Jump to content
Impact Bumpers
MaxDiesel

Time for a top end rebuild ?

Recommended Posts

Just had my third measuring session and the results are:

 

- All crank journals in spec :) so just a clean and polish required here

 

- All valve stems tapered beyond max spec :mellow: so new valves added to the shopping list

 

I think I've finished compiling the list of stuff that needs replacing, here it is - hopefully useful for the next person undertaking a rebuild:

 

1 x Top End Engine Gasket Set 930.100.907.04

1 x Bottom end gasket set 930.100.901.04

12 x Valve Guides (std) 930.104.321.00

6 x Inlet valves 930.105.409.13

6 x Exhaust valve 930.105.419.51

12 x Valve spring sets

6 x Piston Rings 930.103.986.00

24 x Head Studs 993 spec 993.101.170.51

12 x Con rod bolts 964.103.176.00

12 x Con rod nuts 993.103.174.02

2 x Timing Chains - continuous 993.105.529.00

1 x Guide Rail Brown 911.105.222.05

5 x Guide Rail Black 911.105.222.06

4 x Oil Return Tubes 901.107.351.01

1 x Main Bearing Set 964.101.901.00 (930.101.901.00)

1 x Big End Bearing Set 930.103.147.00

2 x Intermediate shaft bearings

3 x Oil pump lock tabs 999.039.001.00

9 x Flywheel bolts 930.102.206.00

9 x Clutch bolts 900.067.045.02

1 x Inlet Manifold Joint Rubber 930.110.573.01

1 x Throttle mounting O ring 999.701.124.40

2 x Vacuum elbows 928.574.717.02

6 x Injector seal sets 944.110.901.00

 

What've I missed ?

 

(Still got to meaure the con rods to see whthether they need re-bushing)

Share this post


Link to post
Share on other sites

Not a lot of progress to report as I'm waiting for all the new bits to arrive now - hoping to get the new guides and valves this week so I can get the heads finished.

 

Had another bash at removing the exhaust studs this afternoon - managed slightly better than 50% success rate:

 

Four more out, threads cleaned and ready to go: :rolleyes:

 

DSC00296.jpg

 

Then one more out, but three in need of repair/helicoils:

 

DSC00298.jpg

 

Can't believe how stubborn they are to get out - tried many different methods: heat, impact gun plus stud chuck, drilling then easy-outs (managed to shear two of these in the studs !) etc. but none worked every time. Going to get the machine shop at work to drill & fit the helicoils - that way I can be sure they'll be straight !

Edited by MaxDiesel

Share this post


Link to post
Share on other sites

Max a good repair on the exhaust stud threads is to get the hole machined out bigger and an insert screwed in, much stronger than Helicoil.

Baz

Share this post


Link to post
Share on other sites

Slowly gathering all the bits for the rebuild - got the new valves & guides today (Thanks Tripe) so I can get on with my heads now. Also got my second batch of stuff back from the platers - including the case hardware:

 

DSC00302.jpg

 

Had my engine stand adapters zinc plated while I was at it - will be putting one of them on ebay at the weekend:

 

DSC00299.jpg

 

Managed to get my inlet manifolds on the flow bench at work earlier this evening, interesting results:

 

manifoldflow.jpg

 

The flow variation cylinder to cylinder isn't anything like as bad as some make out - I suspect some of its hype to promote extrude honing ! There are some differences - Cylinder 1 has the best flow at 632 kg/hr versus 597 kg/hr on cylinder 3 which was the lowest.

Even so there's only ~5% difference between the max and min so Porsche did a pretty good job in the first place (as usual !). Going to have a closer look inside the manifold next and see what we can do to improve the flow.

Share this post


Link to post
Share on other sites
Just had my third measuring session and the results are:

 

- All crank journals in spec :) so just a clean and polish required here

 

- All valve stems tapered beyond max spec :mellow: so new valves added to the shopping list

 

I think I've finished compiling the list of stuff that needs replacing, here it is - hopefully useful for the next person undertaking a rebuild:

 

1 x Top End Engine Gasket Set 930.100.907.04

1 x Bottom end gasket set 930.100.901.04

12 x Valve Guides (std) 930.104.321.00

6 x Inlet valves 930.105.409.13

6 x Exhaust valve 930.105.419.51

12 x Valve spring sets

6 x Piston Rings 930.103.986.00

24 x Head Studs 993 spec 993.101.170.51

12 x Con rod bolts 964.103.176.00

12 x Con rod nuts 993.103.174.02

2 x Timing Chains - continuous 993.105.529.00

1 x Guide Rail Brown 911.105.222.05

5 x Guide Rail Black 911.105.222.06

4 x Oil Return Tubes 901.107.351.01

1 x Main Bearing Set 964.101.901.00 (930.101.901.00)

1 x Big End Bearing Set 930.103.147.00

2 x Intermediate shaft bearings

3 x Oil pump lock tabs 999.039.001.00

9 x Flywheel bolts 930.102.206.00

9 x Clutch bolts 900.067.045.02

1 x Inlet Manifold Joint Rubber 930.110.573.01

1 x Throttle mounting O ring 999.701.124.40

2 x Vacuum elbows 928.574.717.02

6 x Injector seal sets 944.110.901.00

 

What've I missed ?

