2.7L Engine Rebuild Questions

[Tom '74 911]

Instead of continuing to start a different thread for every question that comes up, I thought I'd finally start a single build thread for my 2.7L rebuild.

As it sits now, I've got the case halves back together and am ready to start installing the pistons & cylinders as soon as the piston ring compressor I ordered arrives.

My first question is about sliding the cylinders over the headstuds. Is it normal to have to squeeze the headstuds together a little to get them narrow enough to slide the cylinders on? The machine shop did install case savers for the headstuds, so the holes in the case are not original. I think the holes in the cylinders are 80mm apart and some of the headstuds measure as much as 84mm apart - enough of a difference that the cylinders do not just slide on smoothly. Is this common?

I did check the headstuds themselves when I reinstalled them and they were all pretty darn straight as far as I could tell.

My second question is regarding the crank pulley - is it OK to install and run it W/OUT the AC pulley part of it?

I'm sure I'll have more questions as I progress!

Thanks,
Tom

some photos:

A few of where I started a little over a year ago. Classic 'ran when parked', but had had a recent engine fire due to burst fuel line in the engine compartment when the PO tried to start it. The engine was a complete junk show when I took it apart.









Most recent photo (I'm a little further along now).



New 2.7L RS P&C goodness unboxed and ready for cleaning before install.



Can I leave the AC pulley off?

[Flat6pac]

The AC pulley is an aftermarket add on, leave it off
Install the studs and see if you have a porquepine look, sounds like it.
That’s on the machine shop.
Bruce

[Bb5280]

Tom, I am a bit further along than your project. I am just about ready to put the carbs back on (using web. 40's) and put the engine back where it belongs. I had ollies do the machine work and have built a race engine for vintage racing. I purchased new head studs from Supertec and yes, I had to gently manipulate the studs to get the cylinders on. Once I cleared the threads, they slid down right in place. There are plenty of threds on here about circlip tools for the piston install - I highly recommend taking a look at them and either fabricating your own or purchasing one. I did and it made that process super quick and easy. I mated the case halves 3 weekends ago so it is all pretty fresh. Good luck!

[mikedsilva]

no, it is not normal for the studs to be poking out at different angles... The cylinders should slide down with no friction on the studs themselves.

Who prepared the case?

[cgarr]

If they used case savers those get real close to the cylinder edge and don't leave much room for cylinder base sealing. how much edge is left in those areas?

[Tom '74 911]

Thanks for the responses and sorry for the delay in getting back - real job gets in the way of fun job far too often...

I had a few minutes this afternoon to investigate the headstud spacing further. I don't think I have the full-on porcupine effect going on, but my guess is that what I DO have is maybe on the outside range of acceptable.

The holes in the cylinders and heads are spaced at 80mm and the average spacing of the headstuds seems to be about 82mm. Some are at 80mm, most are closer to 82mm, there are a few at 83mm, 84mm and even a few at 85mm. This does create some havoc and the cylinders and heads are not simply sliding over their respective studs in ANY location w/out some gentle or even significant pressure to pull some of the headstuds closer together. Sometimes the pressure needs to be applied diagonally, sometimes North/South, sometimes East/West - just depends on the location.

One thought I had was that maybe my headstuds are slightly bent, as I am reusing the original steel studs. I did roll them on my flat, formica workbench before installing them and none seemed bent. Today, I identified some of the biggest out-of-spec offenders and rotated them 90 degrees and 180 degrees to see if any of the measurements/spacing changed - which they did NOT. So I think the studs themselves are not the issue.

I think there are only 1 or 2 cylinders where the headstuds are really out of whack and will require significant pressure on the studs to slide on the cylinder and head. I haven't tried for real yet as I am not excited to damage the fins on a brand new $$ cylinder. I am planning to clean up one of the original junk cylinders to do some test-fitting tomorrow. I think it'll be doable, will just require a little butt-clenching for an unfamiliar novice.

The machine shop did use case savers and there seems to be enough meat left at the cylinder edge. Not much to about that at this point anyway I suppose. Interestingly, although I didn't measure every location, by eye, it's not the same amount everywhere.

Thanks again for the comments & help. I will report back how it goes tomorrow when I hopefully will be able to spend a little more time fiddling around with it. Also, I now have a piston ring compressor in-hand so I can move forward w/the next steps if I am comfortable with my investigations etc...

