[Tiger Paw]

If your filter inspection is good, no debris, I'd check that your ignition timing curve is good. Late timing will cause high exhaust and piston temps. These raise oil temps really high, hence low oil pressure.

[andrewT]

Originally Posted by 70 bird

Change out the break in oil and look for metal/cut filter open. What were the bearing clearances set at?? I have a 351w with .003 bearing clearance that has 15 psi. warm at idle. I have been beating the snot out of that engine with a turbo for 3 years with no problems.

I have been reading posts like this all over other drag racing forums which makes me slightly less worried

Originally Posted by Dragncar

Something is wrong here. My old 455 done in 1990 still has 60-65 lbs during warm up with fresh oil. Has 50lbs hot at idle.
I would cut the filter in half like right now.

Originally Posted by Mike Davis

Who built the engine?
I would ask that person for a recommended oil weight as they should know the clearances.

20/50 is way to thick in todays world.
I run 5/30 RP XPR, 80 Cold, 30 Hot Idle, 70PSI at 7200 RPM.

I built the engine. The clearances were 0.002 with plasti-gage...I don't live in Georgia, 50 is not thick if you want safe operation, at least thats my opinion. I'd rather have thicker oil to save my parts even if it is less than optimal

Originally Posted by JSPONT

Sounds like you have an issue, cut the filter, then fix the cooling system. 240 degrees is way to hot.

small leak in rad, stock flex fan, like I said I just had to get the car running to break it in and seat the rings. Kinks need to be addressed still


Thanks fellas, will drain the oil, check the pump and filter and report back!

[78w72]

just my .02 on the oil weight, but 20/50 on a street engine is way too thick, especially with an 80psi pump in a cold climate. whats causing your low pressure i dont know & hope you figure it out, but most people will agree that 50w oil is just robbing power & causing undue stress on the pump rod. 10/30 or 40 will provide all the film strength most engines need.

but more important & contrary to your statement of, "50 is not thick if you want safe operation, at least thats my opinion. I'd rather have thicker oil to save my parts even if it is less than optimal." thick oil, especially in colder temps does not flow very well & causes wear at startup & under load because it doesnt flow through the bearings & cool as well as thinner oil. flow/cooling is more imnportant than thickness for most engines... & unless this is a pure drag race engine i would re-consider the 50w. maybe try a good 10/40 or even a 15/40 diesel oil that has higher zddp.

but if you need to rely on 20/50 to get 20psi at hot idle, then i think there is something else going on, but hopefully its the break in oil casuing the low psi. change the filter & try 10/40, if you have good psi, thats all thats needed, thicker is not better. best of luck!

[Stormin]

Hi Andrew

Thanks for the compliments on my car.
It was a long project and of course.. never finished.
Really missing you at Norwalk! That was a lot of fun! Hope you make it there this year with us... the plan is to bring my car as we brought John's pile of bolts there last year.

As for your car... would be good to know for sure what oil pump you put in there...
and a good rule of thumb too really is... to have 10 lbs of oil pressure for every 1,000 rpm.
It would still be good to check for issues... ie.. cut open oil filter.. check for debris.. but.. you may not be far from where you need to be after you do oil change.. and yes.. definintely get the cooling issue under control!!!

you have my number? phone me sometime.. let's catch up!
Will take you out for an "Italian sausage".. hahahaha
I'll buy!
Maybe we'll drag John out with us!

talk soon
NB

[charlie66]

There is nothing wrong with using 20/50 weight for street use. I have been using 20/50 for 30 years . I never had any of these problems described in this thread with using it.. In cold weather all you do is warm the engine up longer. What do you think happens when it warms up? It gets thin.. What do you think happens to the 10/30 oil as it warms up , it gets even thinner! Thicker oil will stay thicker as it gets broken down compared to the thinner stuff.When the clearances in your bearings are .0025 - .003 its ok to use 20/50. These motors are from the 60's and 70's. What do you think all the racers used back then? Straight 50w - 20/50 all the time. Well its the same motor today as it was back then . So using the same oil would be the thing to do today..

