Special getting closer...

911hillclimber · Post by **911hillclimber** » Tue Sep 18, 2012 5:51 pm

Ripped the bloody engine back out. Taking it to Bob's next week to have the cam timing checked.
Sick of this thing but a weekend away at SPA will help!

911hillclimber · Post by **911hillclimber** » Sat Oct 06, 2012 6:41 pm

Bob checked the cam timing out.(this was my first attempt at timing)

1.3mm on the left, 1.4 on the right so not too bad...corrected (!), a leak down test followed.....

Leaking like a sieve, hissing everywhere on # 3/4 5

Got it back home yesterday and passed 40 psi into each cylinder with valves closed and then listened for the hiss, and if there was one, loud or light and from the carb, the exhaust or the block (breather hole)

Results below:

So:
Cylinders/pistons/rings seem ok.
All new exhausts valves are ok, but 3 inlets leak two very badly where new valves/new seats have been installed.

Off with the heads tomorrow and a long re-visit with the lapping paste. Boring or what?

Uk911 · Post by **Uk911** » Sun Oct 07, 2012 8:02 am

Stick at it Graham, it will be worth it when the new season starts at loton........Mark.

911hillclimber · Post by **911hillclimber** » Sun Oct 07, 2012 12:00 pm

This car IS going to work (next year...)

Heads off this morning, flew apart.
I conclude I'm good at taking things apart, 5/10 when putting them back together.

It is very clear #5 cylinder is not working (leak test showed huge inlet valve leak)
The head is as clean as when i assembled it.

The cylinders 4/6 which sit either side of it show combustion. #4 is fed from the same float bowl as #5.
#4 is burning, 5 is not.

Thus ignition in the wrong place or no fuel. My bet is no fuel.

Will re-lap all the valves so no leaks hopefully.

haasad · Post by **haasad** » Sun Oct 07, 2012 8:34 pm

Stick at it you know it's worth it...those exhausts look very pocketed compared to what I'm used to seeing on smaller capacity engines. Are the margins ok and is the stem protrusion within tolerance. Could be just the image but worth checking IMHO .

cheers

andy

911hillclimber · Post by **911hillclimber** » Sun Oct 07, 2012 10:24 pm

I think the early engines have a much shallower 'hemi' head than the 3.2's, or the valve angles are different.

I've re-lapped heads 4 and 5. The exhausts hold back the cellulose thinners, no leaks, but the inlets show a small weeping.
Thinners is very penetrating.
Did you try anything like a fluid leak test Hassad?

I plan to re-install head by head with a 40 psi pressure check when torqued up before fitting all the cams etc back on.

All very tedious going over this work again, and I've my 911 to fix up yet!

Need to remember this car is great when working...

haasad · Post by **haasad** » Mon Oct 08, 2012 7:45 am

Hi , I've never done a check using any fluid but I do always blue the new seat to check proper contact and land. put a thin smear of blue at three points on the valve 120 degrees apart pop the valve in and pull it into its seat then turn it 120 deg. You should have a witness mark transferred to the seat in blue all the way round and about 1/16 inch wide. Always worked for me but my 911 engine hasn't run....yet.

cheers

andy

911hillclimber · Post by **911hillclimber** » Mon Oct 08, 2012 12:51 pm

Just 'borrowed' some eng blue as i remember your thread showing this.

I have a nice slate grey band about 1mm round the valve and seat. The blue will prove it.
Strangely hard to get round here in the heart of the industrial midlands....bet you can get skiploads in China!

Someone else has said a bright light shone down the port viewing from the chamber in the dark...in the garage...

Sounds scarey for several reasons to me.

1
On my own in my garage with this spooky engine
2
I might see light through the seat(s)

Two strokes are easier.

Bruce M · Post by **Bruce M** » Mon Oct 08, 2012 5:15 pm

Chrono tools is quite useful for those sorts of things

911hillclimber · Post by **911hillclimber** » Mon Oct 08, 2012 8:05 pm

shining a good high intensity torch into the ports DOES work a treat!

Puts a different light on the subject of valve lapping...

The exhaust valves are all light tight.

The 3 leaky inlets are a different matter.

Maybe I should just fit all new inlets and to hell with the cost.

911hillclimber · Post by **911hillclimber** » Sun Oct 21, 2012 6:03 pm

After some messing about and my wifes birthday treat away, got back to work on the engine suitably refreshed.

Bought all new inlet valves and set to lapping them in. Using the cellulose thinners and high intensity torch method of leak detection all heads 1/2/3/6 lapped in a treat, fluid and light tight inc the exhausts.

Heads 4 and 5 were a different matter, these heads having had new guides and seats by the engine machinist I will never go to again and I doubt they went in as well as Porsche did it way back....

After a lot of course/fine lapping get #5 tight as the others.
# 4 exhaust is tight and the inlet is just weeping fluid and I can see about 30 degrees of light in one area of the seat. I can't get rid of it so I hope some carbon deposit will do the trick.

All this because of a shabby machine shop.

Got the heads on and came to the cam timing.
Came to turn the engine over and it locked-up solid.

Why me?

Turned out the timing chain had come off one row and it took a full hour to fiddle it back on.
What a game.

Anyway, all timed up now and should be back in the car next weekend with a good following wind.

Will it run on all 6?

Ants · Post by **Ants** » Sun Oct 21, 2012 8:34 pm

i'll keep my fingers crossed for you
Antony

haasad · Post by **haasad** » Mon Oct 22, 2012 7:46 am

Yes, fingers crossed its ok.... but a valve that is not seating would be a worry for me.

andy

KS · Post by KS » Mon Oct 22, 2012 7:55 am

Agreed - don't just let that go. You really must get that one valve lapped 100 per cent. It won't cure itself. IMHO, of course...

Bruce M · Post by **Bruce M** » Mon Oct 22, 2012 10:37 am

I'd be very wary of doing any more than a very light cut with lapping. It wears both the seat and the valve. If it need more than that, I'd recommend getting the seat recut with proper a cutting tool and the valve refaced or replaced.

I wouldn't leave it either.

DDK - Die Deutschen Klassiker