Colortune device

Tweety · Post by **Tweety** » Fri Jul 31, 2015 9:21 am

Doug,
Will an engine be richer or leaner under load? that way I can tune it a little for that.

steptoe · Post by **steptoe** » Fri Jul 31, 2015 9:56 am

should be richer than stoich. 14.7:1 to deal with the load which might typically be high 12 to high 13:1 ratio - if you had a reader ...

a way to see a too lean sort of flame would be to see what it looks like getting revs up, then see colour while backing off - mine goes off the scale on LPG whose stoich is 15.5:1 and the scale goes to 29.9:1

Tweety · Post by **Tweety** » Fri Jul 31, 2015 11:00 am

got ya Jonno, richer easy to get richer under load.

The guy from Honduras Jeszek told me his ea82 has 162 as his main jet secondary which is a lot richer than my 145 currently. Me thinks there is room for a 155. I have 150, 155 and 160 available to use.

Started up the cold engine this morning. Has no choke fitted. After one minute I couldn't detect a rich exhaust. Good primitive sign.

steptoe · Post by **steptoe** » Fri Jul 31, 2015 5:56 pm

Remember the olden days when jetting settings printed in manuals had differences for sealevel and at altitude ? Well, I think Jes is a little closer to sea level than you are.

I used to find whenever I hit the sea level region with my high comp (230 psi) engine would ping, get it back into the 500 -600 m above sea level, pinging gone again.

Morale is use others jets as a guide only. You need to jet to suit your driving style me thinks, you unique 3 peed auto and lightweight birdie

tambox · Post by **tambox** » Sat Aug 01, 2015 9:04 pm

Don't fall into the trap of "I run this in my engine of the same type" and my jets are;
Your cam is different and your manifold is different, bore size, compression??
We "blue printed" two engine's and dynoed them as an experiment, with Webers, even they were slightly different.
Just use the others for a guide, then trim to suit, which it looks like you are doing.
Set it to what looks/feels right on yours.
I know its harder the way you are doing it, we would run them with a gas analyser on the dyno, then tune the jets/emulsions by drilling/soldering.

A carburetor is a compromise, that is one of the reasons EFI is much better (although a lot of them is compromised as well).
Both will work well, if properly done, those that know about every detail for tuning carbies are getting few and far between (retired).
Except for the Tony, the newcomer

So, you have richened the idle's, leaned the primary and changed the secondary mixture ratio, but adding more fuel.
Have you got Weber "equivalent ratio table" to show you jet ratio's vs a/f ratio's?
In a way Weber's are great as they are infinitely variable, but..
To quote the Weber book" Emulsion tubes are a mystery to many"

From what you have done/doing you should get it in the ball park, which will be brilliant, well done.
They are hard to get perfect, but getting what you want is the best.

Tweety · Post by **Tweety** » Sat Aug 01, 2015 11:34 pm

Haven't got got that ratio table. Will look into it. Thanks

steptoe · Post by **steptoe** » Sun Aug 02, 2015 9:35 am

yeah, and how many over the years have taken a beast to the dyno shops, got it back to feel it is a bit lacking, gone ahead and retuned it and been happy with own tune ?

My hand is up ! I took a beast to be tamed and got back a kitten. All I wanted was the dizzy curve to suit the changes. I got back an invoice for their labour, a grubby, mismatching 'new' HT lead for one pot ( they could have walked a block to the other tune shop that supplied the Magnacore leads and got me one that matched !)

Ignition timing was set as if each mark represented the same timing mark values on a V8 and not the six it was, the dwell value was out of spec and the invoice had disclaimer blasted across it "COMPRESSION TOO HIGH FOR STREET USE" 230 psi cranking speed

. Story is it was pinging its head off on the dyno because the rooster heads advanced timing way beyond factory spec of 4* plus or minus 2* and they gave it back to me like that !! WTF they did not retard timing to reduce ping ...no fliipin' idea !!

I got home, corrected their misguided adjustments, gave the advance weight springs in the dizzy a squeeze with pointy nose pliers and a tune shop has never seen this beast since in the last 30 years !

Keep at it Tony and maybe make notes as you go ....

Tweety · Post by **Tweety** » Sun Aug 02, 2015 4:05 pm

mmm, well Jonno my dyno guy did warn me the 38/38 was too large for the ea81. More relevant was the new owners comments on the project of mine.

He graciously rang me upon receiving the 38/38 and air filter unit from his ebay purchase. I asked him what its going on and he told me a Datsun 1200. But it was highly modified. Then I told him of my ea81 and the 15/55 cam. No, that would work very well was his immediate reply. A very high revving cam would be a different story. I think he is right.

Anyway, I sympathise with you Jonno because I've had that done to me as well.

I've been away for a few days and took an economy test. I didn't use the second throat at all during this trip and was surprised with the acceleration from the 32/36 without using the second throat. I mainly cruised at 105-110 kph) I got 25mpg. I think I can improve on this.

After refilling I rode up the mountain toward my place and used full throttle. What a great result. See this fairly steep hill is about 1.2 kms long and since buying the trike I've gone up it occasionally with WOT to see what speed it would achieve as a measure of its power. This is the comparison

VW 1916cc - 70kph 2nd gear
ea81 weber 32/36 when first installed 80kph (2nd gear)
ea81 supercharged 105 kph top gear (serious harm to the ozone layer)
ea81 SPFI 93kph top gear (never achieved full potential)
ea81 recoed new cam etc 98kph top gear

As you can see I'm delighted. Not much change needed on the jets now. So got home and changed the 65 idle jet to 60. 60 is much more common and as they are easy to change I went ahead. Also changed the secondary main jet from 145 to 155. Primary air jet from 180 to 170.

Primary Main: 140 .....................140
Secondary Main: ......... 145...to 155
Primary Air: 180..................... 170
Secondary Air: 160 ....................180
Primary Idle: ...................65 ...to 60
Secondary Idle: ..............60.....to 55

Used the colortune to tune it. mixture screw is just over two turns out. I went for a spin. mmm, more power again on WOT. this is getting impressive. Still smooth when secondary comes in. Certainly the engine isn't rich running. No black smoke, idles nicely etc.

Will read up a bit now on webers that Tambox is going to send me.

tambox · Post by **tambox** » Sun Aug 02, 2015 6:00 pm

Good to see the economy still exists.
That's the key to a good tune.

According to the weber book, yea, you'll get it soon.
A 38 on your motor would work well @6500 rpm.
The 32 peaks @ 5300 rpm, bit more sensible.