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MG MGA - can a 1500 block be bored to take 1600 pistons?

I'm replacing the tired Magnette 1500 in my '57 with a proper MGA 1500. I'm in the process of rebuilding it. Does anybody have experience boring out a 1500 to accept standard 1600 (1588) pistons? I've been told this will not present any problems, but I wanted to check for any gotcha's from other people experience.

Thanks
brucep

I bored out my 1500 block to take 1600 +40thou pistons with no problems. I had to rebore it and was given a good offer on the pistons so I thought why not. You might find that standard 1600 pistons are getting hard to find.
malcolm asquith

I did the same as Malcolm, also without problems. If my calculations are correct it yielded a displacement of 1628 cc. I also changed the carb needles to those used in the 1622 (I don't recall their # and don't have my records available at this writing) figuring that if the factory saw fit to change them with the displacement increase I might as well too.
Marcin Deupree

I have no first hand knowledge, but this web page has articles about boring a 1500 out to a displacement of 1622 and even 1698. http://www.mgbmga.com/tech/index.html
Jeff Schultz

DEFINITELY.

It makes a HUGE improvement to the car too. You can get a County brand piston easily and cheaply (complete with rings) that will fit and has the correct height and dishing on the crown.

You may find it runs better with the richer needle. I would also recommend a distributor refurb at the same time.

Then add a lightened flywheel, and you will again see a BIG improvement.
dominic clancy

Bruce;
My 1500 is bored out to 1600 +.040. A very sweet runing engine. Be sure to check your new compression ratio; you will be squeezing more cc's into the same size combusion chamber! Good luck Bill.
w.g cook

Compression concerns? Aren't the heads the same on 1500 and 1600s?
brucep

If you increase displacement and leave the combustion volume alone youi increase the compression ratio. No big deal in regard to what you are doing.

Frankly, if you are going to bore out to around 1622 size, you may as well use the late larger valve larger chamber head - but then you need to use 1622 pistons to get the compression back.
Bill Spohn

Wull, why not go with a 'B' three main block?
Huh?
It'll almost bolt in, and now you have some torque!
Plus, it can be bored out even more.
Yeah, yeah, I know I'm greedy.
Safety Fast
Dwight
Dwight McCullough

Why not open the 1500 block up to 1800cc. I know that twin cam 1600 blocks have been opened up to 1800 without sleeves, so it might be possible to do it with a 1500 casting. If it were necessary to sleeve and bore off center then using a 1800 block might be cheaper but keep in mind that with the 1800 block you have to use a B crank and rods too. The torqu comes from the cc's not the casting.

Frank
Frank Graham

fyi. Thanks for all the input. I made my decision. stock 1600 pistons were ordered, and my machine shop has been they will match the bore to them. The shape of these pistons take controlling the compression into account. Rebuit 1500 carbs will have appropriate needles fitted for 1600ccs too.
brucep

This thread was discussed between 26/01/2005 and 02/02/2005

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This thread is from the archive. The Live MG MGA BBS is active now.