Mixture tests

So the meter came.

I ran £20 of 97 Texaco through the car today, not my favoured fuel it doesn't run that well in my engine, needs booster added.

The meter is no doubt useful but doesn't really tell me anything I cannot feel, when its good on the gauge it feels good!

It did enable me to make some firm jet decisions and see my crossovers in my detail.

I had the main circuit setup 125main - 7 tube- 170 corrector, the meter told me this had a decent cruise mixture and mid range but leaned off a bit at the top and high end WOT, I setup like this as it was a bit stodgy at mid range cruise on 125-7-160 I was using at the sprint on the way home...I find air correctors "air brakes" also slow the start point on the mains, hense my movement to 170, but at the same time they lean the top end also. For whatever reason I choose to leave the main at 125 that day.

I tested numerous combo's 120-7-170, 128-7-170, 128-5-160, 125-7-160, 120-5-160, 120-5-150, 125-5-150, 118-5-140, 115-5-140, 115-7-140, 118-7-140, 118-7-150, 120-7-150, 125-7-150 using a combination of high speed motorway testing and low speed A-Road work. None of them ideal.

Was a touch hot today for the sweetest running, the car was much nicer on my final evening run with 20C air.

I ended up on 122main-7tube-160 corrector, this gives me 13(ish) air fuel ratio 80-110mph on the motorway with a partial throttle opening and gives me 12.2-13 at wide open throttle from 4500-7500. Oddly when I reduce the throttle opening at these speeds it goes 11.1 rich till I get to 3500rpm then goes back to 13ish, not quite sure what that is about, maybe the progression is adding fuel again as the plates pass the progression holes and the load is low and the fuel isn't being burnt just ejected...Its these C carbs I think!! It doesnt have a downside its just a happening..

The meter reads 14.7-15.1 at a closed throttle from any speed and read 16-17 on the 48 idle jets. In the low end-the car doesn't like anything less than 13.5-14 in any situation bar closed throttle, can't expect a race cam to enjoy stiometric fuelling..It likes max rich in progression when you open it up or accelerate gently.

I noted the idle circuit was running a bit rich and long on 50idle - 7850.1 holder, which confirmed by reason for using the 170 corrector...I couldn't detune the progression as its starts to miss off idle.... I tested 48idle and 7850.3 holder, holder a stage richer than my usual 1 but the 48 is too lean at 1000-1750rpm then the mix was good, better than the 50 and 1 holder I think. Missing forced me back to the 50 and 1 holder.

So I drilled the air hole on the 1 holder out by 0.1mm (I think 8-) which seemed to do the trick but possibly another .1mm will be even better. I'll stew on that before wasting a set of holders if its no good. I can't use anything less than 50 idle I just wanted the high end of progression to lean out a bit. Oddly people NEVER use holders leaner than 7850.1...This helped an occassional miss when you decked the throttle from low rpm.

The engine likes the gauge to read max rich during transitions from cruise to power, also possiblty the pump jets adding their fuel making it read rich for a short time and any attempts to lean this out a bit results in a loose of smoothness and the odd hickup, so I left it rich.

All in all worth £60 but I have been on these jets before. Bar modifying the idle holders. The proof of any pudding is what it feels like on the next day, so we will see!

Fitted some new lockheed/delphi brake shoes and adjustment my handbrake as well...Its been a minor pain in the bum on this super low rear susp as when it bumps it shortens the cable as at static its inclined.

I increased the stiffness on my rear shocks too and gave the drivers side 1 more click than the pass - gave the tyres a touch more pressure, think where not balanced to eachother(shocks)...I was doing 6500rpm in 4th gear and hit some manic yumps on this road and the tyre bottomed out on the arch! not the outer arch but the bloody top of the wheel arch! I smelt rubber! the arse end waggled about and it wasn't pleasant at all 8-) When you run out of suspension movement the load has to go somewhere then be released - not quite a brown pants job, would have been for a passenger me thinks , it lurched left and right with a mind of its own!