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MG MGB Technical - Ordering new engine today

Hello and Merry Christmas to all.

I've decided it's finally time to face facts and replace the tired smokey engine in the B, I've been doing a little reading and exchanged a few emails with Chris at Octarine Services. I'm going to go for the following and thought I'd take advantage of all our shared knowledge to ensure that there is nothing I've missed. Just to point out that I use the car as the daily driver.

Spec,

capacity: 1868
piston: 1798 - 1868cc County (cast)
crank: Standard
gear: Simplex
Camshaft: Piper 270 (fast road)
Flywheel: Lightened (16 lbs)

Full engine balance, ARP con rods bolts. And the cherry on the top, a Peter Burgess Fast Road Head. Was also going to ask for it to be painted Red, as I thought this would look ace in my BRG B.

So my question is, Do all of these choices work well together, and is there anything else I should be thinking about before handing over the credit card.

With thanks

Craig
c smith

compression ratio? and what revs will you drive it to?
Stuart Robson

Good point about the compression ratio, is it worth going higher?, what are the trade offs?

I'll drive it as high as it will rev, my current engine gets a bit hairy around 5000. It seems to run out of steam.
c smith

I think it may be pointless asking for opinion on this board as we all have different ideas. Chris arguably knows more about these motors than all of us put together and besides he has a working relationship with Peter Burgess. Let Chris make the recommendations and you won't be disappointed.
Iain MacKintosh

Merry Christmas to you Craig!!!
Maybe you want to add some high quality brake pads to that order? You might need them to stop your new bundle of fun!

Jeff Schlemmer

C.Smith-Yes to Ian. Tell Chris what you want and he will tell you how and how much. If you walk in with a jamble list, you're just stirring the pot. A few more days here and you won't have a clue what you hink you want, as we all are so absolutely compelling in our laser thinking for you! I do like the big brake idea ( and a FastRoad,Big Valve grind as the cherry-topper for just the few pence more!!!) Cheery New Year to all. Vic
vem myers

Just for info, the CR will be 9.5 to 1 and rev limit is 6,200 rpm although the engine will make max power of around 115 bhp at 5000 rpm (90 bhp at the wheels).

One recommendation would be a fast road dizzy to match the engine.
Chris at Octarine Services

i had a standard engine and had a peter burguess fast road head 285 cam with single k a n air filter and carb fitted with new needles .it produces 94 bhp at the wheel.dont bother with the piper 270 theres no difference to the standard cam.be brave and go for the 285 i love the burble. i allso had fitted aldon dizzy 101by2 about £100 with electronic ignition it was recomended by peter and what a differece it made. iff you want advice just ask them , by the way its now alot better on fuel about 30 to a gallon
daz

Dear Craig:

I believe that you may have overlooked ordering one for me! I'm sure it's not too late . . . .
PS Jones

Hey Daz- I'm wit chew!Really, its time this be said about those P cams I feel. My Burgess supplied P285/ BVFR head idles at 650 with barely a lump and scoots to 6300 without a bit of hesitation. First time it happened during breakin, I somewhat freaked when I saw the tach over 6k and the engine sounded completely unstrained. Since, I have sneaked up past 6.5k ( Peter installed duel springs and we bored the rod channels), again with engine sounds suggesting boredom. This car runs a short second behind the SC car when I measured all last year,0-60, yet drives the city steady and peppy!In this mix however an Aldon recurve with pertronix and a measured 9.5-9.75 CR is mandatory or you hamstring the cam's potential . Cheers and Ecstatic Nuevo. Vic
vem myers

Craig-
Yes, your listed modifications will work together quite well. Since you're using the car as your Daily Driver, the Piper BP270 camshaft is quite appropriate. The previously-suggested Aldon-modified distributor is also a god idea as its advance curve does well with that camshaft. I'd recommend Aldon Distributor #101BR2. Its for engines fitted with a Piper BP270 or BP285 camshaft. The 101BY2 is for stock engines equipped with the HIF4 carburetor with manifold vacuum advance. The only further engine modification that I can recommend would be the retirement of the single-row Simplex camshaft drive chain and sprockets. A dual-row Duplex camshaft drive chain and sprockets is much more durable and as such will keep the timing accurate far longer than the Simplex system. However, a freer-flowing exhaust system, such as the Peco Gray System will help the engine acheive its potential.
Steve S.

Steve
What is your experience with life expectancy of a single row timing chain? I tore down a '78 with 147,000 miles and the cam was flat, the valves sunk up to 1/4" into the head, but the single row chain appeared to be in good condition. Engine records showed nothing but tuneups for the life of the car.
The important difference as I understand it, is the single row timing chain gear is advanced by 4 degrees.
Barry
Barry Parkinson

Hi Craig.

You might like to consider buying some running in oil to get your new engine off to a good start, I do believe that it is worthwhile.

Don
Don

Steve S - Thanks for you comments regarding the Dizzy. After reading around on the forum I am going to buy the Aldon 101BR2 as suggested. There is a lot of info regarding electronic ignition on here, and although I've not totally decided I'll probably go for the 'Ignitor' type that you can order with the Aldon Dizzy.

A Peco system is also planned, but that will have to wait a while.

Excited already and I'm not getting the engine for a few months yet....... It'll be like a belated Christmas....
c smith

Uprated oil pressure relief spring.

You don't want to try to install this item after
the engine is installed in the car!
Daniel Wong

Barry-
Your single carburetor engine wasn't exactly a high-rpm engine, so the Simplex chain was adequate, though nothing more. For an engine with dual carburetors and a hotter camshaft lobe profile, higher engine speeds will be used on a fairly regular basis, so the Duplex chain is the better way to go. Without examining your 147,000 miles Simplex chain I can't say what condition it really was in. However, if you want to find out for yourself, compress it along a straight edge and, using a vernier caliper, measure the distance between the pins over the greatest length possible, then stretch it along the straight edge and remeasure. If the difference is over 3% (Yes, that little a difference!), then the chain is, from an engineering prepective, effectively worn out. Yes, yes, I am aware that the tensioner compensates for far more than that, but that's just to keep the chain from wobbling around and ruining both the ignition and the valve timing.
Steve S.

after investergation dont bother with a peco,the mg engine does not need it.its not nice to drive at speed.i was advised to get a 3 branch manifold and then i had a standard bore system one silencer and then a bullit box just to give it a nice tone. moss do a ss range called falcon only 200 pounds all in
daz

Back before we could afford calipers and micrometers old-timers used to judge the wear in a chain by holding one end horizontal and seeing how much the other end sagged compared to a new one. Can't give you a percentage, but was suggestive of wear.
Edd Weninger

This thread was discussed between 29/12/2005 and 07/01/2006

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