Jump to content

Mk3 Spitfire engine and gearbox rebuild


Recommended Posts

Hello all.

After 5 years and 15,000 miles of happy smokey high-rev motoring, I've finally bitten the bullet and pulled engine and gearbox out of my trusty Spitfire. It's got 90k on it and is standard size bore and crankshaft. I did the bottom-end 4k miles ago but the main bearing clearances were slightly slack (or those King bearings are slightly thin). Oil pressure was ok after that. 

My first question to the experts:

- is there any reason I shouldn't change the cam bearings? I'm sticking with the original cam for now, and the existing bearings look alright. But might as well renew them while it's easy... right??

DSC_7379.thumb.JPG.88700586183d7d790c710d03307d6422.JPG

Some general background.. the two main objectives for this project were:

1. cure the alarming oil consumption via a re-bore

2. convert gearbox to overdrive

(Also have crank journals measured & ground or polished, sort the persistent gearbox oil leak, tidy up the bulkhead while engine's out, various other bits & pieces)

The time constraint is I want to be back on the road by July, in order to run her in thoroughly and do all snagging before RBRR at start of October. And I've also got work, life, and a 1300fwd-shaped albatross taking up valuable attention and money... 

I was originally thinking of a more radical camshaft. Last winter I did some head work (which I'll detail below when time allows) and fitted a 4-2-1 manifold. Then over summer finally managed to get the HS2 needles approximately right (much richer than first thought). And in the end was really happy with the performance improvement -  actually ending up sideways without meaning to occasionally! Which didn't happen before. So decided to stick with the standard mk3 cam for the time being rather than open another can of worms. 

For the gearbox I need to do some more reading. I bought an allegedly refurb'd D-type OD unit two years ago and believe I have most of the ingredients to connect it to the box. But definitely need a few more bits and a lot more expertise. 

Anyway the block is off to the machinist tomorrow morning, and I shall update as this thread as I go along.

Thanks for reading,

Pete

DSC_7512.JPG

DSC_7384.JPG

Link to post
Share on other sites
  • Replies 72
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

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' 

Posted Images

Ok..... that's two Triumphs in bits.  Have you got a bike? :tongue:

Changing the cam bearings shouldn't be a huge challenge and they are cheap enough.  Though there is always the "if it ain't broke....." alternate view.

I Have found King bearings to be a touch thin in the past on the 6 cylinder lump.  This using Plastigauge, which tends to make the pros sneer, but on one occasion (Vitesse engine build) I had enough bearings kicking around to repeat the measuring process with VP2 and Glacier alternatives.  They both gave 0.001" less than the Kings and a result that was more in line with expectation.  Those crank journals were a touch small as it was a NOS crank and possibly a "second" which had then been tuftrided and polished (uninstructed), which hadn't helped.  This engine doesn't get great hot idle oil pressure even with the VP2 bearings but it doesn't seem to care.  Might be worth mentioning to the machinist as if they decide it does want a grind then they can make sure they grind to the top end of the size range.

I'm a fan of the Mk3 / Vit Mk2 cam profile.  Pretty hot cam for a 60's production unit.  Just a bit short of lift.

The gearboxes are fairly straight forward and if your current non-OD is the main donor and known to drive well, that is a great start point.  There is a always scope for disappointment but I'm hoping your lousy luck is used up now......

Link to post
Share on other sites
26 minutes ago, Nick Jones said:

Though there is always the "if it ain't broke....." alternate view.

This is what I was wondering about. Generally the less I muck about with, the less goes wrong! 

I'll see what the machinist reckons tomorrow. And yes good point if the crank does need grinding, i'll tell him to err on the big side. I wouldn't object to leaving it as is, and having slightly slack clearance. I measured it to be maybe 0.2 thou over spec with plasti-gauge, two measurements 90 degrees apart. I think it's nifty stuff, not sure why anyone would sneer at it.

Link to post
Share on other sites
7 minutes ago, PeteStupps said:

I think it's nifty stuff, not sure why anyone would sneer at it.

