1500 engine rebuild?

[mpbarrett]

Just back from a tour of Scotland, about 1700 miles over 4 days. I knew the engine was using a bit of oil but it has used over 4 Litres during the trip (full to empty or below at the end of each day.
It was driven quite hard but seems to have enjoyed drinking the oil, apparently it was very noticeable when following it....

I have just done a compression test (cold) and get 150, 150, 140, 75, on the cylinders  if I add some oil to No4 the compression goes up to 90.
I have also noted a lot of oily smoke from the rocker cover breather and a very strong pulsing from it when the engine is running.

The engine is,  I think a 1500 MG engine (FP1326E) but with a very good condition Ivor Searle Stage 2 head on it. It also has full mapped EFI and ignition.
I am assuming that it will need a rebore (rings gone on No4?) if so whats best? Strip it and do it myself or get a rebuilt rebored short block from someone like Ivor Searle?

If I am doing this what other improvements are worth doing  to the engine,  balancing, different cam etc. I don't want to go for very peaky engine but a bit more power and ability to rev safely would be nice.

The EFI has transformed the car much quicker and nicer to drive than when on SU's, I guess the fuelling is better over the whole speed range and the SU's were worn.

I would really appreciate any comments and suggestions.

I also need to fix the gearbox (no syncro on second and plenty of oil leaks) but that's another post!

Cheers

mike
 

[Pete Lewis]

ive had a day trip tour around ivor seales   excellent place , very impressed with the measures  and data logged throughout the build process

as used by club shop .

but  DIY is always a good hobby,   a bit of care measuring  the bores it may only require re ringing  but 1500 are not so good at longevity

certainly  it will need crank and shells examining   but DIY will save a lot of £££s

Clives got a lot of low down on these engines ...???

Pete

[Clive]

I managed to destroy a fair few! 

The smallish increase in compression with oil suggests not just rings?  But I don't rate compression tests as far as accurate diagnosis. So all will be revealed once head off.

Rebore may be required, certainly a hone and rings. Never used new pistons so can't help with choices there. However, but the very best bearings you can find. 

Then an oil cooler and a really good oil. Miller's CSS is the best I have used. That helped the last 1500 engine survive! 

Can, spit MK3 profile sounds ideal for you. As to balancing, one I had was done that way, but got similar results with the digital kitchen scales. 

 

[thescrapman]

How did you manage to balance the crank on the kitchen scales?

Mk3 cam profile good, I think Canleys do that on a 1500 blank.

[Clive]

30 minutes ago, thescrapman said:

How did you manage to balance the crank on the kitchen scales?

 

Trade secret.

(didn't bother, just did rods and pistons. Engine was very nice, maybe I was lucky. But no real difference between that and one than had been fully balanced by Oselli)

[mpbarrett]

Clive

do you think it is worth balancing the 1500 engine?

cheers

mike

[Clive]

In all honesty, the 1500 engine will never be happy revving hard. My fully balanced one died at Goodwood down the pit straight, oil pressure plummeted to zero at 6000rpm, all over very fast. However,an oil cooler was not fitted at that point.

So another crank was fitted to the engine,  with no balancing being carried out. I didn't notice any change to the way the car felt. And I wonder if the benefits are at higher rpm that are used with a 1500? But that is all just my experience, and if you are happy to get the crank/front pulley/flywheel/clutch cover all balanced then do it, but if you change the clutch the benefits would be lost so use the very best clutch you can find (original, proper B+B are around, but I would hesitate to fit a First-Line made B+B as currently sold)

The "blueprinting" I did on another engine seemed to help.To be fair it was a small bearing 1300, built from 2 using the best condition block, head and crank, then weighed all 8 rods and pistons separately, and managed to get a set that as a combined piston/rod were within 1g of each other. New rings and hone, set of glacier bearings and Payen gasket set. Lovely engine, even Doug and Katie  Foreman borrowed the car for an autosolo and tried to kill it to no avail (did beat a TR7V8 though!). Think that build cost me under £20, the parts were bought when NoS was still cheap and plentiful

If you do get it balanced, I have heard good things about a company called "Vibration Fee" but have no idea on costs. Suspect a heavy wallet may be required!

[JohnD]

Everyone says that 1500s can't rev, but why?

The criterion that matters is mean piston speed (MPS) in meters/sec.   This parameter is used because what really matters is piston acceleration, but that's really, really more difficult to calculate!

