seems it might make my life easier and the amount of time shorter if I did that.

Also, please give me some reasons why it will take a couple days to actually drop it into the car.....clearances, etc....

I want to do everything I can do before I do the swap since I need my car to commute to places and time is money.

thanks for all your help so far!
 
#11 ·
http://www.kennebell.net/ They are pretty expensive but you definitely get a lot of intake for the money
;)

If you use the coil pack brackets from your engine they might bolt on to the new engine, I don't know if all brackets would be the same and I don't know if they may have bolted something else in its place.

Getting the engine wired up with a nother harness would problaby be a good idea if you want to minize down time. You better get yourself a spare 97 PCM to have flashed too.

I said a couple days to put it in just because there is a lot to do. You have to ease it down into there, both the motor counts up, hook the A/c lines up, , get fuel lines that are the proper length, hook the fuel lines up (I am 99% sure for your swap the stock ones will not hook up), put the throttle cable on, hook the steering shaft back up, put the underside of the dash back togheter after hooking the steering shaft back up, put the radiator back in, put all the hoses on, hook up the power steering, fill the power steering, fill the coolant, hook up the main wire connector, hook up, bolt the converter to the flex plate, refill the tranny fluid, etc, etc, etc, etc, etc. There's a lot to do. Give yourself some extra time, double check to make sure everything is connected, MAF, cooling fan, etc. It takes more time to pull it out than put it back in because tearing things apart is always easier than putting them back together. Even tearing it out is going to be a long one day.
 
#12 ·
So a good idea would be to get a game plan done and make a list of everything that needs to be done. When taking the parts off...such as the steering shaft....is it usually self explainatory. Most of the things you mentioned are pretty easy since I have done that so many times before......fill fluid, etc..

About the fuel lines....will I have to buy and bend metal tubes...fabricate my own lines? Or can I just get high pressure fuel hoses and hook up that way?

When putting the coil packs on, I do not see any obstructions...and they do not have to be in the exact same spot either.

To me, it seems the engine itself is attached to the tranny, to fuel and coolant lines, and to the chassis.....is that really that hard to rip out? You see, if it is all really that hard, and I can find a guy that will do it for less than $1200....I will get it done.

I really want to do it myself though....since I have done everything else myself....brake upgrades, full suspension upgrades and replacements, etc...I think I would ahve sufficient ability to do it. and save $$$$

I only wish they made a full list of things that need to be done....and how to do them instructions.....You are awesome for putting your prices on the boards..but it is tough compiling everyones info into one giant list.

I have about $2000 to spend....I allready have the motor lined up...so the 2g is for everything else....

If anyone out there could make a list of what they did, in order....that would be ANGELIC!!!

So, 4 cam bird, youer suggestion would be to integrate the mark engine with the T-Bird wiring, or use the Mark wiring and computer (replace it all) just to make sure...

Thank you again for being such great help...but these are questions that, I know you can understand, need to be asked before doing such a swap.
 
#13 ·
FoMoCoSVT said:
I only wish they made a full list of things that need to be done....and how to do them instructions.....You are awesome for putting your prices on the boards..but it is tough compiling everyones info into one giant list.
But that would make it too easy. Half the fun of engine swaps is being somewhat original.

-Rod
 
#14 ·
It isn't really hard to get out, you know, you pretty much have all the things I listed for putting it back together for taking it out, there isn't much I didn't list there.

You're best bet is to keep the coil pack brackets in the stock location so you don't have any spark plug wire issues. There is a little bridge that the wires attaceh to above the alternator, you might want to fabricate or find one of those since being coil on plug you're engine probably doesn't have it.

As for the fuel lines, I believe the connection point on a 98 Mark is on the driver's side of the engine, although I could be wrong. I believe on a 97 T-bird it is on the right side of the engine, again, could be wrong, you have both engine so you can see. I really don't know exactly what you needed for a fuel line. The 94 Bird and 94 Mark fuel rail connection was in about the same place and I was able to use the stock lines.

