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MG MGB GT V8 Factory Originals Technical - MG V8 3500 Oil Pressure
|I recently took delivery of a 1975 Factory MGB GT V8. The only modifications I can find are electronic ignition, k & N air filters, and aftermarket headers. The Odometer reads 98,000 miles which is consistent with the condition of the car. It goes like hell. No squeaks or rattles.|
My question is what oil pressure should I be running at idle and at 3000 rpm? There is some valve train noise when it is started from cold. Nothing to major.
After about 4 seconds, it quites down.
Thanks for any input.
|My newly rebuilt '63 Buick 215, similar to the old 3500 V8 runs at 50 psi at idle. No enlarging of the oil passageways but I am running a high volume oil pump. I haven't checked what it is at 3000 yet.|
|42psi at revs (all temps) - 34 at idle (cold) down to 20 ( California daytime). |
The system works on volume rather than high pressure. Change; the oil at 3000m (use cheapo 20-50 high detergent) - the rad when it get tired and the fans before they pack up and it will cope with 110 degrees Fahrenheit and give you another 150,000 miles.
discerning choice - enjoy!
|Thanks for the responses. The guage reads 45 to 50 lbs cold and about 45 lbs warm. Idle has been about 30 lbs. I will keep the oil changed and look after the fans. I run a few small 1293 Minis and they behave well in our Valley heat. One does watch after the cooling systems in this part of the world.|
|Those readings seem a bit high to me, everything I have read and seen say 42 which is why Roger was as specific as that. A maximum pressure running and a minumum at hot idle is one thing (OK, two) but a better indication of engine wear is how much you have to rev it to get 42 when hot, I have heard of 2k, mine is worn and higher than that. There is also 'hot idle' and 'hot idle'. I can go for a blast down the motorway on a 90 degree day come to a stop and idle and it can be between 25 and 30. But leave it long enough stuck in traffic with the fans cutting in and out and it can drop to 15. I believe the higher idle pressure immediately after a run is the effect of the oil cooler. Mine would idle in the red on a 95 degree day, with no other untoward effects other than a slightly rough idle, 'cured' with a smidgen of fast idle which also helped keep the revs up. I tried an uprated rad (same external physical appearance and dimensions) which helped a bit but not as much as I hoped. The biggest benefit came from work on the fan electrics - not only making sure there were no volt-drops en route including in the relay, but by providing an additional local ground from where each fan mounting bracket bolted to the slam panel and a thick brown direct from the apare alternator output spade to the spare 12v spade on the relay. On a 90 degree day I shut the car in the garage and got the ambient going in through the grill up to 106 and the temp needle didn't get more than 2/3rds the way from N to H, fans running constantly.|
|My oil pressure readings listed above were from memory. I just took delivery of the car and have only driven it twice. About 4 miles each time. Just around a large country block. I still need to get the car registered. Once registered, I will list more accurate numbers. I wanted to know what "normal" was. I did not want to run the car if the pressure was low. I go home from work at night and look at the car in the garage. It will take about two weks to get the car registered. The wait is horrible.|
|..and you may experience some oil consumption. Dont worry until it gets to 1% of fuel consumption.|
|Now that's something I don't consider I have (I'm assuming the '1% of fuel consumtion' is a joke but the general principle not) and am surprised considering the 180k miles it has done, at least 80k since any major work. Mine does about 3k miles from Max to Min, but usually I only let it get about half-way down. In the early days it did seem to me to be noisier when down near Min, on previous cars it had never bothered me. Whether it is just loss of sound damping with the lower level or something more sinister I didn't wait to find out.|
|The oil was at the max level when I took delivery of the car. I will record the milage and see how long it takes to get to the min level. Intersting to hear that people get high milage out of these engines. At the rate I am going the car will last a long time.|
|I believe I remember why my oil pressure is at 50 psi...when I installed the HV oil pump, I also fitted the 50 lb relief valve spring. Think this would do it?|
This thread was discussed between 24/11/2003 and 02/12/2003
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