3.2 engine rebuild advice.
 

Hi
I have an -84 3.2 engine in my car. Recently I noticed an exhaust leak and found one broken head stud on cylinder 6.
I decided to get right on it and do a quick change, I purchased Supertec studs and gaskets from Pelican and some while-your-in-there-upgrade-cams from Camgrinder.
Today I disassembled the engine down to the block and thought that I would examine the heads and valves while I was at it.
I found that every single valve stem was out of spec, didn't expect that. I can't verify how many miles are on it since I bought it second hand, but it should only be around 25000 miles, but it has been stored for almost 10 years before I bought it. So far it has shown very little wear. It runs strong, consumes very little oil, but the valve stems has a taper to the valve head end. Valve Guides is probably not that great either.
Another strange thing, one of the intake valve guides has had some work and has a "sleeve" insert. If I hadn't seen that I would have sworn that the engine never had been opened! It is possible that it has 25000 miles on a previous rebuild and they kept the valves...
I had not planed on splitting the case, but I'm not so sure now.

Is it possible to have worn valves after 25000 miles??

Should I open the case and examine the bearings?
How much extra money is it if I open her up and I don't need to change anything, just a few nuts and bolts?

Bummer on the stud find. Great choice on head studs. If you don't know how many miles are on the engine, have the valves and guides done. Sound like this engine has more miles than you thought. If the cams and rockers were good then playing the odds the bottom end should be good. Judge it based upon how much wear was on the top end.
Most bottom ends are good for 200,000-250,000, if the engine has been well taken care of. I did a full rebuild due to two broken studs. Parts are not a lot more to go all the way but there is cleaning, balancing, polishing and all the extra labor/time. Some decisions based upon the wear that you can see on the top end generally is similar on the bottom end. The other is cost. How much do you want to spend?

My rebuild was great fun to do and the engine is much stronger due to a few performance mods and larger P & C's.:cool:

I had a 97 3.6 with about 60,000 miles on it. Steve Weiner suggested not splitting the case, but remove rods and inspect bearings. The bearings looked good, so I did not split the case. He's the man, afterall.:D

Emerald

The cams and rocker are looking very good. One rocker was a little more worn and the cam lobe on that rocker showed sign of wear on the backside, so I guess that valve have been tight at some point.

I'm leaning towards splitting and do quick check just for my piece of mind. I would like to install ARP rod bolts since I'm pushing 6800 today.

I have been thinking.
Are valve stem wear that important??? Mine are worn 0.02 mm, limit says 0.012, but that is tiny compared with valve stem to valve guide clearance of 0.15 mm (intake) and 0.20 mm (exhaust). That is 10 times more!!

Would be great if an experienced engine builder would offer their opinion.

I have no hands on p-car build experience yet, but with other build experience IMHO if the EX valves are treated then the that surface may have been compromised with the 0.02mm loss, which may lead to faster wear going forward and more frequent valve clearance adjustment requirements. EX valves are notorious for getting pitted anyways, so it may help your new motor's performance overall to cut a new seat and replace the outta spec EX valve.

I bought an '86 3.2 with @65,000 miles on it. The valve guides were shot. The intake valves were in spec., but I installed all new exhaust valves. From what I have read, exhaust valves should not be reused. Don't take chances with the valves, If one fails it can take out the entire engine.
Bottom end was in good shape, as well as the cams and rockers. New rings were installed, had the nikasil cylinders cleaned up.
I only have about 1,000 miles on the rebuild. It running great, no noticible oil usage yet, no puff of smoke on startup, and no oil leaks.

I have just gotten the heads back from the machine shop. I replaced the exhaust valve guides and valves.
A friend had a used set of exhaust valves from a 965 that was in good shape.
Also the machine shop cut all the seats and valves, intake and exhaust.

That's the way to do it! If you're gonna do it at all do it right;)

You don't mention replacing the intake valve guides. Were they in spec.? The 3.2's are known for valve guide wear. Newer guides are supposedly better material.
Have you checked the cylinders, pistons, and ring lands? Excessive clearance in the ring lands will cause problems.

Intake valveguides where in spec, had the machine shop confirm that.

Cylinders and pistons "looked" ok. Ring lands I measured and the clearance was in spec.
I'm not that worried about the engine, it consumed very little oil, no strange sounds and was recently dynoed to almost 270 fwhp with only external modifications.
I'm also adding 993SS cams from camgrinder to the mix now :)

As I rebuilt my 3.2 over the winter and also did not replace the intake guides, may I ask....

What if any wear was there on your intake valve stems?

Yes, there was. They were in spec, but just barely.

safe,
You are doing everything right. I would not split the case. No justification for it. Even if you want ARP rod bolts you still don't need to split the case.

Good Luck,

Mark

Update:
The engine is back together since a few weeks, leaks oil from cam towers... crap...

Was on the dyno yesterday for tuning, kind of an anti climax powerwise, I'll have to talk to camgrinder about it.

Safe

How much did it dyno?

10 hp less than with stock cams... 255 fwhp.

Which is a lot less than the 20+ argument that sold me the cams...

That sucks :(
was it on the same dyno? have you find any wrong with the cams?

Same dyno, the weather a cool autumn day. The engine just didn't breath as well. Maybe I can change the timing from 1.8 mm to a more stock 1.4 and gain back the lost power. But it will cost me money on the dyno (~$300), a lost work day, a tank of gas and a lot of time...

To be clear, this 3.2 has 50mm ITB's on it. There is something up with this combination, and I do not believe it is camshaft related.
Here is the dyno graph,

http://drcamshafts.com/pp/magnus.JPG

This is a good comparison of the stock 3.2 cams vs. the 993 SS cams in a 3.2 engine,

http://drcamshafts.com/pp/PorscheStock.jpg
http://drcamshafts.com/pp/PorscheCam1.jpg

Could it be that the carbs need rejetting to match the new cam profiles? Did they run and air/fuel ratio on the dyno?

No carbs, EFI system. The power curves you see is after dyno tuning.