Pelican Parts Forums - Questions about a 3.2 in a SC

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Questions about a 3.2 in a SC

I'm going to look at a 78 SC on Sunday. The car has a 85 3.2 litre engine swap done by the previous owner.

The car needs a respray but since I want it solely as a DE car, I'm comfortable with that. The price ($7500) seems pretty good assuming the engine has compression and leakdown numbers that are in spec. Mileage cannot be documented.

I need advice on:

- Compression - am I correct that I should see compression readings somewhere in the 155 - 175 with no more than 10% variation

- Leakdown - no more than 10%. This should be done cold right?

- Have those that have done this swap added a carrera cooler up front or is the SC loop able to cool adequately?

- Any other issues in regard to dropping the 3.2 into the SC that I should be concerned about?

Thanks for your help.
Craig
88 Club Sport - See it at: http://www.pelicanparts.com/cgi-bin/pmpre/pm.cgi?login=88_Club_Sport&ID=123515&ID=123515&act ion=display
95 Ducati 900ss
77 Yamaha RD 400….. the wheelie machine

I believe it is more important that the numbers all be within 10% of each other, rather than how high they are.

The loop cooler would handle normal street driving, but if this is to be tracked, I would invest the modest $ to install a carrera cooler.

My dad has a ’81 SC w/ a ’86 3.2 in it and I’m his mechanic for it. It’s a nice conversion for it. The biggest concern would be premature valve guide wear but the leak down should give you a good idea if the engine is sound.

Make sure all the gauges work properly, it will be an indicator that they knew what they were doing. A Carrera oil cooler is a must IMO. For a track car you might want even more cooling.

That price is cheap. It might need a lot of suspension work like all the bushings if they haven’t been done. Good luck!

Even if it needed valve guides that price sounds pretty good...

When doing a leak down I think you can tell what it needs depending on where you hear the hissing of the air leaking out...right? Perhaps BA's book talks about how to use a leak down test to evaluate a motor's condition.

I would be interested to see where the DME unit was mounted and if the wiring looks clean. Seems like you would have to run the DME wiring harness from the engine compartment to under the seat or something. I'd also pay attention to the fuel lines and how they were adapted from the CIS fuel line system. Perhaps before looking at the car you could get an understanding of how the fuel system works on a 3.2 car and a CIS car and then look to see where the lines hook up and if it was done properly.

DME should be under the drivers seat. The conversion is a lot like the 3.6 conversion but the engine fits perfect and mates to the 915 w/o issue, b/c that's how it already was.

Thanks Guys..... I'll post an update after I check it out. If the motor is tight, it may be a good way to get back on the track without jeopardizing the Club Sport. I realize that is what the Club Sport was intended for but with only 26k on the clock, I'm never able to push it to the limit on the track.....It's just too nice.

Ryan....agree about the cooler, I ended up putting one in my 80sc when I was time trialing it. I'm sure you are also correct about suspension, but I do expect to be doing a bit of suspension work in preparation of track duty.

IMHO Valve guide wear will not show in the compression or leak down numbers unless it is very excessive.

Valve guide wear will show by a huge plume of blue smoke at startup after sitting. So get the seller to leave the car unstarted before ou show up and then have him start it with you behind the vehicle.

The other time you can see valve guide wear through blue smoke very nicely is if you WOT it at higher rmp and then get off the gas apruptly. You can do this test when you take a friend to the car viewing and intstruct him to drive behind you.

PPI still a must. The 3.2 will want the radiator oil cooler, there is a reason porsche put that on the 3.2. :)

George

I looked at the car on Sunday....her goes:

Motor/Trans:
It had not been started in 6 weeks, it fired right up and there was no blue smoke to indicate any premature guide wear. The car went in to the shop today and the following were the results:
Compression: 135, 140 , 140 , 135, 140 140
Leakdown : 5, 4, 4, 4, 5, 4
The trans has approx 80k on it.....syncros seem ok.
So, based on what each of you have said above, it would appear the motor is pretty sound......agree?

