Sorry - let me rephrase more clearly... Last time my mechanic took out the muffler, he commented that the cats had been gutted. That was news to me, especially considering that the car passed CA smog checks with flying colors year after year ;-)

Right now, I'm debating (for the same cash outlay) a lift that fits 911s (and will also work on my 912) or a set of SSIs+muffler - same price.
The lift is winning for now ;-)

Is there any chance the "gutted" cat converter is part of the problem? I would think that in theory any backpressure (if it hasn't been gutted properly), or increase in exhaust flow would have been compensated for by the Motronic....but is there any chance that it can be causing the problem?

Since it appears that you have tried everything (haven't read every post, so I may have missed things)...what about checking that out? It is a PITA to pull the muffler and/or cat.....but not that hard....

I know when I put SSI's on my '75 ('78 engine), the reduced back pressure required some richening up of the CIS to compensate....but I would think that Motronic would do that automatically.

Oh yeah, one other minor idea, please ignore if it has already been suggested,....is the rubber seal that surrounds the front oil cooler shield intact? Is there any chance that there is a gap that allows the air flow to bypass the cooler somewhat? Also, do you have the fan on the front cooler? They may not help much, but every little bit helps..

Dennis

lots of good info here im trying to figure out my hot running problem also. Mine is much hotter than yours though 240-260 normaly. Iv got a bunch of things to check now. Anyway as for the lift/jacking dilema. I made myself a set of ramps out of 2 4x4s screwed together side by side and a 2x8 screwed on top and a stop at the back (sorry no pic) but they work great for low cars and there super easy just to drive up on. On the front of my car i have to back up onto them because they dont fit under the front valance. But there great super handy. Good luck with your problem :)

Grady,
Did you get the hoses backward?
http://forums.pelicanparts.com/uploa...1192164330.jpg

Could you be more specific like what the CO at idle numbers are and CO at 2500 rpm?

I find it best not to assume anything when encountering a problem such as this.

Joe

I'll research this more when I get back to Denver.

Best,
Grady

how do you tell if you have the bad sump plate?

Subscribed. I am looking for help with my '82. I have a lot of the same issues.:mad:

A few people asked if I could update this thread since I started it...

My car definitely runs somewhat cooler than it used to when I started. Cool enough to satisfy me at all times ? No. I seriously think that cannot be achieved on an SC with high mileage - especially for track duties - without a front cooler, but anyway.... But I now run consistently less than mid gauge temps even on hot FL days (90+) at sustained 85+ mph speeds. That's not bad.

Best bang for the buck? Assuming you have a carrera cooler already, undoubtedly the adjustable thermostatic fan cooler switch. By switching from a porsche switch to a manual switch to this, I've found out that it's much easier to keep oil cool in the first place than it is to lower its temps once it got hot... I've set mine up to activate the moment oil enters the front cooler. Period...

Worst results? The attempt at ducting more airflow to the cooler. Seems like there is plenty of flow already, it made zero difference for highway use (might have on track though).

In between? Timing.... While I had mixed results with advancing it too much, the exercise had me verify that my vacuum lines were working, and they were not quite as "vacuumy" as I wanted. So now my distributor operates as it should. Of course since I did this at the same time I cleaned the primary cooler, I don't know what's what exactly...

On one hand I really do think SCs run hot, and not much can be done -and the "cool" ones have defective gauges ;-) On the other hand, my car ran "too damn hot" for 178000 miles so far, and it's still purring like a panther....

Greg ... thanks for the update. It is much appreciated.

Long time... Long enough that since then my SC since got backdated and I put another 10K miles on it, at *fair* temperatures for FL weather anyway...

Just wondering if in the last year or so anybody managed to dig up a *correct* ignition timing chart for an 83SC per chance... since I was told Bentley was not to be trusted...

The reason I ask again is that yesterday I replaced all plug wires, distributor cap and rotor, and rechecked timing. It was 10deg BTDC at idle, way more advanced than specs (actually I did that for a reason, at the time, but had forgotten why)

I retarded it back to factory specs (5 deg BTDC at idle, vac lines unplugged, which becomes something ATDC with the line reconnected), and today on my cool morning commute where the car normally runs cool, it ran HOT. So, to those who said in the thread that running more retarded should not make the car run hotter, well on my car anyway, you'd be wrong ;-)

I'll reset it to 10 tonight, I think I got to 10 at idle because that was what netted me the best correct advance at 4000 rpm without pinging... I forget, 32 or 35 maybe? I'll recheck tonight !

Is it possible to get that distributor recurved to run without any vacuum involved, and have the correct advance/retard for my CIS motor ?

Greg,

The factory ignition timing spec for your engine is "not above 25 BTDC @ 6000 rpm". This translates to around 5 BTDC at 950 rpm (no vacuum) on a new distibutor with new springs and you should check the advance at a high speed, rather than rely on the idle setting. Your distributor has vacuum advance and retard. The advance improves mileage at cruise and is a good thing. The retard is strickly an HC curb idle emission device and it increases the heating of the engine and oil at idle. Every SC I've seen runs cooler in traffic with the retard disconnected and the idle reset.

