8000 rpm/300 bhp 3.2 rebuild

[911hillclimber]

Indeed, too easy just to buy 2 fancy bolts for £100 each and loose 2 weeks at least waiting for them to arrive.

Nice way to finish the day!

[911hillclimber]

Big step today, the build of the short block, 4th time for me, still makes me nervous.

Preparation and cleaning the order of the day, and all Boy Scout stuff, "Be Prepared".

Tools laid out and cleaned, all the bits required from the gasket set (which has an excess of some O rings), fresh sealants, cleaner, sockets sets and cleaner.

Lots of work then The Moment and the clocks starts ticking, 40 mins to get it all up tight.

Went well, not much drama (that came later) and even felt I was a near expert, but far closer to dangerous with a little knowledge. Dempsey Handbook always there, great book to follow.

All fasteners tight and checked 3 times to torque, fiddly chain ramps in place and time to stand back and admire the architecture of the air cooled flat six, an engineers dream.
With everything tight, time to turn the crank, hopefully more than 720 degrees.

Fat chance as the crank came to a very hard stop after 45 degrees. What a horror, first thought was the one con rod was hitting the oil pump (you can get that scenario if you change to a bigger pump).

Found #3 rod solid. Backed off the crank and the rod was free. Stared at it (no swearing oddly) and thought I would hold #3 in it's correct position, ie about the centre line of the bore as if with it's piston.

Crank moved freely, 5 revs and all is well and SO VERY SMOOTH.

Decided to suspend the rods with elastic bands as noted on an engine rebuild at Greatworth Classics at the Autojumble. All rods now 'on centre' and the crank is beautiful.
Flywheel on with ARP bolts and all the right potions for assembly to 70 LbFt.

So, the end of a day, great to get this one done too.
Just need some pistons for the fun to continue.

[Gary71]

Big moment, feeling that crank turn after the big torque up is SO nice!

[911hillclimber]

Yes, funny how it seems such a big step forward, must be when the crank turns so readily and constant smoothness.

Gasket set had one too many red O rings for the through bolts! Should have counted out first.
Totally stuck until the pistons turn up, but mad a tool today to dti the valves for the can timing, that's another BIG step!

[Cortina]

I suspect this will be too late (guess as far as you are concerned, heads are "perfect" and ready to fit) but ?? Are you aware of the (assuming you are in the business of building perfect cylinder heads) need to measure and shim each valve to suit it's assembly (seat , springs , caps , valves, collets , grinding , etc etc) so that the "correct" (equal) work is being done by each spring ??

I would guess not. Building perfect heads is not a quick and easy subject - don't get me started on gas flow. I am not the expert (but I do know a couple and did have work done by another - Bill B.).

I'll give you the brief theory , and you can have a go the next time .................
For the spring (or springs) to work to their best. They need to be close to (NOT over) their limit. Their limit being when they go coil bound. There have been papers written on how close is close : Measured normally by the number of thou between coils when the valve is fully opened. It's not a big number !!
The aim is to get to this magic figure for each and every valve : Since each component is different (in theory they are all the same , but they won't actually be !!). then once you start down the road - each set of components must stay together and must stay with their allocated position. This MAY help explain why engine builder A can get that extra 3 or 4 hp out of the same engine that builder B does , and also why he is much more expensive ?

right - time to go back to my shed (928) , hope this is of interest ...... that's all it's meant to be !

[911hillclimber]

Thanks, and have been through this lot a few weeks ago.

I am limited by the shim thickness to set the installed length of the springs in the heads.
Porsche shim thickness is 0.5mm (seems crude) but Gary has seen 0.25.

Without a magnetic surface grinder, hard to shim better than 0.5mm. I managed to shim all mine to +/- 0.5 to the 36mm spring height given to me by Kent Cams for their cams I have bought.

I think it was 36mm but around there.

This is longer than the stock Porsche valve springs, so I ended up with a lot of spare shims.

Please never refrain from questioning me about what/why I'm doing things, the more checking what I'm trying to do here the better....

[Cortina]

Thanks, and have been through this lot a few weeks ago.

I am limited by the shim thickness to set the installed length of the springs in the heads.
Porsche shim thickness is 0.5mm (seems crude) but Gary has seen 0.25.

Without a magnetic surface grinder, hard to shim better than 0.5mm. I managed to shim all mine to +/- 0.5 to the 36mm spring height given to me by Kent Cams for their cams I have bought.

I think it was 36mm but around there.

This is longer than the stock Porsche valve springs, so I ended up with a lot of spare shims.

Please never refrain from questioning me about what/why I'm doing things, the more checking what I'm trying to do here the better....