 

(Still got to meaure the con rods to see whthether they need re-bushing)

 

some items on my build sheet you might consider?

 

oil pressure switch? 91160623000

oil pressure sender? 91160613500

oil breather pipes? 93020738501/93020738601

big end bearing shell - Jaz list a diff p/n 93010314715

oil plug - 99906402602

drain plug - 94410719701

 

Are you doing clutch too? Clutch fork update etc? clutch master, slave?

Fuel pressure regulator?

2x crank reference sensors? 91160621501

2x heater hose 93021162201

 

Jaz also use NGK 'racing plugs' - NGKB8EVX

 

Cheers

Shirish

Share this post


Link to post
Share on other sites
some items on my build sheet you might consider?

 

oil pressure switch? 91160623000

oil pressure sender? 91160613500

oil breather pipes? 93020738501/93020738601

big end bearing shell - Jaz list a diff p/n 93010314715

oil plug - 99906402602

drain plug - 94410719701

 

Are you doing clutch too? Clutch fork update etc? clutch master, slave?

Fuel pressure regulator?

2x crank reference sensors? 91160621501

2x heater hose 93021162201

 

Jaz also use NGK 'racing plugs' - NGKB8EVX

 

Cheers

Shirish

Thanks Shrish - there's a few more for the list then... I guess the oil senders are done as "while you're there" parts. Did you have any problems with your crank senors pre-rebuild ?

My clutch looks quite new, I've measured the friction plate and its fine also the flywheel thickness is well in spec, looks like it had the fork update at the same time as the clutch. Will check out the B/E part numbers.

 

You might want to look at rocker shafts and bushes in the rockers too.

Good point, shafts looked OK but will check the rocker bushes also.

Share this post


Link to post
Share on other sites
Thanks Shrish - there's a few more for the list then... I guess the oil senders are done as "while you're there" parts. Did you have any problems with your crank senors pre-rebuild ?

My clutch looks quite new, I've measured the friction plate and its fine also the flywheel thickness is well in spec, looks like it had the fork update at the same time as the clutch. Will check out the B/E part numbers.

Yes Matt, 'whilst' you're in there's...' No problem with sensors beforehand, just did it for piece of mind. I swapped out anything that was difficult to get to without dropping the engine.

 

You should also consider engine thermostat 'o' ring seal if you haven't already

 

Shirish

Share this post


Link to post
Share on other sites

Did some more "whilst I'm there" bits today...

 

Right heater flap off, looks like it'll be fine after a bead blast and coat of paint:

 

DSC00325.jpg

 

Left heater flap.... looks like it'll turn to dust if I put it in the bead blaster, anyone got a spare ?

 

DSC00324.jpg

 

Flaky, rusty oil tank out:

 

DSC00326.jpg

 

Degreased and pressure washed - better condition than I thought but needs a couple of hours with the wire brush next....

 

DSC00328.jpg

Share this post


Link to post
Share on other sites

These arrived today - they look too good to use:

 

DSC00365.jpg

 

.....and £180 cheaper than the 993 Divalar studs :rolleyes:

 

Last delivery of parts from Tripe due tomorrow (cheers Jeremy !) and I'm nearly ready to start putting it all back together again.

 

Also collecting crank with newly polished journals and heads with new 3 angle cut seats tomorrow...

Share this post


Link to post
Share on other sites
I did not spot this earlier, did your plater's hydrogen de-embrittle?

I hope so - must admit I didn't check though. It's one of the processes they do:

 

London & Brighton Plating

 

Will check in the morning - thanks for the tip.

Share this post


Link to post
Share on other sites
I hope so - must admit I didn't check though. It's one of the processes they do:

 

London & Brighton Plating

 

Will check in the morning - thanks for the tip.

 

 

I'm a bit rusty (sorry) not been involved in plating processes for a while, I worked on setting up a manufacturing line for a missile system in the 90's and we had a load of bother with some fasteners that had not been baked hot\long enough.

