rebuild 3.0 or used 3.2?
 

I have an 1981 911SC with approximately 170,000 miles. There is one broken headstud on exhaust side of the #6 cylinder. Recently, that cylinder has developed an oil leak and is losing compression. I believe the head gasket is blown. Otherwise, the engine runs well (4 bar+ oil pressure and no smoke). It is definetely down on power and seems winded by 5K RPM. The idea of a 3.2 swap seems appealing with little down time and increased power, especially at the top end.

My fear with rebuilding is that when the engine is actually disassembled, I will need, at the very least, one new cylinder/piston/head (if I'm lucky!)

1) If I decide to swap, what is my 3.0 worth in this condition?

2) I'm capable of a DIY rebuild, but I like the ease in tuning and upgrading of the motronic 3.2.

3) Other than rod stretching and worn valve guides, what problems do 3.2's have? Are broken headstuds as common as with 3.0's?

I'm on an extremely limited budget. What can I expect to pay for a used 3.2 in good condition?

Your knowledge is greatly appreciated.

TODD

I'm sure you've already done some cursory figuring. Suppose a 3.2 with brain costs $6000. You might get $2000 for your motor. Could you do the rebuild for the 4K diff? I bet you could. Wayne says no in his book.

I guess it all depends on how thorough you would be in the rebuild vs. having a used motor in your car. Any way you slice it, the job ahead is expensive.

Or, would you necessarily have to take a $4000 hit to sell the car? Maybe you get out altoghether and get a Carrera with the issues already taken care of by someone else.

but if you rebuild your current motor, you have a known quantity. If you buy a 3.2, who's to say it won't snap a headstud sooner rather than later (unless it has been rebuilt).

I'd say rebuild what you have...so then you'll know what you have. A full rebuild probably will not be necessary. In terms of costs on factor will be if you decide to rering during the rebuild. Then you get into the aulisil (sp?) vs. nikasil (sp?) cylinders. There's a long thread on the engine rebuilding forum about reringing aulisil. With my last rebuild I needed to replace the pistons and cylinders so that drove up the cost accordingly. From my experience it is hard to nail down rebuild costs until you get in there to see what really needs to be done.

Oh and other option would be to buy a used motor from partsheaven or dcautomotive and sell your motor as a core. Of course a used motor would be an unknown quanity to some extent but you would know about compression, leakdown and headstuds on the front end. Buy a used SC motor for 4500 (or so), sell your motor for $2000...to me that would be the easiest solution.

A 3.2 swap would be more expensive and a bit more complicated. But you would get more power and electronic fuel injection.

All a matter of time and money I suppose :)

Also, FWIW, there are alot of miscellaneous hidden costs with swapping a 3.2 into an earlier car that aren't often brought up. New clutch, pp and throwout bearing, possibly a ring gear, fuel pump, fuel lines, fittings, and all the other little things. I bought my 3.2 for $6k, but the swap ended costing closer to $7k by the time I was done....

Mike

Ante up and go for a 3.6 conversion...


"Where's the beef" 3.6 litre that is where it's at....


Unfortunately it has a tendency to drain the ole bank account :)

This is cross posted to the Engine Rebuilding forum.

I know you don't post here often, but please do not do that in the future.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/176244-rebuild-3-0-install-used-3-2-long.html

What a quandry! I'd love to install a 3.6 or even a 930 motor, but this is out of the question. I bought this car as a toy (read: second car), not to spend 2/3 of what I paid on an engine rebuild. My budget is about $4K. I'd much prefer to find a good running 3.0 and maybe drop in some hotter cams and exhaust. On the other hand, a self rebuild is tempting.

I agree with Nostatic -- any used engine could end up being another "problem motor". What I'm trying to do is get my 911 back on the road and running correctly for a minimum cost. In
a year or so, I will be in a much better financial position to upgrade.

Any other suggestions?

Despite the 3.2 being bulletproof, I think Todd's right on this one. If you rebuild the 3.0, put tensioners in, and do the rest of it "right," you'll have a great "zero time" engine as they say in the aircraft biz. My first choice would be a 3.6 conversion. Absent that, I'd go the 3.0 rebuilding route.

For $4K go the rebuild route. Sourcing a solid 3.2 is not that easy right now. you'll find plenty at 80K - on miles that have been out of the car a while, but the likelyhood they will be problem free is questionable. Besides the additional costs of doing the swap right is out of your 4K budget.

The 3.0 is a great motor. get yours back in shape and enjoy.

rebuild hi mi 3.0L for $4k?
 

Do you really think you are going to rebuild such a high milage 3.0L for $4k? The p/c will probably be out of spec. I used out of spec p/c in a rebuild and regretted it. New ones are over $3k. Reconditioning the heads is another $1k. You are already over $4k and haven't done the head studs, reconditioned rockers and cams, etc. I seriously doubt you could rebuild your old engine for $4k without cutting corners which I once did and regretted. Guys, tell me where my projection is wrong.

I've had top end rebuilds on two 3.0 motors. First time cost me $2500 and the second time $3500 because it needed P&Cs. I suppose it depends on what you mean but cutting corners. If parts are in spec they may not need work or reconditioning. Depends on the condition of parts once you get in there. A 180K SC motor could be just fine on the inside.

http://ourworld.cs.com/Chuck21401/shortblock.jpg

I had to make a similar choice between rebuilt 3.0 and a used 3.2 or 3.6. I chose the 3.0 and had some extra goodies thrown in for the same price. Sometimes when on a tight budget it pays to spend a little more for a sure thing. For a little more than a good used 3.2, You could have your 3.0 professionally rebuilt with a warranty. The 3.2 engines are not getting rather old and used-up too. With a little bad luck, you could have a 3.2 needing rebuild this time next year and be in the same position as you are now, but with $4-6K less in your pocket.

If you buy a used 3.2 you don't really know what you have. You can be lucky to find a good one, but the opposite is also possible.

If you rebuild your SC engine you know exactly what you have. Also if you're going to replace cylinders & pistons you might rebuild with 3.2 cylinders & pistons. That way you'll have a 3.2 SC with a little more power although not as much as a Carrera 3.2.

In the first half of the 80s Ruf made some 3.2 liter SC engines. I think they had 220HP. Just an idea.

The more I think about it, the more I want to rebuild the 3.0 myself. At this point, I have a running (but in need of work) engine. If I tear it open, I'm forced to invest whatever it takes to repair the damage this broken stud has caused. Even though Wayne wouldn't approve, I'm going to attempt an "economy" rebuild -- fix what needs fixin!"

One question: Does a strong SC engine normally pull hard to redline? Even before my headstud issues, my engine felt flat by 5600-5800 RPM.

Thanks again for all the suggestions. When I make a final decision, I'm sure I'll have many additional questions.

mine pulls strong to the redline

Mine pulls strong to redline, but I have a fresh engine with 2K since it was rebuilt. It cost me more that $4K, but I had someone else do the work. I'm glad I went this route instead of buying a used engine. I feel like my engine will be strong for many years to come.