Need advice on 2.7 rebuild
 

Hi everyone, been on pelican reading up a lot and getting a better idea of tinkering with my car. Had a lot of help from a member on these forums and just after some additional opinions for my 1975 911s

Issues so far with the engine/CIS:

1) cylinder 6 doesn't fire all the time. I got a leakdown and compression test done and it came back with acceptable figures. Spark plugs were replaced about 500 miles ago with full service done and the spark plug on cylinder 6 was clean. Swapped the spark plugs around after the compression/leakdown. When car is warmed up you can sort of hear a hissing noise every now and then which I was told is likely cylinder 6? If I rev the car past approx 4500 RPM, power still comes on. Wrench says that it cylinder 6 seems to fire above a certain RPM?

2) wrench could hear a 'tractor' like noise coming from the engine after putting the spark plugs back in and all. Car wasn't idling well but we checked oil and it was low so topped it up and seems to be ok. Suggested that this may be broken head studs. I was told by the PO that he had the engine rebuilt almost 8 years ago with dilivar studs which i've since read aren't the best. Is it easy to check for broken head studs? Read here that I'd have to take off the lower valve covers to check?

3) I've had CIS issues since i've had the car and have gone through the hassle of replacing the FD and adding a check valve to my aftermarket pump(PO installed). Car idled better after this was done. We checked the injectors after leakdown/compression and injector for cylinder 6 isn't spraying straight. Its spraying at an angle. Also when the car is in the 'ignition on' position but not turned on, we checked 2 of the injectors and they were leaking. This is not meant to happen. I have ordered some used injectors so just waiting for this to come.

4) When I first bought the car, paid to have a diffferent wrench do a valve adjust. New lower valve covers(used) were installed.

5) Getting a lot of oil leaks from both the engine and transmission. Told this was relatively normal but still leaks more than it should?

So thats sort of where I stand right now. The pelicanite who has been helping me has suggested upgrading to the 3.0 instead of rebuilding the 2.7 which would be awesome if I had the $$ right now but being in Canada, sourcing a motor for a decent price is harder.

If i'm going to get rid of the 2.7, should I try give it a go? End of the day, if i screw it up i'd still just buy the 3.0 anyways? Thing that scares me is my lack of knowledge. I'm going to order Wayne's engine rebuilding book, already have his 101 book and thats great for starting out.

Either way it looks like its going to be big $$ but just trying to figure out the most cost effective way of doing things and best way to learn more about my car. Been awesome using the pelicanite here as he lets me watch and answers all my questions rather than just sending it to a porsche wrench and just parting with $$ and learning minimal.

My next step so far is doing the fuel pressure tests on all CIS components to see whether that may be attributing to my issues.

Sorry for the essay but just a dilemna as i've already parted with a fair bit of money and seems like I'm just covering the same ground.

Barney

You are asking perhaps too many questions. First read Wayne's book when it arrives. That will help you no end, and give you more confidence.

While waiting for it, pull all four valve covers (You already have the book describing that) and check each cylinder head stud for torque. Apply maybe 24 lbs/ft to each barrel nut, and note which ones tighten up. If you have any which turn but won't tighten up, you have the dreaded head stud problem. If you have nuts or nuts with a stub of stud on them, fall out when you take your covers off, you need look no farther.

Back when, we all replaced our steel studs with Dilivars. Worked for me, but maybe long term corrosion or some other issues started raising their ugly heads.

You can always swap another injector into the #6 position to see if your issues there are injector related.

Maybe broken head studs?..what kind a wrench is this person?...you had the valve cvrs off...no guess work should be allowed..
I would deal with one problem at a time
at the end of the day you will have the info.
The other thing is...has there been any updates to it?

Not yet.

Havent had a chance to take the valve covers off.

It was definitive about the pulled head studs, just a possibility.

sorry-read too fast...pretty EZ to ck studs..
CIS- Could be numerus vacume leaks will your cause of #6 not working @ low RPM...I hope
all EZ to fix
Once you do the stud study...you might be in great shape
Being rebuilt 8 yrs ago you might have all the latest updates..except the stud argument....I went steel, right or wrong way too late now......
Oil leaks....we all might have a few..but the transaxle should not be leaking