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| Engine oil weight suggestions for running under load at idle https://www.slantsix.org/forum/viewtopic.php?t=66286 |
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| Author: | Jase [ Tue Nov 09, 2021 6:12 pm ] |
| Post subject: | Engine oil weight suggestions for running under load at idle |
Took my first adventure in the slant powered M37 this afternoon. I skipped over the usual shake down cruise type adventure and went right to the wood lot. Really only engaged the front axle for the low range and slower travel speed it provided. Twice while idling along the wood road, first gear, low range, the engine almost stalled due to terrain changes on this very unimproved path. I can't say I that the engine was lugging much as it responded easily and quickly to the throttle. Yet the oil light flashed on for an instant, on two separate occasions. No idea what the RPM's dropped down to, but tone of the engine had that "gonna stall" quiet absence of sound. Maybe my idle speed is a bit too low... but I am wanting as slow a ground speed as possible. While the woods path is not rough, there are some very low cut stumps, and occasional rocks to lumber over. I don't know if this engine is whupped or not, It looks fairly clean on the top end when I was adjusting the valves. The oil pan had some sludge, but no obvious glitter. At present the sump has 5W-30 in it. I am thinking my idle speed Is too low, and I will look at that.. My question is: IF the engine is whupped, and the clearances are loose, what oil would be best to use for the purpose of protection at and or just above idle speed? I have no problem with doing a rebuild on this engine at some point, but NOT this winter.. I guess I should hook up a mechanical oil pressure gauge to get a bit more insight as well. |
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| Author: | cpslntdchrg [ Tue Nov 09, 2021 6:28 pm ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
I remember reading that 1 bbl carbs might not like much shaking and changes of attitude. Do you have a Holley 1920? Is the carb ok? (Float level? Float spring? Carb reservoir baffle?) |
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| Author: | Jase [ Tue Nov 09, 2021 7:13 pm ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
Quote: I remember reading that 1 bbl carbs might not like much shaking and changes of attitude. Do you have a Holley 1920? Is the carb ok? (Float level? Float spring? Carb reservoir baffle?)
It's a Holley 1945. I don't like it much, but at the speed I am traveling there is not much jouncing about.. There are some somewhat steep up and down grades which it did fine with.
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| Author: | Charrlie_S [ Wed Nov 10, 2021 4:21 am ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
I would run 10-30 oil. If you have the stock OEM oil pump on the engine, using aftermarket replacement pump, will give more oil voluum at low RPM. I don't normally like the aftermarket "high voluum pump" (C-66HV), but in your case (low RPM) That pump should work, if your engine already has a standard aftermarket replacement pump on it. |
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| Author: | Jase [ Thu Nov 11, 2021 4:07 pm ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
Quote: I would run 10-30 oil. If you have the stock OEM oil pump on the engine, using aftermarket replacement pump, will give more oil voluum at low RPM. I don't normally like the aftermarket "high voluum pump" (C-66HV), but in your case (low RPM) That pump should work, if your engine already has a standard aftermarket replacement pump on it.
Thanks Charrlie, for the recommendation of 10-30 with a stock pump, and detailed options above and beyond what I thought I was asking for. I appreciate your sharing of suggestions that could actually band-aid the low oil pressure at idle issue. I slept on your advise and realized I should try a mechanical gauge first, and then look at the pressure relief valve if needed. It has about 50 PSI at idle, and I never saw it go lower than 22 PSI idling at 600 RPM when warm. Not sure those are great numbers, but I was expecting half that, or worse. I am smart enough to know better than to trust the idiot light.. and now I have numbers to work with so I can compare what 10-30 produces. |
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| Author: | Charrlie_S [ Thu Nov 11, 2021 5:19 pm ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
Quote: Quote: It has about 50 PSI at idle, and I never saw it go lower than 22 PSI idling at 600 RPM when warm. Not sure those are great numbers, but I was expecting half that, or worse. I am smart enough to know better than to trust the idiot light.. and now I have numbers to work with so I can compare what 10-30 produces. |
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| Author: | Jase [ Thu Nov 11, 2021 7:21 pm ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
Quote: If those are your actual numbers, I wouldn't change a thing. They are very good. |
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| Author: | Dart270 [ Fri Nov 12, 2021 4:55 am ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
Yes, I would not touch it. You are in great shape. Any momentary loss of pressure will be compensated by films of oil that stick around long enough, esp with today's oils. 22 psi at 600 RPM is excellent. I guess the light is only going on when it's almost about to stall? Lou |
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| Author: | Jase [ Fri Nov 12, 2021 6:16 am ] |
| Post subject: | Re: Engine oil weight suggestions for running under load at idle |
Quote: Yes, I would not touch it. You are in great shape. Any momentary loss of pressure will be compensated by films of oil that stick around long enough, esp with today's oils. 22 psi at 600 RPM is excellent. I guess the light is only going on when it's almost about to stall?
Yes, the light goes out quickly on start up, and I've only seen it blink twice for an instant, at just above a stall RPM what ever that is. Lou I was quick to assume that it was operating at 10-12 PSI at idle and became worried that crawling along in that manor would wipe out the bottom end if I did it for any length of time. My woods roads are as narrow as can be and mostly unimproved, so slower is always better. Thus most of the corners and tricky sections are at idle, and usually with the throttle in the closed position, but there are times when it needs just a little more air/fuel to grunt through or over something.. it is those moments that worried me. I am relieved that 22 PSI is good for idle, and I will leave the 5-30 in it. Thanks Lou, |
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