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SC2 engine puzzle

Old 09-19-2015, 03:29 AM
echo1's Avatar
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Join Date: Aug 2015
Location: Northern Kali
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Default SC2 engine puzzle

Hi Guys,

I'm back. I've got my 2000 SL2 sorted out, after discovering the low mileage engine I initially picked up for it would not work. So I went looking for a chassis to put it in.

I ended up locating a decent '98 SC2 with a worn out, but sorta running motor.

My good engine has the 9 bolt exhaust, but takes and aluminum intake. I believe that makes it the one off '99 motors, as the plastic intake from my 2000 would not bolt up.

What am I up against installing this '99A (?) motor in this '98 SC2. Is the exhaust going to hook right up, or will the down pipe flange/elbow be different? The current engine has the 5 bolt exhaust.

Will I be running into ECM or emission issues too. If it's not straight forward, I've got a line on another '98 DOHC.

If it's not too expensive of a swap with the engine, I'd like to change out to a lower mileage auto tranny at the same time. 220K on the SC2.

Thanks for any input. What I've really been after is a wagon for this engine, but they're hard to find. PAX
Old 09-19-2015, 12:38 PM
derf's Avatar
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Upon further consideration, it would appear that the plastic intakes started in 2000, but the 8 bolt exhaust manifolds started in 99 -- meaning there is a typo in the swap guide that every site has ---they were all derived from a swap guide on the original website.

Without you coming along, there's no telling how long the error would have remained, I will fix it. Looking at others posting to the net, they had the same confusion going on. Thank you.


So your good engine is not a "one off" 99 DOHC, it is a standard 99 DOHC.

Putting a 99 DOHC into a 98 SCC2

Different part numbers for (down +flexpipe) lead me to believe this will be a PITA, since there must be a difference in distance from the face of the exhaust manifold flange and the side of the engine (facing front of car). Since it's all custom bent from the factory, I'm not sure you could modify it. If the 99 exh mani flange sticks out further than he 98's you're gonna have to get creative; if it is the other way around you might be able to make an adapter piece with a flange on end. Or you could go completely custom......


91-99 PCMs were all manufactured by Delco. The 98 and 99 prob have similar programming -- can't guarantee of course. I would pull the plugs from each, take a pic, and compare the two. I would definitely use the 99 PCM w the 99 engine to ensure proper engine management. Oh, and see next paragraph, which pretty much nixes use of the 98 PCM anyway or at least requires a flash if possible at all

99 seems to have been the first year of the smog (air) pumps on the S series. Therefore, it'd be safest to swap the whole wiring harness to ensure you have the connector for it -- but then comes the issue of wiring from the PCM to the pump relay and the pump relay to the pump. So then I GUESS you swap the UHJB too -- otherwise there will not be a spot for the relay -- which then means you have to go through the entire UHJB comparing 99 to 98 to ensure that is the ONLY difference... uugghhh

Tranny swap :? to Auto

Not sure what's in there now -- PLEASE MAKE YOUR SIGNATURE!!!!!!!!

Auto to Auto --shouldn't be an issue
5 spd to Auto -- diff ballgame

Last edited by derf; 09-19-2015 at 12:40 PM.
Old 09-20-2015, 01:01 PM
echo1's Avatar
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Join Date: Aug 2015
Location: Northern Kali
Posts: 43

Thanks derf,

I think I'll just hold on to my good '99 DOHC and find the RIGHT wagon to put it in. It only has 30K miles on it.

The newly acquired SC2 has an auto tranny working fine, I was just going to try and put a lower mileage/rebuilt unit in if I stabbed this '99 in it. But now I think I'll just put a '98 in there. It running but has cam/timing chain issues, and with 220K miles, I'd just as soon change it out and rebuild it at some later date.

Somewhere I've read of the '99 mid-year exhaust/intake issue, which is why I referred to my motor as "99A" by quote.


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