Fuel Pressure Gauge & Shimming

[dpantazis]

I'm a Fan of the Washers... There is no spec on them either but I've found > 3 < will get you 68/70 psi on >MOST< PSDs.

Joe-

What kind of washers are prefered?

I think I have figured out what I have done different. I am using #2/#3 washers INSIDE the brass spring housing/plunger under the spring. The total stack of washers is propably 30 thou for the 4 of them. These things are tiny.

In a previous post, you mentioned using a dab of grease to hold the washers to the FPR cap. Are you using bigger washers on TOP of the spring. There in lies the difference in washer thicknesses. If you are using something like a
#6 washer, I would guess that the stack of 3 is more like 90 thou to 0.1" in thickness.

It kind of makes sense to me now. The BB is 0.177 diam, so with the seating of the BB in the spring, its propably 0.15" compression to the spring. I got 80-85 psi which is way too much.

I understand from other posts that these FPR springs are not precision springs, but perhaps instead of using washers as the incrment, perhaps it is better referenced as a dimensional range of shimming.

So we have a choice of thicker washers on top of the spring and thinner washers under the spring to fine tune the pressure.

I stoped my the stealership to pick up the special square cut o-rings to go on the fuel return line that unscrews form the FRP cap. They come as a 'set' of 6 for all the hard fuel lines with a description page of what goes where. freaking $13 for all 6. -mad P/N 9C387. I gotta find a IH dealer closer to me!

These are no ordinary orings, they are like short pieces of tubing and until i get back to the truck and take things apart, I don't see how the fit over the flare and under the nut.

Thanks again for your help.

Dennis

 

[BIG JOE]

FPR things

Joe-

What kind of washers are prefered?

I think I have figured out what I have done different. I am using #2/#3 washers INSIDE the brass spring housing/plunger under the spring. The total stack of washers is propably 30 thou for the 4 of them. These things are tiny.

* # 2 or 3 washers are to small. If you look down in the brass sleeve, yul see a VERY small orific. That orific is for the fuel pressure to bleed off when you shut down. just a guess but I think the # 2/3 washers are cocking, in the inside of the spring... yer prolly looseing what ever shimming yer trying to get. AND, you may be blocking the orific... not a big thing, but could be, at some point.

In a previous post, you mentioned using a dab of grease to hold the washers to the FPR cap. Are you using bigger washers on TOP of the spring. There in lies the difference in washer thicknesses. If you are using something like a
#6 washer, I would guess that the stack of 3 is more like 90 thou to 0.1" in thickness.

*. The Grease thing was for those that want to put the shimm >in< the FPR >cap< (the BB, etc). I prefer, in the brass sleeve, under the spring. A #4 washer is TT close to the outside diameter of the spring seat, when they are incerted in the brass sleeve. they make a near perfect seat for the spring, yet leaves the orific unrestricted.

It kind of makes sense to me now. The BB is 0.177 diam, so with the seating of the BB in the spring, its propably 0.15" compression to the spring. I got 80-85 psi which is way too much.

*. Yip, I think so too.

I understand from other posts that these FPR springs are not precision springs, but perhaps instead of using washers as the incrment, perhaps it is better referenced as a dimensional range of shimming.

*. Right, there is no tension spec for the springs. NEW, they are purdy close to the same. Time weak'ns them. Thats why FORD sez 50 to 60 psi is "acceptable" (not for me). Shim stock would be a way to go... but IT is what IT is. I prefer to add #4 SS washers to get where I want to be. I stay with the word; Washers, cuz it's easier fer guyz like me, to indentify with

So we have a choice of thicker washers on top of the spring and thinner washers under the spring to fine tune the pressure.

*.I stay with #4 washers Under the spring Only. I've done a Bunch of shimming that way..... always had good luck getting 70 psi, at idle (static) 65-68 at speed. Creature of habit, I guess.

I stoped my the stealership to pick up the special square cut o-rings to go on the fuel return line that unscrews form the FRP cap. They come as a 'set' of 6 for all the hard fuel lines with a description page of what goes where. freaking $13 for all 6. -mad P/N 9C387. I gotta find a IH dealer closer to me!

*. Whatcha guna do. They gotum, we gota pay'm.

These are no ordinary orings, they are like short pieces of tubing and until i get back to the truck and take things apart, I don't see how the fit over the flare and under the nut.

*.They'l fit, use a little slickum... or take the return line off. It has a section of Rubber fuel line that slips over the other end, where it transitions from the engine to the frame, on it's way back to the tank. You can slide it on from there but Clean the line good.

Thanks again for your help.



Dennis

No Probs... that what we're all about

JOE

 

[dpantazis]

I still don;t get it

I spent the morning draining, purging and taking the FPR cap of like 4 times. its a time consuming job.

no shims- 50 psi, maybe 55 baseline.

i could NOT get ANY #4 washers to fit inside the spring housing or at the top of the spring under the cap. Maybe if someone could post a pic of the washers they use it would help others. The WIKI page is a bit misleading. I still don;t see how you are getting the #4's under the spring. putting the washers under the brass seat is a no go either, the hole in the FPR housing is clear through to the filter (a magnet on a stick will retrieve the washers from the filter bowl).

i chucked up a drill chuck in the lathe and turned a brass mushroom, with a 0.015" diam shaft and 0.19" diam head, 0.1" high head. i inserted this at the top of the spring so the mushroom bears against the Y shaped boss on the cap. the diameter of the shank is snug in the spring but not large enough to spread the spring bigger. i reassembled and fired it up. got 90 psi on the gauge. WAY too much.

took it apart and removed the brass mushroom to face it down. a little quick fractions i decided to take it down to 0.05" high and reinserted and reassmebled. fired it up and i am a hair over 60 at idle. for now, this is good enough for me!

right now the engine is soaking in simple green and i am hoping to clean it while temps are above freezing.

i should have taken pics through out the process but not having a helper and greasy oily fingers i did not want to use the camera.

putting on the square washers on the fuel return line is a major PITA! the only way i go them on was to soak the washer in a cup of hot water and grease the snot out of the return line and use a bit of dielectric grease to slick it all up. the "oring" is not square, but a shor section of tube and does not deform easily. it appears that it acts like a constant tension snubber to push the flare into the FPR cap. taking off the metal hose at the rubber hose connection liek BIG JOE said will work too but i got lucky putting it on from the front side.

dennis

 

[CHPMustang]

I file down the edge of the washers all the way around so they'll fit nicely in the bottom of the brass seat. We also have some photos of the shimming in the ARTICLE from Big Joe
Here's one of my photos from filing a shim down to size.