As for wiring, I make no recommendations. Read whats out there and decide how you want to do it. My notes probably wouldn't help you one bit though since you are using two totally different animals.
 
#15 ·
4 Cam Bird said:
You will also have to buy valve covers for a 1st gen Mark (will be black and very expensive) or for a 96-98 Cobra (will be silver and much, much cheaper).
Good luck finding the Cobra valve covers. One side (I forget which one) was discontinued from Ford a while ago and I got the last one there was (my uncle is a Ford parts manager and he had to check inventory from every Ford dealer in the country to find me the last one). I see used ones for sale a lot on eBay and at the corral and stuff.

Also about the wiring, at first I was planning on using every wire under the hood of a Mark VIII in my car. Once I got that engine out and stared into the empty engine bay and saw all the wires that are actually involved, I changed my mind real quick. Then I swapped the harness from my old engine, onto the Mark engine, and believe me it was SIMPLE. Took me a little over an hour to plug everything in, extend a couple wires, and splice on a few connectors you need from the Mark harness. Once again though, I'm not sure how different the 98 engine is compared to the 93, this is just my experience. I'm still betting even if more of the connectors on your engine were different, it would still be easier to splice them on the T-Bird harness and use that rather than use all the wires from a Mark VIII. Just my thoughts

- Mark
 
#16 ·
I will either use older Mark covers from a yard or purchase new covers found for the cobra engine. they come either polished or plain....I was searching one night and came by a site that sells them...

As for the wiring, Mark, what you are saying is easiest is to use the T-Bird wiring harness and computer? If that is the case, I will purchase a new harness and computer so that i can begin the connections bofore i drop it in.
 
#17 ·
FoMoCoSVT said:
As for the wiring, Mark, what you are saying is easiest is to use the T-Bird wiring harness and computer? If that is the case, I will purchase a new harness and computer so that i can begin the connections bofore i drop it in.
This is exactly what I have been told to do also. Go ahead and buy a new harness and EEC.
Send the EEC out and have it re-done to opperate the new DOHC engine and also be set up for any aftermarket options you may be adding.
Then at the same time you can be wiring the new harness to the DOHC engine and be ready to drop it in once all is ready.

I have been told many a times to do it this way, and it is the way I will go once my DOHC is ready to go in.

p.s. To anyone that knows, do you really have to change to the older Valve Covers(96-98 Cobra)? My DOHC will be an '01, can't I just use the newer covers with my coil pack/plug wire setup? Haven't looked at the two side by side, so I was just wondering. Thanks.
 
#18 ·
No, you cannot use the newer coil on plug valve covers with the old coil pack plug wire set up.

When did you buy the Cobra valve covers and have trouble getting them? I guess I have had mine for going on 2 years now this month. If they discontinued the Cobra ones, I am sure they discontinued the Mark ones, they are the same thing, both part numbers are on the inside of the valve covers, one number says silver at the end of it and the other says black. One of my valve covers was actually coated black and then painted silver over it, the inside was still black.
 
#19 ·
4 Cam Bird said:
When did you buy the Cobra valve covers and have trouble getting them? I guess I have had mine for going on 2 years now this month. If they discontinued the Cobra ones, I am sure they discontinued the Mark ones, they are the same thing, both part numbers are on the inside of the valve covers, one number says silver at the end of it and the other says black. One of my valve covers was actually coated black and then painted silver over it, the inside was still black.

Got them back in late October. Only one side (forget which one), was discontinued. The other side was still available at the time, not sure if it still is or not.

- Mark
 
#20 ·
If you decide to use the coil on plug ignition you will also have to find an 97-98 mark ecu, and rewire the engine harness to match the ECU pinout.

If you changed the valve covers back to the 93-96 Mark8 style, then you can use your 1997 Tbird Ecu and just hook up all your harnesses to the motor, get a chip or ecu flash tune from SCT.

Good Luck!
 
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