Spitfire 1500 Engine Rebuild

[Anglefire]

At some point in the nearish future, I will be stripping and rebuilding my Spitfire's engine.

It's currently (As far as I know) standard - though is from a Dolly 1500! 

I don't want to build a racing engine, but would like to do some sensible upgrades to improve reliability and drivability. Whilst I don't have a bottomless budget, I would rather spend a few quid more now and not regret it later!

I would like to fit a sports exhaust at the same time too.

I've read that a Newmans mildroad cam is a good option, and payan gaskets are the best, but what bearings and rings?

TIA

[Pete Lewis]

The 1500 long stroke is not the best for reliability and can suffer serious big end  and con rod failures ifnused in a hurried life

It does age quite quickly,  upping the power wont help much in reliability 

Clives the best on this 

Pete

[Clive]

For a road engine there are a few simple things.

The spitfre mk3 profile cam is very good, or even the TR5 profile. Newman a decent supplier so may have variations worth exploring.

You will need some headwork, and a skim o achieve a higher compression ratio (depends on the cam)

4>2>1 manifolds easy to source, and the canley single sports box would be my choice.

Get the distributor modified to match the cam (the Distributor Doctor) and find somebody to set the carbs up on a rolling road.

 

Payen gaskets where possible, use the best crank bearings you can find (vandervell but you will have to be VERY lucky) and you WILL need a thermostatic oil cooler, and millers CSS20/60 oil a good idea. 

100bhp should be achievable fairly easily. But do no explore the rev range too often (maybe get a rev limiter!)

[JohnD]

And here's the reason why.   Mean piston speed (MPS) is a simple calculation using the revs and the stroke.    It's a surrogate for the actual stress calculation that works out the acceleration of the piston, which is a LOT more difficult!    Once MPS goes up to 20 metres/second, you can expect reduced reliability and early failure, unless the engine has been specially designed and built and/or made from exotic materials.  For instance, the 2014 Renault F1 engine has a stroke of only 53mm but is limited to 15,000rpm!    The mean piston speed will be 26.5m/sec.

On our engines:

2L & Spits Mk1-4                1500        
Stroke(mm) =    76            Stroke(mm) =    87.5    
                         MPS(m/s)     MPS(m/s)
Rpm    5000    12.67            14.58
             5500    13.93            16.04
             6000    15.20            17.50
             6500    16.47            18.96
             7000    17.73             20.42
             7500    19.00             21.88
5000 rpm may be a conservative limit even for a 1500, but it's easy to see that the longer stroke engine approaches the 20mps limit far sooner than the earlier engines.

Another way to look at it is to work out how much the piston weighs in use.  Weight is mass times acceleration, and  I've done this for a TR6, the worst possible case.   On the bench, a  piston and gudgeon pin weighs 346gms, but this is under 1g, the acceleration due to Earth's gravity,    In the 2.5L, at 6000rpm the piston reaches more than 2000g, and weighs nearly a tonne!

[Anglefire]

Thanks Pete and Clive - as I say, I'm not after a racing engine or even upping the power particularly. I would like to strengthen the bottom end - if that is actually possible? I'm guessing not particularly. 

Vandervell were the bearing of choice when a friend of mine built a 2ltr pinto for rallying as alternative bearings failed after about 3 events (Spectacularly the first time!) 3 times until he put the Vandervells in and were find after 6 events.

So, if not Vandervell, what other makes are recommended? 

I have seen someone fitting an extra thrust bearing by machining the cap to suit - but keep some material for retaining the extra and existing bearings.

 

[Anglefire]

Thanks John,

I'm more than happy with 5000rpm - my currently daily is diesel so tends to live at less than 3000 - actually a lot less unless booting it (its a 3tr BMW so has lots of power and torque!)

[JohnD]

Angelfire,

(proper name, please!?)

Strengthening the bottom end isn't an option, unless you go for a steel billet crank and conrods.

"Blueprinting" the crank, making absolutely sure that it is built to precise spec, with best quality parts, is what you have been discussing with Pete and Clive.

Protecting it by reducing the stress.    Lighter pistons and lighter conrods, by reducing their mass.     Grinding off unnecessary mass from conrods, should be followed by polishing and shot peening, which does increase the strength.      In this way, conrods can be made 15% lighter and stronger than the OE ones.

Bearings shouldn't touch surfaces!   Protection by optimising the oil supply is another option.   Opening out the oilways in the block, cross drilling and ovalising the orifices are all possible, as is optimising the oil pump.  This should enable even 'inferior' bearings to be long lasting.     I always use bearings supplied by Jigsaw Racing, and with the above, they are long lasting, even in high revving engines.

