Hopefully theres enough members still kicking about here to help?

Long story short.. dropped a rebuilt KLDE engine in my V6 (was a KF) and she's not running right. The engine gets really hot, like you cant touch anything under the bonnet without scalding yourself. Not sure I can trust the dash guage as I took the needles off to instal indiglo tacho a while ago and the only way I was told to calibrate is to let engine run for a minute or two and put needle back in the middle of H and C. It stalls a lot just moving it off the drive. I've tried the 10 + Ground trick, which improved idle, but once the car gets up to temp (about a minute) the engine sounds lumpy, like a slight misfire. Timing belt was done and its all aligned correctly. Sparkplugs look good and HT leads seem fine (I pulled them one by one and listened for engine noise change) Ditsy has had a new cap and rotor.

Where else shoud I start troubleshooting?

So from when cold and as soon as you start it what does the temp gauge say? To me fro scratch the needle would surely be at cold when first turning the ignition on with a cold engine
Does get to temp quite fast too, is the thermostat working ok? Engine will run poorly when it gets too hot, maybe get hold of one of those handheld temp thingy's that are being used at the moment for measuring peoples temperature with this corona business going on

If it's waaay too hot to touch anything then it's overheating. The engine won't run right when it's overheated.

Some queries:
Do the cooling fans come on when the engine's hot? If not, something's wrong and you need to investigate.
Is the coolant at the correct level? Not just in the bottle, but in the radiator too.
Has the coolant system been bled properly? Bubbles in the system can prevent proper coolant flow and cause hotspots.
Does the heater blow hot air? If not, there's a coolant blockage or lack of coolant somewhere, or the water pump isn't pumping
Is the coolant flowing around the system
- does the top radiator hose get hot at the entry to the radiator once the engine's up to temp? If not, then there's a blockage somehwere- maybe thermostat, maybe radiator
- does the bottom radiator hose feel cooler (not cold) than the top? If cold, the radiator may be blocked, if hot then it's not dissipating heat properly- maybe clean the fins but it coould be the radiator's shot.
- is there a substantial temp gradient across the radiator? If so, then the radiator's partially blocked and needs replacement.

Yes getting a temp 'gun' is a good idea, you can test all of the above temp items.

Is the timing right? Too advanced or retarded can both lead to overheating and bad running.

I think a better 'calibration' would be to put the needle on "C" when cold. Note if the sensor in the new engine is different to the old then the temp gauge may be meaningless. Ditto the ECU temp sensor which is usually an entirely separate sensor to the gauge one you view. If the ECU doesn't get the right temp everything can be off- cooling fan startup, ignition timing, air/fuel ratio, etc.

Patrick

I'd say Patrick has done a good summary. Follow those ideas and you'll have some direction on what the cause is.

Ah thanks peeps for your replies. I've been busy with the newborn to really get out and do some in-depth investigation, but I did manage to yesterday and had a temp gun to read some numbers. To begin, I looked at the temp needle on the dash upon starting and it was on the first 'C' notch. I let the engine run and watched how long it got up to temp (needle in the between H and C ) and it was 10 minutes give or take a few seconds. The coolant pipe on the left side of the engine (looking from front) was reading 75.9°c and the thermostat on the right was about 65.8°c. After leaving the engine run the fans did come one as they should.

There's enough coolant flowing around and I had previously "burped" the engine by squeezing the pipes. The blowers blow hot air too.

You might say its maybe not overheating, but I dont remember the KF engine being that hot when it was in. I mean, you cant unscrew the oil cap without using a rag as its that hot.

I think I'll look into the timing maybe as the engine still sounds ill. I'm also thinking of swapping the O2 sensors for new, see if that makes it run better.

Is the water pump OK, and / or is the belt tight enough to turn it?

My KF was overheating fast, and I couldn't figure out why until I spotted that the pump was only spinning intermittently, because the belt was slipping.

S