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MG MGA - What engine is this?

I just received a 1500 engine in trade for a 1800 3 main block I had. I responded to an add, and it turns out this guy lived 5 min away. He had rebuilt it for his race (MGA) but found it was still to slow for him. It has but a few hours on it. It looks great with polished rods, street cam, new pistons and rings, Block boiled, and the inside of the block coated (See Pic). However, the only problem I ran into and just discovered is it has no provisions for a mechanical tach! The hole was never drilled into this block! Can anyone identify what this block came off of? Other than that it appears to be a perfect match!


WMR Bill

The BMC "B Series" engine was used in a wide range of cars and only the MG version had provision for a mechanical tachometer.
If in England or Australia there is a long list of cars with this engine. In the USA it would probably be from a Nash Metropolitan.
Looks like you will need a MGB electronic tachometer.

Mick
Mick Anderson

This is a picture were the tach should go. Does anyone what type of replacement electric tach I could use that looks the same as the MGA's?


WMR Bill

Wow! You anwsered my question before I even had it posted! Is there any particular year I should look for with the tach? Also were do you connect the elec tach to?
WMR Bill

The MGB had the electronic tachometer from 1968.
These tachometers can be polarity sensitive. If your MGA still has a positive earth you need to get the tachometer from an early MGB which had a positive earth, not a later one with a negative earth.
Attached is the MGB diagram for fitting the tachometer.

Mick


Mick Anderson

You'd need an RVI2401/00B electronic tach from a 65-67 MGB. Same physical size as the MGA tach, but labelled as a 'Smiths' instrument rather than 'Jaeger'. Also the indicator needle is a bit different looking from the MGA tach. They are positive ground, but easily converted to negative and can often be found on eBay. I bought a good used one recently for about $50. As expected, the MGA Guru tells all about it here http://mgaguru.com/mgtech/dash/dt201.htm.
Andy Bounsall

If you have the engine dismantled, you can have the place for the MGA tacho machined out and fit the standard tacho setup.

If you want to go the electronic tacho route, I have a couple of them in the cellar both need a look over, but if you need one, mail me offline
dominic clancy

Thanks Dominic, I have one also, however, the problem is with the cam shaft. The end of the cam that is in it is much bigger and will not receive the gear needed for the tach. to convert to another cam would require new bearings.
WMR Bill

The early cam had provision for the tach gear. Just stick in an early cam and have the hole drilled in the back of the block (the mounting holes for the tach drive are already there).

There is no reason you'd need to change cam bearings to do that. The bearings are identical.
Bill Spohn

"The BMC "B Series" engine was used in a wide range of cars and only the MG version had provision for a mechanical tachometer."

Mick, it's been awhile, so I could be wrong, but I believe that the Riley 1.5 also had a mechanical tach. Think I have a manual somewhere......
Bill Spohn

Hi all , i had the same problem when i changed to a 1622 block having put a rod through my1500 , i asked through this forum & was advised that you could drill through without a problem using a tank cutter with an arbour !! after some silly quotes from machine shops i decided to give it a go ,£15-00 & 15 minutes time plus a small amount of grinding we were in busines , as the rev take of is on a flange the hole does not have to be so precise , the motor looks as it should & all the instruments match. good luck , Colin
colin daly

This thread was discussed between 01/08/2008 and 03/08/2008

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