Ca you run both an elec. and a mechanical oil pressure gauge on a 258?

[marc]

Maybe I should spin another topic but here goes. The mechanical gauge confirmed that the j10's oil pressure goes to ten after a highway run. Took a tac with me and, when I pulled off the freeway after a 40 min. run, it was idling in the low to middle 500s in gear and 10 psi on the oil pressure guage. After a ~20 min. cool down, it was idling faster and had a higher pil pressure, 13-14 psi. Thoght maybe the solinoid idle is set wrong?

[tgreese]

500 seems low. What do the tune-up specs say? I would guess 700-800. The engine should always idle slower in gear. Temperature should not matter to idle speed. What does the book say? I wonder why you are asking instead of reading the tuneup specs.

Oil will get thinner and pressure will go down with increased engine temperature.

There are two possible purposes for an idle stop solenoid. First is to boost the idle speed when there is additional load, like the AC. Second is to completely close the throttle flap with the key off, stalling the engine. This is to prevent run-on aka dieseling. There should be some discussion in the TSM.

[marc]

Tim, read the TSM, read Haynes, tuned the carb according to the label on the engine compartment. If only it were that simple. I will look again at the TSM but I am curious, the solenoid was extended when I pulled off the freeway and was still at idle in gear. %00-550 is low and would account for the difference in oil pressure but why it would take half an hour on the freeway to show, this is a mystery to me. The solenoid is working against the throttle return spring which was originally too weak to return the throttle fully to idle, replaced it with a stronger one but if it is too strong, it maybe pushing the solenoid. Will run through the other carb idles as well.
Marc

[letank]

oil pressure of 13-14psi at 500 rpm, is good....

Now increase the idle speed...

as for the solenoid, it does not have enough strength to push on the throttle, when you accelerate or when the high idle speed is set with the choke, it position the throttle stop and the solenoid follows

[marc]

Letank,the issue is that at 550 rpm, the oil pressure is 10 psi. I suspect that if it were idling at 650, the oil pressure would be 13 or more. One possibility is that the carb should be tuned at a higher "operating temperature" than I used. While the temperature gauge had reached the operating position,possibly the engine had not.
Marc

[marc]

Took the J10 on a ride to get it to it's "operating temperature" and then tuned the carb. Today, ran the truck from Seattle to Anacortes, 81 miles on I-5. I was concerned that, with prolonged running, the oil pressure might bottom out. It had gotten down to 10-11 on the mechanical gauge after the earlier 30 minute test ride. At idle in drive, it remained at 11-12 today's entire trip with 5-30 high mileage oil. On the first trip, the truck had been idling at 550 during the freeway trip. Today it was idling at the more normal 650. Reassuring that it never went below 10. Below spec but above the 10 psi/1000 rpm line. Interested in people's thoughts about this. thanks