engine rebuild

[Ignatzcatz]

Still in the doldrums a bit waiting for my engine to appear although it has now been line bored and chromated. My man doesn't have a dedicated engine assembly room at his works but there is an attached area which he will be giving a mega clean to ensure no nasties, earthbound or flying decide to be part of my Porsche engine. I fitted a servo and vacuum pump to the car, plus a few bits of associated brake lines plus a new VW Beetle type 1 master cylinder as mentioned earlier. I wanted to flush and re fill the brakes with nice new dot 4 brake fluid but I did realise there would be a whole lot of air that had to be expelled. I don't do anything fancy when it comes to brake bleeding, just an old can with a bit of fluid in it, a length of tube, back out the bleed nipples then pump away. I had been doing this for a couple of days and wasn't getting much joy but I was getting a lot of air. I had a think about the situation and remembered that I had fabricated a dual threaded push rod for the master cylinder as it was a single outlet to match the single outlet servo as opposed to the dual circuit 911 unit I had previously fitted. The pedal didn't feel right so I backed off the pushrod and in doing so I believe I enabled fluid to pass into the cylinder where before the bits inside the cylinder were not allowing the cylinder to be re-charged. Once round the car to bleed all the calipers again and bingo, I got the rock hard pedal I was after. I ran the servo with the vacuum pump going and the pedal needed just half the push or maybe less. So it looks like I actually did something right this time.

[Ignatzcatz]

After the Christmas break it's all go on my engine build after Gary at GDC finished his major rebuild of the very first long wheelbase 911 no.001. The heads are all built now with the combustion chamber volumes matched nicely and the valve spring heights checked. Piston ring gaps are done and the cylinders got a hone to get the correct clearances. The cam carriers are off to be ultrasonic cleaned and the stripped down Webers will be chucked into the same vat. When the carbs got completely stripped down a fair bit of grit and general debris was found in the carb bodies which I suppose was not surprising but worrying all the same because I wasn't running any air filters on the carbs when the engine was the old 2.4. I only had the ram pipes mainly because there is so little room between the carb chokes and the engine lid, even more restricted at the rearmost choke. So filtration for my new 2.8 will be definitely required but I shall have to give this some thought as I do not want those large bath loofah affairs one often sees on modified engines. Any ideas on this problem would be most welcome.

[Ignatzcatz]

There was a problem with clearances on my engine. On a trial assembly Gary found a minor discrepancy, only half a thou, a bit less in fact but when I'm pedal to the metal giving the wee beastie heaps I really don't want to wipe out a bearing or much worse. So the cases went off to Mr Fulljames's machine shop for correction and now all is reading where it should do. We are nearly there and I contacted Stuart down at Rothwell motorsport to get the lump booked in for dyno break in and tuning runs. Unfortunately Stuart is currently absolutely overwhelmed with race engines for customers who want them for the upcoming season. Stuarts' forte is the Coventry Climax old fire engine pump engines and there are a load of classes using this engine from sports racers all the way through to classic motor bike and side car units. No worries, it's just going over to Neil Bainbridge for this dyno session, the only worry is that it's going to be a load more expensive but hey ho there's no scrimping now, And don't you love those rods, sex in steel, much too nice to be hidden away in my enIMG_1489 - Copy (2) by Graham Kerr, on Flickrgine!

[hashman]

Those definitely look like a nice bit of kit.
I bet you cant wait to try this engine out.

Karl

[hot66]

I always think rods are the best looking internal bits of high performance rebuild

[Ignatzcatz]

Agree, and I wish they would make some very small ones so you could have it on your keyring or on a chain on a necklace, hey, boys wear them now, it's a shook up world . . .

[KS]

I always think rods are the best looking internal bits of high performance rebuild

Agreed...

[Ignatzcatz]

Looks like you're a couple short there Keith

[KS]

Looks like you're a couple short there Keith

Nah, I want to go fast - all that extra weight slows you down.

[Ignatzcatz]

There is always something that stops the flow. You have to stop and sort it, like a tight bearing and this time it was a minor issue to the engine cases. I had selected an aluminium sump plate kit for the engine, no, it won't make it go any faster it's just a bit of bling you can see if you happen to be looking at the underside of the engine. However it didn't fit because my machinist hadn't clearanced the cases. OK at the time he didn't know I was going for this ally piece to replace the standard steel item but although this minor issue could be addressed with a simple angle grinder it did mean the engine had to be fully masked up to obviate any inclusion of foreign bodies. So, masked, ground, jobs a good'un, back to the assembly.

