Wanting to upgrade my 1500 to 1622 - need pistons

[Walston]

Hi I recently got an MGA and I am somewhat of a newbie to MGA's.

I am redoing the 1500 and would like to go to the 1622 flat top pistons. Does anyone have a set? I have not had the block bored yet, so I can use what ever size can be found.

It looks like the 1622 / 1800 3 main connecting rods are pretty hard to come by. I am not building a race car, so I was thinking I could use the existing connecting rods by reamed them to accept the larger pin. Anyone have experience doing that?

Thanks for the help!

Wally

 

[bob67bgt]

Wally, Welcome to the BCF. I would just rebuild a 3 main MGB engine and be done with it. 1622 and 3 main rods do interchange but they will not just go into a 1500. If you want to experiment i may have a set of 3 main rods around and i also may have a extra 3 main MGB engine under the bench. Tony will probably also have anything you would need. When i built a MGA keeper many years ago i did a 040 overbore 1500 with hotter cam and biger valve head. I only put up with that a little while before it all came out and a stock 3 main MGB engine went in. Best move i made with the car. Anything you do thats custom will be a problem if or when it breaks. The BCF can get you thru any problems that you run into! Bob

 

[Walston]

Thanks Bob, points well taken. I have 2 1500 engines so I has trying to find a way to use what I had. I have read that if I bore to 1622, put on an early 70's head (which I have), a better cam (which I have) and a few other minor things I could be in the 90-100hp range and I would be happy with that. That is why I was looking for pistons and rods.

On the connecting rods I have read 2 different things, one that the existing rods can be reamed to accept the larger pin and I have read that you have to swap to the 1622 connecting rods. Just looking for guidance.

I'll think about the MGB 1800 option, you may be right.

 

[bob67bgt]

I think if you look up the numbers for the connecting rod bearings the 15 and 1600 will interchange. The 1622 and 3 main MGB will interchange. I'll have a look in the parts pile in the next couple of days and see whats left in there.

 

[bob67bgt]

I had a look in the moss book and all the 3 main rod bearings are the same. So 1622 or 3 main MGB rods should work for a oversize conversion on your 1500. sending PM , Bob

 

[billspohn]

The 1500/1600 crankshaft is crap. They break with gay abandon if stressed, and any crank that has been in service for the last 50 years has used up most of its usefull life already.

Ditch the 1500 and buy a 3 main MGB engine, you'll be much better off. If you really want the 1622 size, buy a good used Austin A60 engine from Canada. They are easily convertible to MGA Mk 2 spec with a set of flat top pistons and drilling out the tach drive.

 

[billspohn]

PS - don't even think about beefing up the engine unless you plan to fit disc brakes to the front of the MGA!

 

[Walston]

PS - don't even think about beefing up the engine unless you plan to fit disc brakes to the front of the MGA!

Already done, thanks

 

[billspohn]

PS - don't even think about beefing up the engine unless you plan to fit disc brakes to the front of the MGA!

Already done, thanks

Excellent!

Then you'd really get the benefit from a 3 main MGB conversion. Just bolt on whichever backing plate came off your 1500 (there were 2 different ones), stick an early MGB front trans cover with clutch fork and bearing in the front of your trans, and you can bolt the MGB engine into place. That's all there is to it.

If you want, you can even reuse the 1500 style clutch, which saves some parts swapping, but it isn't as strong as the later MGB diaphragm clutch plate. Either way, you'd still use the 1500 driven disc that matches your input shaft spline.

Here is a picture of a 3 main MGB in a Mk 2 MGA - had I bothered to grind off some extra metal at the back of the block, it would be a dead ringer for any MGA engine.

 

[bob67bgt]

The only thing about running a MGB diaphram type clutch is on some MGA transmissions there is a clearance issue with the pressure plate. Its easily fixed with a grinder on the inside of the bellhousing. Just check for one full rotation of the engine before sticking the engine and trans back in the car. Bob

 

[trrdster2000]

Wally, when you are done with all that I have the 1622 transmission to go with your project. Don't know how much difference is in this one and a early MGB. Anyone???

Wayne

 

[bob67bgt]

Starter location by about a quarter inch and the rear mount are different. Bob

 

[Walston]

Thanks Guys you certainly gave me a lot to think about.

Merry Christmas.