How to build a 2.7?
 

I've been plugging along restoring/restomodding a 77 911 Targa. It is a budget build, being done in less than optimal work conditions (a rough garage / good shed). The goal is a cool 911, reliable, that is used for spirited drives, possibly a track day or two. As far as I know, the engine is original, with the thermal reactors having long ago been removed. Car was parked 25 years ago, supposedly in good running condition.

Well, fast forward, I finally got the 2.7 to fire up. It's not humming like it was in 1977, but it does start and run.


Theres a nasty oil leak somewhere behind the airbox, and a clean and rebuild of the injectors and fuel distributor is needed. So, at this stage I'm debating about whether to continue the spot repairs, or to go ahead and pull the engine.

Looking to y'all for input and guidance. Do you pull the motor and look at a top end rebuild, or continue with it in the car? If you go rebuild at this time, would it be 964 cams and 2.7 Nikasail cylinders with the CIS, or some other configuration?

Here's how we did my 2.7 and it pulls strong.

JE Lightweight pistons
Dimon Eligin SC Cam
SC air filter box
SSI heat exchangers
Dansk two in one out muffler

This was 12 years ago. It leaks a little but runs great!

One consideration is whether you need to have emissions checks on the engine. If not, eventually going with RS pistons/cylinders, S cams, and Weber carb’s really wake these engines up. Need to machine the case for CaseSavers as well. These mods are far from cheap, so I’d chase the leaks and drive it until funds are available todo it right.

Start here...no need to jump straight to rebuilding the thing.

https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/21-Oil_Leak_Fixes/21-Oil_Leak_Fixes.htm

C,

the bit of work involved in removing the engine/trans to be able to easily inspect and resolve the leaking issues will be well worth the time and trouble.

There are many old hoses and wires between you and the source of those leaks....it'll be MUCH easier with engine out, and most likely you'll solve most, if not all of the running issues by replacing hoses & cleaning connections encountered along the way.

PD

I'd do a leak down test (or at least a compression test) to find out the condition of the valves and rings. If they are good, fix the ancillary things, tune it, drive it, and save money for when you want to do a rebuild in the future. I built the 2.7L in my '69 with longevity and dependability in mind. I has: JE 9.5:1 pistons; Nikasil cyliinders; E cams; Webers, balanced (not really a necessity); thermal barrier coated piston tops, valve faces, combustion chambers; dry film coated main & rod bearings, cam lobes & bearing faces, valve stems, oil pump, & some other things. This was some years ago, and a proper rebuild on a 2.7L now would be very expensive, especially with case machining (which mine needed).

I appreciate the input! In SC we dont have to worry about emissions, but who knows how long we will be located there, so I'd rather keep emissions in line if possible.

The idea of dropping the engine to access the hoses, etc. isnt something I had considered. but I can see the merit in that.

A compression test and leak down will not give an accurate diagnosis on an engine that has not been run for awhile, rusty valve seats and valves will cause false readings. Get the leaks fixed replace rubber bits tune it up and drive it. Once you have 500 miles on it and knock the crud off the valves do the tests and see what is up.

If you want a build like Overlander 80 mentioned, I have a set of SC grind cams I was going to use on mine....before I found out it was bad enough to need a full rebuild.
I initially intended to do a CIS with the SC grind.

Cough....cheap ITB and EFI setup....cough

pampadori, mind elaborating?

For reference, I have a 76 Targa S that was a garage find and had been sitting so I can sympathize with the while you’re in there mentality. I would also prioritize changing your 42 yr old fuel lines while the engine is out. This guy makes fuel line replacement kits, he’s on Pelican forum too.

Mason_paul@yahoo.com

Have you heard of triangle of death? Likely oil leak locations.

Exactly this is the triangle...
- breather oval seal
- sensor plug or it's seal
- oil thermostat O-ring

and since you have the oilcooler off, it's your chance to adress the spot behind it according to tech Bulletin:

I will frwd tech bulletin via email.

Thanks Frog76S! Fuel lines have been replaced, though I'm running the front fronts into a plastic gas jug until I'm ready to buy a new tank!

Yes, please forward that article when you can.

+1, I don't think a cheap ITB/EFI system exists, aren't they all $4k+
If someone has one that's only a little bit more than my good Weber 40s I'd be all over it :D no better time to upgrade than when the engine is out of the car being rebuilt.

Triumph ITBs is what Pampadori means. They are about 150-200 each side. Clay makes a great linkage kit for them. But yes, by the time the harness is done, crank triggers, sensors, COPs, injectors, pump, fuel lines and all the fabrication, and an AEM Infinity 506 ECU running it all it is indeed still a good more more than a set of carbs but very worth it once set up IMO. I can’t say enough about the flexibility and overall drivability when done right.

This.
The CIS will be easier to rebuild/get running well than any of the mentioned projects. Get it running well, then decide. In the meantime there are plenty of things to do to get it running well. There are plenty CIS primers available, buy/acquire them all, keep them near the toilet and read until you understand completely. If you start dicking around with changing the intake system, you will ultimately sell the entire mess on Bring a Trailer. Fix what you got, run it.

Update on this... after pulling the CIS, and going through it to get decent fuel flow, replacing injectors and cleaning the CIS, we decided to do a pressure test on the cylinders. All looked pretty good, considering, four of the cylinders at 150-155. One at 143. All held the pressure well. The exception is #2, which got zero. Ran it several times and got the same result.

We are in the middle of the snowball effect here. Alternator was fired too.

Looks like once I figure out to clean out the fuel distributor and get the CIS back together, how to it's time to drop the engine.

Is it reasonable to spot replace cylinders?

I wouldn't just assume that you need to change a cylinder/piston. I'm thinking more like a valve stuck open. A leak down test should help pinpoint. You should actually be able to hear the leakage.

Wow! That hadnt occurred to me. maybe because I'm learning as I go! :)

Ya know, when we were doing the compression test, we had 4 done, and I was getting excited by the results we were getting, and then the zero. I was baffled how we could get 4 at 150-155, and then the goose egg. It would be awesome to avoid a rebuild!

Dont know how I'd do a leakdown test, but I have the CIS and runners off. Would putting some blaster and marvel mystery oil in through the injection port and letting it soak be a good option for releasing a likely stuck valve?

Here's an "order of magnitude" leakdown test you can do:

- Crank that suspect cylinder to top-dead-center where both intake and exhaust valve should be closed (distributor rotor pointing toward the corresponding plug wire).

- Lock the engine so it won't turn.

- Connect compressed air to the spark plug port.

If you hear air leaking from the intake port, you've got an intake valve problem (won't close, burned valve, eroded seat, etc).

If you hear air leaking from the exhaust, you've got an exhaust valve problem.

If you hear air leaking from the case breather, you've got issues with rings/piston.

If you hear air leaking from around the cylinder head, you may have a blown head gasket or enough broken head studs that things are trying to separate (rare to get zero compression from this).

If you find it's a valve, I'd start by removing the rocker covers and determining if the valve is stuck open (might be able to see directly with the intake runners off on the inlet valve). Having the covers off will let you verify valve clearances and see the back side of the valve stem move (or not) as well as find any broken head studs.

Hope that helps.