Help with Engine and Gearbox Identification

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garfield
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Help with Engine and Gearbox Identification

Post by garfield »

I own a 1958 Austin A35 that came with a 948cc engine. I am trying to confirm it still is a 948cc engined car. It's an A2S5.

I'm currently in the process of completing a full mechanical restoration of my car, and I am a little confused about the size of the engine and gearbox I have removed.

I think I have a 948cc engine and a 1098cc gearbox. Is that even a valid combination?

I've attempted to do some research of my own using this forum and other related websites. However, I'm stuck identifying (and convincing myself) what size engine I have in the car. This is mainly because the engine numbers and markings do not match up precisely with advice I've found in other posts.

Here is what I know:

1. My car has a ribbed gearbox, which I understand should have been a smooth case gearbox originally? I believe ribbed boxes would have been fitted to vans and larger capacity engines. Possibly my gearbox is built for a 1098cc engine?

2. The clutch I removed, does not look like a 948cc clutch based on diagrams in my Haynes manual and spare parts on eBay. It's like a 1098cc clutch.

3. My engine number starts with 8G163 GP***** . I understand this means it's a Gold Seal engine. According to this book https://tinyurl.com/yb6sxxnj (found on this forum), Gold Seal engines with engine numbers starting with 8G16 belong to 948cc engines. However, mine starts 8G163 and not 8G16.

4. The engine number also has AD marked on the engine number plate. I understand this means a standard bore engine and a 20thou crank

5. There are no other size markings on the engine that tell me anything. The engine size marker near the fuel pump is missing.

The markings I do have on this side of the engine are 11E (left of the fuel pump), MWOG 4 162 (centre) and 12A 497 (right-hand side).

6. The head taken off the engine has the code 2A629 SM, which I think can fit different engine sizes?

7. I've attempted to measure the engine bore and this was approximately 63mm

Given the above, am I right to assume I have a 1098cc gearbox with a 948cc engine?

Is there anything else I can check to confirm my assumptions?
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Paulc
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Re: Help with Engine and Gearbox Identification

Post by Paulc »

Over 60+ years it isn't unusual to see car with all types of combinations, in fact an original engine is probably unusual. The bore of an 848/948cc engine is 62.94 and for a 1098 64.58, so it looks like you have a 948cc engine (or an 848cc!). Are you sure you don't have a stamping on the engine, above and to the left of the petrol pump that will have 950 on it? What head to you have fitted? The standard 1098 would have a 12G202 head, I think the 948 is 2A628/2A629 (again indicating a 848/948cc engine). The ribbed gearbox was also used on the 848cc vans (and maybe the AV6 948cc van). The ribbed box is meant to be a stronger box than the smooth box, all that is needed to fit a 948 engine to the ribbed box was the thicker backplate from an 848/1098/1275 engine. Do you know what size your clutch driven plate is, the standard 948 is 6" 1/4".
Chris T
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Re: Help with Engine and Gearbox Identification

Post by Chris T »

My copy of BMC's 1098cc Parts List (AKD 3419) has 8G 163 as low compression 1098cc engine, superseding 8G 127. The missing 950 block casting supports this. The 1098 marking is via a riveted plate which is easily separated. 8G 16 is indeed for a 948.
Chris T
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Paulc
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Re: Help with Engine and Gearbox Identification

Post by Paulc »

Chris, but why does it have an 848/948 bore, the 1098 is much bigger.
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Duncan
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Re: Help with Engine and Gearbox Identification

Post by Duncan »

going by the A-series Wiki (here: https://en.wikipedia.org/wiki/BMC_A-Series_engine ) the 848cc was used for A35 van between '63 & '68, also the ribbed gearboxes are supposedly used on vans after '62...

If the head is off, measuring the stroke should confirm what the cc rating is (68.26mm for 848, 76.2 for 950)
Chris T
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Re: Help with Engine and Gearbox Identification

Post by Chris T »

Paulc wrote:Chris, but why does it have an 848/948 bore, the 1098 is much bigger.
No idea! The riveted engine id tag can easily be switched too...
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Bill
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Re: Help with Engine and Gearbox Identification

Post by Bill »

Surely the 11 is the giveaway. The 948 has 950 on it doesn't it?
Alan
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Re: Help with Engine and Gearbox Identification

Post by Alan »

looked a moggy engine recently supposedly a 948cc. it didn't have 950 stamped on the block though.........
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Bill
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Re: Help with Engine and Gearbox Identification

Post by Bill »

Alan wrote:looked a moggy engine recently supposedly a 948cc. it didn't have 950 stamped on the block though.........
Oh! That's that theory out the window then.
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Re: Help with Engine and Gearbox Identification

Post by Alan »

not really bill. did only Austin stamp 950?
Modified 1963 AV8 A35 Van
Modified 1972 Rover P6 3500s

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Alan
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Re: Help with Engine and Gearbox Identification

Post by Alan »

i reckon it was a converted transverse engine. possibly a 998 engine??
Modified 1963 AV8 A35 Van
Modified 1972 Rover P6 3500s

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Edosan
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Re: Help with Engine and Gearbox Identification

Post by Edosan »

Sounds to me like engine and gearbox are from a late 848 van. Bore is correct at 63mm and its mated to a ribbed box which would be correct. 1098 engine would be 64.6mm bore. Maybe great engine to update an 803cc if you don't want to fall foul of power increase rules for new MOT guidelines, not sure of exact BHP comparisons though. :wave:
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Re: Help with Engine and Gearbox Identification

Post by gazza82 »

Power increase issue has been binned .. it's now "similar engine" so as long as it is an A-series you will be OK .. although 5-speed conversions might not!

So that's a 1430 big bore conversion then .. :whistle:
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Re: Help with Engine and Gearbox Identification

Post by Edosan »

:thumbs: great news, hadn't heard that so my 1098 is fine although had been in since the 80s anyway :wave:
Paulc
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Re: Help with Engine and Gearbox Identification

Post by Paulc »

I'll stick a Datsun 120Y engine in since they are similar engines!!!
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