Body
It was originally metallic blue and then has a poor grey respray over it. It's pretty ugly. The left rear fender flair has been hit but can be fixed....not major. No rust that I could see. Seems to be a solid body. Chrome trim that could do with some work.

Interior
So so.....as expected for a '78 vintage car. No power windows :) Air is after mkt below dash but not sure that is an issue since it will most likely come out. All gauges work.

I see no reason to believe that for the price, this will be a good DE/track candidate.

I need to call the seller back tomorrow....anything else you recommend I consider?

Thanks for your help.
Craig

Sounds like it is mechanically in presentable condition! Great news!

However, seems like you are unhappy with the paint and body. Will it be bearable for a while like that or will you have to go in and fix the damage and repaint the car right away? That can be a can of worms and is very expensive if done right. Even a cheap paint job will run 3k and up.

It all depends on what you are after and how important cosmetics are. Sure sounds like a decent start for a fun car that you can work on as time and money permits. I always think it is good if they are in running condition as you can have fun and take it from there.

Keep us posted and good luck!

Cheers, George

PS: Make sure you do not overpay this beast. I think it is not a very valuable car, even with a solid drivetrain. It is after all an engine repacement and has sever cosmetical problems.

Sounds like a great price and should be an excellent track car. With regards to the oil cooler, I still have the SC trombone cooler in mine and while I run very warm on 100 degree track days, I have managed to keep it out of the danger zone. Adding a duck tail to the rear helped keep the temp under control. I intend to add a cooler for safe measure, but you can track the car without doing so. For street use, the trombone is more than adequate.

Sounds like a great deal, engines looks to be strong but for sure add the carrera cooler or 84-86 brass row cooler, it helped mine on hard runs by 30 degrees.
If you remove most of the trim, headlights, taillights & rubber and do the re-install for the paint job you should be in the 2400 -2800 range for a good job.

Rick

Thanks again for the feeback guys. Once last thing that I did not know untill today was the the PPI mentioned the clutch to be "heavy". The mechanic indicated the pressure plate maybe failing. Given the intended use, I need to count on a motor drop and a clutch it would appear. I'll need to search for help on that :)

Anyway, looks like the SC will be sitting next to the CS for Christmas. The seller agreed on $5750.00.........

Craig

88 Club Sport - See it at: http://www.pelicanparts.com/cgi-bin/pmpre/pm.cgi?login=88_Club_Sport&ID=123515&ID=123515&act ion=display
95 Ducati 900ss
77 Yamaha RD 400….. the wheelie machine

I know you shouldn’t go by the actual compression numbers but they seem very low for a 3.2. The 170 range would be more inline for a 32.

Tim

$5750 seems like a steal to me. A tired 3.2 motor alone would go for around $2500-3000, no?

Heavy clutch could be a number of things. Things not expensive like a clutch cable or pedal bushings. Let's hope that's the case. Could be other things like release bearing or guide tube wear. Neither of which are all that expensive, just that you need to pull the motor to address them.

If you're going to do a cooler, then don't skimp and settle on a loop cooler. The radiator/Carrera type is the way to go.

Wayne posted this awhile back regarding compression tests (note the part I put in italics):

Quote:

So what to do with the results? In general, compression tests are limited in what they can tell you. It is important to remember that different compression testers may give different readings as well. Cranking the engine faster (with a stronger battery or high powered starter) may also skew readings. The most useful piece of information that you can glean from them is how each cylinder compares to the others. All of the cylinders should give readings that are very close to each other. This would generally indicate an engine in good health. A good rule of thumb is that each cylinder should read a minimum of 85% of value of the highest cylinder. So, if the highest reading is 150 psi, then the minimum acceptable reading would be about 128 psi.

