SC 3.0 way slow
 

New to me, rebuilt (25K) 3.0 SC. Feels sluggish. Comes up at 4 - 5000, but then tapers off. Any ideas? Should be perfect; is not.

You are speaking in very relative terms. Stock SCs are not particulary fast. Have you driven other stock SCs?

Unless all the maintenance is up to date, I'd go through the ignition components, set the timing, set the mixture, adjust valves, air filter etc. to get it to square one. If it still feels sluggish (compared to another stock SC), you should investigate further.

George

What do you compare to? These are not lightning fast(good for their day) But they are not slow or slugish. It should be rather smart to 4000rpm and then real quick to 6000rpm. What year? I would check the timing and fuel mixture. Also have leakdown done. Maybe a tuneup?

Just a guess, but maybe timing or cam timing issue?

Cam timing does not kill power like that, at least not until you are WAY off, to the point where you will risk valve damage. ;)

George

Gcrafty - take the car down to Bear's chassis dyno. Dyno-Pro Research INc, 5330 Tennyson St Denver CO 303 455 2443. It's been a while, so I don't know if he is still in business or at this location. His website has (or had) a bunch of SC dyno sheets, mine included. Compare yours. Much better than any seat of the pants. And there must be other chassis dynos in the metro area.

My rebuilt SC showed disturbingly small numbers compared to others until I took off my old, blown out, Triad/Bursch glasspack type muffler and put on the open exhausts someone had along with them at a dyno day the Porsche club put on. Then I had around the high end for torque and the low end for HP for stock 3.0s with '74 style heat exchangers , which correlated with my cam setting more or less. Turned out loud didn't necessarily mean worked well.

Walt Fricke

Again before we assume something is, in fact, wrong, tell us what you are comparing it to. Did you drive something fairly quick before you bought this car? A Corvette, Mustang, Mitsubishi EVO, WRX Sti, etc? If so, the SC will feel sluggish when compared to these cars (as will a US spec Carrera, btw). Remeber, these cars only had about 180 HP when new and the power delivery was (and is) a little peaky. SC's and Carrera's have a better low to mid range than the earlier smaller displacement engines but they still don't give you much until just past 4,000 RPM or so, then they come alive and pull nicely to 6,000 RPM or so before tapering off again. However, if you do a redline shift the next gear should drop you right back into that 4,200 RPM sweet spot for another decent pull.

If you short shift these things (less than 4,000 RPM on the upshifts), they feel kind of sluggish.

You might check to see that all your vacuum lines to the CIS WUR and the dizzy are all in good order and are reciving vacuum at the right throttle closed time. After my rebuild, I noticed the same thing at the top end, then I realized that my vacuum was not right. Once I got that all lined up, the car had much more at the top end.

check that you are getting cpomplete opening at the throttle body. Many are incorrect.

20 some odd years of no distributor maintainence can lead to sticky advance weights and blown advance/retard diaphragms. My dist. was hammered.... crusty and whatnot and I live in california where corrosion is less than most states. One of the most overlooked components on the car at these advanced years. Search under distributor rebuild and learn.

good luck

When I dropped my engine the experienced guy helping pointed out that my bell crank bushings were gone. I presume they were once plastic. So there was alot of play with the bell crank. My friend pointed out that when the accelerator was depressed, because the bell crank had so much play, there was a long delay before the bell crank opened up the throttle switch on the engine. I think that is the correct terminology.

Thanks for all the replies. I think a timing check, vacuum check, and a look at the fuel mixture is probably in order. And a look at the distributor. The former owner was meticulous, but it doesn't mean these are adjusted correctly.

I have only driven one other SC, and it was a BAE turbo conversion. It, too, was pokey under 3000. I am comparing to my MFI '72 that was not rebuilt and had ~140 hp. It didn't seem much slower and did pull hard above 4000. The SC just seems NOT strong where it ought to be strong.

I've got a NA Toyota MR2 with 115 ponies that seeems to perform about the same, and it has no torque curve at all.

Just a thought here. Was the car originally from your area? Boulder is high, like 8 or 10000 ft above sea level, or something like that, right? Check to see if your WUR is working correctly and if you have one w/ the altitude feature. Also make sure your mixture is right for this altitude.

Hmm, if it feels like your MR2 then I'd say something s's not right (like you guessed all along). I wish I could offer more than basic advice but I can't because I've got a Motronic equipped Carrera and I have no experience with the earlier fuel injection and ignition systems.

Everything I've read in this thread seems possible so I'd check all of that stuff. By the way, one of the guys on this board had all kinds of issues with his engine and finally found that his distributor was the main culprit (although there were a host of other smaller issues too).

Good luck. Have you posted pics of your new car, btw? This is a tradition on this forum. It is required or you will be banned (just kidding).

I too had a 72 and the sc is noticable faster.

Get back to basics. Does the throttle open all the way?

-Joe

My 79 SC was a real slug last summer and I planned to sell it.
But I gave it one more chance. In September I put on a Bursch steelpak muffler and Fabspeed airbox cover and the beast awoke. These cars respond to small changes with great results. You can shed a lot of weight by ditching the AC and factory seats. :cool:

like said over and over, compared to what ? GT 40 ?? yup slow compared to a Yugo ? ought to be fast... in the end a dyno will tell the engine health

Very helpful. If it hadn't snowed on me when I was out there with my head under the deck today, I would have begun with the timing and distributor check. Manana.

Paul, we're at about 5700 feet. Weakens a car by 10-15%, but then everything I drive is weakened.

I can't figure out how to post the pictures, Scott

Re picture posting:

When you select "POST REPLY" in the lower right corner of the thread on the bottom of the page, you'll end up on the main, more capable, reply page as opposed to the "Post Quick Reply" section down on the very bottom of the page. Anyway, near the bottom of the reply page you'll have a hyperlink that says "Click here to Upload a Photo...". You'll get a smaller window with a "Browse" button. Press that and it'll direct you to your computer's file system. Locate a photo you want to post and select it. You'll then be re-directed back to the previous window except that this time you'll see the file path to your picture in the small little window. Select the "Upload Now" button and after maybe 5 to 15 seconds the file will have been uploaded to Pelican's server and you'll be redirected to the original reply page, this time with the full address to your picture. You won't actually see the picture until you post the message or select "Preview Reply" in order to see what your pic will look like before it's actually posted (a proof-read, of sorts).

That's the main way to post a picture. There is another way, but I won't go into that right now (just to keep this post within reason).

Good luck and let's see some pics.

If you r used to a turbo car, there is no losses with it generally at higher alt.