 

Also I'm wary of plating, I chucked all the bits and bobs from one of my Lambrettas in for BZP, including circlips...they just snap....

Share this post


Link to post
Share on other sites
I did not spot this earlier, did your plater's hydrogen de-embrittle?

Good call Ben - spoke to the platers today and they admitted they hadn't de-embrittled the bolts.... even though its one of their standard processes. :angry:

 

I was aware some post treatment was required and had pointed out that they were high spec. bolts when I dropped them off. They've confirmed there's now a risk with using these bolts - also that the de-imbrittle process has to be done <5hrs after plating, ideally ~2hrs.

 

I'm waiting to talk to one of our specialists at work about how much this may have effected the bolts - I think its got a lot to do with the ratio between the surface area and size of the fastner plus material spec. etc.

 

Agreed with the platers that the next step was for me to get a price for new bolts and then to go back for a chat.....

Share this post


Link to post
Share on other sites

Some more progress....

 

Oil tank finished - flushed out with petrol and then brake cleaner:

 

DSC00378.jpg

 

Heads progressing:

- guides replaced & reamed

- new 3 angle cut on valve seats, all vac tested with new valves

- stainless steel exhaust studs fitted

 

DSC00368.jpg

DSC00375.jpg

 

New valve springs due Monday so heads finished soon

Share this post


Link to post
Share on other sites

That all looks dead posh and nice and shiney!

 

Bit of a bugger about the plating, hope it works out ok, good idea to talk with someone clued up on the subject, you might be alright.

 

My understanding is that ideally they go straing from the final wash into the oven for 24 hrs, I seem to remember that its to do with the cyanide used in the plating process, but I'm no expert.

Share this post


Link to post
Share on other sites

Finally starting to put it all back together again - hoped to get the bottom end together this weekend but didn't quite get there....

 

Gave the crank a final clean and assembled the rods & big ends:

 

DSC00384.jpg

 

Cleaned out all the head stud threads and sealed all the case dowels:

 

DSC00387.jpg

 

Trial fit for the oil pump and inter. shaft - all ok:

 

DSC00401.jpg

 

All ready to go togther:

 

DSC00398.jpg

 

Until a slight hitch... the dowel that locates No 8 bearing had disappeared ! Reckon it must have come out when the cases were ultrasonically cleaned :(

 

So progress on hold until I can get another pin (900.012.061.00 / 5H 8x10) - hopefully in stock at Porsche or a standard size pin I can buy locally.

Share this post


Link to post
Share on other sites

What you going to use for assembly pre lube?

 

I got a tube of graphogen, seems ok, I've never bothered on previous engine rebuilds, just used a smear of oil.

 

I used a smear of engine oil on my MG engine and it holds 60 psi hot so I can have done any damage when cranking it up. I'm a believer in not doing all that cranking to get the pressure up, but just firing it up. I know there are varying opinions on that.

Share this post


Link to post
Share on other sites
I'm a believer in not doing all that cranking to get the pressure up, but just firing it up.

I go with that too, but fill the filters and all that to help as much as poss.

Share this post


Link to post
Share on other sites
What you going to use for assembly pre lube?

 

I got a tube of graphogen, seems ok, I've never bothered on previous engine rebuilds, just used a smear of oil.

 

I used a smear of engine oil on my MG engine and it holds 60 psi hot so I can have done any damage when cranking it up. I'm a believer in not doing all that cranking to get the pressure up, but just firing it up. I know there are varying opinions on that.

Likewise I've never bothered with assembly lube before - just clean oil in the right places. I rebuilt my old 912 engine like this 10 years ago and a colleague of mine is still driving it today with no problems.

 

I did a bit or searching around on Pelican on why assembly lube is always recommended on 911 engines - one reason given is to avoid the oil washing the case sealent away before its set - sounds fair enough. So I've bought a tub of Redline Assembly Lube. I've used it on the big ends so far and it seems to work fine.

Share this post


Link to post
Share on other sites

Time for an update - managed to get away from work early today so had a good session in garage tonight:

 

Fitted new rod bolts and tightened to 15Nm +90 deg +90deg, didn't enjoy doing the second +90deg !

 

Assembled everything into the crankcase:

 

DSC00413.jpg

 

Loctite 574 applied to all the mating faces:

 

DSC00414.jpg

DSC00415.jpg

 

45mins (ish !) later all torqued up - and the crank still goes round :rolleyes:

 

DSC00418.jpg

DSC00417.jpg

 

Time to relax with a large glass of red wine !

Share this post


Link to post
Share on other sites
Looks GREAT! :ani_clapping:

 

And torqued up better than most specialists would ;)

 

It does look great. :signs118:

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.

×
×
  • Create New...