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Discussion Starter · #1 ·
Well,

I've been through


Well,

I've been through the carbs a second time, doing fine adjustments as the motor now has almost 900 miles on her. Overall driveability is very good...with the slightest of transition stumble. The stumble does seem to be noticeably worse on cooler days, leading me to believe that the slow speed jet is still a bit too lean.

Mixtures are spot on...I did finally verify my settings using the Colortune device. A real PIA to use, but effective never the less.

Despite all the carb tuning...and double checking of carb synch, the engine just doesn't sound "on"...She doesn't quite howl, as I remember, particularly at high RPM. I did a couple of rolling 5-100km runs with a GPS and a stop watch. No apparent problems as times were in the mid 4 second range...(She pulls very hard, eh?)

However, rolling on from 100K on up, performance just seems a bit off, based soley on feel.

I re-checked the carbs, with interesting results:

Idle-Perfect
Off idle-Left side and right side off by 2" of vacuum
Full throttle-Left side fully open, right side has another 15-20 degrees of throttle angle before fully open!

Seems the linkage female pieces, from the cross linkage to the Webers are a bit worn...and possibly the geometery of the two arms which actuate the carb linkages may be a bit different.

So...from what I can see thus far, the greater the throttle angle, the greater the carbs (left to right) go out of balance.

This scenario would certainly explain the "lack of howling..."

I've ordered the linkage ends and hopefully, the weather here will hold long enough to make the repairs...and see/hear/feel the difference.


Regards,
David
 
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Discussion Starter · #2 ·
>>I did finally verify

>>I did finally verify my settings using the Colortune device. A real PIA to use, but effective never the less. <<

Were you able to get the mixtures closer to dead on with the Color Tune? or was it just a verification excercise?

Regards, JRV
 
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Discussion Starter · #3 ·
JRV,

Much to my pleasant su


JRV,

Much to my pleasant surprise, my mixture settings were on the money, with no adjustment, or less than 1/8" turn needed...

Reading the plugs indicates another story...as the entire right bank appears to be running a bit leaner than the left. This, in conjunction with the overall sound of the engine lead me to look a bit further into the carb synch issue.

Thinking this problem through, I have an idea to use a dial indiacator to measure the relative rest positions of the cross arm linkage and see where I am at off-idle and full throttle.

I really want to tap into the individual headers, to read specific cylinder HC/CO levels. Oddly, there are no taps on the 365, yet both the 512 and 512i cars have them. Any (easy??) ways to install taps, without (wishfull thinking) removing the headers (a true PIA)...?


Regards,
David
 
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Discussion Starter · #4 ·
Hi David,

not knowing anyth


Hi David,

not knowing anything about your particular linkage: is it possible the arms got switched from side to side somehow? the other thought I had was that the problem could be a combo of both arms being the wrong lenght for some reason rather than just one?

On the test ports question: the header walls are so thin that simply tapping something in invariably leaves a protrusion sticking into the exhaust stream. Now whether a small protrusion of a small diameter tube would be an issue is up to you to decide.

I would say 1/8th in. pipe fittings tapped in with accompanying long pipes (bundy flex brake or cooper tubing) set up like TR's with relative ease of access would be the most striaght forward and one option...if you find that unacceptable, welding bosses on the pipes, drilling holes and using caps/plugs would be the next direction to think about.

Regards, JRV
 
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Discussion Starter · #5 ·
If you want to go the welding

If you want to go the welding route Pegasus sells weld on EGT port adapters that are smaller than the weld on O2 sensor adapters.

Regards, JRV
 
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Discussion Starter · #6 ·
David,

I don't think an


David,

I don't think anyone has asked or if posted I may have missed it. With the higher compression pistons (11:1 ?)are you recognizing any additional noticable umph in your back side or do you still need to get things sorted out?

Drew
 
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Discussion Starter · #7 ·
Drew,
Good question...and it


Drew,
Good question...and it hasn't been asked before. The motor is pretty well sorted, and I'm not sure if it can be any better. The overall driveabilty is now approaching my modern day Audi in terms of engine flexibility...other than cold starting.

I think the biggest difference with the raised compression is that power now starts to develop at a lower RPM range than before the rebuild. Now, real push you back in the seat power starts at about 3200 rpm, versus 4500 rpm with the lower compression pistons.

Oddly, it starts easier now...though I'm not sure if that change isn't due to the ignition system finally working properly.

With just 1000 miles on the motor, I haven't been running her extremely hard, though I've seen red line in the first three gears more than a few times, as of late. Hopefully, a few driving days with remain before the snow comes...

Overall, she's an absolute blast to drive, more so than ever before!

Thanks for asking,,,


Regards,
David
 
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Discussion Starter · #8 ·
Another glorious day here in U

Another glorious day here in Upstate NY....near 75 degrees. Another 100 miles logged today, and she runs famously.

Pretty soon it will be time to fit the snow tires on....HA!

I just love this car!

David
 
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