DO NOT be tempted by an external oil line to the cylinder head.  This reduces flow to the mains.  But Kas Kastner, the US race engineer who led Triumphs competition effort there, fond that flow to the mains could be optimised by external lines, instead of the internal oil gallery,  in the "Kastner Octopus".     But this is for high revving engines, not road use.

 

But all the above are expensive and competition related.  For a reliable road-going engine, careful building, in clean conditions will get you one tha is long-lasting!

JOhn

PS just noticed - you DO call yourself "Anglefire"!    Is there a howitzer story there?

[Anglefire]

Hi John

sorry real name is Mark - I’ll update my signature when I get 5 !

anglefire is my forum name across all forums I use. And is actually a spelling mistake, made the first time I used it. But I’ve stuck with it for reasons long since forgotten!  

Thanks for the information  - especially the bearing supplier.  

I’m only really in the planning stages as when I do pull the engine, I’d like to do things like make sure the head is lead free - I’m told it was done by the guy who rebuilt it before the last guy who I bought it from. But no proof or paperwork so I’m assuming it wasn’t. 

Bottom end I might just get it balanced and reground if needed and look at different pistons and rods but also look at budgets. At the end of the day if it needs a rebuild every 40/50k it’s not  the end of the world as that is plenty of years use! 

 

[Anglefire]

I spoke to the distributor doctor today - after looking at the website - and have ordered a standard replacement dizzy for mine as a starting point because I replaced mine with one from ebay after getting issues (Which I suspect were really down to the carbs) and I am getting some issues with pinking and the like, that could be caused by a cheap chinese one - of course it could be something else, but I decided to start from a good place!

I'm also probably going to get another engine and after a bit of general inspection (The one I'm going to look at has already been largely rebuilt) and replacing the oil and water pumps - which haven't been done and then swap engines over  - it also has a twin exhaust and a 4-2-1 header which is almost new. 

I can then, at my leisure, rebuild the one in my car now and either sell it on or do another swap.

[Clive]

Re the pinking. How have you set the timing??

If you have just set it to the "book" spec there is every chance it will not be ideal. Mainly as we now run unleaded fuel, not old 4 star! So I always set timing by ear, drive the car and try to get it to pink. Keep advancing the timing until you do, then retard just enough so you don't get any pinking. That is as good as you are  likely to get it, though DD can of course alter advance curves to suit your engine spec, or go for a mapped ignition!

 

Otherwise, enjoy the car, collect the stuff you need and don't put yourself under pressure! The cars are to enjoy, not be a burden.

[Anglefire]

Timing is set by ear - to be honest one reason for the rebuild/replacement is that the timing is all over the place when I use a timing light - which is either due to a crap dizzy or the pulley moving (Which is not as tight as I'd like - but the bolt is very much tight! - I think there is some end float issues amongst others!) 

And its fine until it gets to temperature and then driven some more so is really hot - and given I found the other day that the overflow pipe was too short into the expansion bottle so was drawing air back in rather than water when the engine cools - so I suspect the engine was then getting a bit too hot at the top occasionally.

But yes, I do enjoy it and try and go out in it as much as possible - I bought it to drive and not be a show car. 

[Pete Lewis]

do make sure you stick to 97+ or better fuel,  **95 ul was for side valves and mowers when these cars were born.

if you look under the rocker shaft face if its stamped TKC1155 its could already  be an unleaded head  there's some disparity over these numbers depends on 

supplier 

 

Pete

[Anglefire]

Thanks Pete - as it happens I picked up a "new" engine today - has been largely rebuilt - needs a new oil pump as it wasn't changed, but does seem to be well done overall. 

Head has been gas flowed and the inlet ports "matched" apparently and it came complete with rebuilt carbs, alloy rocker cover and a twin pipe sports exhaust and 4-2-1 header.

Did mean I had to buy an engine hoist, load leveller and engine stand this week too 

I'll look for the head stamp and see what it says. The engine number is FM91xxxHE - which I know is Spitfire and High compression - E for engine?

[rlubikey]

"High Efficiency"

Cheers, Richard

[Anglefire]

Thanks Richard. A bit too obvious for me that! 

