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I thought I'd share my latest efforts in preparing to get my carburetor dialed in using the Zeitronix Zt-2 Wide Band Data Logger. Possibly others can benefit from my efforts if/when they decide to do the same and the solution I came up with should work with any wide band data logger. The Wide Band Data Logger I'm using is the Zeitronix Zt-2 along with their LCD option and a computer that logs the data for later review. Initially I thought I'd only log the AFR, RPM's, and vacuum, but after a few initial tests I came to the conclusion that throttle position data would be very valuable data as well.

I found a brand new GM Throttle Position Sensor on eBay for $8.80 including shipping which I was confident I could fabricate a bracket for. The GM part number for it is "AC-DELCO 213-900". The correct plug/connector with a length of wire from my local NAPA cost me more than the sensor. I fabricated an arm out of a scrap of flattened copper tubing that I soldered to the arm of the sensor. I drilled and tapped four 2/56 holes, the lower one I installed an R/C linkage ball in. I used a scrap of 3/32" aluminum angle to fabricate a bracket that mounts the sensor on the drivers side rear carburetor stud. The bracket is notched so it can't twist or move at all. I located, drilled and tapped another 2/56 hole in the carburetor throttle bracket and installed another R/C linkage ball. Then I used two R/C nylon sockets that mate to the balls with threaded brass ends and a piece of appropriate wire soldered between them of the correct length. I heat shrunk the brass ends and wire to make it look a bit cleaner.

Below are eight photos I took at various stages of fabrication and installation. I put captions above each photo to explain what you are looking at. Following the installation I did some initial testing with the car in my garage. At idle the sensor reads 5% and at full throttle it reads in the low 90% so I'm happy with the range I was able to get with the linkage used. One interesting thing I noticed in the initial test data was when stabbing the throttle to the floor for an instant and then letting off, from the instant the throttle shuts down to idle position, the engine continues to gain over 1,200 rpm's from flywheel inertia and momentum. Makes sense but seeing it revealed clearly in the data is kinda cool. Hopefully over the next few days I'll get some actual data logging while driving done. When I do I'll report the results back here. So far I'm very pleased with the Zeitronix Zt-2 system.


Here is a photo of the sensor as manufactured.



Here is the aluminum bracket to mount the sensor to the carburetor base.



Another view of the aluminum bracket.



Here is the modified sensor mounted to the bracket.



Another view of the modified sensor mounted to the bracket.



A view from above of the modified sensor mounted to the bracket.



Here it is mounted to the carburetor with the linkage in place.



View from the front with it mounted to the carburetor and the linkage in place.


Scott
 

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It is great to see others getting into 21 st century technology to dial in 50yr old + technology engines...and go beyond the Simple AFR gauge.
And great when others take the time to sit down, think thru and make bits and pieces themselves rather than something off the shelf.

Just rem If u have a miss and when dialing timing in the AFRs go 'lean'.. it measures O2 a miss has more O2

And once u get into it, u will notice other 'idiocincies' like u mention above...

I have also used a magnetic dial clamp to mount the TPI

And a knock sensor I would put a little above the TPI

Excellent move.. a whole new world opens up in front of u...
 

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Well thank you Steps and Tom for the positive feedback. Tom, I don't know that anyone will see enough of it to ask questions. It's completely hidden by the air cleaner which wasn't even a thought when put it all together the way I did but I'm okay with that. :)
 

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Good mounting, nice job.
Is there room for the connector to plug into the TPS?
 

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Good mounting, nice job.
Is there room for the connector to plug into the TPS?
Thanks Everett, yes the connector fit with plenty of room to spare. The reflection from the chrome coil cover makes the sensor look much closer to the coil than it actually is. I did one 15 minute data logging session while driving this morning and it worked flawlessly. Looking forward to examining the data when I get a chance and the make some adjustments/changes based on what the data reveals.
 

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Nicely done. You'll find all this very useful dialing in the carb. It is paradoxical that the EFI systems that need monitoring/adjusting the least are commonly running a WBO2 yet carburetors not being nearly as accurate with fuel dispensing, are mechanical, and prone to need more frequent tuning do not. I've used Zeitronix for a 5 years and lover their products. I mounted a GM 1 bar MAP sensor on rubber mounts just behind the carb as well.



One of the logs:

 

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Thanks George, I too purchased and installed a GM MAP sensor. It's so nice to not have to guess what is going on with fuel mixtures. Good to have another known Zeitronix user out here as well :thumbsup:
 

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I have been using a innovate LM1 several yrs now.
Get the timing curves in ball park
then set the butterflys.
Set each of the carb circuit mixtures individually
go back to timing curves, establishing the idle and the total pionts and knock/ advance curve at light load, if have a knock sensor....
Then adjust the dizzie to hit those numbers keeping under the knock curve with the VA...
Non EGR initial+VA =idle initial +cent=total all up (initial+cent+VA) stay below 40/42 degs unless have a knock sensor
Then go back and make any adjustments in carb circuits if need be, re check timing.

And careful with vaccuum readings, dont get trapped in the idea highest vaccuum is most efficient...

And Im sure that u will find the numbers improve to such an extent it will pay for the logger with (against old school thinking) power also increasing.

What is nice is getting an engine that has all the 'go' components (cam carb headers compression, fuel type) matched to a given rpm range, matched to street use....over one that isnt.. the differences once dialed in in power , and espec economy are dramatic.
Dedicated track type engines dont lend themselves to street use anywhere near as well... espec if a 'mix' of components
 
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