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Mk3 Spitfire engine and gearbox rebuild


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Bugger. Yes even with warming/chilling a bit of persuasion is required. 

Maybe I'm getting senile though but I don't remember the bearings being quite as tight back when I was having to do the job in a lockup many, many years ago.

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Hey Pete, good so see you are on the merry-go-round! My experience with the cam bearings is that they are very easy to change, tap the old ones out with the new ones as you put them in. Just make

I can smell the stench of EP90 from here. Probably your GA (although usual code is GB?) 'box is from a Herald, identical in every way to an FD one. I think this looks quite worn out judging by the

Or possibly you need 'the fourth' 

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8 minutes ago, Escadrille Ecosse said:

Maybe I'm getting senile though but I don't remember the bearings being quite as tight back when I was having to do the job in a lockup many, many years ago.

No previous experience for comparison, but getting the bearing off the old input shaft required some serious walloping, which I'm sure the neighbours appreciated after 9pm... 

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On 5/10/2021 at 12:27 AM, PeteStupps said:

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Going back to the stuck gallery plug, how idiotic would it be to tap the middle of the plug with for a left-handed thread, and try winding it out with a left-handed M8 bolt? Think the plug is 1/2". Taking the block back to the machinist means more time off work, and they won't do it while I wait so will have to make 2 round trips. 

Could just leave the plug as is, but I want to be sure all the oil ways are well cleaned after seeing Speedysix's grim recent experience. And it would probably come back to haunt me somehow or other. 

Likely worst-case result: M8 thread strips, leaving me a hole which I can use for inspection / cleaning, and then tap to 5/16" and put a little plug-within-a-plug... or is that too ridiculous?!

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Most likely your bearing has twisted a tiny fraction as it slid down.

Find a piece of pipe that is a similar diameter to the inner race of the bearing and tap it down with hammer. The best device would equally touch inner and outer race at the same time, but as that is not as easy to find inner race will suffice. DO NOT drive the bearing down with the outer race only, this will kill the balls inside.

To make it possibly easier (and to cement the argument with 'er indoors) give it a warming with a hot air blower first, hairdryer will work!

Phil

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Posted (edited)

I think that plug is in a state where I would consider welding a bolt or even a nut to it (if possible) and hope the heat breaks it free, I'd be reluctant to knowingly introduce swarf to the main gallery. But maybe I'm paranoid?

Echo Phil on the bearing, piece of pipe is the way to go. I don't remember mine being particularly tight, but then again I'm in the envious position of owning a 20T press (reluctantly purchased after I lost a battle with a Renault wheel bearing...)

input_bearing_press.thumb.jpg.4c8db26076cd79f71d317f67a2381787.jpg
 

Edited by JumpingFrog
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Ref the bearings, I’ve done quite a few of these over the years using nothing more than hammers, brass drifts and the occasional tube.  They are tight, but not that tight - usually. The only one that needed a good walloping was clearly knackered already....... was more knackered after!

Ref the plug, my usual technique is to drill a through hole that’s just big enough to belt a splined bit into, and then lean on that. Mostly this technique is used on the aluminium plugs with no Allen key hole, but I’ve used it on rounded out steel ones as well. I have an elderly set of splined bits that are made of pretty tough stuff. 
 

Not sure if the 4 pots are the same but on the 6s the threads are different at front and back of the main gallery.... goodness knows why .....

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On 5/13/2021 at 3:52 PM, JumpingFrog said:

I'd be reluctant to knowingly introduce swarf to the main gallery

I did wonder about that too, but decided it would be fine because I'd be able to clean it thoroughly once the plug was out of the way. Which would be very soon with my fool-proof plan

On 5/13/2021 at 7:36 PM, Nick Jones said:

Not sure if the 4 pots are the same but on the 6s the threads are different at front and back of the main gallery.... goodness knows why .....

Nick this made me wonder whether it was left-handed and I was trying to turn it the wrong way! But the parts book shows the same number for front and rear plugs on the 4-cylinder.

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A deflating weekend in various ways, personal and mechanical. But I'll start with the good news: 

The spring compressor worked nicely as a press. Had to make a spacer the right size to bear on the inner race, then it was satisfyingly simple. 

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Saturday morning I had a dreary drive up to Romford to drop my rotating assembly in for balancing at Gosnay's Engineering. 