[78w72]

Originally Posted by charlie66

There is nothing wrong with using 20/50 weight for street use. I have been using 20/50 for 30 years . I never had any of these problems described in this thread with using it.. In cold weather all you do is warm the engine up longer. What do you think happens when it warms up? It gets thin.. What do you think happens to the 10/30 oil as it warms up , it gets even thinner! Thicker oil will stay thicker as it gets broken down compared to the thinner stuff.When the clearances in your bearings are .0025 - .003 its ok to use 20/50. These motors are from the 60's and 70's. What do you think all the racers used back then? Straight 50w - 20/50 all the time. Well its the same motor today as it was back then . So using the same oil would be the thing to do today..

im sure 20/50 is ok for most engines, it wont make the engine blow up, but just because you used it for 30 years doesnt mean its ideal for an average "street" engine... it robs power & causes stress on the pump rod & cam/dist gears etc. & more important it doesnt flow & cool as well through the bearings.

as for the, "What do you think happens when it warms up? It gets thin.." that is not true.. multi viscosity oils dont get thinner when they warm up, they get thicker as far as "pumpability" is concerned, whcih is what the engine sees. the numbers of 10w40 for example are the cold & hot weights of the oil... when cold it pumps as a 10 weight, when at operating temp it pumps as a 40 weight. yes it "looks" thinner when you drain it hot but thats not what matters inside the engine.

& cold weather initial start up is what causes the wear with too thick of oil... "In cold weather all you do is warm the engine up longer." that is the worst thing you can do, let a cold engine idle to warm it up with super thick molasses flowing oil.

the rule i have always followed & is what my & many other engine builders suggest is, you want to pick an oil weight that provides adequite psi for your engines intended purpose... full on race with loose clearances a thicker 20/50 is ok... for a more street type engine with .002 (like the OP has) 20/50 is not needed... especially in canada!

do a quick google search or do some oil research & you will see that hot oil is not thinner as far as the engine is concerned & too thick of oil than whats needed is not a benefit in any way. oil debates can & usually will become never ending so i was just stating my opinion thats based on research ive done & what ive been told for many years by people that do this for a living... i will leave it at that.

[JSPONT]

Oh lord another oil debate. Not all oils are created equal. 10/30 or 20/50, they all have different pour rates also. Do some research.
The oil is NOT the problem with your engine. CUT YOUR OIL FILTER AND INSPECT. It will tell you a story. 2 thousands is a little tight but plastic gauge is not perfect either.

[charlie66]

Originally Posted by 78w72

im sure 20/50 is ok for most engines, it wont make the engine blow up, but just because you used it for 30 years doesnt mean its ideal for an average "street" engine... it robs power & causes stress on the pump rod & cam/dist gears etc. & more important it doesnt flow & cool as well through the bearings.

as for the, "What do you think happens when it warms up? It gets thin.." that is not true.. multi viscosity oils dont get thinner when they warm up, they get thicker as far as "pumpability" is concerned, whcih is what the engine sees. the numbers of 10w40 for example are the cold & hot weights of the oil... when cold it pumps as a 10 weight, when at operating temp it pumps as a 40 weight. yes it "looks" thinner when you drain it hot but thats not what matters inside the engine.

& cold weather initial start up is what causes the wear with too thick of oil... "In cold weather all you do is warm the engine up longer." that is the worst thing you can do, let a cold engine idle to warm it up with super thick molasses flowing oil.

the rule i have always followed & is what my & many other engine builders suggest is, you want to pick an oil weight that provides adequite psi for your engines intended purpose... full on race with loose clearances a thicker 20/50 is ok... for a more street type engine with .002 (like the OP has) 20/50 is not needed... especially in canada!

do a quick google search or do some oil research & you will see that hot oil is not thinner as far as the engine is concerned & too thick of oil than whats needed is not a benefit in any way. oil debates can & usually will become never ending so i was just stating my opinion thats based on research ive done & what ive been told for many years by people that do this for a living... i will leave it at that.

It does not matter what the multiviscosity oil is, at the operating temperature the viscosity is going to be lower than the starting viscosity temperature. The multiviscosity oils have viscosity index improvers that allow the oil to resist a change in viscosity due to the increase in temperature. What this means is that the change is a gradual lowering of the viscosity rather than a large drop off at higher temperatures. With that the decrease in overall viscosity means that there is less torque against the oil drive shaft, and if it was an issue which its not, that's why they make the hardened steel pump shafts. Ive been using them for a long time now with zero issues..

[GTO FIREHAWK JOHN]

Hey Andrew, let's get together maybe Californias! for Sandwiches on Norm!!!!

I run 20/50 VR1 Valvoline in mine from Napa. You'll have to add the zinc additive as yr aware of. And I put 15/40 now when the weather gets cold. I have the Butler pro 80lb pump & it hit 100lbs when cold!

