Finally running, big thanks

[ahh911]

Finally up and running 81sc, sounds good, dry, power I'm not completely sure about but it ran very well till I followed some instructions on moving the cis plate up a little, etc.. ended up with surging/mild bucking at 2krpm because I messed with the mixture screw and didn't take notes, ughh it's like I'm in my late teens again with my mom's old Jetta.

Big thanks to all who helped on the board and in PM mode, always taking the time to reply, very cool and appreciated.

Best Regards,
Phil

[ahh911]

Wow, this car is fast! And so darn smooth at idle and up in rpms (5.5K so far). Before work began it sounded like a train at high rpms and vibrated at stop signs quite a bit, I thought it was normal. This now vibrates less than my wife's car.

You won't believe this, two problems, one the connector was damaged at the airflow sensor switch so fuel pump would run, fixed that up today, but this was the biggie, I had the entire oxygen sensor harness lifted up, so it wasn't working. I thought the cdi high pitch sound was the FV. Only when I put one of those little oscilloscopes on the lambda duty cycle test port did I wonder what the heck was going on. I had tuned the engine using the oxygen sensor and a multimeter originally so that it had enough fuel over the 2k-3k stumbling area, so it was rich at idle and lean up top. Anyhow, with this connected right and warm idle duty cycle around 50%, I am surprised at how fast and nice this car is. Amazing little cars.

Phil

[flat6pilot]

Congratulations!

I saw on another thread you had the engine out and had trouble getting it reinstalled. But that was it, maybe I didn't see the thread.... What all did you do to the engine? Was this a rebuild or were you chasing nagging issues?


Yes, they purr just fine when you have them back to spec. and running like they should.

[ahh911]

Thank you Kyle,
I've posted quite a few of the issues needing resolving, it was a lengthy battle, some of it more document/spec inconsistencies, some of it parts out of spec, other's shipment damage etc..

Here's what I had and did:
1981SC purchased fall 2019, no rust, clean and very original, was looking for 3 years and it popped up right in town. Previous owner 14 years in underground garage, the one before 10 years, then it was supposedly pulled from the states in around 89. No accidents that I can see or reported. Straight, compression tested by garage and ok. 87K miles, but more like 100.

How it was running:
Puff on 4 out of 5 startups, oil.
Started well, too well, I think sensor plate connector was open even then.
Coming off of gas around 4.5k rumbles of backfire.
Idle at red lights would dip up and down 400 RPM at times and run with vibration.
Power seemed pretty good.
Ticking from right top bank when hot, metallic in nature with "stethscope" long screwdriver.
500 Miles I drove it.

Always my plan to Pull valve covers right after purchase. So, the same week:
Head stud on left and one on right bank, no surprise but dissapointing, I'd asked the garage to check and he said something about invasive, mmph, don't even have to empty the oil, just put it on a jack so the car slopes the oil into the reservoir, pull off covers, easy check. Also, pitting on cyl 4,5,6 I cam shaft lobes.

Dropped engine using oil sump filter plate as suggested, bought a 24 inch long neck hydrallic jack, that did the job. Tilted the car forward on the torsion bar caps, another jack under tran mount, easy but unnerving.

Up on engine stand, cleaned what I didn't get from under the car earlier. Tooth brushes, basic green type oil remover, etc... till no grit.

Removed all bits. 2 bolts broke in the entire operation, they were one tin bolt in back and one air shroud bolt. Both on cam carrier, ended up drilling them out later on drill press, can't tell the difference.

Exhaust stud bolts, as suggested oxy/map combo from homedepot with small nozzle. 4 shots of red on average per exhust nut/barrel nut with penetrant to shock. All exhaust stud nuts came off the heads with zero damage.

Head bolts, very easy to remove, again as suggested, Map at inside of case (13 year old son doing this) and the 20$ nut extractor kit from the hardware store (I've posted this). Even the broken stud close to the case came out, very nice method.

Sent heads off to be machined by racing shop that specializes in Aircooled Porsche for larger shops. Parts came back with 1 broken fin near intake, cosmetic I suppose and one stud jammed into another pair of fins. ughh... Then I did a light test and the valves were leaking. (posted on this too). Ended up that just a little 320Grit did the work with a dedicated lapping valve. It was less than 1/2 thous off, so not a biggie. New exhaust valves, new springs (springs were aligned so that I could pass a 1mm or so wire between inner and outer springs, that way no contact as it was meant to be for this design). Valves seats cut, mating surfaces slightly trimmed back. 5 shims everywhere ( I measured everything), not a bad job all in all, new exhaust valves. New valve guides, measured those too, good.

In the meantime, 6 new injectors (they are too cheap to re-use or re-build, 24$ each?), new plastic inserts, o-rings, rubber air coupling boots. Vacuum/pressure to the intake and all leaks plugged, etc... Every component checked for vacuum and correct operation, as well as resistance, (Decel/startup valve/auxair fridge,etc) The entire injector/air intake was put on a plywood fixture and hooked up to the car, fuel pump run and the flow rate noted (first time with the orig injector and fuel filter to fush out crap), then a second time with new injectors and new fuel filter. Flow rate into six bottles measured over varying plate lifts. Cold start injector tested using boroscope and attached to thermotime switch, activated as expected and no leaks. Fuel system, good as it ran well no need for pressure tests yet. Also, I checked the vacuum hoses to the distributor, the idle retard? one was plugged up at the throttle body, i think this was the cause of the 400rpm jumps at idle at times. Checked every hose/vacuum etc.. Cleaned runners.

