berni29

Hi There

I have a couple of weeks off work soon and I am looking to reassemble my 993 engine. It is on a stand with the top end stripped. So just conrods sticking out of the case.

I have the following replacement parts:

Reconditioned and fully rebuilt heads
Secondhand low mile P's & C's
Wrightwood racing gasket set
Power steering belt
Distributor belt
Alternator
Fan bearing
Tensioner ramps

Everything else will be going back on the engine having been checked and cleaned. I have not touched the injectors, but did run BG 44K through the car pre assembly.

My cams are the early 964 type with the woodruff keys.

Is there anything I should be getting ahead of time that I might have forgotten?

How much time should I allow bearing in mind this is my first time?

Edit, one of the top distributor bearings is past it's best. Does anyone know where to get replacement bearings? It came apart when I pulled the shaft out. It does go back together, but the inner top race is stuck on the shaft.

Many thanks for your thoughts.....

Berni

geolab

On first reflex,
I would definitely change both chains, you have the new ramps
and pump seals

as for the distributor bearing, you can put it back together and re-grease. The top should disengage from the shaft.
Take some pictures of where you are with the distributor...
ps: you can mount the distrubutor when engine is in the car no problem if need be.

berni29

Hi Geolab

Thank you for the reply. I was wondering about the chains. I am not splitting the case, but can get the split link chains so may well do that. Pump seals, you mean power steering pump seals? Will do if so.

Also I was going to leave the head studs. My engine is an early one with the studs that are threaded at each end. The later 993 ones are threaded all the way from what I understand. Is that right?

I will take some distributor pics as soon as I get started. I am really hoping to get it all back together and running.

All the best

Berni

Bill Verburg

To time the cams w/ hydraulic lifters(if you are still using them) you will need either the factory tools or a temporary mechanical rocker arm and adjuster as well as a means of tensioning the chains

geolab

No I did not know you did not split the case, I meant the oil pump seals.
For distributor, no worries. Maximum, you will mail it to me and I will get it done.

dgmattingley

I've heard/read from various sources that reassembly can take about 40 hours, no idea if this is accurate and interested to hear replies as I'm starting the exact same project. Good luck!

berni29

Hi Bill

I am a bit confused about the timing. I have the 964 style cams in my 993 because it is an early engine. I cannot adjust the lifters because they are hydraulic, and the cam position is locked to the sprokets by the woodruff key.

So the only change to timing has to be at the distributor no?

Sorry to be so dim, and I have read about the timing, but only on the 964 or 993 (without the sproket keys).

Geolab, thank you for the offer! Hopefully it will be OK. I will have a very close look at the bearing and mail you a pic as soon as possible.

Thank you in advance



Berni

IXLR8

Supposedly they are not available.

This will be one of my winter projects. I am making a jig so that I can open up the inner diameter of the bearing to fit the distributor shaft. This should be fun.

If all goes according to plan, I will be supplying these bearings. Of course if one of my bearings were gone, there would be more of an incentive to get started on this. I rebuilt my distributor last winter.

race911

What am I missing here? Cam timing is (nearly) infinitely adjustable. Just depends on whether you're "early" or "late" on if you're using the sprocket-and-pin setup or by tension. And for either you do need a 964-and-earlier rocker arm/foot.

bobt993

Ken, there may be a difference in the euro version considering the early build, but I have not seen one. To the OP your cams have the woodruff key which does alone should not limit the timing. The 964 timing chain setup has a variable sprocket for setting the timing on top of the key way. In the later 993 some of them have the key slots anyways (which is ignored), but timing is set roughly by using a set of alignment guides in place of the cam cover left side and where the power steering pump mounts right side. The covers fit into the slots on the end of the camshafts. The cam is actually locked in place by torquing the bolt on the end of the cam holding the chain gear in. From this point, you still must verify cam timing using a solid lifter and a tensioning tool for the cam chains since the cam chain is tensioned from oil pressure. I suggest you pay an expert to do this and observe the process. Buying the alignment tools alone would be more expensive than paying for some help.

