73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: JJSZABO on February 14, 2008, 09:24:52 am
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Has anyone added a permanent fuel pressure gauge to their 4bbl Q-jet? If so, how did you do it? Pictures?
I want to do it and do not want to reinvent the wheel. Thanks.
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Sure, just put it on your fuel pressure regulator assuming you have one? Otherwise knowing your fuel pressure is kind of pointless. Fuel volume is more important than fuel pressure with a carburetor so unless you are running a high performance pump be it mechanical or electric you shouldn't need a regulator or gauge unless you are trouble shooting a problem.
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I only ask cause I am suspect in how I installed my mechanical fuel pump. I will soon try to start this thing and I thought that if I installed a fuel pressure gauge it would tell me right off if the fuel pump is working properly - maybe I am thinking too much ::)
What you said makes sense though Vile - thanks.
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Jeff, I made a "test" fitting for a q-jet using an extra Big nut,where the filter goes (long style,Pont,Olds) a flat washer (to cap off the big end) & an extra fuel line nut w/a short piece of in it, all neatly brazed together. I drilled a hole & brazed a 1/8" pipe coupler on the side of the big nut for the gauge or line to the gauge. This way you can remove the stock line, install "the rig", test & put back when your done. This way is a little safer than some rubber hose set-up,ect. Lorne
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What are you in question about on how you installed your fuel pump?
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This is the book I used to "finish" the crate motor
(http://i123.photobucket.com/albums/o317/jjsabol/Book1.jpg)
These are the instructions along with the instructions from the fuel pump:
(http://i123.photobucket.com/albums/o317/jjsabol/scan0001-2.jpg)
This is the fuel pump:
(http://i123.photobucket.com/albums/o317/jjsabol/41216.jpg)
The instructions say to install the fuel pump pushrod and then install the fuel pump so the pushrod pushes the fuel pump cam. My concern is with this step. When I finished and then spun the motor I didn't feel or hear anything from the pump.
It has been MANY years since I had to deal with a mechanical fuel pump.
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Well u gotta make sure the Rod Is on top of the fuel pump arm...U gotta hold the rod up there with some grease then install the fuel pump or else the rod will slip under the arm
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That's what I "think" happened? The rod was held in place with assembly lube while I installed the fuel pump - I even did it twice to be sure - maybe I am being paranoid? ::)
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Well if ur getting gas...it works.. if ur not then u no the rod dropped If u wanna make sure Get a inline clear fuel filter..
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Hense the reason for wanting a fuel pressure gauge - If I have pressure it is installed correctly.
I do not want to keep cranking the engine without it firing - do not want to damage the new cam.
Well if ur getting gas...it works.. if ur not then u no the rod dropped If u wanna make sure Get a inline clear fuel filter..
Ahhh - good idea, didn't think of that ;)
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lol.....If you want to use a fuel pressure gauge u should...a lil eye candy dont hurt nothing...And if it makes u feel better knowing u got steady fuel pressure why not...Or try it my way....When ur clamps rot out and it starts to drip...just let it go...The Steady smell of gas and fumes rising from ur truck will also let you no....:D j/p
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When I swapped my fuel pump, the new pump would NOT go back in when the rod dropped..I managed to hold the rod up and get the pump in place without using grease, but it wasn't my idea of fun.
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You can't get the pump on there if the rod dropped, well maybe with a large hammer. If you installed it, as you said, it will be fine.
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I could of swore one time i installed one and it slipped under the arm....??
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If by some reason you did pull it off to get the pump on there with the rod dropped, it isn't going to do anything to the cam. If you were able to I am impressed...
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Maybe i thought i did...Who knows...It was a long time ago since i had done it
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If i could revisit this topic.....because i really need to. (me and my problems....)
1) i am also thinking/wanting to put a fuel pressure gauge on my stock Q-jet with stock fuel line. But of course it is very tight. i suppose i could get a tube bender and bend the line slighly to the left (if viewing from the front of the truck)? i don't really want to cut into the stock line.
a) Mr. Hauling, could you, if possible, post a picture of your test rig setup?
2) If #1 above is not practical right now, i am also thinking that i would put together a totally new fuel line just for testing purposes---this way i can just take off my stock line and put in the "temporary line" for quick testing and then re-install stock line etc. What are some quick, easy, AND SAFE ways to do this?
i'm thinkng to get the appropriate fuel fittings for the pump output side and the carb input, do you know what sizes they are? Then, a rubber hose. And then, of course, a "T" fitting for the mechanical gauge.
