Fuel Injection gear pump relief hole orientation

[Jerry G.]

Re: Fuel Injection gear pump relief hole orientation

I have used one distributor. Two different pumps and have spun it using drill to see if I can replicate without pumping fuel. The one area I'm thinking through right now is the modification done to prevent lean condition at high flows. It's a restrictor in the spill valve nozzle area that reduces the effective area that the "thumbtack" acts on. This helps with control but also would restrict spill back into fuel reservoir if the annular area created for the given travel of the "thumbtack" is inadequate. But if this were true I would think I would go rich at high RPM and its pretty stable. Have to think about this some more. Believe me, I wouldn't be going through all this pain if I wasn't determined to be at Monterey with my original injection on it.

[George J.]

Re: Fuel Injection gear pump relief hole orientation

Jerry,
I know this is throwing "stuff" at the wall, but I would try a different distributor, and see if it still does this. In my mind, I keep thinking it is some sort of alignment, or harmonics issue. Correct me, one of the mechanical engineers, but I think the forces on these components increase squared to the increase in rpm's.
I also think posting some pictures might produce some questions from others.
I am really pulling for you to get this sorted Jerry. I know how frustrating it must be. Hang in there!

George

[John D.]

Re: Fuel Injection gear pump relief hole orientation

Bill and others. When AC assembled the pumps on the assembly line they did so 100% dry. This info came to me from Frank Sciabia of Rochester Products in old days. But I like using a thin oil myself. My favorite miracle oil to use is "Speed X". It's really good stuff.
So Jerry you have tried other pumps you say. Were both of the pumps restored or rebuild by the same person? Sounds to me like you may have a "drag" on your pump gears or pump shaft.
Measure the height of the gears and the height of the spacer. The original pumps that came with the FI's only had 1/2Thousand clearance between the height of the gears and the spacer.
My 63, the LWC has a NOS pump on it. But before I put on the re-restored Fi I put a viton pump seal in it. For educational purposes I measured the height of the gears and spacer and was amazed to find the clearance was twice as much as I am used to seeing.
So I called my pal Gal Parsons and told him what I discovered. He said he was aware of that fact and since I called he gave me a tip. He said to me that I just discovered a secret that he has used for an eon. Gail liked the .001 clearance and set all his pumps like that by lapping the gears a tad.
Another thing Jerry is this. Some of us have the pump shaft soooo tight in the carbon bushings that it is starving for lubricant.
I feel for you Jerry as you have probably bought more cables than anyone else.
A FI drive cable is like a fuse. It breaks to prevent further damage to expensive parts.
You did hit on a point though with the spill valve.

Qt Jerry: Have you always been using the modified spill valve? Did you break a lot of cables before using this spill valve? The Grady Davis car I worked on as a kid had one of these spill valves that had a restrictor in the bore. A smaller thumbtack and a sleeve going in the bore. Well Dr. Blatchly's race car (formerly Grady's) used to go thru sooo many cables and he was not a happy camper. He hollered at old JD and Timmy (head mechanic). Timmy replaced the spill valve and the cables lasted a lot longer.
Just recently I sold that modificed spill valve (had it since I was a kid) to someone here.

Change the spill valve Jerry. If your restrictor is not in the spill valve then get rid of it where ever it is. That restriction really makes those drive cables whip to the point that they practically break doing a simple flow check with a drill. JD

[Jerry G.]

Re: Fuel Injection gear pump relief hole orientation

Thank you John that's helpful. I'll get busy. Jerry

[Jerry G.]

Re: Fuel Injection gear pump relief hole orientation

Well , I said it would turn out to be something obvious.
I ran a test with the unit on a bench and tested the internal relief system (Spill valve to fuel meter chamber). The spill valve to spider line was blocked by my antisiphon valve. I used an air drill to drive the cable which pumped fuel around the recirculating circuit. At about 500 RPM the air drill was working , at 1700 RPM the cable twisted and looped. AhHa! So I started following the fuel path. I got to the the screen in the bottom of the spill valve chamber and found it not only filled with black crap but bulged in by the pressure differential. Definitely a problem. I didn't expect to see junk in this screen because a year ago i replaced the fuel cell and replaced all fuel lines with armored lines which are internally coated with a teflon liner. There also is a 10 micron filter in the line in the engine compartment. The only line left is the one from the fuel filter to the fuel meter. I need to think about this some more but I'm feeling better about this problem. In the meantime I'm have a stronger cable and housing being made for me in England and if I ever figure out how to post a photo on this board(I've tried) I'll show you a little piece of jewelery I am having made to replace the cable all together, Clem's idea.. I'm going to clean everything up and rerun my bench test.

Joe I appreciate your idea, I am looking for anything that could be problem. I have run with two different housings and without housings. I've run with synthetic lubricant and with dry. I even put Marvel Mystery Oil in the fuel. I'd kill a chicken and dance in circles if I thought it would help. I'm sure this will turn out to be something that I'll look back on a think it should have been obvious but it's not so far.