It is important to note that this would be an acceptable figure, but not necessarily ideal. In all practicality, all of the cylinders should be very close to each other (within about 5-10 psi). On a newly assembled and run-in motor, compression numbers are usually within this range. As the engine ages and certain parts wear faster than others, one or more cylinders may experience a bit more wear than the others. This will definitely show up in the compression tests. Needless to say, if you have all of your cylinders in the 150 psi range, and one cylinder is down around 120 psi, that should give you cause for concern. The important thing is to remember is that you want to gather consistent readings across all of the cylinders, without focusing on the actual values. If a reading is significantly off, go back and test that cylinder again to make sure that the measurement was not caused by some sort of fluke, which is often the case.

So what causes variations in compression tests, and why can’t they be used as the final word on engine rebuilds? The problem is that there are several factors that effect the final pressure read by the tester. Engines running with very aggressive camshafts have a tendency to give low compression readings. This is because there is significant overlap between the intake and the exhaust stroke on the cam. During high-rpm operation of the engine, this overlap works to give the engine more power. However, when turning the engine at a low RPM, as with a compression test, the overlap causes some of the pressure in the combustion chamber to leak out before the valve is closed. An early 911S engine, for example (with its high-overlap cams ) has a tendency to give lower compression readings than the 911 CIS engines (1974-83), despite having a higher compression ratio. This is caused by the aggressive overlap of the camshaft.

Altitude and temperature also affect the compression readings. Manufacturer’s specifications are almost always given at a specific altitude (14.7 psi at sea level), and 59° Fahrenheit. Both temperature and barometric pressure change as you go up in altitude, so you will need to correct your measurements if you wish to compare it with a factory specification. The following chart provides conversion factors for correctly compensating for changes in altitude:

Compression Test Altitude Compensation Factors Altitude Factor

500 0.987
1500 0.960
2500 0.933
3500 0.907
4500 0.880
5500 0.853
6500 0.826
7500 0.800
8500 0.773

A standard compression reading of about 150 psi at sea level in Los Angeles would measure significantly less in the surrounding mountains. For example, at an elevation of 6000 feet, the expected reading would be 150 psi X .8359 = 125 psi. The cylinders would be reading low if compared to sea level measurements, yet perfectly fine at this altitude.

Another factor that can alter compression test readings are incorrectly adjusted valves. If the valves are not opening or closing at the correct time, then one cylinder may read vastly different than another. Make sure that your valves are adjusted properly prior to performing the test. For the complete procedure on adjusting your valves with the engine inside the car, take a look at Project 18 in the book, “101 Projects for Your Porsche 911.” Along the same lines of thought, premature camshaft wear can also lead to variances in compression readings, however, this type of wear is not normally common on the 911 engine.

You can determine if the rings are causing low compression readings by squirting about a tablespoon of standard 10-30W engine oil into the cylinder. Crank the engine 2-3 times to spread the oil around inside the combustion chamber. Then retest the compression. If the readings shoot up significantly (45 psi or so), then the problem is most likely with the piston rings seating to the cylinders. Squirting the oil inside the combustion chamber in this manner allows the rings to temporarily seal quite a bit more than they would dry. If the compression readings do not change, then most likely culprit is a leaky valve.

-Wayne

Looks like good compression #'s when altitude correction is made! Good that the #'s are all close in value.

Craig,

Pull the AC unit and wait till early summer for an EBAY listing. That'll pay for a portion of the cooler or paint job.

Great deal...good luck.

Excellent deal you got there. You really can't go wrong at that price. Wayne's writeup about compression testing also gives good insight and is very correct. I think the absolute numbers are always overrated with us gear heads.

Once you are done painting, I think you should trade it for like an 81 with the original 3.0. ;) How about wine red metallic?

Cheers, George

Sorry George but after all of the work I expect to put into this beast, she'll be a keeper :)

The seller has been absolutely amazing to work with.....real nice guy. He paid for the pre-inspection (never heard of that) and also through in new plugs while they were out and changed the oil/filter! Can't get much better than that. He's even having it flat bedded over on Saturday (snow's in the forecast).

