Low oil pressure after rocker change
Discussion
There have been two posts recently regarding lower oil pressure after changing the rockers. I started my 96 Griff to run the cam in today and am experiencing lower than normal oil pressure.
topic1
topic2
pressure is:
abt 25 PSI cold at 2000 rpm: used to be 40 psi before rocker change
abt 15 PSI warm at 2000 rpm: used to be 30 psi before rocker change
abt 10 psi warm at 1000 rpm: used to be 20 psi before rocker change
I will try the old shafter/rockers, however this seems to be an every increasing issue.
Any comments
topic1
topic2
pressure is:
abt 25 PSI cold at 2000 rpm: used to be 40 psi before rocker change
abt 15 PSI warm at 2000 rpm: used to be 30 psi before rocker change
abt 10 psi warm at 1000 rpm: used to be 20 psi before rocker change
I will try the old shafter/rockers, however this seems to be an every increasing issue.
Any comments
You should check the oil supply hole in the head / rocker gear.
Check the size of hole in the old rocker gear vs new. You might have had a flow restrictor in the old and not known it purpose..
When fitting Kenne Bell replacement rocker gear we are encouraged to fit a restrictor to the oil flow to the valve gear - so the cam gets more oil !
I'll have a look for the bit of paper specifying the hole size.
Found it - it recommends rotating the pedistal shim so the oil feed is blocked. Then drill a 0.065" inch hole..
Check the size of hole in the old rocker gear vs new. You might have had a flow restrictor in the old and not known it purpose..
When fitting Kenne Bell replacement rocker gear we are encouraged to fit a restrictor to the oil flow to the valve gear - so the cam gets more oil !
I'll have a look for the bit of paper specifying the hole size.
Found it - it recommends rotating the pedistal shim so the oil feed is blocked. Then drill a 0.065" inch hole..
Edited by rev-erend on Friday 27th November 13:35
From what I can gather it seems to be bit of a minefield and the 'bad batch' of alloy rockers was just the tip of the iceberg? Recently someone asked about replacements and I suggested going to V8D to make sure they got 'matched' rockers & shafts, IIRC the reply was that they weren't fully confident in supplies they were getting!
If it was me I'd fit decent used rocker arms on new shafts, I have a couple of sets locked away if I ever need them for the Landy..
Recent posts seemed to suggest that there was some slightly different tolerances between arm bushing and shaft diameters, but more apparent visually it seemed there was a bigger/deeper groove in the arm bushing IIRC. I can only assume that it is the clearance twixt bush & shaft that affects the divergence in oil pressure? Apart from swapping bits to get a better a tolerance the only solution I could envisage would be to use thin shims each side of the arm to try and stop the oil pissing away? I'm not keen on the 'historic fix' of restricting oil supply at the head/pedestal as it seems to me that the pressure is required to make the arm bush 'float' IYSWIM.
Nowt's ever simple is it?
This is probably why lots of folks will be encouraged to install steel rockers, or even uprated roller rockers in the future. It is kind of worrying in a way that the supply chain has obviously been compromised - is it the effect of LR ownership ie BMW, Ford... Not the kind of support we have come to expect from LR's, but then again we are using the engines in a way and to a state of tune that doesn't really knit with the LR remit?
PS Al, I think a lot of the confusion with the KB's is due to the design including the oil passages to the rocker tip and pushrod cup. I do use the hollow pushrods, and have pedestals that 'fit' the rockers.. Seems several installation 'methods' have been used - even machining the arms down to fit on std pedestal & shafts???
If it was me I'd fit decent used rocker arms on new shafts, I have a couple of sets locked away if I ever need them for the Landy..
Recent posts seemed to suggest that there was some slightly different tolerances between arm bushing and shaft diameters, but more apparent visually it seemed there was a bigger/deeper groove in the arm bushing IIRC. I can only assume that it is the clearance twixt bush & shaft that affects the divergence in oil pressure? Apart from swapping bits to get a better a tolerance the only solution I could envisage would be to use thin shims each side of the arm to try and stop the oil pissing away? I'm not keen on the 'historic fix' of restricting oil supply at the head/pedestal as it seems to me that the pressure is required to make the arm bush 'float' IYSWIM.
