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Engine rebuild advice


thebrookster

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Now I know that this has been covered in various other threads, however I am completely new to tuning engines, so I would be grateful if people could humour me here in re-hashing :D

As mentioned in an earlier thread, I am looking at having to replace the clutch in the next couple of weeks, probably with a Borg and Beck. However, since I need to rebuild my engine at some point anyway, and it would make it easier to do the clutch than removing gearbox, I have decided that whilst the engine is out of the car I shall do my rebuild now. Unfortunalty I am running on a fairly limited budget just now, so can only really spare 300/400 quid for this.

What mods can I make to the engine for this type of budget? And more importantly, what benefits will I gain from these mods? I am not touching exhausts or carbs etc (these will be done later in the year when money allows, I am happy running slightly sub-standard for the time being), purely looking at internals such as cam etc (although I appreciate that new carb needles will be needed). What exactly should I be looking at buying? Ideally I wish to increase torque (if that is possible) and basically make the engine perform a lot better for road use. Is it worth getting the block re-bored and skimmed? And if so, what costs am I looking at here? Pistons? I will probably do bearings and oil seals etc anyway, what are the best brands to go for? Is it worth getting any work done on the cylinder head or is that to cost prohibitive? Also, is it worth getting a lightened flywheel?

Is there anything else I should be looking at, and is there any of the above work that I can leave to a later date without requiring a full strip down?

I would very much appreciate any help that people can give me here, and if they have the time to spare I will also be extremely grateful for any explanations etc (aimed at a noob tho :D).

Many thanks,

Phil

(suppose I had better mention that it is a Spitfire 1500 engine I am rebuilding!!)

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crikey.
It seems that you are not into revving the engine hard, so you should be OK there with the 1500.
Is there anything wrong with the engine, or is it a bit tired?

Worth checking the engine over for compression, oil pressure etc, so you know what its like to start with.
The sump will need to come off for crank/bearing inspection, plus removing the sludge in there. You should replace the bearings/thrusts unless they are perfect, ideally with vandervell (spelling) it is worth the money to get them, avoid the county tin ones at all costs, but they do a fair quality trimetal bearing if you ask. Glacier OK, but vandervell the very best. You may need a regring too, so don't buy until you know.
Likewise pistons. You could leave alone if all is well, I have found it is rare for the bores to wear badly, its usually cranks that go. If pistons come out you will need a hone and new rings though.
If you want to improve, then a cam could be the way to go, but not wild if you want increased torque. Maybe a mk3 profile, or TH5. The TH5 may be a bit peaky though fot your tastes? others will no doubt offer advice here.
A full balance is worthwhile and not too expensive, but it all depends on budget and what machining needs doing!
Headwork is really beyond budget to pay somebody, but a skim may help, and maybe a little DIY work to the ports, just to clean things up, and get the easy extra power.
You will need to strip the engine before you know where to start, and seek advice from those who REALLY know! (ie not me!)

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3 or 400 quid doesn't really allow you to do anything in terms of tuning.

You'll need to take the engine apart and look at what you've got - what needs to be done. You may not need new pistons etc

At most you can probably get a cam (TR5 profile) and get the whole thing balanced. Skim the head a bit and that's about it.

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Phil,
There is an excellent and comprehensive Guide, to Spitfire engine building and 'for High Performance' but the details and advice there will be most useful to you, I hope.  See: http://www.totallytriumph.net/spitfire/engine_building.shtml

John

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Smoothing and flowing the ports shouldn't cost much, I did my GT6 for about 10 packets of cheap grinding stones (£1 a packet!). Get as much info as you can, I can recommend Kas Kastner's GT6 Tuning book, only about £7! I assume he did one for the Spitfire?

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Thanks for the advice!

Cliftyhanger - reason for engine rebuild is due to rather excessive oil burning (in my opinion, she goes from the upper mark on dipstick to lower in less than two hundred miles). I am getting smoke on take off, and gear changes (particularly downchanging with high revs). This to me suggests that I need to replace the piston rings, although I shall probably see about doing something with the valve seals whilst I am at it. Having considered the matter a bit more, I have come to the conclusion that I shall leave any major tuning work until a later date, and aim just now for a solid reliable engine. As you suggest, I am looking at replacing bearings etc, piston rings and any skimming/honing necessary. If my budget will allow it, I shall also consider a lightened fly-wheel, however this again is not urgent. I shall also see about getting the whole thing balanced.

JohnD - thanks for website, I have perused it and am getting a lot of very useful info from it. Great One!!

Don Cook - I shall look into getting this, having also heard about it elsewhere on the forum. Anyone know of any suppliers of it in the North West of England??

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thebrookster wrote:
Cliftyhanger - reason for engine rebuild is due to rather excessive oil burning (in my opinion, she goes from the upper mark on dipstick to lower in less than two hundred miles). I am getting smoke on take off, and gear changes (particularly downchanging with high revs).


Sorry if this has already been covered, but do you have an external rocker oil feed fitted to the engine? These are often the cause of excessive oil consumption on otherwise healthy engines,
Cheers,
Bill.

