engine rebuild

[diescher]

Hi

I´m restoring my porsche 911 2,4 S (1973). And now I´m beginning to rebuid the engine. I have a question.
What´s the better way to clean the engine case? Can I blasting the engine case? What do you recommend?

Regards

[schmidt]

God no, dont blast it, what is your experience level with restoration work? Are you doing the work yourself? How much of the work are you able to do yourself, ie engine, paint, interior. This will help better answer the question.

[diescher]

The car is restored by proffesionals. Now the car is resprayed in light yellow and the interior is new (buyed in Germany).
I am restoring the car to original standards.

[Steve@Rennsport]

Hi:

You are probably not going to like hearing this, but I'd kindly suggest that you have a qualified professional who is well experienced in rebuilding mag-cased engines do this project for you unless you can afford the financial consequences of any mistakes you might incur.

There is a LOT more to this than meets the eye,....

[911scfanatic]

Steve, can you expand on this (relative to an experience DIYer)? Are you talking just lower end? machining? assembly? It would seem if you have the inspection and machining done by a pro you'd be set from there. At most, an experienced DIYer would go the extra step of having the lower end assembled by a pro. Thanks.

[Fritz A. Ficke]

Just to expand on the sand or glass blasting, it is the worst on soft material like Magnesium or Alu. if you blast the inside of the case it will diffentely release glass particules in the oil, The glass imbedds in the soft material and no amount of scrubbing gets it all out, but heat when the engine runs will let the stuff loose.

[fryardds]

I will give a strong recommendation to what Steve said. The case should be sent to a very qualified machine shop for evalution and machine work. That is only the beginning though. If you haven't already done so you should buy Wayne Dempsey's book on how to rebuild a Porsche engine. It will give you a very good idea what you are up against.

http://www.101projects.com/911-Rebuild/index.htm

[Steve@Rennsport]

Steve, can you expand on this (relative to an experience DIYer)? Are you talking just lower end? machining? assembly? It would seem if you have the inspection and machining done by a pro you'd be set from there. At most, an experienced DIYer would go the extra step of having the lower end assembled by a pro. Thanks.

Hi Bill:

LOL,...As you can well imagine, this is a complex subject and really can't be thoroughly addressed on an internet BBS.

Mag-cased engines require FAR FAR more preparation than their aluminum-cased cousins and that involves very precise measurements, machining, and care in assembly. Honestly, this requires experience to get the results that most people expect; trouble-free engine life of 100K miles or more.

I've seen the whole spectrum from improperly machined-prepared parts to sloppy assembly to "rookie" mistakes and the consequences were all the same. The whole thing needed to be redone and in many situations, some expensive parts were ruined.

DIY'ers simply need to understand that while they save the $ 4-5K in labor to assemble a motor themselves, they assume all the risks if something is wrong in the preparation, machine work, quality control, and final assembly. Sometimes, problems do not manifest themselves until the engine has some time on it.

I sincerely hope you understand that I'm not trying to discourage anyone from undertaking such projects; my only point is to ensure that people do not make such a decision without all the facts at hand,.........

[911scfanatic]

No, I'm cool. It's all about ROI and risk management--in particular relative to the mag case. At what point does a DIYer reach an acceptable level of risk? I've got to think that if the concern is with mag cases, then if you have a pro do the lower end hasn't all the special concerns with the mag case been avoided (if I'm making sense)?

And, I'm not being cute here or trying to break your balls. I'm honestly asking because I'm planning to build a 2.8 off of a 2.4 7R case, and I've been leaning toward letting a pro do the whole lower end and then do the rest of the assembly myself. Reason is that I see the lower end as where most of the magic is, in particular with the mag case, and I want it to be perfect. Plus, it makes sense for balancing and a bunch of other reasons. From there I think I can live with the risk and check things 200 times and get it right.

[kenikh]

I'm planning to build a 2.8 off of a 2.4 7R case, and I've been leaning toward letting a pro do the whole lower end and then do the rest of the assembly myself.

Not to sidetrack, but DUDE! Why would you bore the spigots of a 7R 2.4 for 92mm pistons when 2.7 7R cases are a dime a dozen! These cases are really starting to command a premium IF you can find one. This is one of the rarest cases on the freakin' planet. They are best left to 2.4 CIS restos. At least think about it.