Pressure vs. time

[BigBlueIron]

No this isn't about a Cummins PT pump, thank god lol.

Oil pressure, how long from engine start until you see the gauge physically move??  I'm curious how my 390 compares to the average.

[jayb]

In my experience that depends a lot on the size of the line coming from the engine to the gauge, and the length.  Also temperature can play a big role.  In general, a longer line will delay the reading longer than a shorter line, a smaller diameter line will delay the reading longer than a larger diameter line, and cold temperatures will also delay the reading longer.  For my cars which generally use a #4 AN line about 5 feet long, in the summer the response is 1-2 seconds.  A while back I had one of those small copper lines with lots of twists and turns in it, making it about 8 feet long, and that one would take up to 4-5 seconds to show movement in the summer.  Also, the needle didn't move up the scale very fast with that one; might take 10-15 seconds to reach 50-60 psi.

[BigBlueIron]

Absolutely, sorry I omitted what line I'm using. Currently it is the small copper line but plan to up it to -3 or -4. Standard pump, horizontal filter mount.

The reason for this question is I have 2 turbos on this engine with 1/4" hyd line for oil supply. one about 5' and 3' for the other. I have this gut feeling that on initial start up I'm starving the engine for oil trying to fill all of those empty lines. After it had sat for a week or so I started it up and counted to 10 before the needle moved.... that worry's me. If recently shut off its considerably quicker. Also the last engine in this configuration showed oil starvation on the new cam bearings. (engine swap for other reasons)

Ive thought about adding an Accusump simply for preoiling. I know they recommend 1/2" line but I figure 1/4 would be fine since I'm only concerned with preoiling? But that is money not currently available. So thought about adding a check valve to keep those large lines full of oil.

 I also dislike the horizontal filter mount but it fit the chassis like it was made for it, 1950 F1. Any negatives to that style of mount??  Always used the vertical mount whenever possible, I like the idea the oil won't drain out no matter what even though it shouldn't anyway.

[e philpott]

I crank my chokeless carbs for about 4 seconds before the oil pressure gage needle starts to move , then pump three times and start it up , once started it takes my gage a couple more seconds to get past 60 psi

[mbrunson427]

Sounds like a scenario that requires a Melling HV pump, rather than the standard volume pump, just to make sure you have enough capacity for everything you've added.

Check valve idea doesn't sound like a bad one at all.
https://www.summitracing.com/parts/vpe-11190?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-vibrant-performance&gclid=Cj0KCQjwx43ZBRCeARIsANzpzb8XamWsS0WLLrY0DEzNlfQDq1B1EVdHMjjDrIn_b9YQGHSRTv_dB-YaApOTEALw_wcB

[fryedaddy]

I noticed something else that comes into play.it takes thicker oil longer to register too.i used some straight 50 weight once and it took forever to move the gauge vs 10w30

[fekbmax]

Oil accumulator.  Great addition to any of these old engines.  Mild to wild.

[cjshaker]

Oil accumulator.  Great addition to any of these old engines.  Mild to wild.

This ^^^
Pre-oil everything before it even turns over. That will eliminate any possibility of dry starts.

[gt350hr]

   Using the -4 line like many of us do also makes the reading more "sensitive" to pressure changes.

[BigBlueIron]

Sounds like a scenario that requires a Melling HV pump, rather than the standard volume pump, just to make sure you have enough capacity for everything you've added.

Check valve idea doesn't sound like a bad one at all.
https://www.summitracing.com/parts/vpe-11190?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-vibrant-performance&gclid=Cj0KCQjwx43ZBRCeARIsANzpzb8XamWsS0WLLrY0DEzNlfQDq1B1EVdHMjjDrIn_b9YQGHSRTv_dB-YaApOTEALw_wcB

I had inquired about a HV pump for this application sometime back, when I had the pan off. A few of the resident pro's said the standard would be just fine. So that's what I used if I would have had a HV available I would have used it. I think I will add a check valve might not make any difference but I can't see any negative effect.

I noticed something else that comes into play.it takes thicker oil longer to register too.i used some straight 50 weight once and it took forever to move the gauge vs 10w30

True, I will also be going to a 20w50 in attempt at a little more hot oil pressure. This engine is "worn in" addition of 2 more leaks cant be helping. Plans for a fresh engine are in the future but this one gets me driving.

Oil accumulator.  Great addition to any of these old engines.  Mild to wild.

Agreed, and as mentioned I want one but funds are going to other areas right now, like a windshield! lol


Thanks for everyone's replies.

[gt350hr]

  Cam bearings can be "hurt" by a timing chain that is too tight I fixed a 289 that had four sets of cam bearings in it in less than 100 miles of use ! Instead of "prying on" the timing gear with the tight chain , I used one with a touch of slack and the engine has been running/racing for SIX years since. Gerotor pumps like Ford uses are very efficient at pumping oil . If you have pressure , oil is flowing. Too many think oil pressure alone keeps metal to metal contact from happening. There is more to it than that.

[wayne]

You can run a kill switch and turn it over until it gets pressure then start it i see a lot of people do this.

[BigBlueIron]

  Cam bearings can be "hurt" by a timing chain that is too tight I fixed a 289 that had four sets of cam bearings in it in less than 100 miles of use ! Instead of "prying on" the timing gear with the tight chain , I used one with a touch of slack and the engine has been running/racing for SIX years since. Gerotor pumps like Ford uses are very efficient at pumping oil . If you have pressure , oil is flowing. Too many think oil pressure alone keeps metal to metal contact from happening. There is more to it than that.

No worries of a chain to tight on this engine. I replaced the worn out chain with a low hour used one and it went together very nicely. Also took that opportunity to swap out the incorrect fuel pump eccentric and hardware.

You can run a kill switch and turn it over until it gets pressure then start it i see a lot of people do this.

When I wired the ignition in the truck I kept it the same as stock. Meaning I utilized the original push button starter with a ground to activate solenoid. Which does allow me to crank without ignition if I so wish. I don't like doing that for some reason, just seems wrong to me. But maybe I should try doing it more.