Andrew:
I've given up using engine numbers for identification. It is
unusual now to find an original engine that has never been unbuttoned.
The Peter Burgess Book. How to Power Tune MGB 4 cylinder is a great
reference, and I absolutely recomend owning it.
In a nutshell. The 18V is a good block. Casting quality is good
and it has the main cap bolts. The crank is high tech cast iron, fully
balanced and holds up well. The single timing chain set and cam are
normally replaced during a rebuild with dual row and a sportier grind.
Make sure that the harmonic balancer and front cover match. The
timing marks do change.
Heads are a whole other issue. Since they tend to crack, there is
no way of matching head type to engine number.
Things to look out for with heads.
Non Smog Port. Could be pre-68, or could be a UK import. A UK import could
have any of the following smog port designs, but without the ports.
Smog Port Heads. Regular (1.562") Inlet Valve or Big (1.625") Inlet Valve
With or without water choke carburetor port at rear of head
Inline or offset oil passage to rocker pedestal.
All of the late heads interchange, so long as the correct rocker
pedestal is used. Since most heads will require exhaust seats, the slight
difference in seat hardness from one to another is no longer important. The
big valve head as found on some 73-74 US and many UK heads has a slight
breathing improvement.
The 18V engine is a good unit to rebuild. The only downside is the
press fit con rod design. The late type full floating rods are very rare,
and my machine shop is not happy with the idea of honing the later rods to
accept pin bushes. Since I have a stock of press fit pistons, I'm going
that way. Luckily for my race engine, I have a couple of sets of NOS full
floating late straight cut rods. These tho' have to be lightened before
use.
Hope this is of some help
Kelvin.
> -----Original Message-----
> From: Andrew B. Lundgren [mailto:Lundgren@iname.com]
> Sent: Thursday, February 17, 2000 8:58 AM
> Cc: 'mgs@autox.team.net'
> Subject: 18G -vs- 18V, differences?
>
>
> What are the differences between the 18V engines and the
> 18G's? I know the following:
>
> Smog stuff. (later G's also have the air manifold...)
> One year of the 18V has something funky on the water system
> for the choke I believe.
> The 18V use the simplex timing chain and gears...
>
> Anything else?
>
> The reason I ask is the '70 parts car I just bought has an
> 18V in it from a '77 car if I am correct. The number is: 18V
> 890AEL 007... (forgot the rest...)
> My current engine is an 18G D ..... Forgot the rest.
>
> -
> Andrew Lundgren
> lundgren@iname.com
>
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