Oil pressure at idle
 

I have a 283 that I just rebuilt and put all new goods in it, oil pump included. At idle I'm gettin' about 20PSI. This seems low to me. At cruising speeds it runs in the high 40s. Does anyone know what ranges I should be seeing. I know I'm runnin' high RPMs on the freeway, 3 speed Saginaw with (at my estimate) a 3.73 gearing.

Speaking of gearing, In 3rd at 65 I'm doing about 3200 RPMs. I have 31" tires. I did the one tire rotation and marked the driveshaft. Came up like 3.73. With stock diameter tires wouldn't this be in the 4s? Say 4.11 or so?

Thanks,
JD

Re: Oil pressure at idle
 

That sounds fine to me. In the "Truck Data Book" from 1969 it says (for the small blocks) "Normal pressure (psi): 30@ 1170-1200 RPM"
I've seen other sources say 10 lbs per 1000 RPM,and yet others say other things,but 20 at idle is real good imo.

Re: Oil pressure at idle
 

BTW,I've got 3.73 gears and 31" tires(235/85/16s) and in high gear I'm doing 60 at 2500 RPM and 75 at 3100 RPM.If you had 4.11s you would be 2755 at 60.

Re: Oil pressure at idle
 

The newer engines do not even have a spec for idle pressures. They only test them at 1500-2000 rpm. I believe that the oil pressure lights come on when pressures get below 3 psi. The pressures you are getting sound fine to me. My 283 runs about 15-20 psi cold idling and about 45 psi cruising at 50 mph.

Re: Oil pressure at idle and gear ratio
 

Thanks guys. My tach reads about 3200 at 65 and like I said, that's with 31" tires in 3rd! Maybe my tach's not reading right but I did get around 3.75 driveshaft rotations per one tire rotation. Now with standard diameter tires this ratio would go up but it sounds like lower gear than even 4.11?????

What where the standard gear ratios offered in 67 on the LWB, 3-speed Sag with the 283?

Re: Oil pressure at idle
 

I don't know but I have a tach that reads way too high. They did make a lower gear than 4.10 but you would definitely be buzzing at 75 or even 65.
Check the ratio again carefully (turn the wheel and multiply the DS revs by 2 with an open diff.and one wheel stationary). Temporarily hook up a shop tach and check your accuracy too.