SU HIF Carbs Set up..

[Valhalla]

I've posted on the LPG forum, similar sort of issue with a LC ex-military V8 running in a RRC. The conclusion I came to was that the cams are fine (I had a look when I had to change the inlet manifold gasket for the second time in 12 months - first time to fix the leaks built-in by Landrover, second time to fix the leaks built in by someone with a screwdriver near the coolant hose connections) but the tappets may well be collapsing.

Is this also a possibility for the HIF carbed unit above? My current problem car has twin 175CDSE's, and I have also done everything under the sun to get these to "factory perfect" standard, knowing that the more I run the engine, the worse the effects are of me trying to get the mixture right across the two (I have never had any problem in 30 years tuning the Rover V8, not until this one...) Same symptom of poor pickup out on the road, blackened plugs (eventually failed on 5 cyls out of , massive fuel dilution problem in the oil sump. Yet from cold and part-warm, the engine is an angel, no issues whatsoever. Fresh Castrol GTX 15W/40 semi synthetic will make things better for a short while (minutes rather than hours) then it all turns pear-shaped.

I know that the tappets have had a miserable time in their short life so far (I think the engine has fewer than 6000miles on it) due to misbuild issues typical of all these green-painted units (wrong dipstick lengths, that sort of thing), so it wouldn't surprise me to find something lurking in that area of the engine.

[DEVONMAN]

Hi,
Just a few suggestions which you may have already considered.

Punctured or incorrectly fitted dashpot diaphragm.
Fuel pressure too high.
Float level too high.
Worn needles and jets.
Cold start Enrichment stuck on.

Regards Denis

[Valhalla]

Thanks for the points above. I'd already discounted the worn needles, as both carbs appear to be almost new, but the fuel pressure is one of the things I was going to measure again. I measured this with the engine static some time back, but it has occurred to me that the pump may well be packing-up, or the return line blocking after a while, and either of these is going to make setting the carbs a bit tricky......

Definitely on the cards to see if the diaphragms are OK, as I have noticed that the undamped air valve response to snap-shut of the throttle is slightly different from one carb to the next (the "good" carb appears to respond to the manifold vacuum more faithfully than the "bad" carb by having an undershoot on the air valve drop as the throttle closes)