flathead oil pressure what grade of oil to run?

i put 20-50 in my roadster and on start up when engine cold i had about40 lb and after running at idle fo 15 minutes or so 10 lb a little higher idle like 12-15 is my oil to thin should i use heaver grade? my motor is old but i'm running it till i build a better one. i ran my car for the first time for a long time today outside it ran pretty good about 165 at idle for 20 minutes but oil pressure thing bothered me also i have an external oil filter on my fire wall will this rob pressure? thanks billy

 

Billy
A fresh flatty only makes about 30lb's at idle. Id say your ok as long as you have any.

 

i do not know what a flathead v8 should run , but the oil is ok . i run in my flat 4 , it has only like 1-3# when hot . 20/50 is good oil ............ steve

 

I run straight 30W Rotella in the Merc. Pressure goes from 50 at a cold start up to 35-30 at speed to damn near 0 at hot idle on the stock gauge. Been like that for 6 years now so it must be ok?

 

ANY flathead oil pressure at idle is good oil pressure.

 

So you guys think i'm ok on the oil pressure? It was like 9-10 lb runnig for 20 minutes when i gave it gas it went up to 12-15 but i wont realy know till i drive it.

 

Hey buuuudddddddddddy, I run only straight 40 or 50# . The thicker the oil the lower MPGs. Check for leaks on the sending unit line. Did you get the pedal welding done?

 

been running mine hard ! for 18 years on castrol 20/50
40 psi till it warms up then 10-15
would not go any thicker unless it`s smoking

 

and my old gauge would show almost no oil pressure after it warmed up ?
check your gauge

 

20/50 in the summer....50 lbs going down the road and 25-35 at idle it drops a bit more the hotter it gets, your car is coming out really great. Oh yea not sure about the oil filter, my roadster doesn't have one, I just change the oil a bit more often.

 

She smokes a little out of the breather/fill tube while running and after shut down . I havent run it on the street yet but i might add some stp to thicken it up a bit. I will run it a little more then drain it then put some 50w in it. Billy

 

Disconnect the oil filter and see what you get, you need a .062 restrictor in the filter supply line. If you don't have one = low O/P.

 

The motor is realy clean inside no sluge. As for the oil line to filter its 1/4 copper in and 1/4 copper out.and the gauge comes right out of the block with copper line no plastic .billy

 

Like I said temp. block off the supply to the filter and see if that makes a diff. If it does you need to put the restrictor fittling in the supply side.

 

Loose the filter, 20w-50 ok you could try Pennzoil 25w-50 racing oil but change oil every 2000 miles or less. Found with flatheads bearings lasted without oil filter if oil changed every 2000 miles.

 

I was told to use a non detergent oil. Anyone else heard this ?