Here's a few photos:

[Flat6pac]

You might try installing the P&C unit with just two studs in place then once cylinder is seated install the other two.
It gives me more hand room to install the piston clips and it might give you more freedom on installing the porcupine effect.
Bruce

[Tom '74 911]

Bruce,
I've thought about doing just that and may go that route. I would still have to deal with the larger gaps between the studs when installing the heads, although I think they are a little less delicate than the cylinders, where the headstud holes run through lots of thin fins...

Hoping to spend some time on this shortly.

Thanks,
Tom

[Flat6pac]

The thought being, the threads are 10mm the shank center is 8. Seat the cylinder then lift it slightly and the shank center may give you the lateral movement you need.
Bruce

[Tom '74 911]

So, success using Bruce's suggestion of installing a P&C unit with just 2 studs in place. I installed #1, so I could check the deck height.

I was wondering how accurate my numbers might be as the cylinder isn't torqued down yet... I used 4 hold-down nuts, but I can't imagine that it's the same as actual headstud pressure after being torqued down?

Also, my deck height measurements were a little inconsistent, but generally hovered between 1.30mm-1.34 mm, which is between the target numbers suggested in Wayne's book (1.25mm-1.50mm).

Since the pistons are pretty flat-topped, I was not planning to do the solder crush test at this point to verify deck height further. Is that a mistake?

Here's some more rationalizing - there are some numbers stamped in the case above the #2 cylinder spigot - 030, which I am assuming is a note from the machine shop indicating how much they took from the case halves when they planed them flat and line-bored the main bearings. .030" is about .75mm and the base gaskets they supplied are 1mm think, which is .75mm more than the stock, standard .25mm base gaskets that were under the cylinders when I disassembled the engine... seems logical to me...

Yes, I am an over thinker. : )

Anything else I should be checking or doing at this point? My next step is to install the P&Cs for real...

Thanks,
Tom

[Flat6pac]

Reminds me of this scenario I went through 2 1/2 years ago with the 3.2 to 3.4 and 20/21 cams
Bruce

http://forums.pelicanparts.com/uploads24/image1446839997.jpg

[fanaudical]

If it were me, I'd do the solder crush deck height check anyway, just to be sure.

One more thing to check (this happened during my rebuild, but I was reworking a 2.4 case to a 2.7) - Make sure the pistons will go DOWN far enough without hitting anything. I had the back of the skirt on two cylinders hit some internal case webbing. I had to do a little grinding...

[Tom '74 911]

Originally Posted by fanaudical

If it were me, I'd do the solder crush deck height check anyway, just to be sure.

Make sure the pistons will go DOWN far enough without hitting anything.

It's likely that I will do the solder crush test, as you say, just to be sure... and all 6 P&Cs are now installed & the crank rotates freely.

Next quick question - is soda blasting an OK, safe media to use for cleaning the cam housings, valve covers, chain housings etc...? I sent all my parts out for R&R and inspection, including the cam housings, but I think all that was done on the cam housings was some bore measuring, verifying the oil spray bars are clear and visual inspection. They are still filthy on the valve cover mating surfaces and also there is leftover 574 in places. I haven't found a great way to clean old, crusty 574 or decades old gasket material bonded to metal surfaces yet... and was hoping soda blasting might speed the process w/out causing harm.

Also, I have a question on some of the cylinder markings. I am hoping the differences are just date stamp related and not different height groups etc... I put the 3 similarly marked cylinders on the same side of the engine. They are all marked 0/1 B 7/14



On the other side, there are 2 marked 01/A 2/14 and one marked 0/3 A 6/11





Also thought I'd post a pic of the piston ring compressor I used for future rookie builders like myself, which worked great.



And final pic is as it sits now.





Thanks,
Tom

[Trackrash]

You might want to do a compression ratio calculation. The RS P&Cs only have 8.5-1 CR. You can adjust your deck height to bump that up, if needed. With a 1.3mm deck you may find that your CR is lower than what you want.

You can check your deck height with the head torqued, using modeling clay.


BTW, I used a razor blade to get that 574 off.

[Flat6pac]

The neat thing and use of the compression pliers is to pull the fan housing band together and hold it until you get the bolt in.
Bruce