Sorry but this is NOT what I am suggesting you do ... how the *** would Kent cams (or anyone else on the planet) know what the exact dimensions on your head are , what your valve dimensions are , how much grinding in of valves you had to do , how accurate the machining of valve seat faces are , etc etc, etc. No , we are on different wavelengths here. Without a dry run (assembly) and lots of measuring , you have no idea what the shimming should be for best valve performance. But (politely) unless you "get" the concept of what I am suggesting , I am at a loss ........... probably shutting up, is what I should be at !

[911hillclimber]

No!
Don't do that.
This engine pulled 260 BHP in standard form with oversized carbs and a diy exhaust.

I don't think it need that level of refinement, all a bit of a nostalgic blunt instrument on a 40 second assault on a hill climb.

[Mike911scrs]

maybe worth a look at, http://forums.pelicanparts.com/porsche- ... orque.html

as it fits ALL your expectations

[911hillclimber]

That is a committed build, and a mid boggling result but quite a cost!

Interesting that the engine really starts at 4300 rpm, far lower than I would have thought, but what do I know! Peak red line at 9300!!

If I may mike, what are your thoughts on igniting this little engine of mine?

I have the pistons today, so fair bit of prep and check to do, but soon the engine will be completed, 2 weeks most and ready for the ignition buy, and I am waiting on a twin plug spec reply from Clewitt.

I want the simples system to set up on a rolling road and the simplest for my brain.
Would value your thoughts.

[911hillclimber]

Had a pass-out for this afternoon, so decided to check the squish 'height', crown height, and the rest of the ring gaps.

To the first, mounted the piston to the rod with #1 barrel and an old copper base gasket, then added 3 pea sized pellets of BlueTac on the sides of the piston dome and the very top with a smnall piece of cling film over the top so when crushed the bluTac would not stick to the piston.
Advanced the crank well over TDC.
Added the #1 head and torqued the lot to final spec, 26 lbft.
Rotated the crank until you feel the blutac being squashed and then over tdc for about 30 degrees.

Remove the head and measure the crushed BluTac with verniers.
Repeat for the RH side.

Results were 1.72mm and 1.76mm (doubt you can call the last digit accurate) Squish. So, about 70 thou. and the top was about 3mm!
I'm happy with that.

Thirdly, placed the top ring in all the other barrels and all need opening up from a gap of 12 thou to 15 thou, none larger.
JE spec is 17 thou min, the second ring is 4 to 8 thou wider.

Awaiting Peter's gap grinder before I can get serious.

Next step is to build up both sides dry and set the cam timing. (what joy) and then advance the inlet 80 thou via the rocker screw and rotate so carefully the crank 720 degrees to feel for interference.

If clear, drop the inlet back and do the same with the exhausts but to 100 thou and keep my fingers crossed....

[RobFrost]

Engine looks amazing and this care will really pay off. If you ever sell it let me know!

Sent from my SM-G988B using Tapatalk

[911hillclimber]

Thanks Rob, this engine will go with the race Lola when my hillclimb years are up..

Managed some hours getting the engine to a dry build, ready for cam timing and valve interference test.
This too k ages, partly due to my stupidity.

I ordered the cams and forgot to tell them to delete the rear drive pots on the back of the cams as James had warned me. Forgot.

So, spent some time sawing the stubs off and levelling the back, bit nerve wracking on a pair of £1300 cam shafts, but all done. Cast iron is nice to cut!
Checked the fit of the woodruff key in the cams and found them too tight so out with the needle files and some carful thinning of the keys and all was well.

Built the cylinders up missing out #2 and #5 as not needed for this task.
Assembled each side with the engine on it's side so gravity was always keeping the chains in place and slowly got it all together, just the rockers in #1 and #4 heads to fit and I'm ready for endless fun with the DTI gauge.

However, for a bit of relaxation, helping a fellow DDK'r take his engine out of his 911 tomorrow.

[911hillclimber]

Spent several hours on the dry assembly to conclude it.

Got the cam timing of the GE60 to 5mm (range is 4.8 to 5.2) on both sides.
The LHS came on 5mm first setting!
The RHS came on 4.7mm and took several iterations to get to 5mm.

So far, so good, then the evil bit, checking the valve to piston gaps...

Started with the LHS inlet and clearance is 2.5mm (min is 1.5mm allowed) and thus lots of room.
RHS inlet was 2.35mm
LHS Exhaust was 3.25mm (2mm minimum allowed)
RHS Exhaust was 3.25mm

Phew, all ok and room to spare.

Will check it all over gain tomorrow and then tear the lot down.

Have the loan of a DDK ring gap grinder, so gapping all 12 rings next which will be a joy.

Just one pic covers 3 hours.

[Gary71]

Sounds good. Loads of room to spare!

What does the compression ratio work out as?