Back in the garage later I proceeded with the masterplan for oilway plug removal. Remember these fateful words: 

On 5/13/2021 at 3:37 PM, PeteStupps said:

Likely worst-case result: M8 thread strips, leaving me a hole which I can use for inspection / cleaning, and then tap to 5/16"

Things started well. I got my pilot hole pretty central in the plug, and progressively drilled it larger and larger until it was 1/4", and then carefully wound in the left-handed M8 tap. That worked, and in went the bolt. Bolt head fouled on the block before it was tight, so I drilled out a 7/16" AF nut to act as spacer, which fitted into the oil plug recess. Tightened up and gave it some grunt, then snap went the bolt.. Don't know why this didn't occur to me as a possibility.

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Turns out it was a rubbish idea.

I'm going to try and flatten the sheared end off with a dremel, so I've got some chance of centring the drill on it to drill it out again. Or maybe I'll just take it to an expert and stop being a bloody fool

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5 hours ago, PeteStupps said:

I'm going to try and flatten the sheared end off with a dremel, so I've got some chance of centring the drill on it to drill it out again. Or maybe I'll just take it to an expert and stop being a bloody fool

If you've managed to do what you have so far, I think you have proved you have the skills to remove the plug! I missed this bit earlier, but to be honest I think you overthought the process with the LH M8 bolt etc. Nick has given good advice, drill out as much as you can, whack something in and screw out.

Nick's method has one big advantage over your first go, namely the "whacking" step! This shocks the threads and (hopefully) helps break the grip it has attained. A bit of heat here may also be beneficial.

The most difficult step is drilling the hole, as I said above you have already achieved that bit once! The rest is really patience and perseverance. Another trick (if it is possible) is to try tightening a fraction before you loosen.

Phil

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3 hours ago, thebrookster said:

. Another trick (if it is possible) is to try tightening a fraction before you loosen.

Phil

That always seems counterintuitive but you’re spot on it does work.  Soaking it with Dot4 overnight/or a couple of days may also assist, certainly works on stuck injectors and glow plugs.

@PeteStupps you’ve done the hard part.

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Ha, thanks for the encouragement! I've certainly made hard work of it... 

Before I'd rounded the allen keyway I did heat it up for a while and tried tightening first, which worked at the other end but not this. Ok I'll try soaking it in brake fluid (not heard that one before) and then find something strong to wallop into it. I'm not beaten just yet 

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Success, or at least it felt like it. Managed to drill through the centre of the sheared bolt, which then span out pleasingly on the drill bit (being left-hand thread). 

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Then applied heat and penetrating oil for a long while with the block on end. Wound the spare M8 left-handed bolt in and gave it several tickles with my biggest hammer. 

And voila! Turn anti-clockwise and out she comes

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Now I need to purge the self-inflicted swarf from the oil ways. 

What's the best technique for removing the distributor drive bush? And what are the odds of me making a hash of that as well?!  Would like to get a brush all the way through the main oil gallery but that bush is in the way.

Thanks for your time and advice as ever gents :)

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To remove the bush I use a length of threaded rod or long bolt (M10/12 ish) and a selection of washers/spacers plus a bridge bar to go across the distributor pedestal opening.  Don't like to bash as they are cast iron and quite brittle.  This for the 6 pots - fairly sure the 4s are the same - did do Chris's not that long ago and don't remember anything special....

Well done on the plug.  Percussive persuasion seems to be the charm. I think the main issue other than time, is that on blocks that have not been previously molested they are put in with Wellseal, which I consider the devils work.  My usual method is to stick the appropriate allen bit in the hole and give it a good walloping before even trying to turn it.  This seems to give the best success rate, but still < 100%.  On the six pot all the side gallery plugs are allen head, small and taper-threaded so you get lots of practice.......:ermm:

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Much appreciated Nick, left to my own devices I would definitely have started by walloping it! Glad I asked first.

Managed to rig up a long coach bolt and various nuts, washers and sockets as spacers. Came out slowly but without too much difficulty. 

6 hours ago, Nick Jones said:

On the six pot all the side gallery plugs are allen head, small and taper-threaded so you get lots of practice

yikes, I'm glad they're normal hex nuts on the 4-pot. Otherwise I'd still be frigging around with them.

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  • 3 weeks later...

Two small steps forward, one large step back... you know how it is. 

After lots of gun-brush and carb cleaner action in the oilways, I was mostly satisfied enough to prep the block and paint it. Rather than black I went for a colour called "Cast Iron"... so dark grey. Looks pretty nice I think, especially with the brass core plugs (which were inspired by / copied from @michaeljf's beautiful build). 