[Ignatzcatz]

Oh dear, another slight problem with the build. Gary had just completely finished rebuilding the carbs with all new parts including big chokes, the old ones were an absolute sod to remove, a whole day in the ultrasonic bath moving the carb bodies around and around just to get them released. Graded the cylinder heads on height, measured the cylinders and pistons then found the running clearance was a little too tight so honed all the cylinders to get the correct clearance. Gapped all the piston rings, cc'd the heads, checked valve spring heights, fitted the valve stem seals and built the heads. After getting a time-sert fitted into a dodgy exhaust manifold stud hole everything got another mega clean prior to engine assembly which was de-bunging and rodding out all the oil ways. New sprockets went on the chain idlers, I've gone to late model pressure feeders. Also cleaned out were the spray bars for the camshafts and the cam carriers got the ultrasonic bath treatment too. As an aid to better carburettor performance I got some thermos blocks but these had to be bored out to suit my 46IDA inlet manifolds. Nearly there, but found one of the oil jets which lube the underside of the pistons was in-op so that was replaced, stripped the inter gear shaft and ensure the oil ways were spotless, new lay gear and sprockets fitted. Onto the bigger stuff so cleaned and measured the crank again, stone faced the crankcases, cleaned it all again, fitted those gorgeous rods onto the crank then got on with bolting it all up stretching and measuring all bolts . The crankshaft, lay shaft went in and the gear backlash checked, then the oil pump then started to work out clearances and comp ratio. It was only then that due to going for the max size of 92mm barrels and pistons to give 2.8 litres that we found the piston base just touched the bottom of the spigot bore for the cylinders. And additionaly, when the cases were bolted together and checking the main bearing bores, a couple were found to be a miniscule tight. There was just the tiniest wear make on a couple of the bearing shells. On a street engine it would have been acceptable but as the cases were definitely up for further machine work I'm getting a re-hone all of half a gnats cock or thereabouts.
Overall it's going to put the build back another month by the time I've picked up the cases from Gary's shop, taken them down to Winchester for the first machining operation, picked them up then dropped them off down to Dorset for the next machine work, then gone back picked it all up and delivered it back to Gary near Bicester. A bit more grief is that I have decided that I will have to pull out my recently rebuilt and re-installed gearbox because I really don't think that in the tight confines of the rear of my 356 that there will be sufficient room to install the engine on it's own. Gotta keep busy!

[roy mawbey]

My goodness what a lot of work involved to do this work when you have changed so much. I think you have been really busy but what experience you must have gained doing all this engine work. None of that is easy, you have had to think all the time about everything ! Make a mistake and its more than costly!

I have to say well done on all this effort to finish this 2.8 litre engine. My little 1600 super seems like a little toy by comparison to yours !!

Wishing all the best of luck getting it fully assembled and fitting it together with the gearbox !!

Roy

[Ignatzcatz]

Hi Roy, thanks for the kind words. I've rather made my own problems by being greedy. I should have been happy with the old 2.4 engine and gearbox but it was a bit leaky and the box was definitely on borrowed time. I should have gone for a standard 3.2 but greed for horsepower sent me down this rocky road, a course taken by many I'm sure. D day for me will be the end of April because in early May I shall be off to Estoril for the 356 International meeting, I just have to remeber where all the wires went and where all the nuts and bolts go. Happy days!

[Ignatzcatz]

