WillieB's 1275 Engine Rebuild

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

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94touring

Do you know which needle stations to target?  You'll have 16 stations on your needles. 

MPlayle

I still have a few spare needles, but only one is for the .100 jet you apparently have.  It is a BER needle and is leaner than the BDL.

I have a few .090 jet needles.

MiniDave

I'll check my stash, but a BDL usually is appropriate - you do know how to raise and lower the jet to adjust the mixture, right?
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MPlayle

His idle mixture setting is fine (12.5 - 13.5 AFR) per a previous post.  It is the cruise and WOT that are too lean.

Changing the jet level will also affect the idle mixture.  Changing the needle will permit keeping the idle "as-is" while making the cruise and WOT more rich.


94touring

That BDL needle is the leanest of the 3 that Calvert recommends on an equivalent engine build too.  Nothing a little shaving of the needle won't fix though.  I use a fine grit 600 sandpaper after filing to knock down any roughness on the needle.

MiniDave

BDL is slightly richer than BDK tho, right?

so should he be going to a BCE? I might have one of those too.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

MPlayle

According to my SU needle profiles booklet, BDK is actually just slightly richer than BDL from station 5 on up which would be mid cruise through WOT.

BCE is richer than either BDK or BDL and would likely be the better choice based on how lean the cruise and WOT AFR readings were (16-17 for cruise and 18-19 WOT).

I'll toss in my booklet with the stuff I am bringing to the Kerrville drives as a reference.  I will also have my Macbook along where I have a spreadsheet to chart some comparisons.




94touring

I think on the last page I have a screenshot from mintylamb comparing all 3 needles.  On my BCE needle I only needed to tweak stations 10 and up for WOT pulls to redline.  The cruise air fuel was perfect with a heavier spring. 

Willie_B

AF numbers look better on today's drive. Idle 13.5 and cruise 14.5 to 16 with just a tiny stumble if I get hard on the gas. Tomorrow I head to the the mountains for 240 or so miles. Looking for a high of 58 so a great day for it.

94touring

Sounds like just a little more filing and you have it.

MiniDave

#210
Quote from: Willie_B on April 20, 2021, 04:27:10 PM
AF numbers look better on today's drive. Idle 13.5 and cruise 14.5 to 16 with just a tiny stumble if I get hard on the gas. Tomorrow I head to the the mountains for 240 or so miles. Looking for a high of 58 so a great day for it.

Hearing any "rattles" or other untoward noises? Water temp holding OK?

Where did you set the timing? at what RPM?

Clutch working well now? did you  wind up using a different Wok or fix that one?

How many miles have you done now? another 250 and it should be ready for an oil change before you haul it to Tejasss
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Willie_B

No rattles, now that I know what to listen for. Set the timing to what you recommend. Clutch is perfect, got a new wok took the easy way out. Sould be ready for an oil change before Texas for sure.

94touring

What air fuel numbers are you seeing on full throttle to redline or have you driven it that hard yet?

Willie_B

Still putting in break-in miles on it. I will probably push it bit in the mountains today so will know more later.

Willie_B

#214
Feedback from todays 225 mile drive. Freeway back and forth to the mountain fun roads. When completely warmed up idle is 12.5-13, cruise 45-75mph is 14.5-15, WOT 12.5-13. Not bad for just filing down one side of the needle. When it cools I will pull a plug to see how it looks.

The handling is a bit twitchy on turn-in. The back feels like it wants to step out a little. Could a 1/2 degree in front caster have that much difference? I asked for 4 degrees and they set it to 4.5.

MiniDave

in a word, yes.....what are your camber settings?

Why so much caster? makes for hard steering esp at low speeds.

In front I use 1/2 degree neg camber, 3 degrees caster and a tiny bit of tow out

in the rear I use 1/2 degree camber and a tiny bit of toe in

did they get the cross camber even?
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

94touring

Your air fuel is spot on, nicely done. 

My alignment is negative 1 degree camber in the front, negative half a degree camber in the rear, front toe out 1/8 inch, rear should be positive about a 1/16 as is.  I use stock caster.

Willie_B

The numbers I have used for years are
FRONT
toe           1/16" out
camber     -1 degree
castor       4 degrees

REAR
toe        1/16" in
camber  -1 degree

So I should try caster at 3 degrees then?

94touring

Double check your toe on the front too.  Toe in will make it act squirley.

94touring

Oh I assume your on throttle stumble went away?

Willie_B

Yes it did. I may try to tune it more later but I am happy with it now.

94touring


Willie_B

#222
Back at the alignment shop. Even though it was set they say the rear toe is out. So reset that and I asked for the caster to be set at 3.

Update with numbers. When they put the mini back on the rack the rear was .3 toe out on the left and .3 toe in on the right. They set the caster at 3.5.

MiniDave

Rear toe will def make it squirrely in the back. I hope that straightens it out..... 77.gif

Really glad to see you getting some miles on the engine.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Willie_B

Did your list of things needed at500 miles yesterday. Easy and done. Everything looked good. No leaks or issues.