So do I.  I like it.  But then I'm not a precision engineer!  The main "gotcha" with the cam bearings is that you (obviously) need to get them in so their oil holes line up with the holes in the block.

Link to post
Share on other sites
3 hours ago, Nick Jones said:

I'm a fan of the Mk3 / Vit Mk2 cam profile.  Pretty hot cam for a 60's production unit.  Just a bit short of lift.

Hello All

               Is that not what Chris Witor does for the 6 's 

So perhaps get Newman to grind the same for a 4 cylinder?

But saying that The Triumph profile worked well in our 1500 (Canley classics re grind with new followers did lots of miles and was still good before I built and fitted the more tweaked engine!!!!!!!!!!!

Roger

ps It will be interesting to see how the special that (Oldtucker had ground on both lobes when and if I get it all back together and running again!)

Link to post
Share on other sites

The other way to do it is to keep the same cam and use higher ratio rockers, either on inlets only, or all.

But as Pete has already discovered the cam isn’t the limiting factor and if you have to drive in town a lot you really don’t want to be over-cammed.

Link to post
Share on other sites

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 sure the oil holes line up with the holes in the block and not just the holes in the existing bearings :tongue:. You do need to take the rear core plug out which is a bit of extra work.

I did find that the old bearings were very little worn but as I had already bought the replacements I just did the job.

Cams. Like the chaps above say the Mk3 profile is very good especially with some additional lift. Again only my experience but if you want something slightly more radical then I'd go for something with a bit more lift and symmetrical timing. But that's just a personal view and I know others swear by asymmetric timing on Triumphs.

Just make sure that you match the CR to your cam.

If you are after more lift then a cam change is cheaper than high lift rockers if you are putting in a new cam anyway. Although unless the existing rockers are excellent then you'll probably be looking at replacing them too. Personally if going for higher lift rockers I would always use roller ones. Just be aware that this can cause issues with the rocker cover but if you keep the lightweight steel one rather than buying a heavy alloy one then there is less likelihood of a clearance problem. :blink:

The wee 1300 engine can take a quite remarkable amount of cam and stay relatively driveable in town but like the others say the main limiting factor is going to be fueling/ignition rather than cam. Needle and distributor advance experimentation will be required if you stick with the SUs and distributor.

Don't know if you have done it yet but get rid of the nasty Delco distributor and replace it with a Lucas one even if you do nothing else. To keep the mechanical rev counter drive - which is cool - you can fit a 4 lobe cam plate and cap from a Herald or similar to a 6 cylinder tacho drive body to get a distributor that Lucas never made that fits the Spitfire and drives the tacho. Then start playing around with advance curves and limits.

But it is all worth it. But you know that already :biggrin:

  • Like 1
Link to post
Share on other sites

Hmm hmm and thrice hmm. Thanks for your input chaps, you've provoked me into being indecisive again! Was quite satisfied with the mk3 cam but now you've got me questioning what to do....more lift you say...  

Obviously now would be the time to put a new camshaft in, if I ever intend to. But is it something you can reasonably do with the engine in the car? I imagine you would want to drop the sump and support it from below while a helper feeds it through. Obviously radiator will have to come off. Or maybe it's just a completely stupid idea...?!

I am inclined to try Newman's PH2 or TR5 profile, but the reason I don't want to do it now is: I know how slowly I work! Not the engine/camshaft work but sorting carburation & timing afterwards.

[For example, last year my first drive with new head and exhaust manifold was mid-May, and the day I finally felt the carb needles were roughly correct was early November. It's not (only) laziness but other commitments, and the fact that I've got an hour of London before hitting any country roads to properly test performance.]

Link to post
Share on other sites

 

14 hours ago, Escadrille Ecosse said:

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.

Thanks Colin - I might have been too timid. Tried to tap one out with a large socket but it wouldn't move and I didn't want to try too hard! On closer inspection there was a fair bit of wear so will replace them. Or rather, I'll get the engine re-bore place to do it for me.

13 hours ago, Escadrille Ecosse said:

Don't know if you have done it yet but get rid of the nasty Delco distributor and replace it with a Lucas one even if you do nothing else.

er... I didn't know there was anything wrong with the Delco dissy! I've got hold of some decent NOS points and was fairly happy with it. I know Lucas parts are easier to get hold of but didn't realise there was much difference otherwise :blush:

The other thing is, I am a little bit of an anorak about originality for this car. Not deliberately, but I'm only the 3rd owner and have started to feel responsible for it. Hence prefer to stick with SUs, dynamo etc.

Link to post
Share on other sites

Seeing as you sound like you were pretty happy with the car apart from the wear related issues, seems reasonable to keep the standard cam and reap the benefits of your previous development. You’ll pick up a bit from having rings that actually seal.....

You can change the cam in the car and you don’t need to drop the sump, though you do need to lift the head to get the followers out.

Link to post
Share on other sites
21 minutes ago, Nick Jones said:

Seeing as you sound like you were pretty happy with the car apart from the wear related issues, seems reasonable to keep the standard cam and reap the benefits of your previous development. You’ll pick up a bit from having rings that actually seal.....

You can change the cam in the car and you don’t need to drop the sump, though you do need to lift the head to get the followers out.

Spending other peoples time and money vicariously.

There is definitely something to be said for having a good car you can drive rather than some aspirational project that lives in bits in the garage.

As I used to say to The Man, 80% of something is better than 100% of nothing.

Link to post
Share on other sites
  • 2 weeks later...
On 3/26/2021 at 10:43 AM, Escadrille Ecosse said:

There is definitely something to be said for having a good car you can drive rather than some aspirational project that lives in bits in the garage

Why not both? :biggrin:

Well: I have firmly decided to stick with the original cam for now. Half the battle is making the decisions, I find.

Took block and crank to Motortech Engineering in south London, for measuring up and machining. Mr Motortech talked a very good fight on crank grinding (served 4 year apprenticeship, works on all kinds of exotic vehicle cranks, etc) and knew the journal sizes off the top of his head, so hopefully it's in safe hands. Without prompting he said he would grind it on the large side of the tolerance, as "they're a bit too slack otherwise". 

Few days later he rang and said bores would need to be +30, and crank has been ground to -10. New pistons, bearings and other bits are on order. He signed off the phone call by saying "now throw your plastigauge away!" which chimed with what @Nick Jones mentioned above :rolleyes: ... I'll ignore that advice.

Link to post
Share on other sites
Posted (edited)
57 minutes ago, Escadrille Ecosse said:

Good progress then it would appear.

My bank account is shrinking so something must be happening!

With the engine out of the way I started digging into the gearbox. This is a 3-rail, 3-synchro, and not a badly behaved box; a bit noisy in 2nd though, and often behaves like there is no synchro changing into 2nd. Apart from that I need to change the mainshaft to the overdrive type and eventually connect the OD unit. I really have never done anything with gearboxes until the last 2 weeks so don't know what I'm doing! 

Seems like this has been replaced at some point in the past, as it's been painted red and has a GA.. number stamped on it rather than FD. Probably changed pre-1990, as I've been in touch with the 2nd owner who had it from '90 to 2014, and have all the records of work done in that period. 

1906208321_DSC_7579copy.thumb.JPG.357f721675618f21bbfc6fef8e4a54b2.JPG

First thing: there's damage evident on the teeth of 2nd, 3rd and 4th (input shaft gear). Is this bad?! Doesn't show up well in the photo but basically there are some nicks and chips on the teeth here and there. I assume that's bad news..?

1372858882_DSC_7578copy.thumb.JPG.6767e8bf050b22a94a8197ba91208290.JPG

Following the manual, I removed the layshaft and let the laygear drop down. Next job was removing the input shaft and bearing. Haynes advises you to knock it out with a soft metal drift, but I couldn't work out where to hit it. Some cautious tapping on the top of bearing didn't achieve anything. Read some old posts on here and learnt that warming the casing helps, so propped up my garage hair-dryer (yes really) and left it blowing on the front of the casing for 15 minutes. 

