how can the carb affect the oil pressure ?

[ekoms]

well about 2 months after rebuilding the carb it started to leak from the aux pump cover, so I removed the carb & rebuilt it again just to be sure. during the process I turned the rear primary A/F screw all the way in, hoping for a few more miles per tank. the car still runs awesome & its no longer leaking fuel. since the operation Ive noticed my idle oil pressure has dropped from a steady 20 psi to around 16. I also changed my oil & started using Valvoline max life 10-40 while I was working on her. I used to use Castrol GTX 10-40. I know that max life is a synthetic/regular half blend & GTX is regular oil. synthetic is thinner than regular oil, could that have anything to do with it or the fact that I turned in the A/F screw in ? I'm thinking of turning the screw out to factory specs & going back to GTX oil. not sure what caused it. also I recently replaced the oil drain plug & valve cover gasket cause they were leaking some & are no longer leaking so shouldn't the oil pressure have raise a little ?


thanks guys.

right now oil pressure is 16psi @ 750rpm (idle), 40psi @ 1800-2100rpm & 60ish psi @ 3000+ rpm.

[2ndGenGuy]

No, the oil pump and galleys are all totally separate from anything on the carb. The oil pump is driven off of the camshaft, and so engine RPM is really the only thing that can affect oil pressure while the motor is running.

In your case, the oil is the most likely thing affecting your oil pressure. That and different oil filters can also do it. Different viscosities, and different brands, and different types of oil can all affect your pressure. I don't know if a pressure drop from 20 to 16 is anything to worry about. Try putting the original oil back in on your next change and see if it comes back up. Also, isn't 10-30 the recommended oil? That's what I've been using all this time, so I sure hope so.

Edit: Hmm I just thought about it a bit, I suppose that if your idle RPMs dropped a bit due to your tweak of the air/fuel ratio, then there's a good chance THAT is what changed the oil pressure.

[ekoms]

thanks 2ndgen, I will try the gtx oil again & see what happens. if nothing changes I'll reset the A/F screw. Im not sure what else to try.
Im using 10-40 cause its a little thicker, but ya 10-30 is what Honda recommends.

[ekoms]

well I tweaked the carb back to factory specs & the pressure rose to 18psi. so I guess the different oil counts for the other 2psi.

[2ndGenGuy]

Did your idle speed change when you changed the idle mixture?

[ekoms]

ya alittle, but I dropped the idle screw back down to 750 & adjusted the timing too. its still @ 18. kinda odd to say the least.