Mean piston speed is just the stroke, divided by the time taken to travel that distance.    That time is 60 seconds divided by the RevsPer Minute, so at 6000RPM is 0.01seconds

But to spare you more maths, here are some tables:

Early Spitfires (and 2L) Stroke(mm) =    76    
    Rpm     MPS(m/sec)
   5000    12.67
    5500    13.93
    6000    15.20
    6500    16.47
    7000    17.73
    7500    19.00

You can see that the MPS never gets above 19m/sec, when for production cars the limit is 20m/s

1500 Spitfire   Stroke(mm) =    87.5    
    Rpm    MPS(m/s)
    5000    14.58
    5500    16.04
    6000    17.50
    6500    18.96
    7000    20.42
    7500    21.88

The longer stroke means the piston must travel further in the same time, so faster at the same engine speed.   And it goes over 20m/s at 7K.    So 6K shouldn't be a problem.

In contrast, Triumph pushed the stroking idea much further in the 2.5L engines, to 95mm stroke! A longer stroke does give an engine with more torque, and that is confirmed in the difference between the 2 and 2.5Ls, but can they rev?

2.5L        
   Stroke(mm) =    95    
  Rpm      MPS
    5000    15.83
    5500    17.42
    6000    19.00
    6500    20.58
    7000    22.17
    7500    23.75

And the answer is, yes, they can, up to a point!   They are safe, up to 6.5K, but no further, without extensive and costly mods.  So if they can stand up to 20m/s, a 1500, built carefully but not with billet steel cranks, Carillo rods and slipper pistons, should be good up to 7K!

John

[dave.vitesse]

Sorry John, It's been known long term that reving the 1500 is not good for its life. Its the long stroke, three bearings and the nature of the crank.

Back in 1969/1970 when the 1500 engine first appeared we all rubbed our hands and said great, but soon found out its short comings.

Canley did make a Mk3 cam for the 1500. I used this cam in the past in a 1500 and can recommend it. Great for road use.

Dave

[Clive]

Exactly.

My experiences were real, actual driving as opposed to theory. Not many 2.5s live long revved to 7K. In fact my relatively modern zetec has a rev limit of 6750, but I have fitted ARP rod bolts to increase that up to 7250. So maybe the issue is the rod bolts and other bits and bobs.

John, Is your arbitrary 20m/s for modern engines, or where have you pulled the number from? It cannot possibly be the same for all engines. And what is it that fails at 20m/s? Oil film?

[hugh]

Biggest problem is stroke closely followed by heavy 3 bearing crankshaft that whips, and in the case of the 1500 cam that runs directly in the block, seen this destroy more blocks than anything else particularly with lumpy cams

Seen properly built 1500 engines tuned that have been wrecked in less than 10000 miles

[Nick Jones]

As Hugh says.  Heavy, flexible crank and only 3 mains.  Balancing helps, oil cooler helps.  But the best thing to do IMO is to tune for torque because they are good at that, and gear the car accordingly.  Produces a rapid, economical car which is easy and pleasant to drive.  Better suited to road use.

I've seen a 1500 dismantled that sounds a bit like yours, but worse.  That one had no intact compression rings at all, but no 4 was extra impressive in that the piston ring lands had broken up too and one of the compression rings (in fact the longest section of ring left in the whole engine @ 3/4 turn) was cross over between both the upper and middle ring grooves.  That engine completed the 10CR....... in that condition.  Oil use was apparently epic and blowby was straight out of the age of steam with the whole engine bay and underside coated in oil blown out of.... everywhere.  The cause of no.4's problems seemed to be that the water jacket was heavily silted at the back of the block and the bore was somewhat oval, presumably through overheating or differential heating.  Crank and bearings were pretty reasonable surprisingly.  Owner reckoned it still pulled well..... until he drove the replacement engine, which pulled rather better!

Rebore, regrind (probably, the big end journals are very often oval) with new pistons (County ones are fine) and shells should sort it.  Oil pump may well be good to go again (you can lap the housing, gears and end cover to remove light grooves and minimise gear end float provided the between gear clearances are still good).  Don't go crazy with cam choice.  Mk3 Spit grind is a good all-rounder (as already stated above) or maybe a Newman PH1.  Easy to fit cam bearings (as per Mk3), but need to check that you can get a small journal version of the cam you want first.