Then I removed the big circlip from front of the input bearing, fitted the bell-housing bolts to the front of the casing, and then prised the bearing out bit by bit, with two big screwdrivers stuck into the circlip groove and levering against the BH bolt heads rather than the casing. This worked a treat and I felt pleased with myself, which is always a bad sign. 

864834786_DSC_7622copy.thumb.JPG.78b26c48a7ad193a473a628c07775b9a.JPG\

Being a rather dim genius, I didn't consider that the lower bell-housing bolt which I'd refitted would be protruding into the gearbox and clamping the (otherwise loose) laygear in place. After removing the mainshaft & bearing in similar fashion as the input side, spent the next 15 mins trying to wrestle the laygear out of the gearbox casing, it seems to be jammed on something!! :rolleyes:

Edited by PeteStupps
add detail
Link to post
Share on other sites

There's a bit of wear on the layshaft, and the teeth of the rear laygear wheel (1st speed?) look like they've had a hard life. Does this matter? And should I change the shaft or leave as-is? 

1054060705_DSC_7625copy.thumb.JPG.9e63addd35e3833aa80ebd9133cc53eb.JPG

1307398312_DSC_7626copy.thumb.JPG.4ba717c580d0ab50fce79a52adeb6daf.JPG

 

Found another photo showing damage on the input gear more clearly: 

1871632471_DSC_7638copy.thumb.JPG.adc0c16b7231c55205ba4e33425abf62.JPG

 

Next bit to examine was 2nd speed synchro hub. This looks a bit worn but I don't know what's acceptable. However two of the synchro ball-bearings are stuck fast in the hub, and one of those that wasn't stuck had a broken spring. I'm guessing this might explain the poor performance of synchromesh on 2nd gear?

Of the stuck balls, a strong magnet wouldn't pull them out. And now in my wisdom I've bashed one of them further in than it was, so probably need to find a replacement hub... oops

1889285731_DSC_7640copy.thumb.JPG.aa969efa7cb4b03fac56591ed4c41f52.JPG

I've got a spare gearbox that came with my rusty mk2 Spitfire project. However that box looks to be in considerably worse condition than this one, so probably can't anything useful out of it. 

Link to post
Share on other sites

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 cluster (pitting shows hardening has gone through on 1st) and lay shaft wear. IMO in this situation it's worth acquiring a few donors (3 seems to be a good number), and assembling a good one. There doesn't seem to be much demand for 3-rail, 3-sync gearboxes, should be less than £10 each and they are plentiful (or at least this was true when I did mine). But steer clear of ones that don't look to have been dry-stored...

The parts individually (besides sundries like hub springs) aren't really available unless you talk to someone like Mike Papworth, but I think donor gearboxes will be the most economical route.

The hub detent springs are often broken like that, and replacing them will improve things dramatically. I would avoid replacing the synchro rings themselves with new ones, as they have a bad reputation. Better is to mix and match used ones, you can test them on the gear and feel for one that "grips" well.

Edited by JumpingFrog
  • Like 1
Link to post
Share on other sites
2 hours ago, JumpingFrog said:

IMO in this situation it's worth acquiring a few donors (3 seems to be a good number), and assembling a good one

Thanks for this, I think that's going to be the plan. There's a handful on ebay but nothing in the £10 price bracket! I'll ask around though and see what turns up. 

Anyone on here got a 3-rail box or bits they don't require?

Link to post
Share on other sites

I completely agree with David's comments.  Just to add that with two stuck/broken detent ball/springs I'm amazed you had any synchro action at all.

This one looks ok and is not that far from here

https://www.ebay.co.uk/itm/Triumph-Herald-Gearbox/284245138133?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3Ddb3dc238207a4a569d2ee2f1ddd8a739%26pid%3D100010%26rk%3D1%26rkt%3D12%26sd%3D203108652939%26itm%3D284245138133%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganicWithAblationExplorer%26brand%3DTriumph&_trksid=p2047675.c100010.m2109

This one is taking the piss. 
https://www.ebay.co.uk/itm/Triumph-Herald-Gearbox-/203108652939?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338268676&toolid=10044&customid=CjwKCAjw6qqDBhB-EiwACBs6x3_9G9t1apvtCohNttLjsG-ZNoc9SrwH81dyPbg0XH3UQC9dVD4mmhoCm34QAvD_BwE

It is just possible it would yield the parts you need  so would be worth about a fiver to chance it if it were within walking distance....

