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MG MGB Technical - ENGINE VALVES

30+ years ago when I bought this 73 B, there were 6 NOS BMC/MOWOG intake valves under the seat. I'd like to ID them but don't have a clue where to start. There are NO numbers stamped on the top of the stem so I don't know if they are for an MGC AH 3000 or Jag. Is the any place that has a spec to cross reference? They are intakes with 34.85 mm dia (1.373) and .340 dia. stem. They look like TD/TF/1500 but are too small (36mm TDF). Can anyone point me in a good direction or have a cross reference catalog maybe. TIA Russ
RAH Russ

Hello TiA,

I'm not shure of your problem. According to specs inlet should be 1.562"(1.625" for 18V engines) minimum for intake and 1.343" min. for exhaust. May be prior owner installed ovesize valve...
This will bww not so wasy to find.

Cheers,

JGC
J. G. Catford

A pic may help as well as dimensions such as length of valve from tip to fireface. Are the seats 30 degree or 45 degree?
Peter
Peter Burgess Tuning

As Peter says, some other dimesnions would help.
Stem diameter eliminates Jag and XPAG, both 5/16" or 8mm (sorry can't remember which off the top of my head) and would indicate B or C series.
IIRC the very early B series Austin/Morris engines had intake valves less than 1.5".
Paul Walbran

Are you sure they are inlets--
They must be very close to MGC exhaust valve size--??
or later/oversize MGB
What sort of keeper fitting have they got
willy

pics--
William Revit

I think Paul is on the right lines, the early 1200 B series engine had tiny valves. That is why I wanted the fireface to tip measurement and a piccie.
Peter
Peter Burgess Tuning

UPDATE - Hello Gents, interesting feedback. First off, my camera is trashed, gotta get a new one or wait a couple of days for my grandson to help. Here are the additional specs I forgot: OAL is 109.9 mm (4.33") slightly shorter than my TF at 111.9mm (4.40") and the TF has a .314 dia. stem. The top of the valve has the same profile as the TF and the same length. The Tranco NOS TF intake has a 'IN' cast (I assume means intake) on the backside of the face. As I said, I don't know these to be MG and I assume because there were six valves they were for a 6 cyl car, but then again that was a mere assumption on my part. Thanks all.........Russ
RAH Russ

I get 110mm and a bit for length of early 1.5" MGA inlet valve. Checking seat widths in a 216 head(1200 B series) I reckon the diameter of the inlet is around 35mm. I think we have the culprit?
Peter
Peter Burgess Tuning

Hi Peter
"the early 1200 B series engine had tiny valves" yes they do seem really small, lost in a huge chamber ... but then when we have 1275cc in A series, 35.8 is considered big!
I never thought of it that way till now.
Paul Walbran

Nice work Sherlock
lol
willy
William Revit

I must have been behind a tree when they went past----
As far as I know I've never seen a 1200 B series engine
What were they in - did they get to Australia do you think--
willy

William Revit

Wikipedia says this
The 1.2L (1199.6 cc) version was the first version of the engine. The bore was 65.5 mm (2.58 in) and the stroke 89 mm (3.5 in). The maximum power output was 39 bhp (29 kW) at 4300 rpm.

After the formation of British Motor Corporation (BMC) the new B Series engine was used in the following vehicles:

1954–56 Morris Cowley
1954–56 Austin A40 Cambridge
1954–55 Nash Metropolitan 1200 (used unique "2G" engine prefix)
Massey-Harris Combine Harvester

To be honest I always call it the Cowley van head. We convert them to early MGA valve spec and they are ok on the 1500s.

Peter
Peter Burgess Tuning

I guess there would have been the odd Cambridge here
You learn something every day !!
Thank for the info Peter
Cheers
willy
William Revit

This thread was discussed between 17/09/2016 and 21/09/2016

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