911SC Mods/Engine Rebuild

[Guest]

Hey Guys. Well it has been a while since I've been on here.

At last I have decided it is ime to get rid of the smoke screen that follows me around (especially when I nudge the ton). It's time to stop the oil injection onto the exhaust and get an engine rebuild. Any suggestions on what I should or could get done (possibly with a minor mod or two)?

Currently thinking f doing the following:
- Hydraulic Chain Tensioner - install
- Gaskets all around - Replace
- Rings - replace
- Hone the bores

Also while she is at the surgeons:
- Heater butterfly valves - replace
- Air controller cables in dash - replace

Any other ideas?

Another question as well - what amp fuse should be used for the AC? At present there is a 16amp (which I burn out when he AC is on speed 2 or 3). From what I can ascertain it should be a 25amp. Is this right?

I'm hoping to get the work strarted on Monday.

Cheers[8D]

 

[bones]

As you probaly know there is a stack of things you can do to mod these engines but if you want to stay standard wait till the engine is stripped before you make any final decisions. Do you have broken studs? If the barrels are coming off, you might as well check the bottom end too in which case you will be into more money for the job. Valves might need looking at too. Sorry no idea about air con ampage 25 amp sounds right though.

 

[Guest]

Bones. Yea I think (From memory) that I have one or two broken studs. Can't quite recall why think that though.

I want to keep it reasonably standard but am interestedin minor mods if cost effective. I did think of borring it out but not sure abouut that one.

Cheers

 

[bones]

If you have broken studs you will see localised weeping and hear a 'flapping/blowing type sound' as you accelerate. If you are not sure about this then make sure you are as you could be doing a lot of work for nothing. Could be valves or a bad leak from some other place. Boring out to 3.5 litres is a very easy way of getting more power, combined with an early exhaust system or SSIs (about 1.5k fitted though) a lot less if you source the parts and use a Triad exhaust like mine. 964 cams are very 'in' just now. Make sure you have a budget and stick to it or you could end up broke! []

 

[Guest]

Hi SobeUK,
Just had a quick look at my workshop manual re air con fuse.
Fuse 20- 25 amp hot all the time.
John

 

[Guest]

SobeUK,

I rebuilt my SC motor myself about 7 years ago, fired it for the first time 2 weeks ago. Havent driven it yet but it's very eager to rev and sounds lovely. Here's from memory what was done...

204 bhp barrels and pistons with total seal rings
New bearings throughout
964 Profile cams
Rebuilt heads, new valves and guides, and a proper 3 angle valve job on all the seats
New valve springs, properly height shimmed
New rocker arms and adjusters
Hydraulic tensioners and carrera spacers behind them (this gets missed)
New injectors
Early exhaust swap and oil lines to suit
Timing set to different spec (dont recall exactly but it was set to the Bruce Anderson Modifying 911 engines handbook)
Maybe more but can't recall


Regards
Mart

 

[Guest]

Yes I installed the PopOff a year os two back. Well worth while! However the PopOff did actually Pop out once from a backfire when starting. It is a must I agree.

 

[Guest]

Thank you. Sounds interesting proposition replacing the cams. Thanks for the point re the spacers for the tentioners.

I've already got a nice sweet sounding stainless maxflow exhaust - installed a year back. So that will be staying.

Cheers

 

[SJW BASIRE]

I wouldn't hone the bores-especially with one of those grindingstone things on a drill.. It'll take the Alusil coating off and accelerate wear.New rings should be all that is required.The bores are supposed to be pretty indestructible 300,000 miles plus unless there has been a major failure.
You should definately do valves,guides and rockers,chains and Carrera hydraulic tensioners if they haven't already been done.Then there's later type 930 Diluvar crankcase studs to fit unless you want to strip it again at a later date.Porsche spent a lot of time &money developing studs made out of fancy steel alloys that expand at the same rate as the alloy crankcase.The latest 993 spec ones have an anti corrosion coating aswell to stop weak spots forming.Oh and a clutch kit while it's in bits and then the flywheel may be worn.....Basically think of a budget and prepare to double it.[]

 

[bones]

Just to clarify on the Alusil /Nikasil point. You may have Alusil or Nikasil cylinders in an SC, it seems to depend on whether when you car was built they had the favoured and cheaper choice of Aluail in stock or not. (I have Nikasil in my SC). Alusil can be recognised by being non-magnetic and usually have KS stamped on them, Nikasil are weak magneticly and usually have MAHLE stamped on them. Alusil cylinders must not be honed, just leave them alone or replace. Nikasil can be reused and honed with a silica impreganated tool. Don't use Dilavar studs, they are not up to the job and will ultimately fail, common agreed knowledge suggests to use earlier steel studs or expensive RaceWear or ARP studs.

