Another 2.7 rebuild +ITB&EFI

[Neffets]

I did some work yesterday, intakes are done, exhaust I will do later today.
I found half of the valve stem seals torn in half.

[Neffets]

My clutch was stock from 1973 with the rubber dampened clutch disc.
It had to be resurfaced , was 9.43mm is now 8.83mm, had to go that deep to get rid of some localized hardened spots.

[Neffets]

So now all the exhaust sides are done, and i drilled out all of the exhaust studs since they were stuck (tried heating, welding a nut to the stud etc), new threads in all, waiting for new studs.

Next will be to smoothen all the edges from the milling and clean the heads.

[Neffets]

Now with some spare time I started to measure all the P/C's

[Neffets]

And hmmmm, I have the largest cyl/pist combo (group2), and small JE's...

I've read other posts here that ideal p/c clearance to be 0.0381mm/ 0.0015"
And I'm at 0.11mm / 0.004" if I mix large piston with large cyl etc.
Ovalness is within 1 hundreth of a millimeter so that part is good.

So what to do with the P/C clearance? get custom JE's?

[Neffets]

I went to measure again but this time with a scale that reads 1 thousanth of a millimeter,
and then I found this ...
So now they will go to us chrome to be coated&honed with nikasil 0.04mm larger then my JE's.
I measured my cylinders to 4 RA where the piston rings move and the bottom of the cylinder is 7.2 RA
US Chrome says they will hone to between 4-8 RA, and two weeks turn around time.

[Neffets]

In the mean time I've smoothened the transitions in the cyl head ports after I milled them.
And then glass blasted, next will be to fly cut the head.

[Neffets]

Cyl heads need fly cutting




All done

[Neffets]

All cyl heads are now within 0.02mm in height differnece, same goes for cylinders

[cgarr]

How much did you have to take of the heads to clean them up?

[Neffets]

0,35mm, I read somewhere that there is a max to how much one can take of, but I can't find it.I guess I will add a 0.25 extra copper shim in addition to the 0.5mm i have underneath the cylinders.

[cgarr]

Yea .25mm is the max that's to keep within the limits of the chain tensioners and chain box centering without modifications to them. Stock measurement from the cam carrier top of the head to the sealing surface is 84.5mm

[vinceparts]

Awesome thread. Your not interested in selling the carb setup are you?

[Neffets]

So today I checked the torque on my case throug bolts and the M8's, they were all to loose, the through bolts are supposed to be 35Nm, they were around 20nm. Torqued all to spec, and checked crankshaft end play to be 0.22mm
Max is 0.3mm, new I think i read something between 0.12-0.19mm

Then looking at the valves for my cylinder heads, alle the exhaust guides are shoot, measured 0,6mm radial play.... Intakes are good.

took out the guides using the method in this thread, worked as a charm.

Valve Guide Removal

[Neffets]

So now I need to order new valve guides, and then cut the seats.
I borrowed a set from a friend, I see in Bruce's book that the seat angles are 30-45-75 degrees. The valve seats at 45 degrees. Are both the valve and the seat 45 degrees?

The tool I borrowed is 46 degrees?

[cgarr]

Your talking Interference Angle or "pinch" cut the seat and lightly lap the valve and you will see the benefits mostly with air cooled engines. Nice cutters, I have 12 different ones. You have a Valve Concentricity Gauge?

[Neffets]

hm not sure I got that, do I use the 46degree tool or do I need a 45?

What is a Valve Concentricity Gauge? I have tools to measure the roundness of the valve seat.
And I have the cutting tool to straighten the valve sealing surface.

this engine needs more and more parts every day, and I hate waiting for parts

[cgarr]

The neway kit for Porsche uses cutter 642 and 272 are those the ones you have?

[Neffets]

I have 203/212/217/622

The 622&217 will do the job on the exhaust valves. They are too small for the intake.


Found this as well

203 Cutter- 1-1/4" dia. 31° x 46°
212 Cutter- 1-1/4"dia. 15° x 75°
217 Cutter-1-1/2"dia. 15° x75°
622 Cutter- 1-1/2"dia. 31° x 46°
619 Cutter- 1-1/2"dia. 15° x 60°
216 Cutter- 1-1/2"dia. 75°
642 Cutter- 1-3/4" dia. 31° x 46°
272 Cutter- 1-3/4"dia. 75°

[cgarr]

Oh that's right your doing 2.7 heads, that 622 is too small for those intakes? Might have to get the 642 for that? You can extend those cutters to their limits?