 

You could also try 

triumphspitfirespares (Tavistock Steve) on ebay. Suggest asking for Herald (1200 pref, they see less grunt).  He will ship/deliver.  I have phone numbers for him but ebay message tends to get a quicker answer!

Random link to one of his items

https://www.ebay.co.uk/itm/TRIUMPH-SPITFIRE-MK4-1500-GT6-MK3-BONNET-MOUNTING-IRONS/353371430690?hash=item5246941f22:g:530AAOSwpJ5gFYm-

Link to post
Share on other sites

Hi Pete, where are you based. I’m in Dorking Surrey.

I have a GB box you can have. It was overhauled about 1987 and did about 10,000 miles before being replaced with an overdrive box. Been dry stored ever since, not sure of internal condition but can take the top off and get a few photos.

 

Link to post
Share on other sites
4 hours ago, John I said:

Hi Pete, where are you based. I’m in Dorking Surrey.

I have a GB box you can have. It was overhauled about 1987 and did about 10,000 miles before being replaced with an overdrive box. Been dry stored ever since, not sure of internal condition but can take the top off and get a few photos.

John thank you, that's very generous! I'm in South London so Dorking is quite easy to get to. I'll PM you 

Link to post
Share on other sites
Posted (edited)
18 hours ago, Nick Jones said:

I completely agree with David's comments.  Just to add that with two stuck/broken detent ball/springs I'm amazed you had any synchro action at all.

This one looks ok and is not that far from here

https://www.ebay.co.uk/itm/Triumph-Herald-Gearbox/284245138133?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3Ddb3dc238207a4a569d2ee2f1ddd8a739%26pid%3D100010%26rk%3D1%26rkt%3D12%26sd%3D203108652939%26itm%3D284245138133%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganicWithAblationExplorer%26brand%3DTriumph&_trksid=p2047675.c100010.m2109

This one is taking the piss. 
https://www.ebay.co.uk/itm/Triumph-Herald-Gearbox-/203108652939?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338268676&toolid=10044&customid=CjwKCAjw6qqDBhB-EiwACBs6x3_9G9t1apvtCohNttLjsG-ZNoc9SrwH81dyPbg0XH3UQC9dVD4mmhoCm34QAvD_BwE

It is just possible it would yield the parts you need  so would be worth about a fiver to chance it if it were within walking distance....

 

You could also try 

triumphspitfirespares (Tavistock Steve) on ebay. Suggest asking for Herald (1200 pref, they see less grunt).  He will ship/deliver.  I have phone numbers for him but ebay message tends to get a quicker answer!

Random link to one of his items

https://www.ebay.co.uk/itm/TRIUMPH-SPITFIRE-MK4-1500-GT6-MK3-BONNET-MOUNTING-IRONS/353371430690?hash=item5246941f22:g:530AAOSwpJ5gFYm-

Thanks very much Nick, I'm watching those two on ebay and will message the london one. Have bought some bits off the Exeter chap before but they were small and postable! 

I'll try Tavistock Steve as well and see what's what. 

Or I could just up my budget and buy a 'brand new' one from SC Parts...https://www.ebay.co.uk/itm/Triumph-Spitfire-MK3-1967-70-Original-Manual-Gearbox-3-Synchro-Box-NOS-524276/143449359057?hash=item21663f82d1:g:zNQAAOSwfedd17KL

Edited by PeteStupps
Link to post
Share on other sites
1 hour ago, Escadrille Ecosse said:

Blimey!

:blink:

Indeed. Can’t be too many of those left....... though is it wrong of me to think they could throw in the overdrive at that price?

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...