3.0sc engine rebuild

[james ashby]

As i am having problems finding a decent engine, i have considered rebuilding my existing one, is this a foolhardy mission or something a relatively capable person could take on. There must be afew of you who have tried this and there engine is still running! Thanks in advance.

 

[tripe]

I would say a fairly straightforward job so long as you have a modicum of mechanical acumen, a logical mind and plenty of time. A decent engine stand will come in very handy (no more than £50 from machine mart) and essential is a good workshop manual - the good old Haynes covers the strip down and rebuild well, however the Bentley service manual is more comprehensive.

If can take photos with a digital camera at each stage this will help, putting it back together is easier with a few special tools - e.g. piston ring compressor and a good torque wrench is essential. The one area that you might be advised to get some help on is timing the cams when you rebuild it. When I did my first engine I took it to PCT cars and for a drink Nick timed the cams while I watched - very useful! Budget on a least £1,000 for gaskets, rings, bearings,decent oil etc. It would be worth your while having the crank checked by an expert and keep some cash spare for unexpected problems (like broken head bolts, exhaust studs shearing etc). If you can afford it it would be worth fitting a new clutch if the old one's more than a few years old.

Providing you are thorough and have patience this can be a very rewarding job.

 

[james ashby]

Thanks the engine is already stripped by a porsche man, who then told me how much it would cost to put it right. I would be happy to do everything except the valve timing. But by eliminating the labour cost it ist not too bad. What do you think of the book by Dempsey - Modifiying and rebuilding 911 engines - is it worth getting. Thanks again.

 

[bones]

The Dempsey book I would say - or something similar - is a godsend for the novice 911 engine builder, sorry if I upset anyone but don't go near the Haynes it is not nearly detailed enough, the Demsey is the rebuild book of today. When my engine needs rebuilding (years away I think) I'll be using the Dempsey book along with all the other information I have. Having done a partial rebuild on my engine last year and having rebuilt a lot of motorcycle engines in the past it's not too hard but will require, carefull planning, meticulous attention to detail, cleanliness and patience. If I were starting this job tomorrow I would need a spotless garage, an engine stand and a 911 engine cradle (you need the cradle, don't use anything else) Don't try and rebuild the engine on the floor or on a bench. Rebuild the bottom end too it's not worth just re-ringing and refitting the valves. Get a friendly 911 engine builder you can rely on to pop in (pay him for his time if necessary) for the moments when you are unsure, don't rush at all and never force anything. Take particular care with gasket goo and make sure you have the right stuff, a mistake in this area could mean blocked spray bars or oil ways. Have the cams checked as well as the crank. Think about fittng larger barrels and pistons. Valve timing is a piece of cake copared to what else you are going to do.
Special tools you might need are
Flywheel installation tool, crank pulley seal tool.
Metric dial gauge and holder.
46mm crows foot wrench.
Gudgeon pin circlip remover/installer.
Vernier dowel pin removal tool.
Flywheel lock.
Cam chain sprocket holder.
Chain tensioner tool.
You will be able to get by using other tools but you should consider asking your engine buider to hire or lend you what you need.

Where are you if you are near London I'd be up for lending a hand.

 

[tripe]

In place of the tool for removing the dowel pin from the cam sprockets you can use a spark plug - just unscrew the end cap - the thread on the exposed pin is exactly the same as the thread on the inside of the dowel pin - should save you a few quid!

For more special tools have a look at:

http://www.continentalimports.com/porsche_part.html

 

[james ashby]

IM AFRAID IM NOWHERE NEAR lONDON, AND YOU ARE ALL DOING A GOOD JOB IN PUTTING ME OFF. HOW MANY HOURS ARE WE TALKING? i WILL BUY THE DEMPSEY BOOK TO SEE WHAT MODIFICATION ARE PRACTICAL AND REALISTIC, LIKE MOST PEOPLE I WANT THE MOST POWER WITH RELIABILITY, I HAVE PURCHASED SSI HEAT EXCHANGERS AND WILL BE RUNNING IT ON WEBERS. THE GROWL IS JUST SO MUCH BETTER THAN INJECTION.

