phreak97 wrote:
:P Thanks for the reply.
I know the adf is too lean with a 90 thou jet, I just thought it might get me there on a 100 thou.. but I guess it depends if it idles or not:P
How difficult is it to file down a lean needle? what's the process? I have an ancient vane engine analyser which I dont know how to use, but I'd be willing to learn if it would be beneficial.. how far different under load is the fuel usage to unloaded?..
If I finish the car today I would love to take it for a drive.. waiting until half way through the week will suck alot:(
A lot of people would argue that the only way to get the perfect profile for your specific engine is to file or polish your own. I'd largly agree. However, with out a dyno, trying to file your own profile just by doing road runs is a little bit hit and miss.. with practice you could get it pretty bloody close, but you really need to monitor whats happening closely at different speeds / loads to get the most out of it,, and you just can't do that by doing road runs...
You need to be able to measure your AFR while you are driving and record what it is at different rpm and loads, then you can look at it and say... (for example) "ok at cruise its lean/rich/ok, under hard accel its xyz, at idle its ABC" you get the idea? Then from there you can look at your needle,, the top station (first 1/8".... at the thick end fo the needle) is the part used at idle, the next inch is the part used for cruise, and the rest is the part used under hard acceleration/power.
So with your recorded AFR's under different conditions, you can go-->"ok at cruise it was 18:1 so that ok, I'm hardly using fuel good for economy,, but under hard acceleration it was 22:1... that means that either the needle is rising too quickly or the needle is too thick.." so from there you would try a stiffer spring to see if it helps.. if it is still too lean at full power you could try filing or polishing down the power part of the needle, only do the tiniest bit at a time,, remember you can remove material but you can replace it. After shaving off a little, take it for another run and do another recording and see where you need to go to....
Get the idea? Thats probably the most calculated way you can do it with out a dyno. You can get exhaust gas anylisers that you attach to your car while driving. I have one, they aren't cheap ($600), but I reckon they are well worth it.
The other,, rougher way,, is to just take it for a flog and go--> "oh yeah, ok at cruise, but gutless up top, I'll take a bit out of that section of the needle"...
As for trying to tune it unloaded... you can't. Yes, there is a huge difference. But if you're a redneck like me who'll try anything once and do it again if you like it,,, get a set of brake drums you don't want, fit them to the front, put the car on stands, get your redneck friend to hold down the brake a little bit and accelerate at the same time and Hey Presto, rudimentry Dyno
He risks his life will you check the read outs
By the way the ratio you should be aiming for is about 13:1-12.5:1 for power and about 15:1 for a good medium cruise.
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Thats basicly the the idea of it anyway,,, someone else might be able to add more to it.
EDIT:--> most people just file a flat into the needle at the area they need richer... if you have a set of micrometers and a lathe you could polish iit down to size with fine sand paper and match it perfectly to someone elses spec (maybe one posted earlier in the thread)
EDIT:---> ok if I'm going to post all that I should probably also tell you the order that you tune/adjust. First, work out the spring you need, then work out the needle, then work out ignition timing/distributor curve.... in that order
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