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Davemate

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I'm trying to keep the costs as low as possible for my engine re build
I'm hoping the only machine work that will be needed is a crank re grind and hone in the bores.
Is It practical for me to just have the machine shop assemble the crank and Pistons together. I'm happy to install the cam myself.
Do I need to get the rotating parts balanced or is it not really worth it, I just want a reliable engine I'm not building anything special
The only mods will be a "pi type cam" and a witor sports exhaust
Pennies are very very tight

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No reason to get them to assemble it at all. They can just regrind the crank, you can hone the bores and build it all up. Nothing difficult, just be methodical, make sure everything goes back in the same place and so on. I am sure you will get plenty of help if needed :)
Are you going to skim the head for a slight CR increase? I suspect the cam would work better....

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I'd rather the man who grinds the crank fit the crank as he will be supplying the shells and I'll know it's been done properly.
It would appear that my head is not repairable so I'm now looking for a replacement, I will get it skimmed if it's required although that can be done at a later date if needs be

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I would potentially be wanting crank balancing done as well, myself, however if you are re-using pistons and rods, and the engine ran fine before, it probably is not really essential.
If you have a set of electric scales, I would instead suggest balancing the static weight of the pistons and rods together yourself with a die grinder. Likewise honing, see if anyone has a homing tool they can lend you and do that yourself, we use a bobbly brush thing on the ship which does a nice job.

(Like this: http://www.amazon.com/Research-FLEX-HONE-Cylinder-Silicon-Abrasive/dp/B005ANHYF6#product-description-iframe )

And as Clive says, maybe worth upping CR whilst you are at it, and again for me, If I was to skim the head I would also have the block skimmed as well, then you know you have two flat surfaces to work with!

Might be worth asking Mr Radders as to what he did with the Red Shed and follow the same plan, assuming you have the original MkI engine still? Cause that goes very nicely indeed, strongly recommended!!

Cheers,

Phil (Current owner of the Red Shed!)

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thebrookster wrote:


Might be worth asking Mr Radders as to what he did with the Red Shed and follow the same plan, assuming you have the original MkI engine still? Cause that goes very nicely indeed, strongly recommended!!

Cheers,

Phil (Current owner of the Red Shed!)


Mr Radders didn't do anything with the Red Shed's engine other than fit a PI Cam and tune, re-tune, and re-tune the Stromberg carbs again until they were perfect.  :)

No gas flowed head, no lightened flywheel, no sporty manifold or exhaust, nothing! In fact that car has no right to go the way it does for a standard 2 litre.  :o

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1344 wrote:
I'd rather the man who grinds the crank fit the crank as he will be supplying the shells and I'll know it's been done properly.
It would appear that my head is not repairable so I'm now looking for a replacement, I will get it skimmed if it's required although that can be done at a later date if needs be


Dave didn't you get my message saying I have one spare if you want it.

MUT

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I did get your message Ted, and I will take up your offer please,I just asked at the machine shop to see if it could be repaired and apparently it's in a dodgy place.
I'll have to try and sort out a means to get it to me via the club express or a courier
Any offers ?

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What gets balanced ?
The machine chap I was talking to said that he would only balance the crank, I would have thought that the crank with Pistons,clutch and cam fitted
Basically anything that rotates the whole "short engine" not sure if each part is done on its own or as a complete assembly and I'm not sure funds will go that far

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Crank and flywheel should be balanced together, ideally with the clutch pressure plate you are going to use.  Rods and pistons can be done diy though if the engine is original you'll probably fine the rods are pretty close already and a new set of pistons will be pretty close also.

I'd consider balancing to be well worth doing.

Nick

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Definitely agree with Nick.  For longevity, especially if you intend to be anything of a hooligan with the engine, is to be recommended

I was advised that sometimes the original factory crank balancing was a bit marginal and while it is usually OK for basic use having all the rotating masses (crank, flywheel, clutch cover, front pulley) balanced as a set is most certainly to be advised.  Because I was rebuilding the rather rare engine in SCG I took heed of the advice.

Balancing rods can be done easily enough (info in any decent tuning book), but pistons and rods can often be mixed and matched to get the best near balance then finished off with further detail balancing.  Also check compression heights while you are at it because I found the old Stanpart pistons had significant differences.  However when I compared specifications between piston sets of Stanpart and County I found that as has been reported the County ones were MUCH better, both weight matching and compression height.

