Ive taken the 3.9 RV8 lump out of the car for a little TLC, there was a minor oil leak at the timing chain cover which is hard to seal in car so decided now is the time. I bought the engine for £84.00 years ago, put new big end and main shells in it and have run it without much grief for 20 + K miles.
The compression tests indicate between 12.5 & 13.5 Bar so I'm not touching the bores but the oil pressure on startup is 30psi but drops to near sod all when hot below 1500rpm, and when in top gear at 30 mph the engine is only doing about 950 rpm. So the crank is out, looking worse for wear, and is away to Dumfries for a much needed regrind.
The engine has probably 140 K miles on it and being a Rover V8 would probably run on for long enough without any work, but I bought a couple of heads for £60.00 2 years ago, ported and flowed them and replaced the guides and springs so the whole lump is getting worked on.
Its got hydraulic tappets and the spacing (preload) is created by inserting shims between the rocker pedistals and the head, so a complete bank of inlet and exhaust valves have a 'mean tappet space' within a specified tolerance (0.4 - 0.6 thou). All the pedestals have the same thickness of shim so there is no twist in the rocker bar. I checked the lengths of the pushrods and there was a variance in lengths of up to 1mm which would have produced wild preload spacings so the pushrods have now been fettled to be within a few thou of each other.
The tappet spacings must have been all over the place, so hopefully that adjustment together with carefull attention to achieving good preload spacing will see a better low rev running.
John
The compression tests indicate between 12.5 & 13.5 Bar so I'm not touching the bores but the oil pressure on startup is 30psi but drops to near sod all when hot below 1500rpm, and when in top gear at 30 mph the engine is only doing about 950 rpm. So the crank is out, looking worse for wear, and is away to Dumfries for a much needed regrind.
The engine has probably 140 K miles on it and being a Rover V8 would probably run on for long enough without any work, but I bought a couple of heads for £60.00 2 years ago, ported and flowed them and replaced the guides and springs so the whole lump is getting worked on.
Its got hydraulic tappets and the spacing (preload) is created by inserting shims between the rocker pedistals and the head, so a complete bank of inlet and exhaust valves have a 'mean tappet space' within a specified tolerance (0.4 - 0.6 thou). All the pedestals have the same thickness of shim so there is no twist in the rocker bar. I checked the lengths of the pushrods and there was a variance in lengths of up to 1mm which would have produced wild preload spacings so the pushrods have now been fettled to be within a few thou of each other.
The tappet spacings must have been all over the place, so hopefully that adjustment together with carefull attention to achieving good preload spacing will see a better low rev running.
John
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