The body will stay in its current condition this year. I'm going to concentrate on suspension (torsion, sway, shocks, brakes etc) and the interior (seats, harnesses, wheel etc). I'll also need to get 8 x 16's for the rear and put the 7's up front.

The body will probably be next year.....fiberglass front and rear, add the 993 mirrors which the PO just bought and paint her. I'm envisioning the body white with red graphics and the rim centers painted red.

The last project was a 914 2.0 for the track......this one has me more excited!

Gone.. but not forgotten, a 911 in its natural habitat:
http://2kcrew.lunarpages.com/imagehost/PIR911.jpg
Can't wait for pics when she's done.
-the PO

Quote:

Originally posted by aigel
IMHO Valve guide wear will not show in the compression or leak down numbers unless it is very excessive.

Valve guide wear will show by a huge plume of blue smoke at startup after sitting. So get the seller to leave the car unstarted before ou show up and then have him start it with you behind the vehicle.

The other time you can see valve guide wear through blue smoke very nicely is if you WOT it at higher rmp and then get off the gas apruptly. You can do this test when you take a friend to the car viewing and intstruct him to drive behind you.

You don't always see smoke like this when you have valve guide wear. If the exhaust valve guides are the worn ones all the excess oil gets sucked unburned into the exhaust with no smoking.

So, you are telling me the oil will drip out of the exhaust pipe eventually? I would think it still gets burned. Maybe not in a big blue puff all at once, but I don't think it will get away. :o)

George

oh, one more thing. Is it likely that the exhaust valve guides go out all by themselves, without the intakes also being old?

George

Thanks again to all that pitched in with advice. Well, she's home and I'm excited to rip into this project. Wonder if my boss would give me an advance on next quarters bonus :)

The car is solid as suspected. No rust to be seen at all and while I'm not a lover of the color of the interior, it is clean. A couple of sport/race seats, my harnesses and bar from the CS and the interior will be adequate to get going. A roll bar and a light weight black interior will be down the road.

Not sure exactly where to start but I think I'll order up some Sanders 22/29 mm torsions and a set of Bilstein sports to get the suspension going. Since this is being done with a budget in mind, I think I'll look for a set of sway's from a '86 as they were 22mm front and 21 rear vs the 20/18 of the SC. I know I'll want adjustable bars later but this would be a good start/compromise. Thoughts on going the '86 sway bar route vs. adjustable bars?

Craig

http://forums.pelicanparts.com/uploa...1071960504.jpg http://forums.pelicanparts.com/uploa...1071960524.jpg http://forums.pelicanparts.com/uploa...1071960537.jpg

Craig,

Great deal on your new car!

It will be a great track car for you, I'm sure. You've got a ton of things to consider as you begin your modifications.

As someone races here in Colorado, I think I can offer you some good advice.

I would definitely plan to install a front, center mounted oil cooler. The thinner air here dissapates less heat than at sea level. I've screwed around with various coolers and ended up with a mocal but fluidyne makes a nicer one. Save yourself the time and money and just get a big one out of the gate. You'll need it eventually and they cost less than a Carrera cooler/fan set up. Dave at Dart Auto can get you one.

Since your car is to be a track car, I'd go with larger bars than you're planning. I agree with using Sander's but I'd use 23 and 31. This is the current hot set up in Club Racing.

As far as sway bars, I think I'd just leave alone what you've got until you can buy adjustables. I don't think you'll notice a difference between the earlier and later stock ones, especially with bigger torsion bars.

All of this sort of assumes that you will end up Club Racing in the future. If this is the case, pay attention to the rules (downloadable from the pca site) so that you don't end up doing things twice. By the way, you would run in F stock which is a very competitive and fun race group thoughout the PCA (also the one I run in).

There are many of us, local to you that have done just what you are planning. Feel free to PM me if I can be of any help.

