AFR reading

[limeyboy]

How sad is it to post on Boxing day anyway I've taken off my Hooker long tubes and fitted Sanderson shorty headers with badly made ( I did them) 2.5" link pipes to the existing H pipe and boxes.
I also fitted an AEM AFR kit and now have interesting readings.
Went out for a drive today and when I start her up it's around high 13's / 14 which I believe is good for E10 but when I drive cruise it goes up ( leaner) to around 15.5 which is described as "usual best economy " and when I floor it its up around 17./17.5 which is "getting near the lean burn limit", everything I've read says it should be around 11 (rich) on WOT.
Yes there is a possibility of a air leak from the link pipe ( badly made as stated) or headers ( sanderson so no gasket just RTV) upstream from the sensor but she runs great with no popping or banging or hesitation at all and starts easily as usual.
I also put some masking tape on the vacuum secondary rod and I do not believe they are opening and probably never had since I've had her (3,000 miles) how will that affect the running?
I understand the dangers of a lean engine but do not believe it's running / has been running that lean or I think the engine would be dead by now with my "spirited driving".
Going from long tubes to a more restricted shorty header has if anything made her faster off the block but would you expect the change to make her run leaner or richer?
The weather is damp / raining for the next few weeks so "testing" will be very limited!
Any thoughts will be gratefully received.

Happy, safe and prosperous new year to all.

 

[Horseplay]

You should be shooting for average numbers in the upper 12's or very low 13's if accurate. That would be a good running, safe environment for the engine. 14 would be a "perfect" score and not realistic over various driving conditions. If driving you're seeing numbers like 15 for extended time (cruising) you should hear detonation as that is a lean condition. Let's hope your welding skills are lacking and there is fresh oxygen being sucked into your exhaust for the sake of your engine.

Just a reference point, when setting up an injected engine all the aftermarket guys suggest tuning to be in that 12-13 range. You should also remember that with an old school intake and carb, you will almost certainly have cylinders that run on the high and low side of average that you need to consider too. If you are not hearing detonation, I'd drive for a bit and pull and read all the plugs. All the plugs.

 

[limeyboy]

Horseplay, I see where you are coming from and I have always used plug colour (for over 50 years on bikes and cars) for checking an engines health and this one has always run very very clean plugs, never any soot whatsoever and if anything knocking on the door of lean but never any white ash either, just a very good runner ( it had been set up on a dyno a couple of times when it was in the US and was never used much I believe after) the weather isn't good enough for me to go for a steady drive and watch the figures so if it looks like the car will be garage bound for a few weeks (likely) I might take the link pipe off of the sensor side and make 100% sure it hasn't got a big leak.
I also need to try and get to the bottom of the secondaries probably not opening while it's bad weather.