And as my current engine seems to be doing about 28mpg, I'd hate to think what a low efficiency engine is like 

[Pete Lewis]

thats a idea,   

i cant find any  data readily available  that explains the last  suffix  'E'

 

 

 

[dougbgt6]

Spitfire/GT6 site suggests E for engine, to avoid confusion with commission number.

http://triumphspitfire.com/enginenumbers.html

[Anglefire]

Ok, given that I'm going to drop the sump to replace the oil pump, I have decided to also change all the bolts on the bearing caps - gives me the opportunity to inspect the journals and shells and re-oil prior to start-up (its been on an engine stand for about 3 or 4 years) 

Question is, should I Loctite the bolts and if so which spec should I use. I've googled and it seems to be questionable!

[Clive]

I have rebuilt a dozen or so engines (probably double!) and have never used new bolts for any bearing caps. 

I have only ever torqued up to the factory spec, and never had any issues.

If building a performance engine, ARP bolts may be of benefit, but they use their own special lube with a lower than factory torque!! (different torques given by ARp depending on what lube you use on the threads, more torque needed if you use 30weight oil.....)

[Pete Lewis]

I agree you can re use our spec of bolt a number of times , what you cant reuse is more modern specs where the torque has been 

Tightend  to its yeild point these are dangerously likely to fail if re used

More moderns are often spec'd as up to a target torque followed by accurate angular rotation

In stages     on production these  results are devised from watching the toqure climb and rotation

The  meters that measure this carefully stop as soon as the torque rise flattens and rotation is about to continue 

Ive got one in the cupboard gathering dust ...never use it these days

Usefull on troublesome fitting to find the ultimate torque 

Pete

 

[JumpingFrog]

If you want to uprate the big end bolts but don't feel like splashing out on ARP, you can also use Cosworth (YB?) bolts. These used to be cheap, but only Burton power (SC248) seems to have them now (£7.61 ea). Personally, I'd just check the originals for signs of stretch and reuse them. I wouldn't bother changing the main bolts either, and I don't think loctite is a good idea.

When you check the shells, if it has been built with cheap bi-metal ones (you can tell by colour and the markings on the rear) then replace them with lead/copper. Also worth making sure the crank end float is correct (oversize thrust washers usually required, get them the right way round too...). The best currently available bearings are King Tri-metal which most suppliers (e.g. Paddocks) sell. Vandervell do come up on eBay from time to time, but most are showing their age from long term storage.

As JohnD mentioned, you can optimise the pump to minimise clearances between the body and rotor, see: http://tr6.danielsonfamily.org/OilPump.htm

[dougbgt6]

How do we feel about con rod lock tabs? My GT has them and Rimmers show them on TR2 -4a, but not GTs or Spitfires. 

I had a re-used bolt shear, causing catastrophic damage, my first rebuild.  I used new bolts and tabs, but this was 1980s so bolts would be from the good bucket.

https://www.rimmerbros.co.uk/Item--i-105313

 

[JumpingFrog]

1 hour ago, dougbgt6 said:

How do we feel about con rod lock tabs? My GT has them and Rimmers show them on TR2 -4a, but not GTs or Spitfires. 

I had a re-used bolt shear, causing catastrophic damage, my first rebuild.  I used new bolts and tabs, but this was 1980s so bolts would be from the good bucket.

https://www.rimmerbros.co.uk/Item--i-105313

 

Early Spitfire and Herald engines had lock tabs (https://www.canleyclassics.com/triumph-spitfire-mki/ii-crankshaft-and-camshaft). I discussed adding lock tabs with the engineer when I did my Herald engine, but he warned against it. He said he'd had problems with soft lock tabs on other engines messing up torque readings. Triumph removed the lock tabs quite early on in production and never reinstated them despite loads increasing considerably (e.g. 1296cc, 1493cc) . You'd hope they'd have put them back for the sake of a few pence if they reduced engine failure rates...

[dougbgt6]

That's interesting, I wonder why they are on my late GT6 mk3? They don't appear on any of the Canley GT6 diagrams, but they were certainly there the first time I took the sump off in 1979, or there abouts. The last GT6s had a lot of differences from earlier mk3s, I wonder if Triumph went back to tabs?

[Anglefire]

I thought for £30-40 I'd just change the bolts - more for piece of mind rather than anything else - not going ARP as the engine will be pretty much standard.

Useful article on the oil pump too. I'll be making sure that my new one is as good as it can get to the "best" end of the specs.

And I'll be looking at the shells as I said and thrust washers - though it does look from the outside to have been done well (I don't want to knock the chap who did it!) and he didn't use eBay parts, just Canley Classics, Rimmers or Moss.