Another 911SC Engine Rebuild

[porschedude996]

Originally Posted by Lowo

I’m pretty sure this would be a nice motor once you’re done with it

Thanks Lowo

[porschedude996]

Yesterday I got my cams and rocker arms, and Head Studs. Is it Christmas?

[porschedude996]

I called on my Cylinder Heads and they are getting new guides and they should be ready tomorrow if the seats aren’t screwed up. Valves and springs are all good. He said these heads have never been touched. Man these 3.0’s are something else.

[porschedude996]

I pulled all the case studs out to clean, zinc plate, and yellow chromate. Then I cleaned the thrust bearing and #8 and lightly greased them. Then greased the crankshaft and installed it the case to ship to Competition Engineering in Lake Havasu. Clutch cover and flywheel are going as well. I measured the HxWxL and found a Coleman Cooler to ship in. Sixty bucks on Amazon.

Case Cleaning, Case inspection, squirter cleaning, micro polishing crank, and balance the flywheel and cover together. About $700

[porschedude996]

Interesting, I have to look for that one. I have seen videos of valves rotating in the head which was eye opening. The speed and direction changing and both valve spinning totally independent of one another.

If you find a link please share.

Originally Posted by dannobee

Years and years ago, I watched a video on a development engine (single cylinder, lab setting) that had a marker applied to the back side of the rings, so that ring movement while running would show up on an x-ray machine. The rings were moving around pretty good. Sometimes as fast as 15-20 rpm, and not always constant, nor even in the same direction, depending on load and engine speed. After watching that, I concluded that being careful with ring clocking wasn't anywhere near as important as we all thought. But looking at any set of worn pistons and rings, you can see the wear as the rings move around the pistons.

[porschedude996]

I just received my heads that Steve Becker serviced. (Becker6.com) He does excellent work. I was amazed how fast he refurbished them and the look great. They only needed to have the guides replaced and the valves and seats touched up.

Wow! These Flat Sixes are made to run forever.

[porschedude996]

One thing I found out with regard to exhaust port suds, is don’t even think about pulling them. On the fourth stud, in snapped 1” above the head surface. then heated it with ocy/acetylene torch and snapped it flush. It’s a good thing i speak “Easy-Out” as a second language. I drilled it out dead center and tried to relax the remaining stud and it still wouldn’t come out. More heat, bigger drill and still wouldn’t come out. Finally I ended up drilling the hole to the normal size to start tapping a blank hole. it worked well and only got steel crips when i tapped it, no aluminum.

[detroit]

I pulled all the exhaust studs out my heads. Probably half snapped. I just welded nuts on them. The heat from welding yields the studs. They come out pretty easy after that...

[porschedude996]

Maybe i’ll try again. I just had the heads reconditioned and didn’t want to make the assembly lube run and burn. May disassemble one at a time. I have the tools and I rebuilt a set on my 911T some 35 years ago.

Detroit, what replacement studs are you using? I was hoping ARP made a set, but having difficulty find them during my limited internet access at the moment.

[detroit]

My plan was to use something in stainless, but Henry's Ti studs look pretty intriguing.
I'm using a set of Ben's headers though. The flange thickness differs from a factory manifold. I need to get that stack height defined before ordering anything.

[LukasM]

Originally Posted by porschedude996

One thing I found out with regard to exhaust port suds, is don’t even think about pulling them. On the fourth stud, in snapped 1” above the head surface. then heated it with ocy/acetylene torch and snapped it flush. It’s a good thing i speak “Easy-Out” as a second language. I drilled it out dead center and tried to relax the remaining stud and it still wouldn’t come out. More heat, bigger drill and still wouldn’t come out. Finally I ended up drilling the hole to the normal size to start tapping a blank hole. it worked well and only got steel crips when i tapped it, no aluminum.

I disagree, I would remove all the 40 year old and very likely corroded stock steel studs while the heads are off and it's easier to do. If you have ever had an exhaust stud snap off while trying to remove the nuts to change the headers/heat exchangers, you will wish you had spent the $100-150 for a set of titanium exhaust studs, which basically don't corrode.

[porschedude996]

I have changed my view on leaving them and not replacing the studs. I’m not sure if i’ll go to ti.

Originally Posted by LukasM

I disagree, I would remove all the 40 year old and very likely corroded stock steel studs while the heads are off and it's easier to do. If you have ever had an exhaust stud snap off while trying to remove the nuts to change the headers/heat exchangers, you will wish you had spent the $100-150 for a set of titanium exhaust studs, which basically don't corrode.

[dannobee]

If you've ever looked at where exhaust studs really take the heat and rarely break, look no further that how Caterpillar puts studs on their over the road turbocharged diesel trucks. Looong studs, then the exhaust flange, then a spacer of about 1" thickness, then the nut. The added length of the stud allows the expansion to occur over the length of a much greater area than concentrating it right at the cylinder head/flange.

[porschedude996]

Originally Posted by dannobee

If you've ever looked at where exhaust studs really take the heat and rarely break, look no further that how Caterpillar puts studs on their over the road turbocharged diesel trucks. Looong studs, then the exhaust flange, then a spacer of about 1" thickness, then the nut. The added length of the stud allows the expansion to occur over the length of a much greater area than concentrating it right at the cylinder head/flange.

I’m not sure that is possible with the stock exhaust system.

[porschedude996]

I tried the Liquid Wrench soaked for two days and no success. I just purchased a magnetic induction heater for bolt and stud removal. I’ll see how that works.

[porschedude996]

I was installing the cam/rocker oiler tubes in my cam towers and found a clue to the orientation. The larger center two cross drilled holes in the tubes align with the recessed dimples in the tower. Of course the small spray holes go down into the cavities towards the cam.

[porschedude996]

After thinking I reconsidered replacing the exhaust studs. I choose to replace the studs and tried the usual penetrating oil and professional type double nut to extract said studs. I still didn't want to flame on with the valves and valve seals installed. I found a fastener heater and it will arrive tomorrow. I'll see how that goes. I ordered a set of studs from Silverlake Inconel studs. If you going to go, go big.

[Dokeyi]

Would really love to see this when you’re done, I’m pretty sure it would be nice

[Madness]

Looks like a solid build.

Do you have any specific power/rpm goals or are you simply documenting a solid build for posterity?

I'm from Palmdale California. What part are you in?

[LukasM]

Originally Posted by porschedude996

After thinking I reconsidered replacing the exhaust studs. I choose to replace the studs and tried the usual penetrating oil and professional type double nut to extract said studs. I still didn't want to flame on with the valves and valve seals installed. I found a fastener heater and it will arrive tomorrow. I'll see how that goes. I ordered a set of studs from Silverlake Inconel studs. If you going to go, go big.

That's a smart move! I have a similar induction heater with 1,5kw, works well to get the studs glowing cherry red. If you want to remove them I would try a few cycles of hot and cold, together with penetrating fluid, to break the bond and corrosion between the aluminum and the steel over a couple of days.

However the studs should then be cool when you try to extract them (hot they will be too soft). I like to heat up the entire head with a hot air gun (which I strap to a tripod as it takes a few minutes) and then cool off only the studs with freezing effect spray and a small nozzle.

You might still have one or two studs break but removing them in a mill now is much better than having them break in a few years when the engine is assembled and in the car, and you want to remove the exhaust.

Your inconel or ti studs will last a lifetime without worries.