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MGA Forum

1800 3 Main Questions

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zman4011 Avatar
zman4011 Adam Z
San Francisco, CA, USA   USA
At some point in the future I'd like to upgrade the 1500 in my A. I've recently picked up a 3 main 1800 block and crank and want to start collecting the parts I'll eventually need. I know there is some interchangeability with the 1622 (and 1600?) parts with the early 3 main engines.....but I'd like to hear others' thoughts on optimal configurations. This would just be a fast street build.....no track. What connecting rods should I be looking for? Which head? Whats the optimal carb setup?



Don't Have 21st century expectations from a 20th century car



Edited 1 time(s). Last edit at 2017-09-13 01:30 PM by zman4011.

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ghnl Avatar
ghnl Eric Russell
Mebane, North Carolina, USA   USA
1961 MG MGA "Calvin"
In the 1800 engine you'll use 1800 rods. The MGA (1500 & 1600) have a different size bearing.

http://www.mgaguru.com/mgtech/power/pp201.htm



Eric Russell ~ Mebane, NC
1961 MGA #61, 1981 Alfa Romeo GTV6, 1984 Alfa Romeo Spider, 1991 Honda ST1100

3066james Avatar
3066james Jim Cheatham
Amelia, VA, USA   USA
I put an 1800 3-main (18G) engine in my Coupe. I used the original connecting rods and +.003 pistons, the original crank (polished), an uprated cam and the 1800 head. I am using the MGA intake and exhaust manifolds and the MGA carbs. You will find that the MGB water pump will hit the radiator. You will need to use an MGA water pump which is shorter. Talk to Kelvin Dodd at Moss Technical Services when you get to that point.

Jim



Edited 1 time(s). Last edit at 2017-09-14 10:28 AM by 3066james.

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Redhawk1689 Avatar
Redhawk1689 Gold Member Steven Stockham
Salina, Kansas, USA   USA
1958 MG MGA 1500 "Belle"
As with most things technical in regards to the MGA, check out Barney's MGAguru.com website. If you can't find the information there, it probably doesn't exist!

zman4011 Avatar
zman4011 Adam Z
San Francisco, CA, USA   USA
I've read those pages....I was actually interested in your opinions.



Don't Have 21st century expectations from a 20th century car

bikermga Avatar
bikermga Peter Tilbury
Surrey, BC, Canada   CAN
Regarding Jim's note re MGB water pump interfering with the rad, there is an MGB pump with a shorter nose that may be on your 3 main engine. This also ensures that the wp pulley lines up with the generator and crank pulleys.

The MGB front cover is better as it has a proper oil seal in it, not the felt one as in the MGA.

I would stick with the 3 main head and con rods etc. Use you MGA carbs (no need to change choke and accelerator brackets), MGA exhaust manifold (will miss the steering column), MGA distributor (same vacuum pipe connection), and MGA valve cover (for the vent hose from the front carb).

You might have to swap over the rear engine plate if the 3 main has a high starter.

Peter.

3066james Avatar
3066james Jim Cheatham
Amelia, VA, USA   USA
I used the rear engine plate from my 1500 so I could keep the low-mount starter.

Jim

In reply to # 3592006 by bikermga .j

You might have to swap over the rear engine plate if the 3 main has a high starter.

Peter.

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