Track944s

With a longtime '88 944S in the family that will be a track car: I have replaced plugs, wires, oil cooler connections, belts , rollers, water pump, rubber hoses, low temp thermostat, cleaned and powder coated the valve cover and intake manifold, a camshaft , and that plastic chain guide. Down below we put in a Lindsey oil baffle and replaced all rod bearings and bolts. With 200,000 miles, I may need to go further into the engine so I'm looking for recommendations on what items would I be stupid not to replace?

With good compression and no smoke, should I replace valves, lifters, springs? Should I have the rings replaced and the cylinder walls honed? Should I replace the main or any other parts? Are there areas of the trany that need replacing at this point (though no known issues) with a clutch having 50,000 miles on it..replace?

Thanks for for your input and feedback and I'll let everybody know how it turns out.

kev951

with the amount of miles you have on the bottom end, I would keep going.. Also , has the head ever been resurfaced? Our engines utilize a special silicone coating on the cylinder walls (alusil) I am sure there is about none left on your cylinder walls.. This is where things can get very costly. Since its an NA car, you could just drive it to the ground until the bottom end starts pushing oul throught the rings. I am suprised your valve guides haven't crapped out yet. All I can say is, if the car has not been driven on track yet or has not been driven hard the way it should be... you will start to notice your smoking and power loss shortly. All of the compenents need to be checked before you replaced them (valve springs, valves, Pistons, rings, rods, crank, block, head,) you need to take some time and care to check these, or , have a machinist check them for you. But you still need to remove them to check.
good luck

V2Rocket

i'd refresh it all if youre going to track it. that said, the cylinders may not need honing if not scratched.

86 951 Driver

I would at least refresh the head and throw in some rod bearings.

Track944s

Thanks for the thoughts. A few questions:
kev951: It sounds like I need a machinist to get the head and other items checked. I assume special equip is needed to do this, what is it called (so I filter out the shops that just "send it out")?
V2Rocket_aka944 : If I am going this far (taking the engine out), could I realistically increase the size of displacement to say 2.8 or 3.0, or is the happy thinking?
86 951 Driver: I take it the head is a given for you, and if all else looks good, then just the rod bearings--which are done now?

kev951

first of all , the head must be pressure checked and checked for warpage... the valve guides are toast and will need replacing .. the valve seats need to be checked for sealing against the valves. the valves need to be checked for trueness (must be straight) and have no cracks ( they will be cleaned) . the valve springs are checked with a special fixure that measures the working forces the spring is designed to work around. As far as the cylinder walls go, scratched or not, you will absolutley need to have the silicone pastel reappliied( sunnen an30 paste I believe it is called) which will actually make the bore about .001 " smaller. I highley recommend having the bores kissed with a hone (about .002 to .004 ") and then having the sunnen paste applied, assuming you don't need any new parts or need to bore the cylinder walls to the next size up. The piston diameter must be measured in cunjunction to the cylinder bore before any machine work takes place. The crank shaft will get a cleaning and measurement and magnaflux to check for cracks. if you rod and main journals are ok. then all you need is a polish and nitride process for a track car. If the crank has some damage, it will then be cut and oversised main and or rod bearings will be required.. the rods will be reconditioned if ok , so now is the time for arp rod bolts. Have everything balanced by the machine shop or a reputable balancer !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I'm am going to stop now before this becomes a 10 page writeup.. Any machine shop that specializes in AUTOMOTIVE engine work and prefferably in European (just about all aluminum engines) is your best bet. check on yelp too!

MAGK944

I would get the bores and pistons measured first. If the pistons show signs of wear but measure ok, get the skirts coated with PC9 by SwainTech. The PC9 is a good substitute to the factory iron coating applied to the skirts. If the bores measure ok, but show scratches you can hone and finish with AN-30. The AN-30 doesn't make the bore smaller or larger, it removes the aluminum alloy but leaves the silicon particles at the surface in place. In effect restoring the factory finish.

racer

Run it till it breaks.. Nothing would be more depressing than to have all this work done, suffer an oil supply issue and roast the whole motor. $$ wise you are still ahead of the game as this 200K mile motor hasn't cost you anything.

xsboost90

its not a coating. 911's had nikisil coating for awhile. We have aluminum blocks made with a high amount of Alusil IN THEM! When you have the bores polished it brings it to the surface- simple explanation- if they look good and you cant catch a finger nail on any scratches i usually leave them.

86 951 Driver

I would at least have the head refreshed. Take it to a shop who knows these cars. My car only has 127,000 miles, but it valve guides and seals needed to be replaced as it was smoking a little bit after I deleted the cat.

kev951

The sunnen past will absolutely change the final bore diameter making it smaller by up to one thousanth of an inch (.001") which can cause improper piston to wall clearance if not accounting for the change..I also stated that first check before ANY machining sholdl be done.
Happy Holidays!

MAGK944

Please explain how removing material can make the bore smaller? AN-30 is not a coating, it's an abrasive. It's job is to remove the aluminum particles in the Alusil (aluminum silicon) bore thereby exposing the silicon.

Track944s

Thanks for all the great info!. Based on the feedback and our tolerance for the amount of work at this round, we are going to do some head work and fuel line replacement then put all back together. One follow-on question: on the S models, what do the camshafts look like at TDC? The factory manual seems opposite the pics on this BBS. I am good with the crank indicator, but knowing which cylinder's lobes are "up" at TCD is what I am confused by.
The factory seems to indicate that #4 lobes are facing up while the BBS pics say #1 lobes are facing up....Any help would be appreciated.