MUT

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Hello Dave,

the rotating parts are done on a special machine, basically the crank is rested on two rotating supports at the outer bearing journals and components added as the balancing progresses, i.e. crank, then crank and fly wheel, then add damper, clutch etc. Sensors on the rotating supports measure the vibrations that are caused buy out of balance. The operator then removes metal where indicated by the machine.
Rods and pistons can be done at home with electronic kitchen scales to a reasonable standard. Ideally the rods are balanced to equal weights and end to end weights, i.e weight is removed from the heavier rods at either the little end or the big end depending on teh variation. You need a jig to support the small end and the scales weight the big end with minimal friction at the little end and the rod horizontal. Try U Tube for a video of the procedure. Pistons are again weighed and material removed from inside at a low level. You'll need a coarse rotary burr as that is the best and easiest to use.

Alec

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If timing is OK for Dave we're in the Forest of Dean, however just realised I may be able to get it to Reading when a friend visits us in a week or so.  He may be earning his keep because he does not know it yet but he could be ferrying this head and a fuel tank !

We live the other side of the River from Bristol ...... in England!  Takes about 40 minutes depending where you start in Bristol ..... and time of day!
There is also the question of the toll charge on the bridge which is £6.40 at present  :( towards Wales (free coming out of Wales).  As I have a blue badge it costs me nothing so could come over to meet up with you if needed, or if you want to pop over for a social visit anyway you will be most welcome  :)

MUT

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962 wrote:
Dave I would be more inclined to let the machine shop assemble the short block. Most of these places have a nice clean and dust free engine room. At home you have dust and dirt blowing around (not saying you don't know what a hoover is  ;D) and cleanliness is next to godliness when it comes to mechanical assemblies  ;)


This was what I was thinking.

Ps
   Hoovering,sounds like a "pink job" to me,
don't do pink jobs only do blue ones

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Dave, I built up my engine at home. The garage was swept first and is fairly draught-free, so I don't think any dust got into the engine. It took a long time to build, so I always pulled a plastic sheet over it when I wasn't working on it. It was fun, easy and straightforward.

Assembly by the engine shop will probably cost as much as their machining, so you can splash out on balancing, build it yourself and have a better engine for the same price. I recommend check the piston and rod weights. Five of my rods were from the same production batch and within cooee, but the sixth was from a different bin and a lot heavier.

I also had my main bearing housings align-honed, and as a result, when the mains were torqued up the crank still turned freely. As in, a gentle prod with my little finger had it zinging around. Not saying that align-honing is essential, but it's a long, skinny motor.

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Now I'm not a mechanic and apart from the basics don't know much about engines, but why are people saying about balancing the bottom end.
I know on a 'race' engine and the higher revs it's important, but why on a road car?
Is it really worth the extra money when the triumph engine is smooth as is, does it make it quicker, if so how much. Will it last longer? Etc. what are the benefits?

Cheers Andy

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Dave I have never had anyone else rebuild any part of an engine for me.  Partly because in my early years in the 1960s I could not afford it and read much, got advice from my father, and used my noddle and taught myself 'good practice'.  

As a result nowadays to be honest I would have great difficulty trusting anyone to do it for me, though I am very happy to work with someone who is knowledgeable as I have with Gordon (Townley) with the Mk1 PI engine and all its problems.

Rebuilding an engine requires care and patience, reading a few books on the subject and/or talking to friends who know what they are doing - there is no mystery about it.  To be honest you need to do it sometime unless you are always going to pay someone to do it because as Nick says the labour cost can exceed the machining cost.  Besides knowing you have built an engine yourself which runs sweetly would give you more pride in running the car.

If you have any queries about doing the job your friends only a Forum, e-mail or phone call away to help you.

Andy I agree that balancing is not necessarily a prime requirement especially with the six cylinder engine with its inherent balance.  However when highly respected people in the Triumph world with considerable experience of rebuilding engines recommend it because they consider Factory balancing to be a bit marginal who am I to doubt them.
If I was building a bog standard unstressed everyday engine would I do it - probably not.  However if I was building an engine where I would be pushing its performance even a little I would do it.  And with the Mk1 PI engine I would do it as a matter of course simply to rule out a possible source of future failure - finding a long back cross drilled crank is bl**dy hard work  :-/

MUT

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