Learn me BMC A series engines

How much HP can you get out of these in barely streetable form?  Are there any other engines with the same bolt pattern?  The Nissan derivatives work?

-Rougly 125 hp with a 1380 that's suitably warmed up.

-Nothing shares the same bolt pattern

-BMW K100 cylinder heads can be mated to the A-series making it either an 8V Twin Cam or a 16V twin cam

-cross flow heads are available (  https://www.piercemanifolds.com/product_p/99003.849-assembled.htm )

The 1275's are the ones to get, and an early 1275 is preferred (thicker sump flange and an EN40B crank).  1098's generally aren't worth modifying, the early small bearing ones definitely aren't.  But, if you use Hillman Imp pistons in a 1098 and offset the bores you can make a 1098 bigger.  I would suggest getting Vizards book which should give you some insight into what to do to go faster.

There’s an A Series book I was trying to sell on eBay   $12 plus $5 to ship super slow media mail. PayPal or check.  More history than hop up info. 

If you're serious, PM your address, and I'll send you David Vizard's Bible. 

I mean book. 

Hey guys, I can use those books. Listen to Roddy, that's great advice

FWIW, getting to the 125 hp mark won't be cheap if done right.

With the k head, can you also run BMW fi?

any website with the BMW  head info ?

There is  an old Bug Eye Sprite  sitting in the bushes "over there" that might be worth rescuing

I think it was Jeff Schlemmer from Advanced distributors that did the BMW head thing, documented on the mgexperience forum.

Stampie if you were to go this route the 1275 is the way to go.  Throated carbs, decked head, etc.

Check out spridgetguru.com.  If he still has his site up there are some very good engine prep manuals available.  Don’t bother with anything owensdad74 wrote though- that guy is a goof ball.  (I should add that guy is me).

Actually I’ll see if I saved any of my manuals...

Edit: I guess I didn’t.  Here is some Reading for you.

If you do go bogeyed, let me know. I have an early 58 and a 60.

Thanks for the info. I'm looking at a mini based car so wondering if a Grassroots built engine is going to give me what I'd want performance wise. 

You can always go the supercharged route as well

In reply to Stampie :

I've got a 1380 in my Mini. Never dyno'd it, but built it with a tried and true recipe for ~110hp. It's silly fun. 

David Vizard wrote the book. Get it.

Apparently by offset boring the cylinders and offset grinding the crank, these can be take out to 1600 but they become VERY unreliable and don't really make much more power.

OK first since the Nissan derivative was mentioned; the Datsun / Nissan A12/14/15 motors have absolutely nothing in common with or to do with BMC A- series. The particular engine that Nissan built under license is 3 engine generations before that so any conversion will be pretty much like any other non native swap.

The Datsun A14/A15 coupled to a 5 speed gearbox is a very common substitute. We have 4 or 5 guys on Datsun1200.com with converted cars (spridgets and Morris Minor) it's also a well documented conversion on sites like mgexp. Additionally this motor was in production from 1971 though to 2007 so repalcement parts are easy to get. An A15 with ported head GX or H89 head, suitable cam and side draft carbs will make 100hp at the wheels.

Rivergate makes conversion kit to fit the Nissan 60 series 5 speed to a BMC motor.

The BMC A series is a very good engine with lots of support. The few friends of mine that built 1275s were getting 100hp at the flywheel so maybe 75-80 at the rear wheels. Of course in a 1300-1500lb Mini or Spridget it'll go pretty well. I may be a Datsun guy but if I were looking at a BMC car I'd stick with a 1275 as the support is really quite excellent.