Masked off, primed, then painted:

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Plus before and after on the other side:Photo_2021-06-08_12-32-12_PM.thumb.png.fdb64084b1cd5a09fa7661636205d8cf.png

Next I decided to trial fit the old camshaft in the block. Reason for this was one of the inner bearings had been driven in slightly too far, so wasn't located exactly right. This bothered me but I wanted to see if it was actually significant when the shaft was in place. Silly really. 

Slid camshaft in carefully (after cleaning and lightly oiling). Tight fit as you might expect but it went in and I put the sprocket on and was able to turn it. Basically the bearing misalignment looked insignificant, so I was satisfied it was nothing to worry about. 

Then I took the camshaft out: it got sort of stuck at the misaligned bearing and I made the fatal mistake of wiggling the shaft a bit. That misaligned bearing has a little lip which is unsupported by the block, and this has now been deformed by my wiggling. 

Doesn't show up well on camera but you can sort of see what I'm on about here with the slight misalignment  and deformation on left hand side:

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Have ordered another set of cam bearings... :pinch:

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24 minutes ago, PeteStupps said:

Have ordered another set of cam bearings... :pinch:

Ah well….  Not ideal. They are cheap enough. Can be removed and installed with a nut & bolt/studding with suitably sized washers and tubes. Preferable to bashing imo.

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2 minutes ago, Nick Jones said:

. Can be removed and installed with a nut & bolt/studding with suitably sized washers and tubes. Preferable to bashing imo.

Nothing like a gentle squeeze:blink: as opposed to a bashing:pinch:

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1 hour ago, Escadrille Ecosse said:

However the paint job on the block looks fantastic 

Thanks Colin, last block I brush-painted with some 'primer+topcoat in one' stuff, which flaked off all over the place before I even got the engine back in the car, hoping this is more durable. 

36 minutes ago, John I said:

love the colour and brass plugs, great combination. Have you lacquered them so they stay bright and shiney.

Thanks John, like I said the brass plugs were inspired by michaeljf's thread - no I hadn't thought of lacquering them, good plan!

1 hour ago, Nick Jones said:

Can be removed and installed with a nut & bolt/studding with suitably sized washers and tubes. Preferable to bashing imo.

Ah that's interesting, thanks, I thought thumping was the preferred method. Will dig around in the garage and see if I can arrange something less percussive.

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In the interests of variety I had a look at my D-type overdrive unit last night. Bought off a chap who had kept it in a box for many years so I don't know if it's any good. Someone has written 'Spitfire OD reconditioned' on the box at some point though... 

I've bought a new gearbox mainshaft for this O/D conversion, and thought it might be sensible to get those pesky splines aligned before fitting the shaft in the gearbox. Seems to have been a good idea: it's really not very easy to get the O/D to fully accept the shaft. Getting that last inch in took all sorts of heaving and twiddling (as the actress said to the bishop)

Couldn't make any progress poking splines with a screwdriver, so split the unit. Does anyone know if this cone clutch looks ok? Is that what this black bit is?!

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I've currently left it reassembled with the mainshaft in situ, because I fear it'll never go back in if I remove it! Are they supposed to be mega tight? The last bit of travel is more than a sliding fit, it's proper tight. Does this suggest there's some misalignment or could it just be new shaft being a bit large?

Here she is snugly in position anyway.

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They are not meant to be mega-tight.  Assuming you mean tight on the splines, any apparent tightness on assembly should only be down to slight misalignment between the two two sets of internal splines which would resolve when the thing operates.  This would only be apparent with the OD assembled and not (I think?) as you have it there, so if still tight like that I think investigation is essential.  It's needs to be able to slide in service to function.....

Maybe need to dress the corners of the splines?

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Thanks Nick. I disassembled and reassembled a few times to try and get things lined up. Currently the OD is fully assembled with the mainshaft sticking out of it.

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It seems like something is under tension which is causing a slight misalignment; I could only get the shaft located correctly by putting it in while the front casing was resting on the rear, then tightening the casings together while occasionally pushing the shaft home. First time this worked, I then removed the shaft which was tight but came out with good yank. However after that I could not get it back in fully by any means, apart from loosening the casings again. 

Seems like tightening it together causes some slight misalignment between the sun gear, planet carrier splines or rearmost splined bit (name of which I don't know).

Am hoping that it will free off in normal operation as you say, but I really haven't a clue about these devices so maybe ought to give it to an expert :confused:

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