Mike J

Hi Berni,

I assume you have new ringsets, and the tools to measure and install the rings? How about torque tools, you will need both good CALIBRATED torque wrenches, and angle indicators for proper tightening. You will also need adhesives and sealants, especially for the cam carriers to the heads. Do you have the tool to install the clips on the wrist pins?

I timed my 993 engine to 1.0mm lift - that is slightly advanced from the factory setting which appears to be around 0.8mm. You can go a bit more if you want, it will make the car have a bit more grunt at the lower end. I did this with my Targa and most people really liked the way it drove.

In order to determine the specific timing for each camshaft, you will need to measure how much the camshaft depresses the intake valve when you are at TDC. Essentially, 1.0mm is the intake valve stroke in overlapping TDC with 0.1mm valve clearance.

There are several steps to the procedure, including:

- put the crankshaft at TDC without the locking pin in the cam sprockets,
- starting on the left side of the engine, with the timing chains tensioned using a tensioner tool (Its easy to make one),
- position the camshaft on that side so the dot is facing upwards. Use a camshaft tool (P124 I seem to remember) to rotate the camshaft
- setup a dial indicator on the top of the valve spring for piston #1 to measure the total deflection of the valve
- install a mechanical lifter (off an old engine - you can get a used one) onto the intake valve for cylinder #1. You will have to grind off the shoulder of the rocker a bit since the rockers on the 993 area bit narrower than the old ones. Set the blacklash to 0.1mm.
- time the camshaft so the correct lift is happening at TDC (this is several steps condensed into a single sentence!!)
- insert the pin into the sprocket, put the nut back on, and rotate the engine 360 degree to replicate the readings.

Once you have one side, do the right side the same way, but make sure you have done a 360 degree rotation in between.

Once you are all done, make sure the camshaft nuts are torqued correctly, and rotate the engine and measure again to confirm. I did this three times or more until I was convinced I did not screw up too badly.

If this is gibberish or you do not understand this, I recommend you research it until you do. If you get this part wrong, you run a very good chance of ruining you engine due to valve/piston collision.

If you are changing the pistons/cylinders and heads, I would also check the valve/piston clearances. You do that by having the piston at TDC with the cams timed, and then using a mechanical lifter, measure how far down you can mechanically push the lifter down by using the threaded foot until it contacts a piston. This gives you the clearance when the piston is at it top of its stroke to the valves - you need to measure both the intake and exhaust, both sides. You repeat the measurement on both sides of the lobes of the camshafts - because a collision may not occur at TDC, but slightly off that if the camshaft ramp is more aggressive than the piston movement.

Have fun, go carefully! This will take a lot of time, especially if its your first time. I would say a min of 30 hours to get to an assembled engine.

As far as the cam chains, you can replace them but be careful since you did not split the case. Often the sprockets will wear as well, and you cannot replace the sprockets on the intermediate shaft since its buried in the crankcase. A new chain on badly worn sprockets is bad ; but if the sprockets look good then its ok. I would check to see if the chain has worn by comparing the length of say 10 links to 10 links on a new chain. The chains last a long time.

I would visit the Pelican Parts engine rebuilding forum, lots of very good information and help there.

Check out my website http://www.pcarworkshop.com, engine rebuilding articles, for some pictures that might help.

Cheers,

Mike

AOW162435

So, are you a TROLL?


Andreas

bobt993

Bernie, definitely look at Pcar workshop. Mike has a very extensive DIY section well documented and full of good stuff. As Mike suggest you really need the proper tools and experienced help on your first go at putting the engine back together. There are some very big do's and don'ts that can mean taking it all back apart. Even simple stuff like forgetting to install the cooling deflectors prior to the heads and oil return tubes. Centering the heads and proper torquing of the head bolts. Make sure the knock sensors line up correctly since the cylinders can move slightly during assembly (done this one myself). Once you get through the first one you can appreciate the ability of a top mechanic and it will be easier next time around.

berni29

Hi Guys

Thank you VERY much for the helpful responses. I have been reading up and feel much better now. Once I start I will post some pic's etc.

All the best

Berni

geolab

hey Berni , I see you got the Wrightwood racing gasket set.
Where did you find it finally ?