What do I need to buy to tune my worked VN 5L?

[jon]

It cost me $6.95 trade for a new standard thermostat (91deg). I wouldnt say the engine used to overheat. It got hot enough for me get a little worried. Spent a fair bit of money on the engine and was not going to burn it up.
I tested the car before the new exhaust on a 41deg day and had no problems at all with it. The memcal that I was running was for a smaller cam but it seemed to still run ok with it.
As soon as I removed the old exhaust (standard exhaust headers, single cat, 2.5 inch through to the back) and changed it to the recomended (1, 5/8 pacemaker extractors, twin 2.5 inch into twin cats then out with a single 3 inch) Then engine would get hot after a good bootful and would not cool down until I let it idle or turn it off all together. Since this problem become apparent I havent really driven it any where because I did not wanna do damage to the engine.
Jon

[antus]

How hot is hot according to the ECU?

[jon]

I couldn't say. This problem started happening just on 12 months ago when I upgraded the exhaust so since then I have had it parked in the garage. I only found out about this site just under a month ago so i didnt have anything to log the data with.
All I had was the trusty standard temp gauge in the dash that normally sat on 1/4. When it got to just over 3/4 I considered that hot.
As for it running a little lean. It was enough to throw on an engine light with the error (o2 sensor too lean) every now and then.
Jon

[Holden202T]

a good exhaust could well make your engine leaner but i don't really know how just that could make it run that much hotter.....

[v6bucket]

a good exhaust could well make your engine leaner but i don't really know how just that could make it run that much hotter.....

If it was restricted, it could run warmer.
How hot was it actually getting? If your using a std temp gauge, it may not be getting as hot as you think.

[Holden202T]

yeah i know on vn's in my experience the thermo fan never came on till about 3/4 and thats about 98 degrees or something

[jon]

I had no idea how hot it was getting. Only had the standard gauge to go off. It always used to sit on 1/4 and never any higher so when it started to climb (mainly on a warm day) I used to pull over and let it idle and it would come down again slowly.
I have just gone a bought a new clutch fan for it as the one I have now seems to spin a little to freely. The advice you all have given me I can only put it down to that. The radiator is practically new, No blown head gasket, Im not loosing any water.
Have to change a few things on the engine before I start to tune again eg.
Harmonic balancer (timing mark has moved)
Thermostat (taking 71deg one out and putting standard 91deg back in)
Clutch fan.
Once I have done that and I can road test it I will be able to log the problem and get better data if the problem is still there.
Just a quick question on the lean mixture bit, What do you consider to be a dangerously lean mixture on wideband?
eg, If I stomp on the loud pedal and let it rev up to 6500rpm and I get a reading of 16:1 should I cancel the test?
I have never had a wideband keeping an eye on my A/F ratio before .
Jon

[Dazza92VP]

16:1 at wot is way to lean need to bring it back to around 12:1 at full load wot. 16:1 is lean cruise territory

[jon]

16:1 was just an example, At what point would you consider to lean and take the foot off the pedal to avoid engine damage?

[engybenjy]

14 af ratio is pretty lean as a rule when I am on the dyno if I see a 14 at full throttle I stop and change something otherwise you could melt pistons..