Hello all. My 1952 Chevy has a rebuilt 350 out of a 73 camaro. It usually idles at around 40 PSI at idle when warm, which I always thought was a little high. I was playing with the carb and timing and noticed the PSI jumped to around 65 PSI when the engine was cold and then drop to about 57 to 60 PSI when warm. I have no idea what kind of oil pump or pressure release spring is in it. Should I be worried about this? There are no leaks, well no leaks yet (knock on wood )
So what is the weight of the oil? Thicker oil will not flow well at low temps, pushing up the pressure.
57 to 60 too high? My yblock runs 75 psi cold and drops to 40 psi hot with 20w/50 oil. No leaks, no noises or metal in the pan. Been that way for a few years. I've never worried about too high an old pressure until it starts blowing the oil filter off.
At least 10 lbs. per 1000 rpm as a minimum. To high oil pressure is a myth. I idled 90 psi on a 509 big block that dynoed 1800 hp. The only thing that high oil pressure will do is rob hp.
At 90 psi the oil is most likely being forced through the oil pressure relief valve. The quickest way to heat oil up is to force it through a pressure relief valve. It also tends to shear the viscosity index improvers (polymers added to the oil to give it multi-viscosity performance). Heating oil increases the rate of oxidation (it's a chemical reaction, and according to the Aarehnius rule the rate of a chemical reaction doubles with every 10 degree C increase in temperature). Besides contamination, oxidation is the main limiting factor to the life of engine oil. The fast it oxidizes, the sooner you need to change it, or the acid content starts to attack the soft metals and long chain compounds start to plate out and form deposits on the internal surfaces. Shearing of the VII polymers results in permanent viscosity loss. The multi-grade oil you started with starts to become a mono grade. If all your doing is running 1/4 mile at a time and changing the oil every couple of p***es, no problem. If you're driving on the street that's different.
My thought is, if it is an electric gauge you have a sending unit/wiring problem at the sender. The sender is most likely right next to the distributor so if you were messing with timing when oil preasure increased you were probably moving wires around.
We got 60 here and 10 on the other thread. Simple solution is to average the two and we have 35 for both and everybody can go home happy and get a good nights sleep.
It's the gauge. ...... This is what happens when you don't have air bubbles in your gauge line. I couldn't help it sorry My Buick is 60-90+ when cold and settles to 20-60 when warm. Been this way almost 20 years. High pressure is a little harder on the dizzy gear.
The 331 stroker in my 27 runs at a consistent 70 psi and drops maybe to 50 at idle. Been that way for 8 years now with zero problems. Same with the 355 sbc I had in my 23, it ran at about 60 psi when going down the road, sometimes as high as 80 psi. The new 468 Olds Dan recently got back from the engine builder runs at about 60 psi, and Don's 306 Ford from the same guy runs at about 70. Just depends on how you set them up. I like lots of oil pressure. Don
So just out of curiosity, what's too much pressure in a sbc? My 283 is ******* a 100 lb gauge. I'm tempted to pull it back out and change the hv oil pump to a stocker
No oil pressure relief valve and yes we did change oil ( 60 wt. torco ) every p*** due to fuel contamination so you may be right but that's what`s good about this conversation, everyone has their own opinion and that`s ok
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