WillieB's 1275 Engine Rebuild

Started by MiniDave, October 30, 2020, 04:22:55 PM

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94touring

I'm sure it's been posted in here and I forgot, but anything aside from the mild cam like some head work done?  You may want to put a BDK and BCE in your arsenal for when you get ready to tune.

MiniDave

The ports have had some work, but the combustion chambers look untouched from stock. The block has def been decked some, maybe as much as 20 thou based on how much of the piston is above the block surface - approx 10 thou and that most undecked engines the pistons are about 10 thou below the deck surface.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

If it's breathing better and mostly stock with a mild cam, and the 20 over is a factor, BDK might be the better match. BAK is for mostly stock.  I use a BCE which is what Calverst suggest on a worked head and 266 cam. I still had to modify the needle in the upper stations for WOT pulls to 6k.  I'm 40 over and the head work is more aggressive. Put this way if you're mildly lean now the BDK will be perfect.  If you're really lean the BCE is the one to use.  Just have to cross that bridge when you get there.

MiniDave

WillieB is checking his stash first - but I need a gasket. It goes on the end of the gearcase - speedo drive end. I had to pull that cover to remove the laygear to put the oil pickup tube in. I have literally every other gasket for a Mini engine and/or gearbox but that one!

Goes here....

Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

That's why I keep a roll of gasket maker and an X-acto knife kit around!

MiniDave

I have gasket paper too, but that place is prone to leak.....I think a factory gasket will work better
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MPlayle


cstudep

I checked mine, I have several different gaskets but that is not one of them.

MPlayle


MiniDave

I'll call Guido in the morning. If not, 7Ent has them...so does Mania.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Was just looking at those head gaskets again and out of curiosity wondered how much you could raise compression by going with their thinnest gasket on a std 1275 with 3.5cc gasket.  Comes out to a :15 increase or :25 increase with the 4cc gaskets. Not much but if you were on the low side or wanted a little extra oomph it's an option.

MiniDave

#111
I'm not sure that would work, stacking two fire rings on top of each other, I think one would easily blow out.

Speaking of gaskets, Guido had a complete transmission set for $10, so he's sending it along.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

I wasn't suggesting that. Just passing info along for anyone that might be doing head work and wants an easy way to bump up compression.

MiniDave

My bad, I completely mis-read your post - need to wear my glasses!  :-[
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

The opposite end is the thickest gasket would lower stock down about 2:5:1.  I had been figuring I'd need a plate and 2 gaskets to lower my compression for the turbo conversion but this is a much easier solution.

cstudep

what compression are you planning to run on the turbo conversion?

94touring

9:1 should work.  I believe the metro turbo was around there. 

MiniDave

#117
One thing you have to pay attention to with these thicker or thinner gaskets is the relationship of the rocker to the valve as you in effect shorten or lengthen the pushrods. It's not hard to get the geometry out of whack....for example, if you add 250 thou to the thickness of the gasket, you've now effectively shortened the pushrods by that amount too.

The cure is to put a shim under the stands, use adjustable or shortened/lengthened pushrods or machine metal off the bottom of the stands as needed.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Willie_B

I'm glad you started this thread Dave. The more I learn the more I figure out I don't know. Lots of great info here.

cstudep

Indeed same here! I am trying to keep my engine questions located here for future reference so sorry for cluttering up your engine build thread with unrelated questions.

That said, on your turbo build Dan, do you have to run an upgraded oil pump? I was noticing that MED had a turbo specific oil pump that has a higher capacity. the reason I ask is this whole turbo thing has me intrigued. I have always wanted to build a turbo motor up and since I have a few spare 1275 blocks laying about I was thinking perhaps I might travel down that path one of these days. I do miss my WRX and that lovely turbo noise.

MiniDave

The difference between the regular and turbo oil pumps is flow, not pressure. Regular is 6 gpm and turbo is 9 gpm. I think the difference is because most turbo engines (all?) run an oil cooler, plus use the oil to cool the turbo. I think it would be a good idea, but I don't know that it's absolutely necessary....I think it will depend on usage - if you're running track events I would def run the turbo pump.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

#121
Would agree with Dave.  It's not enough to make me concerned.  I should probably run an oil cooler, or at minimum have an oil temp gauge to see if I need one.  Some turbos will also use coolant to cool.  I made sure to avoid one of those for simplicity.

I have a fair amount of info in my 74 broke down thread on it.  Ignition timing and custom things I'm doing.

cstudep

I will have to read through it again, mainly focusing on turbo stuff and take notes I guess.

94touring

The last handful of pages is where it evolves into turbo stuff.

MiniDave

#124
Making small progress on the engine build while I wait for the burette and cover plate to come in that I ordered so I can accurately check the size of the combustion chambers and get an accurate compression ratio.

In cleaning up the thermostat housing I noticed that one of the bolts only had about three threads going into the head, rather than find another bolt with a different head I decided to put studs back in - they're stronger anyway. See the pics before and after.

I also put the new studs in the bottom of the exhaust manifold - one interesting point, those studs are metric! 8X1.25 for those counting..... ::)

I'm also waiting for the gasket to put the trans cover on, one of the pot joints was leaking engine oil into the joint - it's a common problem on these - the easiest way to fix it is just put some JB Weld over the cap on the inside so I cleaned it up good, blew some carb cleaner into the joint and blew it out with air then sanded the surface a little to give it some tooth for the JB to stick to.

That done I went ahead and mounted the engine onto the transmichigan....then I mocked up the exhaust and intake manifolds to make sure my intake would work with that exhaust - only to remember I'll be using my header in the test stand! Oh well....

Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad