FI Distributor oil line, is there an orifice?

[Mike R.]

Is there supposed to be an orifice somewhere in the FI Distributor oil line. My new engine is producing less oil pressure that I expected. Thanks

Mike

[Dan H.]

Re: FI Distributor oil line, is there an orifice?

No, must be another problem. What's your pressure?

[Mike R.]

Re: FI Distributor oil line, is there an orifice?

At idle it show less than 15lbs. Bearing clearances are on the tight side and cam bearings are new. I don't really have a point of reference since I have never had a stock small block. Previous to the overhaul there was a high volume pump which I replaced with standard volume pump

No, must be another problem. What's your pressure?

[John D.]

Re: FI Distributor oil line, is there an orifice?

Mike, Would be really nice friend if in fact we could blame some FI distributor issue or the oil line fittings on such a low oil pressure. But it's not the distributor or fittings.
Are you sure your oil gauge is any good? Try hooking up another one under the hood.
FI distributors: The size of the hole where the 1/8" pipe fitting screws into varies some. But it really wouldn't matter anyhow.
Now to wait for the engine guru's to chirp in. Good luck, JD

I don't like something I just said. On the FI distributors you always have to check the small hole-oil hole where the 90 degree fitting screws in. Make sure that hole is open and not clogged with sludge.

[Timothy B.]

Re: FI Distributor oil line, is there an orifice?

Mike,

I think 15lbs is ok at idle, what's the pressure at approx 2000rpm. The things that effect pressure are the bearing clearances and oil pump gear end play. Did you rebuild the engine and what are the clearances, if they are closer to .003, 15lbs at hot idle is probably normal.

Installing a oil pump with gear end play at .006 or greater can also be a contributor for low idle pressure. I have set mine at .001-.002, my 63 has approx 15-20 hot idle oil pressure, my 67 is about 30lbs hot idle pressure and I wish it was lower.

What kind of pump did you install?

[Mike R.]

Re: FI Distributor oil line, is there an orifice?

My best guess is that I am paying the price for not taking the pump apart and checking clearances. \Main and rod bearning clearnces are tight. The first thing to do is get another guage for a test but I doubt it is the guage since it seemed normal before. I will put the test guage in the hole in the front. I assume that if there was a plug missing in the front then the pressure would be zero at that location.

I have spent the past couple weeks chasing down and correcting little things that were done over the past 45yrs. My high pressure pump had clearances of .0015 which is three times optimium, the ground at the TI amp was marginal, the spark plug wires were leaking current, both the FI plemun and baseplate were warped. THe good news is that there isn't much left. Now I will probably have to drop the pan and check the pump but that is my own fault. I should have checked it out of the box.

Mike,

I think 15lbs is ok at idle, what's the pressure at approx 2000rpm. The things that effect pressure are the bearing clearances and oil pump gear end play. Did you rebuild the engine and what are the clearances, if they are closer to .003, 15lbs at hot idle is probably normal.

Installing a oil pump with gear end play at .006 or greater can also be a contributor for low idle pressure. I have set mine at .001-.002, my 63 has approx 15-20 hot idle oil pressure, my 67 is about 30lbs hot idle pressure and I wish it was lower.

What kind of pump did you install?

[William C.]

Re: FI Distributor oil line, is there an orifice?

15lbs at hot idle or cold idle. When I bought my first C-4, back in 1983, the idle pressure at a stoplight was about 5-6 lbs on the digital readout with the engine fully warmed, and the trans in drive at the light. Came right up when leaving the light, checked with a couple of friends in the Corvette group and they said "normal" don't worry. Never a problem.

[Timothy B.]

Re: FI Distributor oil line, is there an orifice?

Mike,

If your car is a 65 it should have a standard volume/high pressure pump. The only difference between this and the low hp pump is the relief pressure of 60lbs compared to 45lbs. This would have nothing to do with idle oil pressure.

If it's 15 lb at hot idle you may pick up a few lbs after setting end clearance but I would not take the pan of just for this. I would be curious to see where the main and rod clearances are set.

If you go to the melling website they have a video of the leakage from mains and rods set at various clearances, it's interesting to see. I think .002/ is best for these motors and oil pressure will be good at idle.