Probably not cheaper or quicker to do it yourself properly than to just get a random exchange unit, but at least you'll know what's in there!

Nick

[JohnD]

20m/s is a ball park figue widely quoted in industry. See the Wiki page, "Classes": https://en.wikipedia.org/wiki/Mean_piston_speed

Yes, only three mains doesn't help.  But it's piston speed, or  rather piston acceleration that does for it.

Formulas for acceleration reveal some startling results.   At 6K, in the 2L engine the piston experiences 64167 ft/sec^2, and for the 2.5L engine, 81541 ft/sec^2, more than 2000 or 2500 times ‘g’ (a coincidence of numbers!), the acceleration due to Earth’s gravity.  A standard TR6 piston and gudgeon pin weighs 346gms on the bench, but under the 2.5L acceleration would weigh 881.7 Kilograms, well on the way to a ton.

And for comparison,  the 2014 Renault F1 engine had a stroke of 53mm and was limited to 15,000rpm.  Even in this top-end engine  the mean piston speed will be 'only' 26.5m/sec, one fifth more than the 2.5L at 6000rpm.

John

[Clive]

The wiki page implies that a "medium speed" petrol engine figure of 16m/s, and from your tables for a 1500 relates to 5500rpm, which is probably afair figure which makes sense. 

20-25 for sport automobile/bike engines, and best will in the world, our 1960's tech engines are far from sporty in terms of design! Especially as the 1500 was pushing the limit of how far the engine could be "stretched"

Anyway, what is it about the acceleration that causes the damage? Deformation of components? And I would think that the surface area of the BE bearings would have some, errr, bearing as I would expect the pressure on the bearing face (and the stress the oil film is under) to be part of rather complex cause of failure? I find this stuff interesting. And when you consider how fast and the size of the forces, it makes you think how hard the oil has to work to prevent metal on metal wear. 

[Nick Jones]

The forces needed to make  the piston change direction come from the crankshaft - which flexes.  The block probably also flexes being pretty much the same as the original 948 one.  The flexing places uneven forces on the bearings - which fail.

Bore and stroke dimensions are apparently very similar to certain Honda products noted for the ability to rev high and not break - but they have a nice rigid block and a properly designed, 5-bearing crank.

Speaking of bearings - they especially need to be Tri-metal ones on a 1500.  Ideally Vandervell VP2, which are near impossible now at reasonable cost.  Alternatively AE made ones available through Revington TR (you may have to buy  6 cylinders worth) or King/County Heavy Duty (watch the actual dimensions!).

Nick

[mpbarrett]

Thanks for all the comments, very interesting. I like having a torquey engine rather than high revving engine, so will bare the comments in mind.
Bit surprised by the cost of rebuilt engines so will probably do it myself. I thought that I could by a short engine but Ivor Searle will only sell full engines, I realise there are other sources but Searle are just up the road.

Hope to get the head off tomorrow and see what it looks like inside. Means taking all the EFI off which is a shame as it was nicely setup and working well!

Cheers

mike

[Clive]

Think of it as an advantage to take the EFI of. If it is remotely like mine it will give you the opportunity to do a bit of tidying? I actually dread having to delve into my wiring, it all works, but is definitely "prototype" in appearance!

Yes, engine building not cheap. Newman seems to be the go-to cam supplier. But you may be surprised (in a good way) when you take the engine apart.At least I hope so And don't forget CR, if getting a "better" cam it could be raised a little. A certain flawed genius reckoned a TR5 profile cam,  Toledo (low CR 1300, but big valves) head and a 4 branch manifold should make 100bhp on SU's. Think it was about 10:1 ? But a TR5 cam may be a bit aggressive for what you want. I wonder sometimes if the Chris Witor cam profiles are worth looking at? he does one for the 2.5 that has teh same timing as the MK2 GT6 and some saloons(and the same as the spit mk3) but has altered the lift. Maybe worth a read, it is on his site, somewhere. Just an idea.

[Nick Jones]

TR5 cammed engines I've come across (and have been in contact with a 1300 version very recently) seem to have very grumpy low speed/idle characteristics considering their not-that-aggressive timing/lift.  Even with EFI (plenum inlet admittedly). Certainly worse than my Newman PH3/PH2 hybrid.

