Poorly running rover V8 3,5 with SU HIF

[petervdv]

I have a problem with my Rover V8 from an SD1. The engine has been overhauled (new bearings, valves, oil pump, camshaft, lifters, piston rings and valve guides). It is equiped with 2x HIF. The problem is, it does not pull well and is misfiring now and then. Swapped the ignition (amplifier, coil) and leads, plugs ect and this does not improve things. Did scheck the compression ratio and this is good on all cilinders.
I am thinking it is in the HIF carbs. I rebuild these with new shaft, bushes, needles and jets.
If i use the lifting pin trick on the carbs, one is reacting normal and the other is not. If i lift the piston the engine revs gets higher and what ever on adjusting the bolt, t does not change its behaviour. It always revs higher if i lift the pin.
I checked the float levels and how the jets are fitted and this all seems oke.
Thanks for your thoughts in advance
Peter

[ChrisJC]

Is there an air leak somewhere?

Chris.

[petervdv]

Thanks for your reply Chris. I also thought about an air leak and replaced the large vally gasket as it was a bit deformed due to a back fire. Also replaced the airfilters as these were also damaged during the back fire. I recently removed the carb from the inlet manifold to check the float level and checked all nuts on the studs. What kind of leaks did you have in mind. Brake booster?
The original elbows are fitted with the original airfilter housing and therre is a connection for LPG fitted in the elbows

[ChrisJC]

I guess it could be any of the ports on the inlet manifold or carbs(if present). Brake booster, vacuum takeoff for autobox, crankcase ventilation, vacuum to distributor. Probably all could be blanked off for testing.

I would remove everything I could just to eliminate it. Just have inlet manifold + carbs. Then if one carb is still different to the rest, it must be manifold or carb (or joint between the two!). Maybe there is a small port that is open that you have missed?

Chris.