Itinerant Air-Cooled

Colin

I recently went thoroughly through my AFM per your excellent guide on my '77 2.0L. I Rebuilt it over the winter and have about 1`00 miles on the motor now.

other than a hydraulic setup and extractor type muffler its stock

I believe I have done all the proper prerequisite setup
Valves and Timing
No Vac leaks
EEC repair
Gone through the F.I. guide and tested all components
EGR blocked


Been happy with the engine performance and gas mileage, but knew I was running overly rich, confirmed by visual on the plugs

I tuned my AFM by your guide. Spent about 45 minutes tweaking and retweaking the 3 adjustments and am happy with the results, but is there a reasonable way to know for sure im not slowly killing my motor? Like the end of you article says, I'll check the plugs in another 50 miles to read my results. I dont have a bung to access an O2 sensor. Perhaps in the future, eventually. Is there any other way to compute my ratio numbers

Im in Georgia, so no emissions for my vintage, but how ballpark is a tailpipe sniffer if I can go to a test site and see if I can convince them to let me 'borrow' the tester, if possible

Thanks for your imput. I'm just waiting for a confirmation from your other site and I'll post over there as well

-Nick

LC-1, the computer version of LM1 with bung and o2 sensor is about $120 delivered.

aerosurfer wrote:Colin
Been happy with the engine performance and gas mileage,
but running overly rich, confirmed by visual on the plugs

is there a reasonable way to know for sure im not slowly killing my motor?
how ballpark is a tailpipe sniffer

If plugs are not bleached white, you can be fairly sure that you are not killing the engine.

Fuel economy around 16-19mpg is another indication that you are not too rich.

Tailpipe sniffers can lull you into dependence upon numbers that may or may not be accurate. An extractor exhaust does not necessarily give the sniffer a representative sample of your actual oxygen content.

If you have good power (50-60 in less than 8 seconds) (50-70 in 15), good fuel economy (16-19 but not 22-24 please) and the plugs are are not white along the outside perimeter where the ground electrode is, yer good.
Colin

Thank you Colin! That's the answer I was looking (hoping) for. I will be watching it closely.

On a related note, when Moving the wiper CCW at speed (2800-3000 rpm) what should the RPM rise be before it drops?

I tuned mine to have about a 100RPM rise, but yesterday had a friends bus over doing various things and showed him what I had done, but when I moved his wiper CCW it wanted to rev up by 200-300 RPMs. His AFM had previously been opened, but looks like the fine adjust had never been messed with, his bypass screw was full rich however. We did fix some vac leaks on his

That LC-1 does look quite nice and affordable.... will bump that up the list of Ad-ons. Would I be best to put the bung into the afterburner pipe of the 3/4 side or into into the muffler after the heaterbox. Short of 2 LC-1 units, I have no way to have a blended reading

aerosurfer wrote:Thank you Colin! That's the answer I was looking (hoping) for. I will be watching it closely.

On a related note, when Moving the wiper CCW at speed (2800-3000 rpm) what should the RPM rise be before it drops?

I tuned mine to have about a 100RPM rise, but yesterday had a friends bus over doing various things and showed him what I had done, but when I moved his wiper CCW it wanted to rev up by 200-300 RPMs. His AFM had previously been opened, but looks like the fine adjust had never been messed with, his bypass screw was full rich however. We did fix some vac leaks on his

That LC-1 does look quite nice and affordable.... will bump that up the list of Ad-ons. Would I be best to put the bung into the afterburner pipe of the 3/4 side or into into the muffler after the heaterbox. Short of 2 LC-1 units, I have no way to have a blended reading

You're good,
he's lean,
there is no decent place on an extractor.
I used a tailpipe clamp deal on my '73 exhaust, with the understanding that the numbers were less important than the trends I observed.
Colin

So I have gone about 90 miles since my initial post. The bus has run fantastic! The butt dyno says it is pulling a little stronger and gets up to speed as good as ever. I know I am not running around flat out to maintain highway speeds anymore

While I had also chased down and sealed a few vac leaks, I have stopped a pesky backfire closing the throttle from high RPMs, I gotta believe that leaning it out a bit has helped as well. Here is a shot of my #3 Plug. Does everything look kosher or am I now a hair too lean? Plugs are W7CC and new within about 300 miles

Last Fill-up was right at 18.6 mpg over the last 105 miles

aerosurfer wrote:am I now a hair too lean?

If that plug is reflecting a mix of surface streets and highway, yes.
Colin
(I like to see the insulator a little less perfectly white)