 

[Guest]

Hi SobeUK,
About a year to 18 months ago the porsche Post did a fantastic engine build report. The reports were over a three month period. If you can talk to someone at the club you should be able to get copies of the articles, it will be well worth it . The rebuild was a blow by blow detailed analysis and the decision needed along the way including the all important costs.
John

 

[oliverjamesthomas]

You might want to check out www.impactbumpers.com. You'll find loads of stuff regarding the SC engine in terms of rebuilds and modifications.

 

[Guest]

Thanks guys. I'll keep you updated with what we end up doing. I'm taking it down today.

Cheers

 

[bones]

Hope you have a copy of Wayne Demsey's 911 engine rebuild book, if not get one, it is invaluable.

 

[Guest]

Martin

So who did you get to do the 3 angle valve job? And what sort of price was it? On that note can anyone recomend someone who does a sterling 3 angle valve job at a reasonable price - the juys we have looked at are not cheap (apparently their new machine cost over £20,000).

Cheers

 

[Guest]

Well the motor is now in pieces [].

Only one broken stud which was a bonus. One Broken ring and a very loose chain so it was just a matter of time I guess before it all went pear shaped. Now to decide what to do.

Does anyone have any thoughts regarding upgrading to the 3.3 barels and pistons?

Cams look in great condition[]

Barrels appear to be the Nikasil ones and are in good condition.[]

A few issues around the clutch and gearbox were found (rusted clutch arm and bolts). Rather strange considering they were all replaced 2 years ago. So I guess a bit of work required there too.[]

Will be sending off the injectors for cleaning and checking - hopefully will not need to replace but we will see.

Well off to start the list and pricing up of the job - looks like a big one.

Cheers
[8D]

 

[Guest]

Hi Sobe,
Sorry I've not looked on here for a week or two...

Right 3 angle valve job was a bit of a nightmare as the first company I used only had a machine large enough to do 2 angles and then I took the heads to Baldyne's and I'd recommend them. They are a bunch of old boys who do aviation engineering work out of a unit at Biggin Hill Airport.
They can do balancing and machine work and their prices are reasonable (forget what it cost though)

Link here http://www.baldyne.com/

No experience on 3.3 barrels and pistons i'm afraid.
Hoping to get my car back from the painters this weekend and geet the reassemby done.

Good luck with this and keep posting the updates and add pics too

Mart

 

[Guest]

The Latest Update:

Well the bores and heads have gone to the machine shop. Decided to try and keep things fairly original. Just found out some bad news though!

There are two barrels where the seals are dammaged and cannot be skimmed or repaired so the options are to either replace all ballels and pistons and go for a 3.2 or to just replace the two barrels and stay 3.0. Currently trying to find prices.

So at present feeling down and come to the sad realisation that she will not be on the road for the British Grand Prix. Currently having to rent a car as well to get to the office. Actually thinking of a short term lease for three months as that's my guess as to how long my car will take to rebuild.

I'll try and get some pics of her in bits and post them here some time.

Cheers[]

 

[Gary C]

Sorry to hear about the barrels, Go 3.2, then the upgrade will make you feel better.

Would a cheap runabout not be cheaper than renting ?

 

[Guest]

Gary

Looks like I may borrow my flatmates car for work at least. Shold save a bit that way.

On the 3.2 front I was told that there are a lot of bits that would need changing and therefore not to do it. What is involved in going to the 3.2? Is it simply replacing the barrels and pistons or is there more?

Mind you the 3.0 barels and pistons are £412 + VAT cost each so I'm already looking at £970 for the two. Assuming the 3.2 would cost the same all six would be just shy of £3000 at cost price - ouch!

I was also told that changing to the 964 cams also requires a number of other mods. Is this correct? Or can you simply replace the cams and nothing more?

Cheers