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3 Main 1800

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Walt B. Walter Bellhaven
Sacramento, California, USA   USA
I have the opportunity to buy a 3 main 1800 block and crank to rebuild for my A....but the engine tag is missing. How can I be sure this is an 18G or GA block? Does the casting number shed any light (12H750)?

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Basil Adams Avatar
About 12 miles from Sears Point, CA, USA   USA
If there's a date circle it could be indicative. If you pull the rocker cover and the head casting is 12H906, it should be 3 main. The sure way is to drop the pan and count :-) Best of luck. Basil 707.762.0974 basiladams@yahoo.com



Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains

Rotaglide Avatar
Rotaglide Eric Z
Lindau, BAY, Germany   DEU
1960 MG MGA 1600 "Zoey"
Which date shows the "Casting Clock" one the block?

It's the round stamp on the right side.

If the date is between Feb. 64 and Oct. 64 it is a 18GA, before it is a 18G.

This ist the period when MGB's where produced with the 18GA engine.



Genomic Location for MGA Gene:

Chromosome:15
Start:41,621,224 bp from pter
End:41,773,081 bp from pter
Size:151,858 bases
Orientation: Plus strand



Edited 3 time(s). Last edit at 2017-07-15 02:02 AM by Rotaglide.

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Attachments:
MGB casting.jpg    33 KB
MGB casting.jpg

Rotaglide Avatar
Rotaglide Eric Z
Lindau, BAY, Germany   DEU
1960 MG MGA 1600 "Zoey"
In reply to # 3552227 by Rotaglide
If the date is between Feb. 64 and Oct. 64 it is a 18GA, before it is a 18G.

This ist the period when MGB's where produced with the 18GA engine.

Sorry, what I wrote isn't correct, I mixed the introduction date with the production date!

Correct is:

MGB's produced between 5/62 and 7/63 had the 18G engine, and between 8/63 an 9/64 they have the 18GA engine



Genomic Location for MGA Gene:

Chromosome:15
Start:41,621,224 bp from pter
End:41,773,081 bp from pter
Size:151,858 bases
Orientation: Plus strand

johnvall1 John Valentine
York, PA, USA   USA
1963 MG MGB
1971 MG MGB
I'm surprised no one mentioned that both 18G and 18GA Engines are the only ones with a Mechanical Tach Drive, located on the left side of the Block at the rear of the Camshaft.

fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
If it has 19 pan bolts and says 1800 on the LH side of the block toward the front, it is either 18G or 18GA. All 5 mains have 18 pan bolts as well as Sherpa 1622s. No need to drop the pan to count mains.


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
dipstick Avatar
dipstick Kenny Snyder
La Center, Washington, USA   USA
1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
Are there differences between a 18G and 18GA block and crank?



Be safe out there.
Kenny

Rotaglide Avatar
Rotaglide Eric Z
Lindau, BAY, Germany   DEU
1960 MG MGA 1600 "Zoey"
The differences between G and GA are:

-the oil filler cap (non vented vs. vented)
-the front Cover (flat vs boxed)
-the crankcase breathing (non positive system vs. positive system with PCV Ventile on the inlet manifold)



Genomic Location for MGA Gene:

Chromosome:15
Start:41,621,224 bp from pter
End:41,773,081 bp from pter
Size:151,858 bases
Orientation: Plus strand



Edited 1 time(s). Last edit at 2017-07-15 12:03 PM by Rotaglide.

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bills Avatar
bills Bill Spohn
W. Vancouver, , BC, Canada   CAN
In reply to # 3552381 by Rotaglide The differences between G and GA are:

-the oil filler cap (non vented vs. vented)
-the front Cover (flat vs boxed)
-the crankcase breathing (non positive system vs. positive system with PCV Ventile on the inlet manifold)

In other words, nothing significant.



Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
In reply to # 3552211 by Walt B. How can I be sure this is an 18G or GA block? Does the casting number shed any light (12H750)?

FWIW
My 18G engine does not have a casting clock and carries the 12H750 part number.
Only numbers on the block (below)

B



Check your ego Amigo!

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BH_18G_008#.jpg

BH_18G_008.1.jpg    40 KB
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