The later high compression SC's have retarded timing specs because they are detuned to run on 87CLC octane fuel. If you have +100 octane fuel, the ideal timing would be around 35 BTDC. Porsche's initial response to unleaded low octane fuel was to lower compression ratios. This resulted in an unacceptable increase in consumption, so they chose to raise compression and retard the timing on the later models. There is no reason to recurve your distributor to mechanical only advance, unless you change the torque peak with induction, cam or exhaust changes. You cannot recover the mileage efficiency without the load based vacuum advance. Eliminating the retard just involves plugging the line and resetting the idle speed.

So you advise me to time it per factory spec at 5 BTDC vacuum port unplugged, then leave the retard line disconnected from the dictributor (plug it), and reset my Idle if necessary ? Am I reading this right ?

I run 93 octane. So far to make 32/35 advance (can't remember what it was) at 5000 rpm I had to set 10 BTDC at idle. But it was running cooler and not pinging.
It started running hot again because I retimed it per factory specs...

Greg,

Yes, retarded ignition timing raises the engine temp because less of the energy in the fuel does work and more goes into heating the cylinder, head and exhaust. This is SI engine 101.
The vacuum retard uses manifold vacuum (full vacuum at idle) and the advance uses ported vacuum (no vacuum at idle). Make sure the lines are correct, and disconnect and plug the retard line. Your 83SC distributor gives around 20 crank degrees of mechanical advance at best, so you would need to be past 10 BTDC at idle to get 32/35 @ 5000 rpm. No one can tell you how much max advance you can run over the internet. My experience is you cannot run a stock late SC on CIS, especially one that runs hot, over 30 BTDC, on pump fuel. Most of them will ping under load around 4000 rpm, if you have an experienced ear. The octane requirement varies with compression, engine temperature, intake air temperature, oil dilution, fuel composition, etc. and every situation is different. The best way to optimize the late SC, is to remove the oil tank breather from the intake air, set the mixture to 30-40 dwell, disconnect the vacuum retard, run the highest octane fuel you can find and advance the timing. How much will depend on many things, including the weather, and your risk tolerance for holing a piston.

This begs the question ... what about a late SC with 9.5 CR, 964 cams and SSI exhaust?

Would this setup call for a dizzy recurve? If so, how does the tech know exactly "how" to recurve the dizzy when there are so many variables involved with the timing?

Since my rebuild I have kept my idle timing at 5 BTDC which results in roughly 26 BTDC at 6000 rpms. This is what the Bentley states for spec. Certainly I have some room to advance timing but it seems a bit risky. I use 93 octane - mostly E0 too unless I am out of town with the car.

Okie Dokie.. I've just reached the end of the internet (on this board anyway) about timing issues on an SC...

From what I gathered, there are 2 schools of thought, though not all that far apart in results, just different in *how* you get to the magic number... Correct me if I am wrong !

1) everybody agrees that 25 BTDC at high RPM is super conservative and set that way by porsche to account for 87 octane, higher engine compression in 83, and emission crap.

2) Paul, above, recommends that I run essentially factory settings (5 BDTC, netting 25 at higher RPM, give or take a little), but that I leave the retard vacuum line off the distributor and plug it, thereby decreasing the excessive retardation at idle (an emission gimmick) that makes the engine run hot... Paul says you *can* run more total advance because this 25 degree setting is designed to be safe (see #1) but that can only be determined by a pro "testing" your car on a dyno for detonation and backing off a few degrees... So, no hard and fast rule. Did I get this right ?

3) Others, including some fairly famous mechanics on this forum, generally recommend setting advance to 32-35 at high RPM and letting the idle fall where it may - generally higher: like 10-12 degrees. I did that 10K miles ago, I think I ended up at 32 - since I could hear it ping at 35 with WOT and backed it off - and my idle was 10-12, my car ran well enough (it did not self destruct, at any rate) and importantly, it ran much cooler than before.

I can see where Paul's approch is safer as you may not always hear pinging! So for now I'm gonna split the difference. Since, as of last night I am on factory settings - and unfortunately running way hotter - I'm gonna try Paul's theory first and simply disconnect and plug my retard line. The car should run cooler at low RPM and be super safe at high RPMs. I'll measure high RPM advance with an without the advance too, for giggles, because while I know that I have good vacuum in the retard line, I never measured the advance line....

If the car still runs too hot that way (and I suspect it might, but am ready to be happily wrong), it'll be fairly obvious to me and I'll go back to the 30-32 degree settings which I've run for over a year with no *apparent* damage, and which netted me cooler temps. At this point, knock on wood, she's got 185K miles and if she blows, she blows (doubtful since I put 15K miles last year with more advanced timing)...Oh, I run 93 exclusively, obviously.

Either way, that was a super interesting thread. Let me know if I read any of this wrong !

PS: I think I will start a new distributor thread instead of leaving this at the tail end of 8 pages !