drnick

Andrew, those headers look good right where they are and the coating seems to have stood up pretty well - cleanest parts in the engine bay

What finish is on the cam covers - they look sweet!

928mac

Those headers do look nice. It may be an upgrade that I am willing to do, if I can afford it, but they will go hand in hand with a SC and cams.
BTW it makes sense that adding boost will increase blow-by.
To reduce the blow-by past the rings, ring design and tension can be changed.
has anyone researched in this area of ring design and increased tension?
I wonder how much increased ring tension increases cylinder ware?
Thanks for the info on hanging the engine, and for a great tread.

Happy New Year

Tony

I love the SC belt set up...always have!
Have you ever done a leakdown on this engine Andrew? Id be curious to see where its at.

AO

I have not. But I will. Maybe in the morning.

Workshop is clean enough now. Work begins!

MjRocket

Andrew

I wanna come hangout/play in your garage.

atb

Andrew,
Are you running the factory motor mount heat shields (the ones that bolt to the X-member) with your headers?

69gaugeman

Andrew, I had my clutch disk relined with Kevlar by a local company up here called eurospec clutches. If you want to reline your clutch disk I think it was around 160$, but I will check to see. You can call me on my cell if you want more details.

AO

Not with this snow... Come up when it thaws.

Mounts are the Ford mounts (valve sits too high for the SCer. The heat shields are stock but slightly modified with a hammer.

the clutch is fine (I think)... It's the flywheel that needs attention. Not heard of anyone "relining" a flywheel on a 928. I was thinking of getting a good used one or one of Carl's lightweight ones.

AO

Just pulled the plugs and did the leakdown test. All the plugs look okay. nothing out of the ordinary. They are a little black, but that's probably because I was running pretty rich toward the end when I had to increase the AFR to compensate for the intercooler leak.

The leakdown was equally undramatic. All cylinders were about the same. I'm not concerned about the absolute number as this was a HF leakdown tester, I have no idea on its accuracy, and it's friggen cold outside (like about 30*). All of the cylinders are leaking through either the rings or the valve guide seals both are original to the car as far as I know and both will get replaced on this rebuild. Guides may also get replaced if needed.

Next step is to warm up and begin disassembly.

Cyl ______ % age _______ Cause of leakage

1 ________ 35% ________ Rings/Seals
2 ________ 38% ________ Rings/Seals
3 ________ 37% ________ Rings/Seals
4 ________ 35% ________ Rings/Seals
5 ________ 42% ________ Rings/Seals
6 ________ 35% ________ Rings/Seals
7 ________ 38% ________ Rings/Seals
8 ________ 42% ________ Rings/Seals

Plugs 1 through 4 (left to right)



Plugs 5 through 8 (left to right)

victor25

plugs 5 6 7 look much better than plug 8

Imo000

Those leakdown numbers are astronomical. The gauge must be off but, to be off this much? Your primary leak are the valves and the old guide seals just let some of the air pass through. Did you try tapping the valves with a small hammer when the cylinder is pressurised? Carbon on the valve seats usually makes the valves leak and tapping them sometimes brings the leakdown numbers down.

Tony

Ideally the leak down should be done on a "warm" motor, i doubt the engine would even run with those numbers!! I would go out and drive mine then immediately pull the plugs and start the test

also...the leak down tester i have threads into the spark plug hole and with the valves closed you cant really get an idea of the health on the "valve guides" can you? Only the rings and the valve seats?

Take good pics and docs of the "re-ringing"..Im sure i will be down that path at some point.

Ducman82

That's crazy leakage. I ended up making a tester that ran on 100 psi. So the leak down gauge would show, say 90psi. There for I had 10% leakage.

Don't forget to do the special magic to the cylinders so the new rings seat better...... Ask me how I know that.... :-p

AO

Guys... remember it's like 30 degrees in my garage. It's a friggen icebox! I'm really not concerned about the number. The cam covers are still on the car so I haven't done anything other than just do a static leakdown on a cold motor. No matter, I'm pulling the heads, I will measure the valve guides and pull the pistons to measure the bore with the intention of replacing the rings at a minimum. I'm thinking about dishing the pistons to lower the compression a bit and increase boost and advance.

Tony, didn't you do something to your pistons?

I thought about increasing the psi to a higher number, but was sure how valid that would be. The HF tester runs at about 10psi. I can redo the test if needed, but I'm not sure why it matters at this point. All the leakage is clearly through the crankcase. I'm pulling the heads... so who cares. It is what it is. The block is probably okay, but I'll still measure the bore just to make sure. So I don't see why it matters what the LD number are.

What's the "magic" you speak of?

I got the headers and SCer off today. The leaking flud I saw by the water bridge was mostly coolant. Not sure where that was coming from... Hose? Dunno. Must have been a recent development. Tomorrow I think I should be able to get the heads off and start poking around inside the patient.







The beast...

Ducman82

having the cylinders honed with the special silicon paste.... or what have you. due to the special cylinder coating.... i had lots of blow by with new rings, and not touching the block. took the rings a bit to seat, where the old rings did....