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BMC 1.5 to 1.8?


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#1 Simple Things

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Posted 25 November 2012 - 09:55 PM

Hello all....

I bought a doer upper in April and boy is she a doer upper. The existing bmc 1.5 is goosed frankly. I have managed to source a good bmc 1.8 as was originally told this should be a straight swap. Now I am told this is not the case. Can anyone shed any light on he matter? Anybody any experience of doing this and did it prove an expensive job with any new parts needed?

I look forward to some good news! However will deal with reality also!

Many thanks

Jeff

Edited by jeff_ggg, 25 November 2012 - 09:56 PM.

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#2 alan_fincher

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Posted 25 November 2012 - 09:58 PM

Others may know better, but AFAIK, in terms of size, where the feet go, etc the 1.5 should be a straight swap to the 1.8. (The difference is the bore of the cylinders, but externally the block is the same size).

I would have thought most marinisation parts would also swap over too, if you need to do thatr.

Has anybody explained to you exactly the areas in which they think you might hit problems?
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#3 RLWP

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Posted 25 November 2012 - 10:00 PM

I would say your best bet would be to fetch the 1.5 and gearbox out of the boat, put it on the floor next to the 1.8 and swap the marinising parts over. That way you'll find out what you have, what you can use and what you will need.

Richard
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#4 Chris Pink

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Posted 25 November 2012 - 10:15 PM

Where are you based? I'd be interested in the leftovers of the 1.5. I am missing some parts for a rebuild. I have two and one has been used to donate parts to the other and some bits are just plain missing.

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#5 Simple Things

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Posted 25 November 2012 - 10:19 PM

Tanks for both speedy replies. I am told the fly wheel and gearbox are just two of the areas, although more substantial areas, that would need parts replacing. Other things are bolts quarter of an inch out etc etc.... The 1.8 is in excellent condition.... The 1.5 is not....

Chris Pink the boat is moored over in Tarleton (between Preston and southport) if that's any use to you?
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#6 alan_fincher

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Posted 25 November 2012 - 10:21 PM

Are they both engines that are already marinised?

I assume the replacement has no gearbox, and you need to swap the one from the 1.5 on to it?

What gearbox is it?

The gearbox (of course) is not part of a BMC engine, and will not mate directly to it, but instead to a plate on the bellhousing designed for that engine - that plate may be to some extent "gearbox specific". I would have thought if you take the plate over as well, then it would work.

More info needed, I think.
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We have had a wonderful time at the Alvecote Historic Boat Gathering, but all good things have a habit of coming to an end, and now have two boats needing taking "home" together.

We are now near Grafton Regis on the Grand Union (Friday night).

 

Narrow boats SICKLE and CHALICE blog


#7 Simple Things

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Posted 25 November 2012 - 10:27 PM

Yup both engines marinised and 1.8 does not come with its own gearbox. I'm trying to think of the gearbox but I can't quite get it. Will find out some more information on Tuesday as will be going over to the boat.

I think the gearbox begins with a T?? But I'll find out Tuesday...
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#8 alan_fincher

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Posted 25 November 2012 - 10:38 PM

Yup both engines marinised and 1.8 does not come with its own gearbox. I'm trying to think of the gearbox but I can't quite get it. Will find out some more information on Tuesday as will be going over to the boat.

I think the gearbox begins with a T?? But I'll find out Tuesday...


TMP ?

Other possibilities....

Hurth
PRM

and no doubt others.

I think you need to look at whether the box plus the adapter plate it mounts on will all swap over.

If the holes on the bellhousing that the adaptor plate bolts to are in a different configuration, possibly you need to look at swapping the bellhousing too.....

But at that point I'm out of my depth, so will leave it to others!.....
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We have had a wonderful time at the Alvecote Historic Boat Gathering, but all good things have a habit of coming to an end, and now have two boats needing taking "home" together.

We are now near Grafton Regis on the Grand Union (Friday night).

 

Narrow boats SICKLE and CHALICE blog


#9 Simple Things

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Posted 25 November 2012 - 10:45 PM

And I think they are now you mention it! As I say will find out more on Tuesday just wondered if anyone had any experience of doing this. Thanks for all the replies. I know it is doable... Just will it be costly.... Which.., it probably will!
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#10 Tony Brooks

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Posted 26 November 2012 - 08:07 AM

When we set up the training courses at Reading we had to try to make a working marine unit from marinised 1.5 and an automotive 1.8. AS far as I can remember the manifold and mounts fitted (you have to turn the automotive inlet manifold upside down but the 1.8s may be different depending upon its automotive application). The differences were the flywheels and flywheel housings. The 1.5 and I assume the 1.8 in marine form should ideally have a bulk ring bolted to its flywheel but the 1.8 flywheel is larger.

The 1.5 we had used the cast iron, shallow dished drive end plate with the cast iron "ring type" flywheel housing plus gearbox adaptor plate rather than the more modern "all in one" flywheel housing and adaptor plate while the 1.8 had a flat fabricated steel one so the marine flywheel housing would not fit. The 1.5 flywheel fitted the 1.8 but then the starter motor was in the wrong place and would not engage the flywheel. From memory it is deceptively close but not close enough.

Once you have the correct flywheel housing I would expect the gearbox to fit but you may have to change the drive plate over.
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#11 Simple Things

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Posted 26 November 2012 - 08:55 AM

Thanks Tony very informative I will discuss this tomorrow with those that are more knowledgable than me..... Thanks again for the time....
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#12 Simple Things

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Posted 28 November 2012 - 06:38 PM

Update is that the parts needed to fit the 1.8 including flywheel brackets etc etc gearbox etc etc were over a thousand pounds... Most existing parts out by a fraction of an inch.
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