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MG MGA - 1622 block questions

Hi All

Looking for some background on the 1622 block as it was used in the MGA and also in other BMC cars such as the Austin Cambridge A55 MK II and A60. I have a 1600 in my 61 MGA and recently picked up an 1961 A55 MKII with a 1622 block with only 40,000 miles I plan to restore this car.

So how are they the same and how do they differ? One obvious difference is the single SU carb with this incredibly tiny little air inlet in the filter housing. GASP GASP GASP. The Austin runs so much quieter then the MGA despite the smallish muffler. I can see from preliminary work a lot of the bolt on bits are the same or at least very close. Is the bolt pattern the same so as to use an MGA manifold and then use twin SU carbs?

I have since picked up a second 1622 block and tranny from a parts car(Austin A60) and wondered if I worked on this over the winter could I throw it into the MGA next summer (the 1600 block is only so so) therby reducing my down time on the MGA. Would it be a simple bolt in job ?

Any comments appreciated

Ralph
Ralph H .

I don't think the blocks you have, will have the tacho connection machined into them?
Bob (robert)

Hi Relph. The 1622 engine was used in late MGA models, and other BMC vehicles. A bona fide MG 1622 block will have mechanical tach drive. A non MG 1622 block will likely not have mechanical tach drive. The 1622 block was cast somewhat differently than the 1500 and 1600 blocks. I believe that the cylinder spacing on the 1622 is somewhat different. This means that the 1622 crankshaft is also different in the way the throws are machined. I am not sure, but I think the connecting rods are different also. The 1622 head has larger valves than the 1500 or 1600 engines, and is in fact, I believe more similar to early MGB 1800 heads. MGA intake and exhaust manifolds will bolt right onto the 1622 head. The 1622 engine should bolt right into your 1600 chassis with few problems. If your 1622 engine does not have a mechanical tach drive, you will either need to convert your tach to an MGB electronic unit, or obtain an early sprite generator, with a tach drive on the end. Hope this helps. Glenn
Glenn

Ralph,
Bob & Glenn are right - bolts right in. I put a Farina engine in my '62 MKll "A" (someone copped the original engine and stuck in a 1600) after I purchased it to hold me until I got an authentic engine for my car. I took the tach drive and block to an engine machine shop and they bored the block for the tack. The tach drive flat and bolt holes were already on the block. Then for the tack to work, you have to have an "A" camshaft with the drive gear on the back.
Cheers,
Phil
The Other MG Brother - Phil White

Phil is almost right, but you can buy the tacho drive gear on its own. It presses onto the cam, and is such a tight fit that you tend to break teeth getting them off, and you don't need the clip to hold it in place.

There may be piston differences that will reduce the power output of the engine compared to an A 1622 (cf Magnette and MGA engines)
dominic clancy

A non MG block is cast the same, and there is a flat machined where the taco drive would normally go, but there is no hole.

It is possible to cut a hole with a good quality hole saw, and and then fit the drive gear.


Ian F

Ian Fraser

With all this discussion on 1622 engine blocks, here is a question.
Has anybody seen a BMC 1622 block made in Australia? For some unknown reason these blocks have 1620 cast on the front left side of the block, in the place where the 1622 cast mark normally appears. They are the same bore and stroke as the British engines, and the different crankshaft main bearing widths (or more technically correct, bearing lengths on a shaft).

Mick
Mick Anderson

Ralph

If you fit it in an MGA, you'll also need a blanking plate for the hole of the mechanical fuel pump (one blanking plate, two studs and a gasket)

Rutger
Rutger Booy

When I went through this with a non Mk-II 1622 block (was probably a Magnette), it was a a bit of a challenge. The block I had needed to be machined for a tach drive outlet, which was straightforward. The larger problem was that the standard MGA oil pump wouldn't work because the drive spindle didn't line up quite properly. Also, the freeze plug pattern was slightly different, and there were extra bosses machined into the block to hold an alternator. So be careful, particularly with the oil pump.
Mark Lambert

Mick,
My ZA Magnette is fitted with an Australian 1622 block which has '1620' cast into it. It also has the Australian MOWOG logo - 'MOWOG' sitting on top of a map of Australia (with Tasmania missing!).
Peter Daley

Hi there

Does anyone know if it is possible to machine a 5 bearing block (18V) for the mechanical tacho drive?

Many thanks

Ed
Ed Horne

Hi Ed

I just had a look at a 18V and a 1622 block.

Although the chamber at the end of the camshaft tunnel looks large enough to take the camsaft gear, there is not enough room for the skew gear to take the drive to the cable.

As well, the shape of the casting on the outside of the chamber is different, and there is insufficient metal there to be able to machine a flat spot for the skew gear housing.

Having said that - it could be that someone has made an adaption of some sort. You could start a new thread on the MGB Technical board and ask there.

Cheers
ian f

Ian Fraser

This thread was discussed between 20/12/2004 and 01/01/2005

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