I would stick to the Newman PH1 or the Mk3 Spit / Mk2 Vitesse/GT6 /Early PI saloon version.  The latter is the one that Chris Witor offers with extra lift on the inlet.  Only does 6-pot ones AFAIK and I think they are made by Kent.  Who occasionally get confused and put the extra lift on the exhaust apparently!  The Newman PH1 has slightly shorter timing but more lift.  Not tried one in a 4 pot but a mate has one in a US TR6 with EFI and that pulls very well.

Nick

[dave.vitesse]

I used a 1500 in a Toledo with 3.63 diff and overdrive, and in an Herald Estate with 3.89 diff, overdrive and Vitesse 2 Litre brakes. In both cases I tuned the engine for road use so had around 85 BHP. Tuned/built for torque and durability rather than max BHP.  Forget wild cams on a 1500, pointless.

Dave

[Clive]

That is the beauty of the tr5 can, a triumph profile designed for a long stroke engine. But the Witor one looks  intersting, his stuff is well thought out. And agree, so easy to overcam a 1500, or even a 1300.

The EFI will cope nicely with the changes.

[dave.vitesse]

TR5 cam is not good on carbs, to much overlap. On injection no probs.

Dave

[mpbarrett]

Quick update, I have got the head off.

The bore on No4 cylinder has a nasty score mark down the bore, thick at the top so I guess a ring has broken and damaged the bore.
Piston are Stanpart with some numbers on them, 308103, ID7, E75 and they have a F or G mark on them. Don't know if that means any thing to anyone as I was  curious to know if its been rebored and had oversize pistons.

I plan to lift the engine and gearbox (the gearbox needs some work as well.....) and then strip the engine down and pull the pistons to have a look. I am hoping the crank is ok as the engine had very good oil pressure and no nasty noises.... There is a lot of coke on the piston and valves but cleans off ok, the head looks ok.
So the plan is to get this engine rebored fit new piston and check/renew the bearings and then rebuild her.
Re the above discussion I think I will stick with a standard cam either a  standard Spitfire of the PH1 from Newmans.

regards

mike

[JohnD]

The letters on the pistons represent variations from the nominal size.   They were to help the assembler match them to the variations in nominal size of the bores.   Yes, British Engineering was as haphazard as that!

John

[Nick Jones]

The letters are size grades as John says so pistons could quickly be matched to the bores to better allow for production variations.  The differences between them are very small.  They indicate that they are the original factory pistons on the standard size.

The scratch/gouge is an odd one as it goes above the level normally swept by the rings.  Possibly due to a foreign body.......  Also, about half way down the bore there is what looks like rust pitting?  Is that real or optical illusion?  Will be the main problem if it's there I reckon.  Common on engines that have stood for a while but also possible on engines that have been run very briefly (just long enough for a bit of water vapour to condense) and then left for a few weeks.  Was a big problem on my original PI engine (due to being stood for 15 years) but also to a lesser extent on my old Vitesse engine, which I was surprised to find as it was not there in 2008 when I had the head off and has never been stood idle for more than a few weeks since then.

Will be interested to see what the bearings are like....... rule of thumb is that if more than the merest hint of copper is showing through, crank "should" have a grind.  This assumes the original style VP2 shells are still fitted.  VP2 will be stamped on the back.....

Nick

[mpbarrett]

Nick

the mark half way down is real. Its a mark on the surface, but cant feel any thing with a finger nail! I brought the engine second hand about 5 years ago, put it in the Herald but then the car has not been used very much (due to GT6 and TR6) so could be rust marks. The other bores all look good with no marks or scratches but quite a  lot of coke on the top of the piston. When I put the engine in the car I changed the head, I don't remember the scratch in bore of No4 or any coke on the pistons. It never ran very well on the SU's I did play with the needles but the spindles were worn so could never get it working very well.

Nice to know its got its original pistons don't know the history of the engine, I brought of a trader on Ebay he told me it came from a Herald (estate?) owned by someone very active in TSSC. I cant remember his name but I think he was a retired policeman, used to write good article in the magazine! But who knows where it has been over the years....
I might see if I can borrow some internal bore callipers (from where I used to work)  just to see if its round and parallel, just our of curiosity.

We have visitors over the weekend so wont be able to pull the engine out until next week..

My thinking at the present is to get it out of the car, check the bearing and get it rebored. I will pull the cam shaft and change it if needed. The plan is to go for something fairly standard.

Cheers

mike