|12/06/2005 21:40:54||Paul||Just rebuilt my 1498 v4 exhaust outlets 44mm, inlets enlarged, lightend flywheel, fourstud manifold, 40 dfi carb, but the oil pressure is low, runs at about 45- 50 then when warm drops to 40 think pump must be worn. Any idea where I can purchase a high pressure oil pump.|
|13/06/2005 08:13:59||Richard||That isnt that low for a std pump. Kent do a high pressure item , see Burtonspower. That will up it to 60psi +, the Saab rally pump spring will take it a bit higher, but this part is unatainable.|
|13/06/2005 10:14:44||Alistair||Had that problem on mine (which had a high pressure pump!), in fact it dropped to under 20 at tickover when warm. Didn't help by putting in too thin oil - I was foolishly using 10W30 semi synth and it leaked from every orifice & pressure was crap. Improved no end when I stuck some cheap 20/50 in...
Rich - can't you just replace the pressure relief valve spring to maintain a higher pressure?
|13/06/2005 13:00:58||Richard||That's what the Saab rally spring is, but you will have to work out the spring rate for the pressure you require. I have thought about cutting some coils off and fitting a spacer, as long as nothing become coil bound that should up the pressure. You can work it out using pressure, force calcs.|
|13/06/2005 15:48:49||Paul||Thanks for reply, problem seems to be that the front left bank rocker cover is running dry. Will try Burtonpower link. Am using 20/50 oil to see if improves but seems to be the same pressure.|
|13/06/2005 21:28:04||Alistair||Might be worth a flush in case there's some crud blocking an oilway somewhere?|
|13/06/2005 22:55:55||John Wood||Have you replaced the camshaft? I would be suspicious about the dry rocker feed. It might be that the central cam bushing which has the oil feed holes has turned and has reduced or shut off the oil feed hole.This happened when I installed my SAH cam back in 1973. Lack of oil very quickly wears out the rocker shaft and the ball end of rocker adjmnt screws. It could also be that the oil way has become reduced and the camshaft requires the spacer bushing to bring the cam oli groove back into alignment with the oil holes. It is difficult to check this alignment with the heads in situ as you cannot see down the oil hole to the bushing.
I did not know it was that difficult to get HD springs for the oil pump. How do you assess the rating? I have one brand new & unused.
|13/06/2005 23:24:40||John Wood||The HD spring usually wangs the oil pressure over to 100lbs/in when cold and drops to around 70-80 when hot. Saab advised that it should not drop below 50-60lbs under load. It's a while since I cranked up my spare engine which is 1498cc with the gas-flowed heads, SAH cam and oil pump of a 1730cc motor that was in my last road going 96( ex Richard Burdon).It also had SAH adaptor plate on standard manifold with 28/36DCD Weber. Coupled to a SAH rally exhaust and it went like a bullet.|
|14/06/2005 08:06:23||Richard||Mine pumps out at 80psi with the Saab spring so that fits with what John is saying. If you have wear in the cam bearings you will lose pressure (or for that matter in any bearing). You can use part of the early V6 cam bearing set for the centre and rear bearings.
As john says you need good alinment of the bearings and oilways in the head. If you have had the head skimmed alot you will need to grind the teardrop shape back in where the oil feed goes also check the rocker supports are inline with the oil feed and not full of rubbish. Check the rockers are not slopply, this will reduce power. If the wear get really bad the push rod lets fly!
|14/06/2005 08:09:42||Richard||John take the spring to a spring manufacturer and ask them to test it, they then should be able to remanufacture.|
|14/06/2005 08:50:08||Kalle Heikkilä||Stiffer spring? I have usen a thin washer (1-2mm) under the spring, and it/they have worked just fine and the pressure is nice too...
Kalle / www.green-beast.net
|18/06/2005 10:31:25||Paul||Thanks for all the help. I will let you know how I get on.|