DSCN3022 by Graham Kerr, on Flickr
I was asked on email what had I done to the 915 trans and I think previously I only glossed over what was done, so here's what was needed to make the box roadworthy. I knew the trans wasn't a happy gearbox by all the noises it was making when I was trying to keep up with my 911 buddies on the way to Le Mans classic - fast, and the way back - even faster. It went up to MB engineering in Kendal for diagnosis, this was what was found.
5th gear had damaged teeth and was blue, bearing play on the pinion shaft of 4th gear which was badly scuffed plus damage marks on 1st, 2nd and 3rd gear. Diff was marked and the outer bearing in the case was loose. The diff side plate was damaged missing 2 mounting lugs. That was the initial look and from this a list of parts were itemised:
1st gear and imput shaft as the gear was starting to wear, 2nd 3rd and 4th gear which were all worn and scuffed, 4th gear was particularly bad, 5th gear starting to go blue from lack of oil!? An imput shaft bearing - worn and clamp plate, flanged pinion bearing, pinion shaft clamp plate, 2 reverse gear bearings and 1 thrust bearing, pinion lock nut, input shaft lock nut, 2 diff bearings. Pinion roller bearing, possibly an O/S outer bearing due to it coming loose in the diff case, diff side plate, short of two mounting studs, 5 gear bearings, 2 x 1st and 2nd syncro bands, 3 x 3rd 4th and 5th syncro bands, 1 x 1st n 2nd slider, 1 x 4th n 5th slider, 1 diff crown wheel carrier, 6 diff lock tabs and 12 x diff bolts, sundry diff shims and clamp plate shims. Diff side plate and a gasket set. I was advised there might be additional stuff needed when the rebuild was started in earnest. I'd supplied a new Quaife LSD plus 8/31 CWP gears to give me a 3.875 ratio. So work commenced with cleaning the diff case and fitting pinion outer bearing. Build up the pinion shaft to fit the diff case, clean up diff side plate and fit to take pinion depth reading, fit diff shims, check reading, fit shims, check readings again until within setting limits, clean diff, remove crown wheel, clean diff carrier to find wear on planet gears. Fit diff shims and bearings, fit diff carrier to case and fit side plate to take a reading on the bearing pre-load which was found to be within the settings. Still awake? Stay with us. Select diff planet gear set and remove diff carrier from case, fit the set to diff carrier, check fit is ok. Fit centre case and 5th gear set and reverse, torque it all up for diff/lash set up. Loosely tighten crown wheel to diff carrier and fit diff bearings, fit to the box and check bearing pre-load then check back lash,remove the diff and adjust diff shims to gain clearance. Replace the worn set of planet gears, adjust the diff bearing shims to find nil adjustment on outer diff bearing. When the new diff arrived, the crown wheel was swapped and the diff bolts found to be too short as diff is for electric speedo!? Compensating shim is fitted to lift the diff for back lash and diff bearing pre-load. With pre-load and back lash at factory setting finish off the diff set with lock tabs, fit the side plate with a new seal. Check the selector for 5th and reverse is at the correct setting. Clean and fit the end case with new selector shaft seal and fit new diff seals. Clean and fit both drive flanges and check all gears select and shafts turn fully in all gears.
That's all pretty straight forward then. I've rebuilt about a dozen engines in my time, from a 1172cc side valve Ford to a fairly complex 205 Peugeot plus a couple of old V8s buit I have never had the nerve to even think about delving into the mysteries of a modern gearbox. I fitted my 915 into the car just to see if everything goes where it should do, it did, but I had to pull it out as with the severe space limitation that exists with the 356, the engine and box will have to be fitted as one. The car is currently on a lift but I shall bear the weight with an engine crane then juggle it home using a trolley jack, should be lots of fun.

[Ignatzcatz]

Holy Moley, it's only five weeks before the 356 International at Estoril and I've got an engine and gearbox less motor car. And the engine isn't even back together yet, although the bottom end is now all buttoned up after getting the engine case back from being re-machined. However, there are still problems and this concerns the estimated compression ratio. The barrels really need to be raised up but this is impossible because the cam chains are already at their max so a 1.5 base gasket is all we can use. The heads which are completely finished and cc'd balanced to .01cc really don't need to be messed around with. So that leaves the pistons and my ones are designed for a head volume of 68 cc, mine spec out at 63.7cc so they are going to require a quick short back and sides. The exhaust valve is very tight so maching is definitely required here. It is difficult to calculate the total amount of maching required when you are fly cutting the valve reliefs on the piston due to the fact that you are dealing with a semi circle. We have calculated the cut as near as we think correct but we will cc the piston following the first cut then work out how much came be lost from the top of the piston. Lots of fun but very time consuming, however, it is very necessary as the original comp ratio worked out to be somethng in the region of nearly 12 to 1 and it has to be reduced down to a more workable and safe 101/2 to 1.
So the top end has to go back together, then the engine has to go onto the dyno and if - if it all checks out OK, I reckon I shall have about 5 days to throw it all back into the car before I'm screaming down to Portsmouth for the ferry. Did someone say stress? Just pass me that bottle of Jack.