John

[78w72]

Originally Posted by charlie66

It does not matter what the multiviscosity oil is, at the operating temperature the viscosity is going to be lower than the starting viscosity temperature. The multiviscosity oils have viscosity index improvers that allow the oil to resist a change in viscosity due to the increase in temperature. What this means is that the change is a gradual lowering of the viscosity rather than a large drop off at higher temperatures. With that the decrease in overall viscosity means that there is less torque against the oil drive shaft, and if it was an issue which its not, that's why they make the hardened steel pump shafts. Ive been using them for a long time now with zero issues..

im aware of what viscosity improvers are & how they work... what im saying is that a 20/50 oil in a engine with tight clearances is simply not needed & can cause other issues compared to a thinner oil. you dont just let an engine idle to "warm up" too thick of an oil. wear happens at startup & a thicker oil just increases that. when hot, too thick of an oil doesnt flow & cool as much as a thinner oil. & oil flow is more important than oil thickness if its the proper weight to get adequite psi for any given engine. that is a fact.

im not suggesting to use a 0 or 5/20 weight oil, but anything thicker than whats needed for the engine to have good psi is not needed. yes a hardened rod will be stronger if needed, but the other issues are still a concern. ive seen many twisted pump rods & heard of them actually breaking, so there is undue force with thicker oils, to me that is a concern... why would you use thicker oil than needed in any engine?

the OP needs to look at other things like the filter & possible debris holding the check ball open etc. aside from that there may be other issues going on causing low psi. i dont know what purpose this engine is for, but for any street use & even some racing, it should not require 20/50 to get good psi & using 20/50 to mask the issue with .002 clearances should not be needed & is not the answer IMO.

[Elarson]

I threw together a little chart on actual oil viscosities at different temperatures. All data is for Valvoline oil.
Viscosity Index is a rating of viscosity change vs. temperature. It sounds backwards.....a higher VI means there is less viscosity change for a given temp change.
Viscosity is expressed in centistokes. A smaller number is "thinner" and easier to pump.

Surprisingly...note that racing oil has a better VI than it's equivalent conventional oil.

Enjoy,
Eric

[Elarson]

Originally Posted by 78w72

.... it should not require 20/50 to get good psi & using 20/50 to mask the issue with .002 clearances should not be needed & is not the answer IMO.

agree

Eric

[charlie66]

Originally Posted by 78w72

im aware of what viscosity improvers are & how they work... what im saying is that a 20/50 oil in a engine with tight clearances is simply not needed & can cause other issues compared to a thinner oil. you dont just let an engine idle to "warm up" too thick of an oil. wear happens at startup & a thicker oil just increases that. when hot, too thick of an oil doesnt flow & cool as much as a thinner oil. & oil flow is more important than oil thickness if its the proper weight to get adequite psi for any given engine. that is a fact.

im not suggesting to use a 0 or 5/20 weight oil, but anything thicker than whats needed for the engine to have good psi is not needed. yes a hardened rod will be stronger if needed, but the other issues are still a concern. ive seen many twisted pump rods & heard of them actually breaking, so there is undue force with thicker oils, to me that is a concern... why would you use thicker oil than needed in any engine?

the OP needs to look at other things like the filter & possible debris holding the check ball open etc. aside from that there may be other issues going on causing low psi. i dont know what purpose this engine is for, but for any street use & even some racing, it should not require 20/50 to get good psi & using 20/50 to mask the issue with .002 clearances should not be needed & is not the answer IMO.

Looking at the graph, starting at the left , you have the scale of viscosity. Looking at the bottom of the graph you have the temperature at which the oil viscosity is measured at. In the center of the graph you have a map of several different oils, some are straight weight/viscosity oils(SAE 50,40,30) and others are multi-weight/viscosity oils being measured. And on the right is the color coded lines for each oil listed on the graph.

So reading the graph from left to right (starting temperature 40®c/104®f) we see that the oils have a fairly wide spread in the viscosity values for each. As the oils become hotter the viscosity is going to decrease, and it doesn’t matter whether it is single weight or multi-weight, the value is going to decrease. This means that the overall internal friction of the oil decreases with the thinning out of the oil, and the overall pumpability improves decreasing the stress on the oil pump drive components.

The advantage of the multi-weights is the rate of change in viscosity due to the temperature change is much less, as proven on the graph. So you get better oil mobility in cold temperature extremes. Now as the heat kicks comes in we see that the viscosities of the oils do not vary by much at all, so overall power robbing of the “thicker” oils is not as great of a concern as you think. A lot of that was done by the engine manufactures for fuel mileage concerns, because they are EPA regulated to meet certain standards. So that small difference doesn’t mean a whole lot on an individual car basis, but when you use that energy savings over 500,000 cars then the number becomes more significant . So the overall horse power robbing is not really that significant at operating temperatures.

[70 bird]

Charlie, just turn the boost up .2 psi, and you can forget about the power loss.

[charlie66]

Originally Posted by 70 bird

Charlie, just turn the boost up .2 psi, and you can forget about the power loss.

Lol! Very true....

[andrewT]

Thanks for all the advice

Although I am in Canada this is not a winter ride...I was unable to beat the cold temperatures here and will have to wait for warmer weather to get back to diagnosing this as unfortunately I don't have a heated garage/shop to work in