Merlin engine question

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Yamagata ken
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Merlin engine question

#1 Post by Yamagata ken » Wed Jul 25, 2018 8:59 am

I have a question about differences between the UK built and Packard Merlins. I know that the UK plans were re-drawn for Packard, doubtless to convert from 1st Angle (UK) to 3rd Angle (US) projection convention.

My question. Did the Packard Merlins use BSW and BSF fasteners, or were they SAE? In other words, were similar parts interchangeable?

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Re: Merlin engine question

#2 Post by Woody » Wed Jul 25, 2018 9:17 am

Not totally sure, but a R/R Merlin was fitted onto V/ VRA in place of the broken Packard engine, during her UK tour and also flew back to Canada, before being changed back, so possibly not to many differences.
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Re: Merlin engine question

#3 Post by ian16th » Wed Jul 25, 2018 12:05 pm

I believe that there were 4 sources of Merlin's.

RR itself and a specially built Ford plant in the UK.

In the USA, besides Packard there was another plant, Continental?

I do know that when I was working on the Lincoln's at Lindholme, our Engine guys were not keen on the Packard variants. They preferred working on the RR ones.
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Re: Merlin engine question

#4 Post by Yamagata ken » Wed Jul 25, 2018 12:28 pm

Thanks Woody. That's a good start.

@ian16th. I knew about the Ford-made engines, which is why I specified "UK built" rather than RR. It's one of those areas with endless scope for a pishing contest. I've read stuff from Packard fans transmuting "re-drawn" to "re-designed". It's why I'm fishing for a little clarification.

Another point is whether either organisation used metric inches or fractions for dimensions. My brother, who did an apprenticeship as a machine tool fitter, can give you from memory 17/32 inch in thou', but he's a bit bonkers. Not everyone can do that.

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Re: Merlin engine question

#5 Post by CremeEgg » Wed Jul 25, 2018 1:03 pm

Haynes (UK publishers of car maintenance manuals) do an Owners Workshop Manual on the Rolls Royce Merlin - all models 1933 - 1950. Looks like a fascinating read. Not got a copy myself but I would have thought someone on here would have. Hope that helps.

Lucky enough to live close enough to Biggin Hill to have the sound of a Merlin or two at least audible if not visible several times a week. Wonderful sound and only surpassed the other week by some of the RAF 100 flypast coming low over the garden certainly 4 Merlins in the Lancaster and I suspect 6 more in the accompanying Spits and Hurricanes - although I suspect there might have been the odd Griffon lurking in there somewhere. More research required.

So Slasher you're welcome to stay and listen out anytime. Just need to check out the local moonshine situation and arrange for a couple of good handfuls.

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Re: Merlin engine question

#6 Post by ian16th » Wed Jul 25, 2018 1:57 pm

Yamagata ken wrote:
Wed Jul 25, 2018 12:28 pm
Thanks Woody. That's a good start.

@ian16th. I knew about the Ford-made engines, which is why I specified "UK built" rather than RR. It's one of those areas with endless scope for a pishing contest. I've read stuff from Packard fans transmuting "re-drawn" to "re-designed". It's why I'm fishing for a little clarification.

Another point is whether either organisation used metric inches or fractions for dimensions. My brother, who did an apprenticeship as a machine tool fitter, can give you from memory 17/32 inch in thou', but he's a bit bonkers. Not everyone can do that.
Do you mean decimal inches?
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Re: Merlin engine question

#7 Post by Yamagata ken » Wed Jul 25, 2018 2:30 pm

:( Grrr. Yes, decimal inches. Thanks all, it's nothing important, just an itch I'd like to scratch.

The Haynes Manuel sounds good, but they are somewhat rare here. I'll get my brother on the case. Haynes rather lost me with the last one I bought. It's for Subaru Liberty/Legacy and it has chapter 2A on the 3.8 litre V6 engine and 2B on the 5.0 litre V8

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Re: Merlin engine question

#8 Post by om15 » Wed Jul 25, 2018 2:42 pm

Packard Merlins used BSF, I have two ring spanners in my toolbox from a tool kit supplied with each Packard Merlin, both BSF and I used them daily for years working on RR Darts.

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Re: Merlin engine question

#9 Post by om15 » Wed Jul 25, 2018 2:57 pm

Here they are, marked as Whitworth, but fit BSF across flats, they were given to me in 1979 by a fitter retiring that had acquired them during the war. The manufacturer "Blue Point" was part of the "Snap on" manufacturing group.
The spanners must have been specially made for Packard as the catalogue sizes were American imperial A/F sized.
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Re: Merlin engine question

#10 Post by Yamagata ken » Thu Jul 26, 2018 3:10 am

Thanks team. That's very helpful and I'm most grateful. om15: Those ring spanners look very nice, balanced, rounded and will feel good in the hand. You'll need a Velocette to find a use for them, though :)

On the subject of threads (I've mentioned this elsewhere and I hope I'm not repeating myself here) Whitworth is alive and well in the building industry in Japan. They come with metric heads. A few years ago I modified some guttering and none of my stock would fit. Cue sucking of teeth and scratching of chin. Close inspection revealed a non-metric pitch. A trip to the hardware shop and there they were, Fastenings with Wxx labels rather than the Mxx I'd been browsing. I never spotted them because I wasn't looking.

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Re: Merlin engine question

#11 Post by om15 » Fri Aug 03, 2018 3:29 pm

Ken, I have a BSA that I can practise undoing and doing up nuts and bolts, I am unsure of the sizes, each component seems to be held together or attached with different sized fasteners, but the two ring spanners above fit most nuts and bolts.
I also have a set of shiny Snap On BSF combination spanners that I bought new some years ago.

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Re: Merlin engine question

#12 Post by cockney steve » Mon Oct 15, 2018 4:49 pm

IIRC, Whitworth size heads are a size -step larger than the BSF heads, so each spanner end of an open-ender or double ring, has dual fitment....IE 1/4W /3/16 BSF 5/16W / 1/4 BSF This was very useful, as a "short set" would contain 2 spanners with the same size ends , so both a nut and a bolt could be held and worked on simultaneously.

WRT the Merlin, I read that Packard was , unlike RR, not into hand-fitting and therefore tightened all the tolerances so parts were truly interchangeable. I wonder how much this magnificent piece of engineering could have been simplified, had the government not made a bottomless pit of money available to finance it?

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Re: Merlin engine question

#13 Post by ian16th » Mon Oct 15, 2018 5:31 pm

cockney steve wrote:
Mon Oct 15, 2018 4:49 pm
WRT the Merlin, I read that Packard was , unlike RR, not into hand-fitting and therefore tightened all the tolerances so parts were truly interchangeable.
I read somewhere that Ford's did this, as they didn't have the skilled labour to 'fit' the parts.
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Re: Merlin engine question

#14 Post by fareastdriver » Mon Oct 15, 2018 7:58 pm

[not into hand-fitting and therefore tightened all the tolerances so parts were truly interchangeable*]

IT was the same with cars. When I was a lad I would work on both British and American cars. A characteristic of British cars was that the cylinder bores had either an 'S' or a figure representing the bore oversize, the same with crankshaft bearings. This meant that you were required to used oversize pistons or undersize bearing shells.

American cars never had that problem. One size fitted all. It was only after it had been rebored or the crankshaft reground that the size changed.

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Re: Merlin engine question

#15 Post by John Hill » Fri Oct 19, 2018 4:17 am

Cue Henry Martyn Leland.
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