I noticed on my new old rx7 12A (side draft racing carb) that the oil metering block has an actuator lever on it, that I presume went to the stock carb. On my car the actuator is zip tied off. Nothing actuates it. Can someone verify that this is very bad? Any suggestions on how to rig it up to the carb? Is it simply a linear progression that adds more oil as the throttle is depressed? ALso, which way allows more oil to go to the rotors? WHen the actuator is pulled up, or down?

 

yep the rod is supposed to go to the throttle in the stock setup.

pulling up on the pumps lever delivers more oil. the old school trick is just to have it about half way all the time.

 

Thank you very much. WHen I saw that it was not hooked up at all, and just loosely tied off, I felt the blood drain from my face. I'll figger out a way to hook it up to the carb.

Now on to the next issues.........

Dave

 

How can I test if my omp is functioning? The lines are not clear enough to see if oil flows. This is for my 1983 12A with Weber carb. BTW the oil metering lines connect to the intake manifold.

 

There's a test procedure in the FSM.

It's basically like the fuel pump flow test, except done with a running motor; you disconnect the OMP oil lines and run the engine at a prescribed RPM, and measure how much oil comes out, in CC's per minute. You have to do a little manual oil squirting into the carb as you go, to keep the seals lubed.

 

You're fielding my questions wherever I go! I am really concerned then....I disconnected the line from my intake and nothing came out. I didn't rev it, though, but I would think oil needs to come out of there whenever the motor is running.

I better dump the MMO in the tank befoer doing anything. Yikes.

 

i have a dellorto carb..and right now we wired mine open...i did get a gslse omp rod that can be tweaked to work with a sidedraft carb...

 

I think I will immediately pour the mystery oil in the tank,than top it off, then check out the omp output, if any. When I get time I may fab a rod from some straight rod. When I recently purchased this 7, the rod was tied off, but in a 3/4 max level, which would be okay if it is working. Also, choke cable not hooked up. I am surprised at how quickly it warms up - maybe because the lack of oil being metered

 

well..some side drafts warm up a bit faster...if you picked up a gslse omp rod..it is close to what you will need..without much modifications.it is a lot longer...but right now..im still running a little MMO..dont put to much..cuz then you will smoke...

 

What can I say? Was a slow day at work.

I do remember that the output is not a lot. My lines are clear enough to see through, and I remember at idle the oil was only pulsing along like a half-inch a second or so.

Spec is (since I'm home, I can check) output of BOTH tubes taken together should be between 2.0 & 2.5 cc after 6 minutes at 2000 rpm.

 

dunno if you've ever done that test, but 2.5cc's is like a really small amount, like drops.

i have seen one car, that the metering system doesnt work on 5-20oil, it needs 10-40 or thicker, which is odd.

you can hear (and feel, if you know the car, and the difference) when its not getting lubricated.

make sure the oil you use is TCW3 rated, MMO is just red colored kerosene

 

For comparison, your standard science class test tube, 3/4 x 6 inches, holds around 25cc, or 10x as much as we're talking here.

A shotglass is 1oz or roughly 30cc. Figured that might work easier for some of us.

 

Here is the result of my test. My oil metering lines are stock; nylon in appearance, leading to a pair of rubber hoses that go to the intake manifold, due to the weber type carb. Oil comes out of the nylon lines just fine. When I put the rubber lines back on, I suppose it is vacuum line or something, I don't see any oil come out. The lines are not clogged, and when I blow through them, I can get oil to spray out, showing that they work, perhaps when hooked up to the omp and the intake. So it seems like the rubber hose, for some reason, does not work as efficiently as the thinner nylon, but may be assisted by the vacuum of the intake. am thinking that the way to increase efficiency is to extend the nylon lines as far as I can, and reduce the amount of rubber hose as much as I can. How does this logic sound? ANyone else notice this? Do the stock nylon lines go all the way to the carb? The rubber hoses, by necessity, are a thicker ID than the nylon.

 

The stock lines are nylon except for about the last inch, which is rubber, and clamped to the carb barbs with small wire clamps.

The ID of the nylon lines is very small. If the rubber lines are a lot larger on ID, they will have a larger volume per inch. Since the OMP flows such a small amount of oil, it will take quite some time for it to fill the volume of the lines, before oil comes out the other end.

If the rubber lines start out full of air, the OMP has to first fill the empty line before any oil can come out the far end.

Volume of a cylinder (like the space inside the rubber line) equals length, times the radius squared, times pi. (volume = pi * radius^2 * height)

Larger radius of the line creates a large increase in volume, and since the pump runs at a constant volume, increases the time required to fill it.

Your best bet would be to "pre-fill" the rubber lines with oil, then connect them to the nylon lines. That way, any oil coming out the nylon lines will push oil out the other end of the rubber line, since it's already full.