The oil pressure in my 235 at idle when hot has been getting down to a little over 10 and has me concerned,if it was a 216 I would not worry but thinking it might be time for another crank and bearings. The motor has a little over 10,000 since rebuilt but if I can remember correctly the crank was just polished and not turned.
25-30 going down the road? Check the tube that feeds oil to the rockers. It comes out of the head and goes to the rocker shaft in the middle. Sometimes they break and dump all the oil befoe it gets to the rocker shaft. Sometimes the other tube breaks off and it dumps a lot of oil where it was supposed to be restricted.
The 235 in my 47 does the same thing. I grew up driving 60's era muscle cars that generally had 60psi @ idle, it took some getting used to not just cringe at the sight of the 47's oil pressure gauge.
Last year when I had the valve cover off there was plenty of oil flow to the rockers and using regular 30# oil,before I get too concerned I should hook up a different gauge and see what it is as I am still using the original 1937 gauge made for a 216.
I wouldn't. I'm guessing you are not taking any cross country tours. I drove my old 47 Chevy woody up to Cumberland many many years ago. A 2.5 hour drive for a 3 day show with a used 216 in it of unknown mileage. It started to knock when not under a load on the way back. The young kid riding with me said is that rattle in the dash? I was still an hour from home. It made it. I just kept it in a load and let off completely when it reached cruising speed and then back on the gas for a spell. I have no clue what the oil pressure was but it made it home. I personally don't believe that early Chevy 6 cylinders need a great deal of oil pressre. JMO
Here is something that I just read: Oil Pressure: Adequate oil pressure is about 10 lbs for every 1000 rpm. It's not unusual for some engines to have 5 lbs or less at idle. This isn't as big a problem as it may seem, but you DO need to keep the oil level up to prevent bearing damage. Don't let the oil level get low!! If you're not going to beat the car down a drag strip, these low numbers which are common on worn engines isn't a problem generally.
The motor should not be too worn with just around 10,000 easy miles on it,had it running today and heard a main bearing knock until it got oil so something is loose on the bottom end and I am thinking the crank should have been turned instead of polished. I want to pull the motor and repaint it so I am going to see if I can get a crank kit for it and install it over the winter if it holds togather,whats weird is I hear the main knock when hot unlike other motors that did it when cold or sitting a long time.
I put my Snap on gauge on it last night and the original gauge is correct with a little over 10 at idle,I think the rattle in cylinder #2 is getting worse or another cylinder is getting a rattle so its getting 20 w 50 oil and some STP to keep it going this summer and going to keep it off the highways until I can pull the motor and see whats going on. Next motor I rebuild is going to get the crank turned even if not needed as I dont want this to happen again.
Jeff, I had a 216 in my old panel and ran a qt of Lucas in it at all times. Seemed to help quite a bit with the noises and pressure. I love that stuff.
When I revved it up I could not get it past 35 so there is something wrong,its going to get a quart of some additive to get me by until tear down.
I am wondering if it did not like the oil I was putting in it,I have been using a department stores house brand that the 351 in my 55 sunliner did not like and made some noise on the last Florida trip. 20w50 plus a quart of Lucas and its noticeably more quiet,I can not get the 55 to make the noise again since changing the brand of oil so maybe there is something with this stores house brand oil. The oil pressure is up to 15 hot now and will have to do more driving to see if it still has the main knock when hot,its probably still going to have the rattle in cylinder #2 but its had that before I switched to that oil so time will tell.
This is starting to sound like the old Quaker State days. I knew several guys that thought their engine was taking a dump with it, changed brands and the engine "healed" itself.
That durn Lucas turned all the carbon in my engine loose, I had a stopped up pickup tube and 2in. in bottom pan!
rember when you turn a crank on a 235 you need to add shims to the mains , they really need fitting used to pull the shims on old engines so they would not rap under load, not like modern precision fit engines but they work my overhauls used to last 10,000 miles not like the new stuff, but now they got real air cleaners be sure to check your ring lands, you can cut them and install shims to fix. piostons loose, slap on a little Knurl!! the good old days , not really never grab the drag link to pull yourself under the car during the overhaul, they land in your teeth, i know, bad taste
I will need to see who makes that oil for that store but two of my motors dont like it,I only had a chance to put about 15 miles on it and will get it out next weekend and see how it does.
Department Store brand??? I know most of us have to save a nickle anytime we can, but oil is too important to cheap out on. Just sayin... Hope you get to the bottom of the mystery and your 235 gets healed!
Over a dollar a quart cheaper adds up when you have a fleet like mine,I have 8 vehicles I maintain and oil changes are getting expensive.
I am trying to find a good crank so I can get it turned and ready to install over a winter,the thicker oil is just to get me by until i get a chance to pull the motor. The motor was done over 20 years ago and if I got the machine shop gave me the sizes of the journals I forgot,since I want to repaint the motor to the 37 color the 235 is coming out for repairs.
I will pull the pan when the motor gets on the stand,too many things to do until winter when I can rip it apart.
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