Back to the mechanical. Alusil cylinders, took my chances and left piston in, but cleaned out the cylinder walls by inverting them into solution and gently wiping off carbon. Pushed the piston right to the end of the cylinder and soaked it in solution as well but the solution depth was kept under the rings. All carbon removed from piston and cylinder to a visual degree.

Con rod big end/small end measured, good. Bushing good. Replaced rod bearings with gt3 bearings (they are elliptical vs the orig). The glyco (SA) had alignment issues, the gt3 ones did not. Rod bolts were aftermarket oem, the fat part the couples the top and bottom halves of the rod were 4 thous bigger than the originals, I didn't even try to get them in because it would have been suicide (post on that too). Ended up running them on the drill press and shaving them down to originals, now nice and snug. Tightened each one up to 55Nm (10mm bolt) and checked bore dimensions with and without bearing. Very time consuming. All was good. I also measure each one before the 55Nm test and again afterwards for stretch. None noted. (posted this too). Ended up installing at 58Nm with oil on threads only, far less than would be with 20Nm plus 90 deg as suggested but not by Porsche classic, these were published errors in the two repair manuals I was using, B/WD (close to 75Nm, the yield point of the bolts if angle method). Posted about this too.

Installed everything, all new oil tubes, etc.. everywhere. Loctite 574 on cam tower, paper gaskets but brushed on except the timing chain cover gasket or any gasket that might need a quick look.
Rsr seals for what it's worth. Dougherty cam shaft re-worked to original SC specs (Strongly suggest this, torque at 3.5k rpm is what I like, if I want to rev high I'll take my m3, 8k). Craig G did all the rocker refinishing, great guys, good work, fast turnaround. All new rocker shafts, but polished the rocker shaft nut/bolt ends where they contact, a lip can form and prevent proper torquing. All the rocker arm nuts held at 18Nnm (dry no need to counterhold), but went to 24Nm (JohnW and others on board, great guy). Oiled up rocker holes, etc... timing in place. Used the Stromski? timing tool for the earlier cam nut, wow, just bloody incredible, I could time easily to pretty much whatever value I wanted and zero damage to the nuts or camshafts. Measured clearance of valves to piston for every cylinder, ended up going to ~ 1.45mm lift to ensure ~ 1.6mm clearance, didn't bother finessing it past that. Both sides aligned in spec.

Exhaust was original and nice, wanted the car to run like original since it was so as I found it. Took it to local hot rod place and they welded up the cross pipe where the corrugated flexible section was not pinned down. They polished up all exhaust interfaces. I still had to touch some up using Prussian blue with gaskets until I could see a image of the gasket on every interface, this was time consuming again.

I'm tired of writing my life story, so to sum up, all new rubber hoses, DC 111, I understand why DC55 expanding silicone is used in certain areas and it makes sense but I couldn't get my hands on any. Tran got the Porsche lube calistrol 3 or something? Head studs were all steel, all 24. New head stud nuts/washers (waste of money). Optimolly HT where it makes sense, copper nuts for exhaust, but not manifold.... distributor examined, all gearing inside engine examined with boroscope where possible, timing chain inspected link to link, tensioners primed using syringe and oil, rock hard, pumping them is useless.. Engine bay liner new, the old one was crumbly and definetly needs it, (black oem liner, very nice). Replaced shocks in back (orig 81's removed, bilstein) with the original type, or as close to possible, as I want it like it was designed. Odometer gear, all lights replaced, door light switches operational. Everything but the A/C which I didn't try, but is in place and I don't intend on even trying, I leave it there for originality and the next owner may appreciate that as it's not seized. Checked thermostat, etc... Cam oil lines checked, etc....
Flushed oil tank with cheapo stuff... just dumped some in a drained it basically, 16$ of oil. Tried to check every connector for resistance from one end to the other, discovered the heat fan in back had high resistance, ended up using flux and solder to burn away the corrosion till resistance dropped to near zero, then soldered for good measure. I did miss some wires.. had to catch it later.

Post, 300km
No puff on startup, not once.
No oil consump yet.
Better power, very linear.
No backfiring at any rpm under any condition.
No ticking sounds from engine cold or hot.
Oxygen sensor loop working nicely.
Hammering gas and releasing while wife behind, no puff, only little stink.
Can idle from 600 easy with no vibration and at 5.5k it is very quiet, it's almost too quiet.
Starts nicely all temps so far, idles as expected afterwards.
Rear shocks really helped out, can't wait to do the fronts.
Engine temp at just below first box line.
Like original exhaust, a little quiet but that's the way it was. The heat exchangers were in good shape, one access to barrel nut cylinder fixed up.
I can't find a single drop of oil

Plans:
New oil for next year, m1 15-50, I have the cheap stuff in right now. Keep listening for rocker shaft slipping, ticking, etc.. for another 5k km, then whew.

I've missed tons, these are the "highlights", I have a log book with crazy details,

Phil

Two nights ago: