Air fuel ratio testing fun

Since the last topic got off topic and got locked, here is a continuation of it.

I finally got to check the pressure in the cylinders, from #1-6
#1=140psi
#2=145psi
#3=147psi
#4=144psi
#5=144psi
#6=141psi

These numbers are from letting it spin over 4 times. Was that done correctly or should i spin it over till it stops increasing?

So now on monday I'm gonna get my o2 bung moved downstream. Currently mine is about 10" from the manifold, and the directions say at least 14". i dont know if this has any effect on my readings but it concerns me b/c the gauge says im running close to a 12.5 to 13 constantly and my plugs are still white. Slightly off white but not as dark as they should be for as rich as I'm running.

I got a 1968 1.08 autolite that I'll be getting the stuff to put it on the car instead of the weber.

Just figured I'd update where I'm at in case anyone is following along

Thanks guys

I may have done the test wrong. I did not run the carb out of gas. This explains why the compression kept increasing the longer we kept cranking it over. I'll be testing it again here in a few days.

Do it on a warm engine. Disconnect the ignition. Open throttle WOT. Then run compression.
Your previous test shows that all cylinders are equal. Looking good so far.

You didn't mention if the plugs were all out. The engine should be up to temp, pull the plugs and the coil wire and have the throttle wide open when you crank it. Don't smoke It doesn't really matter how many times it turns over within reason, it only goes so high. 3 or 4 is perfect. That's the number you're looking for. The numbers you've got sound good.

I did have all the plugs out and it was done when it waa warm. I just didn't run the carb out of gas.

I know i should run the carb out of gas b/c the pressure kept climbing, like #2 showed 210psi and kept climbing. Thats why i thought i was doing something wrong and only cranked it 4 times. But now i know it should level off, so I'll run the carb outta gas this time.

But yeah i thought the numbers were good so far, hopefully they'll be higher.

"...hopefully they'll be higher...."
if done w/the oil.
Save that 1 till later (if needed)..

I will be testing the compression correctly tomorrow but i figured I'd check the plugs and see how theyre looking. It looks to me they're still lean, but my gauge says im consistently running 11.5-12.5 while driving and cruising. I think my gauge is either crap or needs to be calibrated.

Heres the plugs

Also, is it normal for it to only be dark on one side while the rest of it is still light? My gut says no, and its running lean.

P.S. I'm waiting on the autolite 2100 and adapter, It should all be here soon.

Let me know what you all think.

THose look pretty good to me. You want that color change on the strap right around where it is.

Econoline":3r8qw2ft said:

THose look pretty good to me. You want that color change on the strap right around where it is.

Click to expand...

Do you think the sensor or the gauge could be off since it reads so rich then?

Thats good the plugs look like what they should then

is the oil on'em Bubba saw gone?

chad":1eat0gft said:

is the oil on'em Bubba saw gone?

Click to expand...

The only one with anything that looks like oil is #6. Which like i said I'm not super concerned about since i have a replacement head that i will be hopefully putting on within the next year.

I think you need to calibrate your A/F tester. The plug reading looks ok.
Return it as a defect & get another one or get a second independent test.

wsa111":3orz0dup said:

I think you need to calibrate your A/F tester. The plug reading looks ok.
Return it as a defect & get another one or get a second independent test.

Click to expand...

Would you return the whole thing or just the gauge?

StarDiero75":3kppjkdf said:

wsa111":3kppjkdf said:

I think you need to calibrate your A/F tester. The plug reading looks ok.
Return it as a defect & get another one or get a second independent test.

Click to expand...

Would you return the whole thing or just the gauge?

Click to expand...

Return the whole thing.
Or get a second opinion test done.

wsa111":21cxzl56 said:

StarDiero75":21cxzl56 said:

wsa111":21cxzl56 said:

I think you need to calibrate your A/F tester. The plug reading looks ok.
Return it as a defect & get another one or get a second independent test.

Click to expand...

Would you return the whole thing or just the gauge?

Click to expand...

Return the whole thing.
Or get a second opinion test done.

Click to expand...

Ok I'll give summit a call today

Alright guys, drum roll please... The compression results after doing it properly:

Fuel line disconnected and car ran till out of gas, all plugs taken out, throttle held completely open, choke held open, and is up to temp.

Results:
#1=196 psi
#2=205 psi
#3=205 psi
#4=208 psi
#5=205 psi
#6=199 psi

I think these are pretty good. What do you all think?

Summit it having me call AEM to calibrate the gauge btw. I'll report back on that when that is done

yes that's shows your engine is in excellent condistion!

This could be part of why you're having some pinging issues. The compression ratio must be pretty high on your engine. It will be interesting to see what you find out if/when you pull the head for a head swap.

Econoline":343iyj8l said:

This could be part of why you're having some pinging issues. The compression ratio must be pretty high on your engine. It will be interesting to see what you find out if/when you pull the head for a head swap.

Click to expand...

I was thinking the same. Good thing i switched to 92 octane. We'll see how the car likes the 2100 when i get that on it

What head is on the engine now?