Air Fuel Ratio Gauge

Engine discussion.

Air Fuel Ratio Gauge

by hcap » Fri Jun 19, 2015 11:33 am

I decided to play with some new school technology on my old school ute....
Picked up an Innovate Motorsports Air/Fuel Ratio DB Gauge Kit
The results were interesting but not unexpected...Thanks for your comments/advice in advance
Cold start with choke 11.9-12.1
Idle 16.4
Freeway constant 15.6
Full throttle 13.2
and the confusing one for me 3/4 throttle highway 12.4....
My current setup is red 202 mild cam yt head Hq big base carby on nos manifold.... have others to try as well :D
points
 
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Re: Air Fuel Ratio Gauge

by hcap » Fri Jun 19, 2015 12:32 pm

I realise it Only takes me 6 months to get around to something
http://ejehforum.com/viewtopic.php?f=4&t=11385
 
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Re: Air Fuel Ratio Gauge

by Harv » Sat Jun 20, 2015 7:48 am

hcap wrote:Cold start with choke 11.9-12.1

A little on the rich side, but not bad. Probably find you can start it just as well at 3/4 choke.
hcap wrote:Idle 16.4

Very, very lean idle for a car with no computer control. Turn the idle screw out a bit more.
hcap wrote:Freeway constant 15.6

Little bit lean for cruise. Keep an eye out for pinging under load, and check plugs regularly for signs of scorching. Consider going up one size in main metering jets.
hcap wrote:Full throttle 13.2

Little bit lean, but not too bad. The slightly bigger main metering jet will also help nudge this into the slightly richer side (under load, both the main metering jet and the power bypass valve are feeding the motor... easier to change the main metering jet).
hcap wrote:and the confusing one for me 3/4 throttle highway 12.4....

The carb is running at a slightly lean 15.6 at cruise. As you put your boot into it, the power bypass valve opens. It depends on how strong the internal spring is, and what vacuum the engine is delivering, though sounds like yours opens at somewhere between 2/3 and 3/4 throttle. As the valve opens, you go richer (12.4). 12.4 is not a bad figure for power. As your throttle opens fully, you get more air and go leaner (13.2).

hcap wrote:My current setup is red 202 mild cam yt head Hq big base carby on nos manifold.... have others to try as well :D

Is that an old school New Old Stock NOS, or a tuner Nitrous NOS? :lol:

Cheers,
Harv
 
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Re: Air Fuel Ratio Gauge

by hcap » Sat Jun 20, 2015 7:54 pm

Harv have struck a hiccup could you drop me an email please Thanks Adam
Last edited by hcap on Wed Jun 24, 2015 3:08 pm, edited 1 time in total.
 
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Re: Air Fuel Ratio Gauge

by Harv » Sun Jun 21, 2015 8:34 am

You got email :D

Cheers,
Harv
 
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Re: Air Fuel Ratio Gauge

by hcap » Wed Jun 24, 2015 8:41 am

So here is the next instalment
On Friday night I adjusted the fuel mixture screw to where I wanted it ...having said that the mixture screw was in a shroud and to get to it instead of resorting to my normal tools I resorted to the optometrical ones ....should have realised to stop and ask first ...what I was playing with looked like this
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Re: Air Fuel Ratio Gauge

by hcap » Wed Jun 24, 2015 8:51 am

So the car was idling really well and then all of a sudden went of idle and stalled... I only turned a quarter of a turn I promise Harv~!!!!
So this is what I have learnt ......or since what I have been told ...in the later carb bases and the rules that came in to play with smog gear they didn't like you playing with the mixture and the mixture screw is surrounded by a plastic bush.....which I inadvertently managed to break .....I was taking the ute for a long run on Saturday and alas I had to take the prem instead ...first work problems hey ....So with the help of google and Ax and Harv I found the stomberg idle screw replacement kit that has a brass bush and what I would have called a normal looking adjustment screw.....it arrived yesterday
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Re: Air Fuel Ratio Gauge

by hcap » Wed Jun 24, 2015 8:54 am

So Harv I was wondering in number values what would I ideally be looking for in the above areas that you answered. I have gone up one Jet size as you suggested but can't get it out today to test it
Cheers Adam
 
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Re: Air Fuel Ratio Gauge

by Harv » Wed Jun 24, 2015 5:17 pm

I like the simple explanations and numbers here:
http://www.autospeed.com/cms/article.html?&A=1595

Bear in mind though that these are for modern rockets with computer controls.... the humble Strommie is not quite so sophisticated. Aim slightly on the rich (safe) side of the numbers in that link.

If ya get stuck for jets, give me a yell and I'll send a selection to you in the post. Fit and fiddle until you find what suits, then send the rest back to me.

Cheers,
Harv
 
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Re: Air Fuel Ratio Gauge

by Harv » Thu Jul 09, 2015 7:41 am

G'day Adam,

How'd you go with the tuning?

Cheers,
Harv
 
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