Nowt's ever simple is it?
This is probably why lots of folks will be encouraged to install steel rockers, or even uprated roller rockers in the future. It is kind of worrying in a way that the supply chain has obviously been compromised - is it the effect of LR ownership ie BMW, Ford... Not the kind of support we have come to expect from LR's, but then again we are using the engines in a way and to a state of tune that doesn't really knit with the LR remit?PS Al, I think a lot of the confusion with the KB's is due to the design including the oil passages to the rocker tip and pushrod cup. I do use the hollow pushrods, and have pedestals that 'fit' the rockers.. Seems several installation 'methods' have been used - even machining the arms down to fit on std pedestal & shafts???
Bit naughty but a quote from another site...
at the mention of the BritP word
Tom aka superv8 said:
My measurements: in mm.
After market-
rocker 602154 = 20.62
rocker 602153 = 20.67
shaft 1 = 20.50
shaft 2 = 20.51
Used OE-
rocker HRC 1050 23A = 20.61 horizontal (20.64 vertical)
rocker HRC 1050 24A = 20.62 horizontal (20.65 vertical)
shaft 1 = 20.53 horizontal (20.49 vertical)
shaft 2 = 20.53 horizontal (20.49 vertical)
...
Comparing the shafts the AM actually have the oil holes camfered which the OE hasn't.
...
(then more recently..)
Well I have recieved my new rockers, these are branded Britpart OEM. These others were just rapped in old newspaper. These also have date codes cast into them which is nice, shows they are interested in traceability. The finish of the bore is also much finer and the aluminium looks nicer.
They all measure 20.55mm ID which gives a clearance on my 20.51mm shaft of 0.04mm compared to the non branded ones of 0.11 and the worn OE ones of 0.09mm
So maybe I shouldn't automatically think After market-
rocker 602154 = 20.62
rocker 602153 = 20.67
shaft 1 = 20.50
shaft 2 = 20.51
Used OE-
rocker HRC 1050 23A = 20.61 horizontal (20.64 vertical)
rocker HRC 1050 24A = 20.62 horizontal (20.65 vertical)
shaft 1 = 20.53 horizontal (20.49 vertical)
shaft 2 = 20.53 horizontal (20.49 vertical)
...
Comparing the shafts the AM actually have the oil holes camfered which the OE hasn't.
...
(then more recently..)
Well I have recieved my new rockers, these are branded Britpart OEM. These others were just rapped in old newspaper. These also have date codes cast into them which is nice, shows they are interested in traceability. The finish of the bore is also much finer and the aluminium looks nicer.
They all measure 20.55mm ID which gives a clearance on my 20.51mm shaft of 0.04mm compared to the non branded ones of 0.11 and the worn OE ones of 0.09mm
at the mention of the BritP word This problem was an absolute nightmare for me. It is the oil journals that are cut too deep in the Rockers allowing way too much oil to bleed through.
I managed to get a some second hand HRC-1050 rockers from Ebay and installed these on new shafts and the problem was sorted.
I also asked V8D if they could get hold of decent rockers but the answer was no but they are looking into it so with a bit of luck we should have a good sorce soon.
Using second hand rockers on new shafts is not an ideal solution but it is the best bet at the moment.
Would be realy interested if anyone can source quality rockers.
Chris
I managed to get a some second hand HRC-1050 rockers from Ebay and installed these on new shafts and the problem was sorted.
I also asked V8D if they could get hold of decent rockers but the answer was no but they are looking into it so with a bit of luck we should have a good sorce soon.
Using second hand rockers on new shafts is not an ideal solution but it is the best bet at the moment.
Would be realy interested if anyone can source quality rockers.
Chris
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