By the way, the service manual says that if you have a vapor return line on the pump, the pressure should be 5-7.5lbs. and if you don't, 7.5-9lbs. Which suprised me, and i think it's a bit high, but that's what the manual says for 83's.
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Stewart, I don't have a picture, I guess I could take one, but it's real simple. I've made a couple styles. One, is just a "test" unit made from an extra "big nut" with a 1" long piece of fuel line & nut brazed on a washer (capping off end where the filter goes) brazed on with a 1/8" pipe coupler brazed on the side (for the gauge). The new fuel line nut threads into the carb's original "big nut", then the original fuel line goes in the new "big nut". The other "perminant" set-up is non Chevy carbs have a longer "big nut" fitting where the fuel line goes into the carb (they have a area about 1 1/2" between where the inverted flare is & the treads that bolt into the carb. In this area, I drilled a 3/16" hole brazed on 1/8" pipe thread coupler (one that would be used to attach two pieces of 1/8" pipe) Now one of the small gauges (that have the 1/8" tread) can be screwed in or a 1/8" to tubing adapter (like for an oil pressure gauge) can be used or a 1/8" to #4AN fitting can be installed & braided hose can be used, this set-up, the original "big nut" is discarded. Understand? Lorne
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.........Not really.....i'm a little slow mechanically. But you already knew that. i sort of understand the second "B.O.P." version. But then again not solidly.
That's ok; i've found some stuff in the garage that i can rig up. Do you happen to know what size fitting screws into the "big nut?" i've discovered that both the pump and the carb input are the same size.
(http://i223.photobucket.com/albums/dd31/sencraig/100_0437.jpg)
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.........Not really.....i'm a little slow mechanically. But you already knew that. i sort of understand the second "B.O.P." version. But then again not solidly.
That's ok; i've found some stuff in the garage that i can rig up. Do you happen to know what size fitting screws into the "big nut?" i've discovered that both the pump and the carb input are the same size.
(http://i223.photobucket.com/albums/dd31/sencraig/100_0437.jpg)
Should be 3/8 tube
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Stewart, Yes It's 3/8" tubing. Here's a quick scribble of them...It was easier than putting my coat & shoes back on to go to the garage, besides it's cold out there!
The top one is the "test" version. Basically I took a 3/8" tube cut off 1/2" from the nut & sat it on a plate of steel, then slid a 3/8" fender washer over the tube & brazed the tube to the washer. Then laid the "big nut" on the plate (open end up) & brazed the washer on. with the 1/8" coupler mounted in the side, all you need to do is unthread the vehicle's fuel line & thread the new one in the carb & then the fuel line into the new "big nut".
The lower one is self explanatory, I think. Lorne
(http://i163.photobucket.com/albums/t285/HAULINIT/fuelfittingjpg.jpg)
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OK, thanks.
Also, i forgot to mention, on pg.119, middle picture, of the rochester book by Doug Roe, he has an interesting idea for a pressure gauge take off. He didn't go into detail about it. i personally wouldn't want to try it.
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Is that drilling & tapping the carb body just behind the "big nut"? I've seen that done & I agree it seems a little risky, the casting is not very thick there. For a perminate set-up I like the bottom one in my drawing. Lorne
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Yes, it's drilling+tapping and i don't like it. i think the best way is to bend the fuel line so that the inverted flare of the line ends up an inch or two to the left of the fuel inlet nut.
Example:
(http://i223.photobucket.com/albums/dd31/sencraig/100_0421-1.jpg)
Then get an inline adapter for the gauge and the appropriate AN or NPT fittings. Then, you have a leak free worry free and more or less permanent solution. Or use your BOP nut idea.
http://www.jegs.com/i/JEGS/555/100520/10002/-1
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While we're on the Q-jet nut discussion....Ponder this one a bit. I don't think you'll find it in the Summit catalog. ;) Lorne
(http://i163.photobucket.com/albums/t285/HAULINIT/oldsweekend023.jpg)
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Is that a y-fitting commonly used for multiple air hoses on one line. Kinda like THIS (http://www.amazon.com/Professional-Quality-3-Way-Manifold-Quick-Connect-Couplers/dp/B001AUYN8E) but remove the quick connects?
