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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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Christopher1 Charlie Nash
Oakland, California, USA   USA
I have recently had an early1800 3 main installed in my A by David Laughlin in Richmond Ca and had to have the car towed from his garage back to my home. He turned out to be very unethical and I turned out to be very stupid.

I'm posting this to see if anything he put into the rebuild of the engine makes any sense

When the block was sent to the machine shop he removed the shiny metal plate that identifies the year make and model. When the engine was almost finished I asked him to put the ID tag back on and this , as near as I can tell, is what it reads...18GD-WE-H-604. The W is just what it looks like to me because it is damaged a little in that area. Is this correct for an early 3 main MGB engine?

He used the water pump from the 1500 A engine as well as the distributor and carburetors. The engine sputters and coughs so bad that it cant be driven and continues to run when I turn off the key....... just wanted to know if the interchange of A parts to the B engine has anything to do with it

Cheers to All
Charlie

bills Avatar
bills Bill Spohn
W. Vancouver, , BC, Canada   CAN
Peter pretty much covered it. The 3 main MGB uses 1622 rods and heads. Only other issue is water pump - you need to space the radiator a little bit forward or use an MGA pump (and in any case ensure that all the pulleys line up).



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

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bikermga Avatar
bikermga Peter Tilbury
Surrey, BC, Canada   CAN
Charlie,

Fitting MGA parts to an MGB engine will not cause it to run rough. More likely ignition timing and fuel mixture are your issues i.e., you need to tune it correctly.

Why are you "very stupid"?

Peter.

topdoc56 Gold Member Charles F
Covington, LA - Louisiana, USA   USA
1956 MG MGA
1964 MG MGB
if that is the correct engine plate for the engine, the GD is not a 3 main bearing engine.

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