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heraldcoupe wrote:


Sorry if this has already been covered, but do you have an external rocker oil feed fitted to the engine? These are often the cause of excessive oil consumption on otherwise healthy engines,
Cheers,
Bill.


No, this has not been covered, and no,I do not have this fitted. I have heard bits and pieces about this, and as a result am still no wiser!! If I have got it correct, this supplies more oil to the rocker shaft (cannot for the life of me think what it is actually called!!) than the basic oilways in the engine??
Is this likely to be an expensive modification, and how difficult will it be to implement?

Many thanks,

Phil

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thebrookster wrote:
Is this likely to be an expensive modification, and how difficult will it be to implement?


Sorry, my inference is that the rocker feed kit is a BAD thing. This could have been the cause of your oil consumption with copipous amounts of oil being sucked down the inlet valve guides. The kit diverts oil from the crankshaft (where it's needed) to the rocker shaft (where it's not!). The rocker shaft does not need a high pressure oil feed, a trickle is adequate.
Cheers,
Bill.

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Sorry, I am extremely tired right now, and had misread the post!! I shall certainly not fit one of these then!!

Things are looking better slowly. Following various PM conversations recently, it (hopefully) appears that a rebuild of my O/D may not be necessary, which should hopefully free up some more funds for the engine. Some re-thinking (when awake) is now due.

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Don'y worry, they may then help for a seriously modded engine, but need modding themselves. Ho Hum.
Looks like you need to do some compression testing on your engine, see if you can trace the problem. If you don't have one, beg borrow or steal (otherwise fork out)  a compression gauge, about a tenner on fleabay.
If the rings/bores are bad it may well need a rebore, which will drain your budget when you add gaskets/shells etc. But if you can find the money get it balanced, then it is done. The head can come off easily enough at a later date for any work, get it running well first, it will make a lot of difference.

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It was hopefully my intention to do a compression test tomorrow. Neil (glaramaraman) for whom I work has a gauge, which he allows me to use. I have done cylinder 2-4 before, although I cannot remember what they read. This time around I shall a) move the alternator to do cylinder 1, and b) repeat test with a little oil in each cylinder. I shall hopefully post the results up here so that anyone who wishes can offer advice/interpret the results!!

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Right, compression test just completed. As I could not remember whether or not to do the test hot or cold, I decided to do both. Results as follows:

Cold Dry
1: 175psi / 12 Bar
2: 148 / 10
3: 135 / 9+
4: 130 / 9-

Cold + Oil
1: 100 / 7 (anomoly methinks, too much oil??)
2: 145 / 10
3: 135 / 9.5
4: 140 / 10

Warm Dry
1: 170 / 12
2: 150 / 10.25
3: 150 / 10
4: 150 / 10

Warm + Oil
1: 180 / 12.5
2: 160 / 11
3: 160 / 11
4: 150 / 10.5

I have included bar in case it is useful to anyone, can anyone give any advice on these results??
Also, does anyone know why cylinder 1 (bar anomoly) has a consistently higher compression?

It seems to me as if the gasket is a possibly culprit, although the warm results are all within reasonable limits as far as I know, just at the bottom end of them.

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My 1500 has a 1300 head giving a CR of about 10:1 and has a Piper 270 camshaft.  It gives compression figures right at the top of the green band on a Gunson's tester ie 190-200psi.  I would be inclined to think that 170/180 psi on your No 1 is the only good cylinder and not an anomaly.

The rocker oil feed pipe makes no difference at all to the oil pressure and I have no problem with oil consumption, but I do have seals on the inlet guides.

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On the contrary!

That the oil makes so little difference to any cylinder says that the piston rings are fine.
That one cylinder has a higher pressure, wet or dry, says that the low pressure cylinders need their valves attending to.

And that cylinder head oil feed is verily Ye Spawne of Ye Devile!
Pressure means nothing, rhodes, it's flow that matters.
I think that the consensus is that if you have a new, unworn rocker set and shaft, it may do no harm, but under strain it can rob the main sof flow.   I used to fit one to my race car, and ran bearings until I took it off!  Haven't built a new race engine for a while now!

John

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yep, a leakdown test would be nice to confirm, but whipping the head off should reveal all! Still the problem of oil consumption, but that could be guides. However you previous posts suggest when revving the car or under load, so maybe more investigation needed!

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Hi
175 to 180psi is good for dry and 180-200 is good for wet.
Me thinks that the only good clylinder is one ,  and the reason numer ones is good is it always gets the clean cold air to cool it so does not surfuer from heat build up and the attached wear.

It does sound to me that rings are worn in the others but the lack of change from wet to dry could be the oil you used (what was it how much did you apply ?)or the state of the battery after turning the over for so long !

But in my humble opinion all three cyclinders being low is unlikey and it more likley the rings than just three sets of valves wearing !

But the real proof is when you strip it just like the guys are saying shouldn't cost much just to check it out though
Good luck

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