1275 A+ Engine Build

Started by MiniDave, January 31, 2016, 03:05:42 PM

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Spitz

Did you pull the geabox apart to get that cleeeean?  If not...how

John Gervais

I was wondering the same thing - it looks brand new!   77.gif
- Pave the Bay -

MiniDave

No, that's just several hours with a stiff brush in a solvent tank......it was brand new clean solvent, so it got rinsed out really well. I noticed a few places that did not get clean tho, so I'll probably take it thru round 2.....

A million years ago when I first started as a mechanic I was assigned to clean parts by my boss, when I'd ask him if the part  I was working on was clean enough, all he'd say was "is it clean?"
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Lol that reminds me of my surveying days.  One of my employees asked how much tolerance he had on a foundation we were laying out. I told him perfect will do.   20.gif

MiniDave

Exactly - for some things "close enough" just isn't........same way with building an engine, either it's right, or it isn't. I prefer right.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

I'm going to have to clean the gearbox some more, there's a dirty grindy feel to the carrier bearings.

The diff turns out to be a 3:10 rather than a 3:44. I counted the gear teeth and it's a 19/59
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MiniDave

OK, now it's clean, and the grindy sort of feel to the bearings has gone too.......ready to put back on the engine once the block comes back from the machinist and some parts show up......
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

I have a 62 tooth 3.44 sitting on my bench...  probably another in the spare tranny too. 

MiniDave

Need the 18 tooth pinion too.....and since they're used and worn in together you need the one that ran with this crownwheel, otherwise it'll be noisy. I still need to see why they're different between the Pre-A and A+ gearboxes, all the suppliers show different part numbers for those parts/gearboxes......I think the pinion shaft end is different.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring


MiniDave

#60
Yep - if those are from an A+ gearbox, we're golden.

Need a new locktab for the nut on that shaft and new bolts and locktabs for the ring gear.

Things that could slow us down slightly on the rebuild - having to order shims for the diff, different thrust washers to set crankshaft endfloat, and shims for the flywheel bearing clearance.......won't know till we assemble it what we need over stock....so we order stock thrust washers and reuse the shims we have to start with, then go from there......
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

I'm getting slightly confused because reading this it makes it sound like the pre a plus can be used on later cars 8.gif

John Gervais

Dan, was the cylinder head info useful?
- Pave the Bay -

94touring

Haven't had a chance to look it over yet.  It's on the to do list though!

94touring

Quote from: John Gervais on February 18, 2016, 11:05:17 AM
Dan, was the cylinder head info useful?

Ok cool cause the head I'm going with has 37mm inlets and 29.4 exhaust.  Only difference is I'm going for 10:3:1 compression.

jedduh01

IMO = Just say no to anything higher than a 3:10 !   I love the 3:10 the most -  installed in both my cars!   Moke still has 3:76tho...

for two local guys - I took out a 2:76 out of a 1275 cause it was a bit luggy round hills - installed a 2:9 = World of difference fir him Much less gear rowing - and will actually climb a hill better.  but man that puppy would roll down the interstate with the 2:76

another local - Took out a 3:76 = installed a 2:9 also =   now MUCH MUCH faster in top speed = better for the highway.

to me a 1275 needs a 2:9  or a 3.10 to go anywhere reasonably! on the highway above 65 - mph.

MiniDave

Pre A+?  I only knew of Pre-A and A+, maybe the crown wheel can be used on either, but I think the shaft size is different on the pinion gear. If we're for sure going to change it I'll go ahead and pull it apart and compare this set with the ones out of my Pre-A box.

They haven't done anything on the block yet, the machinist was out for surgery, he'll be back next week, but they'll need the pistons to finish the block, just FYI. He said if he got time he'd do a preliminary hone on the one cylinder to make sure it will clean up at 40 over - but he still thinks it will OK.

I agree with Jedduh, Buzz has a 2:76 in it and it really cruises at 75 comfortably, but I think the 3.1 in this car would be ideal.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Next question then...which gearing would be ideal with a 266 cam?  I remember this 1275 ran nicely with the 3.1, however if I'm building a fast road 1275, is the 3.1 ideal?  Pretty certain my 998 is 3.44 and it doesn't bother me at all. 

MiniDave

#68
the short gears will give you a faster 0-60, the long gears are good for long highway cruises and fuel mileage... are you thinking you'll be below the optimum rev range for this cam profile? I don't think it's that high strung.....

On my trip home from Baltimore to KC Buzz was turning about 4K at 65 mph, 4500 at 70......after I changed to the 2:76 it's 3400 at 75mph, much quieter. It does lug a bit around town at 35 up a hill - it's more comfortable in 3rd - but out on the highway it pulls all but the steepest hills easily in 4th.

If your primary use is carving hills and the stoplight grand prix, the short gears will be more fun, but you'll be shifting more. If your primary use will be driving long distances the tall gears are easier on the ears..... and I think the engine will last longer turning the lower revs - but we're talking big miles, not short haul.

Since you already drove this engine with the tall gears, you should have a feel for how it pulls - and with the HP improvements you're doing it will be even stronger.

Changing the diff is an engine out job, just FYI........but you don't have to separate the engine from the trans to do it.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Yeah I do a combo of driving.  As I recall I liked the 3.1 but it's been almost 10 years! 

MiniDave

John Styers runs the 276 cam in his car and he has the 3.1 gears, just FYI - I could put you in touch with him and you guys could chat about it.....

Johnstyers@gmail.com
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Dean also runs the 3.1.  We've been chatting about it. He's stock minus a 266 cam.

jedduh01

3:10 gives you just about 4K rpm @ 80 MPH - thats Plenty ~!
  70-75 3500- 3800 rpm is OK for the motors to twist.
its only a downshift to pep into the higher rev range .

I'de stay with the 3:1 for sure just cause you have it .    unless you wanna spend a cuple benji's and go for teh 2:9


94touring

Yeah I'm starting to lean towards the 3.1.  I'll have plenty of power on tap and a lightened flywheel to boot.

MiniDave

3 ways you could go - change it now while it's apart and see how it goes, if it's too revvy, it's an engine out job and a few gaskets to change it back.

Or drive it first, if you think you'd like the lower ratio, again - engine out and a few gaskets.

Lastly, just leave it alone.

I may need to change the mainshaft bearings, it's a little growl-ish when I spin the shaft, but that could just be gear noise. I'll know more when I drop the layshaft out to install the central oil pickup, if it's still noisy that's the time to change the bearing.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

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