Top-end Rebuild Time - gulp !

[Jamie Summers]

The time may well have come for me to bite the bullet and get the top-end rebuilt. A cylinder leak test a few months ago showed between 4% and 8% on all cylinders, so absolutely no problems in that department. However the engine has started to blow an increasingly noticeable amount of smoke and use more oil (although probably still within the factory tollerance of 1 litre per 1000 miles) which would suggest to me that there is an increasing amount of valve-guide wear. Perhaps it's my imagination but the engine doesn't seem quite as perky as it once was either. With mileage at almost 100K it all seems to be pointing towards one thing (although as we know mileage in itself is no defining factor). I've done quite a lot of track work over the last year which I guess has merely accelerated the problem. The situation is clearly not dire but my usual specialist has been telling me for the last 18 months that a rebuild was on the horizon, so any other suggestions for other things to explore before taking the plunge ?

Assuming it does need a rebuild the price for the work seems to vary enormously. I neither have the time, knowledge, nor inclination to undertake the work myself so what experience of specialists does anyone have for this job ?

In addition what other jobs / upgrades are worth having done at the same time ? Typically I had the clutch done no more than 10k miles ago so am slightly reluctant to have it done again, although it would probably make sense to. I am toying with the idea of putting in an RS flywheel, however that may just make it difficult to use round town - any experiences ? Also thinking of rebuilding with 964 profile cams. I am reluctant to go for a 3.4 or 3.6l upgrade due to the expense involved but the cams might just give an extra bit of grunt for a more acceptable cost ????

All views / ideas / estimates of costs etc. welcomed !

Thanks in advance,

Jamie

 

[bones]

Wow Jamie this place is getting like Pelican Parts, now if we can just get this forum open to the rest of the net.......Do you have a budget, it would be useful to know if you already have any mods to the exhaust , ignition etc. As a pointer I would say Autofarm, Chris Turner are great rebuilders but not inexpensive. I would go by reputation if you are keeping the car and get some firm quotes. I can't comment on the cams apart form what I've read on Rennlist and Pelican but it's an option. If you haven't alredy done it backdate the HEs and the exhaust and let it breath better. When did you last have the valves adjusted and your mixture set?

 

[Jamie Summers]

Bones,
Engine and exhaust are currently standard. Only mods at that end of the car are a K&N airfilter and a Steve Wong chip. I imagine that the 964 cams would probably require a custom re-chip ? As for exhaust, backdating to SSI would be an option although perhaps more expense than I was after and HP gains on a 3.2 are questionable (full custom H&S stainless system would be nice though !!!). My HEs are in perfectly good nick but maybe updating the rest of the system to a nice stainless system is a possibility.

As for budget, sadly it is likely to be 'limited' ! i.e. I need to find a happy balance of price vs reputation for quality of workmanship (for which one clearly pays). As this is a big and very important job, whilst I have no problem with the general standard of workmanship or price of my usual specialist, I think this is worth paying a little bit more for in order to have it done 'right'. I've heard prices of between £1500 and £3000 for exactly the same job - there really is a massive range !

Jamie

 

[bones]

If you're asking me I would ditch the K&N I believe they are a liability to the engines longevity and offer nothing in performance over a stock filter. Fit the backdated exhaust and HEs for better response rather than more ponies and have a custom chip blown. There is a thread on here about them recently. If you want to do anything else you won't see change out of 4-5000K I wouldn't think. Make sure that you have the rings replaced as well as attending to the heads and valves. Have you thought that the K&N filter might have contributed to this? You don't have to use SSIs if you don't drive it all the year round
The early factory mild steel HEs do the job for a lot less money.

 

[ClubSport 911]

Cars perform worse as ambient temperature rises. Example, in 30 degree C you might lose 5-10bhp on a car like ours - I'd (respectfully) suggest you hang fire with the re-build.

Options to help increase the "zing" factor - run on Optimax. Get Steve Wong to send you V4 of the chip, change rotor arm, distributor cap.

I'll bet you, it'll "feel better"

All the best.

 

[Jamie Summers]

Steve,
Already running on Optimax and V3 (I think) of the Steve W. I take your point on the ambient temp issue and power loss, however I don't imagine that would cause the engine to smoke more and use more oil ? Rotor arm and dizzy cap might be an idea as would cleaning the injectors.

What are the Clubsport-specific engine parts. I seem to remember something about hollow stem valves, would this be a worthwhile upgrade assuming valves are replaced as part of the top-end rebuild anyway ?

How are you finding the Steve W V4 ? Email me offline if you like.

Thanks,

Jamie

 

[ClubSport 911]

I seem to remember something about hollow stem valves, would this be a worthwhile upgrade assuming valves are replaced as part of the top-end rebuild anyway ?

Word on the street, is that sodium filled valve stems were quite novel on road cars in 1987, but now are de-rigeur (higher combustion temperatures caused by pathetically lean burning emissions bound vehicles...)

I think any engine builder would attest, that they fit these valves as standard. Apart from the DME, and Porsche blue-printing, other differences to the engine are minor. Of course, G'box, engine mounts and other running gear is changed, but this is not what you are interested in right now.

 

[ClubSport 911]

u have new mail []

 

[Guest]

Hi Guys

I am currently having my engine completely rebuilt (as Steve knows). I will keep you all up to date with the progression, but due to oil starvation, the sleeve inside one of the big ends (if that is the technical speak??) had worn, and in another, it actually fell out in several pieces when stripped down (which had happenned over a period of time).

My mechanic (Motawerk in Saddington) is working away on it as we speak, but has had to get a bottom end from a written off 3.2 Carrera as a donor to rebuild. I would interested in hearing about the Steve Wong Chip though, so if anyone has experience of fitting, performance and price, I would love some feedback.

(Steve, will post all relevant info from Motawerk to you, please e-mail me to let me know if there is any further info you require)

I will keep yopu all up to speed and maybe get some piccies which I will post on here.

Regards

Phil