 

[bones]

You are a brave man messing with carbs, if I were you I'd fit the Bitz racing EFI kit , it's cheaper and infinitely tuneable , you get everything for $1500. Plug it into a lap top for analysis and you get traction and launch control as a bonus. The base bhp gain is about 25bhp, with SSI s and a Triad exhaust you would be looking at a 40bhp gain with better fuel efficiency, on carbs I reckon you will be lucky to see 15mpg. Personally I'd sell the Webers and go for the Bitz racing kit.
Allow as long as it takes for an engine rebuild, if you have loads of time a week should do it.
http://forums.pelicanparts.com/showthread.php?s=&threadid=139422&highlight=CIS+to+EFI+kit
http://www.bitzracing.com/

PS please try to post in upper AND lower case[]

 

[sep4]

For any owner who feels the desire to remove and rebuild their engine I can give my thoughts!

I rebuilt my very tired and oily 2.7 engine some years ago. Did this single handed in a 20 by 10 foot garage with the car up on ramps. It took care and patience but was not unduly difficult. You must study carefully any literature available - I'm sure the Dempsey book must be the best going but I did mine before these were available over here. I will only mention the problems not mentioned in the books.
The engine with gearbox can be dropped and removed with the car on ramps.Take off rear bumper with any attaching tinwork, the heat exchangers/silencer are best removed now, and on 2.7s, the K-Jetronic setup will take out. K-Jets on 3.0 engines with metal fuel pipes are much tighter for space and may need to be separated once the engine is on ground. Every inch of height is vital. Loosen rear wheel axle nuts beforehand, with car on ground incase you decide to remove drive shafts. There is no engine protection underneath once heaters are off so put something under in case engine becomes unstable when being lowered. Old plastic milk crates are ideal. Ensure everything is detached as the books say otherwise the the engine can be pulled over when lowering. As a safeguard I put long cheap threaded studs down through the engine mounts.
I only had two problems on stripping engine - the cam/sprocket cover area needed tools making up to hold the camshaft end while its nut was loosened, possibly these can be bought or loaned now, and the cylinder barrels were very tight in the crankcase. Two pulled headstuds which had caused the oily engine meant the crankcase going out for repair and the fitting of dilavar studs - costly exercise!
Fortunately crank was good so only new shells were needed. If you need a reground the journals must be specially hardened afterwards. The cylinders don't rebore so new rings is the best you can do. I used the Club engine stand for reassembly - you can turn the engine 360 degrees on this. Two strong men can lift the engine from stand to ground but its difficult to hold the engine tightly. Loctite Multi Gasket 574 sealed the crankcase halves. Cleanliness is essential.
Timing the engine does take care. I borrowed a dial gauge and but they are cheap to buy now. Its safer to do each side with only rockers 1 and 4 fitted. If all rockers are fitted don't turn engine if any resistance is felt, a piston is touching a valve. Check several times the timing.
The cost becomes prohibitive when faults like scored or worn bores are found, or burnt headgasket sealing areas. Its difficult to replace with good s/h items with so many size or height variations, most used items have high mileage or twenty years use will not be good enough. The cost of dilavar studs and their fitting spoilt my rebuild. Prices for all parts vary enormously between suppliers.

I finished with an excellent knowledge of a brilliantly designed engine. It was very clean and reliable. Whether I would do this all again ? Probably not in all honesty. The total cost must have been over the top compared to the value of my car.
James, tell us what area you live in. Someone around the corner may have tools/knowledge or encouragement you need.

 

[Guest]

Hi Bones,
What knowledge do you have of the Bitz EFI kit, do you know of anyone that has fitted and used it? Any good reviews, longevity etc?
Thanks
Ian

 

[bones]

The best testimonial I have had for this is from Noah Pollock a moderator at Pelican Parts plus I emailed a few other people who have installed it . Have a look at

http://forums.pelicanparts.com/showthread.php?s=&threadid=206564&highlight=WUR

to see the kit on Noah's engine and email him. Search Pelican and email those guys who have fitted the kit. After what I have read my only concern about fitting it would be that the system would still need to be repairable in the future. There isn't anything that is now obsolete on my car that hasn't been repairable with some ingenuity so I asume it would be the case with the constantly updated Bitz electronics, the hardware is easily repairable.