Help Identifying camshaft variant for Valve lash

[thematt]

Hey all,

 

Been spending some time on here since installing a surplus BMC 1.8 (Westerbek w50). The W50 manual indicates the camshaft is the older style with lower compression ratio require 0.017 clearance. However, the description of external ribs on the block for the newer style fits what I see. I understand that requires 0.014.

 

I'm looking for feedback on if this is the old style or new style block? Would the old cam fit in the new block? I.e. did westerbeke do something weird potentially?

[Tony Brooks]

Welcome to the forum.

 

I am afraid that I have never heard of high or low compression versions of the BMC1.8D engine, and can't see why it would be needed, as it is only a beefed up 1.5 that had been in production for years. That is apart from the strengthening ribs. It sounds odd to me and as I can't find a free to download 1.8D manual I can't comment, apart from saying that as long as there is a little valve clearance remaining when really hot the actual gap won't matter too much, apart from noise and arguably a very slight loss of power if they are too great.

 

Thanks for asking the question, because if t gets answered I will learn something.

 

More info. Please note, this could be way of the mark.

 

Thinking and Googling pulled this up. BMC/BL collaborated with Perkins to convert their O series petrol engine to diesel, which in marine use became the Perkins Prima. The marine units were naturally aspirated, while the units that went into cars had turbocharges and those did have a lower compression ratio. One of the models was known as a T50 so wonder if the 50 in your title indicates that this is actually a BL O series engine and not a BMC 1.8D at all. If it is then it will have a timing belt at the front, I think.

[thematt]

Thanks for the reply and welcoming to the forum!

 

I was actually referring to the asap supplies manual I purchased. It indicates there are two camshaft variations, which slightly different specs.

 

Oringal 21.47:1 compression, and newer version  22.3:1 compression. The camshaft is slightly dimensionally different too.

 

 

.... and I just found the answer to my question when reviewing the manual just now for this reply. Please see attached!

 

Guess my westerbeke w50 manual is wrong for this engine. The serial lines up with spec '2'.

 

Edit: forgot to reply to the extra info. the block has a 1800D on it. I'll have a look into the info you shared to make sure I'm not messing things up. the westerbeke w50 manual is availble for free online, but is too large to attach if you are curious.

 

Edited April 4 by thematt

[Tony Brooks]

Thanks for that, every day is a school day. I am now wondering if certain applications of the 1.8D had a turbocharger fitted, which would explain the lower compression ratio.  I am also pondering if the different cam profiles and lower compression ratio is related to valve overlap and possibly exhaust emissions (I understand that at one time extended valve overlap was used to allow some exhaust gasses to be drawn into the cylinder to act a bit like EGR). Best not to discuss this because it gets too technical for a general forum.

[thematt]

I'm happy to help! This is the thread that got me thinking 'wonder which version mine is'