dave964diver

Hi Colin,

Thanks for the heads up. Things are buttoned up now hopefully that will not be the case. As I can recall, when you torque the heads and cam housing down onto the cylinders, surely the collective forces create a relatively rigid structure with 12 x arp head bolts creating the tension necessary to prevent too much lateral movement?

I'm certainly not going to tear the engine down unnecessarily.

dave964diver

Quite right, I could have better spent the money on other things.

Hopefully I can upgrade from where I am. I will be taking it to WS and I do have a set of headers on it now plus the cam chaincover bolts are now In For the sharp eyed.

I replaced quite a few of the rockers and all the springs, plus rebushing and weighting all the con rods. Also had the crank polished and checked for trueness.

There was a lot of extra stuff, that I can't care to remember. Probably near 15k worth of parts and labour most of which I did myself. Oil pump was a 1k to start.

I'm hoping to upgrade to motec and itbs in the future provided the heads don't slide off the cylinders that is.

NineMeister

Dave,
With all due respect I would not have mentioned it if I had not thought it important. I do believe in fixing issues before they become a problem, but maybe that's down to my engineering background or more likely from 25 years of building Porsche engines where you can guarantee that anything and everything that could go wrong would. You don't take risks with engine builds, there are fat too many expensive parts that quickly turn to scrap when they decide to have an unannounced party.

Another fix would be to machine & fit hollow dowels in two of the head stud holes of each cylinder and head.

dave964diver

I'm certainly not questioning your knowledge or experience Colin.

But I'm not going to get into a who's got the biggest stick argument by proxy. Not least of all because the chap that put mine together has probably got even more experience than you have and I'm sure you probably know him.

Despite this I'm sure he'll stand by his work should things go wrong and I do believe in a proactive approach. This according to him, is factory spec for an upgrade and there's nothing in the tech data to contradict or confirm the process other than minimum specs for machining. Now if you can show me a case study as to why things will fall apart and evidence that supports your warning then of course I will take heed and strip things down.But I've gotta go with my engine builder on this. Should it fail. I'll be the first to pop it on here and warn others of this machining must.

kos11-12

Hey you own a Porche, so you must be rich ...

dave964diver

Ha! Exactly. Common misconception. Pouring money into a pit of rust and false ideas.

Can't believe how things just spiral out of control. New tinware electroplating, powder coating list goes on and on. Try not to think of it as a money pit but my second 3.2 I bought right and this 964 was bought because it was a shiny thing.

No such thing as a cheap porsche. All cost you something in the long run. IMHO.

Ps I'm a blue collar worker.

kos11-12

The mith of the 911 Porsche, sometimes I am thinking of what I could build for 20 to 25 k , not to mention cost maintenance,
Don't know why exactly I m keeping it , maybe obsession to prove it could be a fast car,

http://www.eclipsesportscars.com/

crg53

Hi Dave, I am curious to find out why your builder chose to machine the cylinder head location lugs off. The cam tower and heads are doweled together, so you can establish the head spacing that way, but how do you know that the heads are centred over the cylinders ?

dave964diver

Right in my simple engineering brain. The cam cam towers provide the base for the heads. The cylinders are positioned by virtue of their position in the case. Cylinders and cam and head assembly therefore are the same. The next question quite rightly would be what is the bench mark for the cam/head assembly and the cylinders.

There is a certain amount of play between the head bolts and their holes and admittedly this could result in the whole cam head assembly shifting as a oner forward or aft on the cylinders. How likely is after the whole assembly has been torqued, time will tell.

There is so little play btwn the heads and cylinders that I can only assume at worst that individual heads might shuffle or float around minutely. Enough to create oil leaks on the heads? I will put it to the test.

Admittedly when they went on before they were even torqued ie just offered up they fitted so perfectly that you would be hard pressed to determine what was head and what was cylinder there was no play whatsoever.

As Colin says I could dowl the interface between the two to prevent any possibility.

Lets see what happens.

dave964diver

The point in question.

dave964diver

NineMeister

Said my bit, due diligence and all that. I've absolutely no intent to pick an argument or question your builder's idea of good working practice so will say no more. For reference here is the relevant page scanned from the factory 964 manual showing the location lugs and how the factory recommend machining the head.

dave964diver

Thank you Colin,

I have this its on page 15-4 of the Bentley Tech data without guesswork.

Still there is no reference to machining a 3.6 head to 3.8 spec. And no case study for reference.

As this is unknown territory i'll be happy to be the Guinie pig. The cost and time to strip everything down out weights the calculated risk. Thank you for you concern. Sincerely

NineMeister

Fair enough.
For everyone's information there is no difference in the machining of a late 964, 993 and 993RS cylinder head sizing or location lugs.

dave964diver

Thought I'd just add an update. Finaly had the car out of the paint shop. Was lucky enough to use a ramp and a paper dolly to put it in. After installing all the front subframe suspension brakes, and other bits and pieces. Including a heart stopping moment when I realized I had put the friction plate in the lwf and clutch in the wrong way around. Had to seperate the transmission and do it again. Clearly written on the friction plate "fly wheel side". That sorted I installed the engine. Filled it with 9 liters of oil. Disconnected the speed ref sensor cracked it till I got 2 Bar of oil pressure reconnected the sensor and it started first time.

Ran it up to temp filled the rest of the oil up 11 liters ish checked for fuel and oil leaks. Pleased to say not a drop but I'll give things time to settle as I didn't take it over 3k.

Definitely needs a map and as it's a bit sesawy at idle but I suspect that's the lwf. A bit tap petty on one side so needs some valve adjustment.

That said I'm very pleased it's running and will hopefully have a shakedown in March next year.