Jess

Craig,

I would definitely include replacement of the suspension bushings in your plans. 1978 bushings have most likely gone south long ago. Upgraded shocks and t-bars are certainly a wise choice, but new bushings are going to be the most effective way to give the car the precise feel you desire while racing. The suspension cannot respond properly if the bushings are tired. Since you have to pull the spring plate anyway to replace the rear bars, the bushing replacement is a wise "while you're in there" thing to do. Plus, the new bushings are cheap (depending on which you choose..........) components that play a large part in how your cars feels- literally.

With only 62K miles on the clock, my car was very sloppy feeling when I first got it. Especially in the steering wheel. At speed, the wheel was really light in my hands and it had an excessive on-center dead area. After refreshing the front suspension (shocks, t-bars, ball joints, bushings, tie rods, rack relube), the steering feel is much more connected to the road and the on-center response is excellent. Feels more like a track car than a road car now.

Jess,
Thanks for your info regarding the cooler/torsion bars. I pm'd you with my contact info so we can talk live. I'm interested in whether you'd go with 23/31's if the car was to be driven to and from the track and what front bumper/valance you are using for a center mount cooler. Look forward to hearing from you.

KTL, do you have a recommendation for bushings?

Craig

Craig,

I replaced mine with rubber bushings. Neatrix/Weltmeister in the rear and SmartRacing's replacement service for the front control arms. It'll be interesting to see how long the rubber ones withstand the stiffer t-bars. Probably should have gone with the Weltmeister street poly bushings.

If I had to do it again, i'd probably suck it up and spend the money for Chuck Moreland's/Elephant Racing's super cool polybronze bushings. They seem like a great compromise for a street/track car. I especially like how you can lube them (and keep them lubed) via the zerk fittings he pre-installs for you. These bushings appear to be the best for ease of installation too. No custom fitting needed.

For the budget minded, the Weltmeister street or track poly bushings are good, but they need some custom fitting to prevent binding. Which can be a bit time consuming the first time you do them.

There was recently a BIG topic about the bushing work.

http://forums.pelicanparts.com/porsche-911-technical-forum/137833-arm-rubber-bushing-installation-advice-needed.html

So, what's the big deal about a squeak here and there? Poly GRAPHITE, the graphite in the material will lubricate things. I don't get the fact that folks start greasing the heck out of poly graphite bushings and machine around on them. If that were needed, it would come like it from the manufacturer. I stuck my bushings in there and have nothing to complain about. In cool weather, if I go over a speed bump, I might hear something. So what?

I had to go in for other reasons and looked at the bushing. Sure enough, after a while, on the inside towards the A arm, there is a nice slippery graphite looking surface. Things are good...

Cheers, George

Quote:

Originally posted by aigel
So, what's the big deal about a squeak here and there? Poly GRAPHITE, the graphite in the material will lubricate things. I don't get the fact that folks start greasing the heck out of poly graphite bushings and machine around on them. If that were needed, it would come like it from the manufacturer. I stuck my bushings in there and have nothing to complain about. In cool weather, if I go over a speed bump, I might hear something. So what?

I had to go in for other reasons and looked at the bushing. Sure enough, after a while, on the inside towards the A arm, there is a nice slippery graphite looking surface. Things are good...

Cheers, George

First off, I've had the Weltmeister "street hardness" A-arm bushings for years with hardly a squeak.
I also lucked out; mine didn't require machining either.

The harder "race" poly bushings are more prone to squeak.
The factory rubber bushings flex to accomodate movement i.e. they aren't a rubber bearing. By contrast, the poly bushing act as bearing. As such, at least one surface will slide against metal - hence the source of squeaks and the need for lubricant. The graphite bearing is not slippery enough.

Because the factory rubber bushing flexes instead of acting like a bearing, the dimensions of the bushing and the surfaces it contacts are not held to very close tolerances. Heck, the rubber is even bonded to the metal surface in some cases. Thus the need for custom fitting and machining when using a non-rubber bushing/bearing.

-Chris