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Smitty, No...It's just a homemade piece. A regular Q-jet "big nut" with the inverted flare seat bored out. I buy steel 37* hose ends at a local hydraulic supply store & brazed it up. Lorne
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So why do you have 2 lines going into the carb?
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Smitty, No...It's just a homemade piece. A regular Q-jet "big nut" with the inverted flare seat bored out. I buy steel 37* hose ends at a local hydraulic supply store & brazed it up. Lorne
Nice work. Brazing seems to be coming a lost art.
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Stewart, It was one of those things...I started with this, but shoulda used that, I have this & I have that. I found my air/fuel meter would continuously rise after about 100' out. I kept adding jet & smaller sec rods, but no fix. I talked to an acquaintance I met several years ago at a track. He has a Buick Skylark that he races in the FAST class (Factory Appearing, Stock Tire. Going LOW 11's with a Q-jet, cast iron intake & exhaust manifolds on bias ply Redline tires!), He was convinced I didn't have enough fuel going to the carb. I was running #8 hose from the cell to the pump (Edelbrock 120gpm), #6 to the carb. Doing some figuring with a flowchart, it should have been plenty. The small bowl of the Q-jet was something he had fought.
I had an extra fitting on the cell, a couple feet of #8 hose, a spare 100gpm Carter pump, a filter I was going to put on my skidloader & coffee can of various fittings. I only had to buy the #6 hose. What I did was hook up the second pump on a toggle switch, she turns it on after the burnout (prior to turning it on, the fuel returns through the Carter pump, which helps eliminate stagnant fuel which would be worse with One #8 hose from the back to the front). My plan is to set up the second pump on a TH400 kickdown switch so it will come on automatically. I wanted to test it turning the pump on before leaving the line & then at the line (once at full throttle) to see if that way is ok. In the end, the meter holds steady & I ended up taking out a little jet which helped for daily driving. The other nice thing... if one pump craps out, I can still get home ;D We set my brother's Mustang up with Two pumps, they are "Y'ed" in the back though & a #8 hose going to the carb & a #6 going to the NOS solenoid. When we did the Power Tours, we would run one pump per tank of gas then switch pumps to keep one from running all day.
As to brazing being a lost art, yea I agree Smitty. It works well when trying to make a sealed item, especially if made up of different thicknesses of metal. Lorne
(http://i163.photobucket.com/albums/t285/HAULINIT/oldsweekend024.jpg)
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That's certainly an interesting approach. So, you run no mechanical pumps on this truck whatsoever?
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No mechanical pump Stewart, I just made a plate to cover the hole. Lorne
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PT.2
OK, next i need to know what size exactly is the inverted flare nut that goes into the fuel inlet nut (chevy, BOP/"big" nut), not the line itself. i know the line is 3/8.
(http://i223.photobucket.com/albums/dd31/sencraig/88d76a75-1.jpg)
And not what size wrench either to use on the nut, i'm talking about the actual threaded part that screws into the inlet nut. i've already ordered two flares from jeg's in order to make up the new line to install a pressure gauge and they both don't fit-----5/16 and 3/8.
b) Do all V-8/6 carbed Gm cars from say, 65ish to 87-90ish basically run the same flares on the carb and pump sides? i may just try a salvage yard at this point and just cut into it (although now this poses a problem because of the metal shavings) and just make up a line from that.
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Stewart, That is what is called a 3/8" tubing nut. Which is different than 3/8" NPT or 3/8" bolt tread (fine or coarse). To get something to thread into & seal, it has to be a fitting for "3/8" tubing to ?". Not what you want, but as an example, a 3/8" tube to rubber hose (barbed end) brass fitting exists & so forth. This is the reason I make allot of my fittings... by the time you get to what you want, you have a thing that looks like a pile of fittings from a junk drawer. Yes all of what you listed will be the same nut/line size.
Are you wanting a permanent pressure gauge? What are you planning to use for a gauge & where are you planning to mount it? Lorne
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1) OK, so now i'm completely confused.
a) At this point, could somebody provide a part# that will accomplish what i'm trying to do? A/N or whatever is fine as long as it works.
2) If all GM's pretty much use the same fittings, i may try the salvage yd. route and use compressed air to blow out the small shavings.
3) No, this is just a temporary line for testing the pump and any other occasion when i would need to test a pump. i got one of those liquid filled Jeg's brand mechanical gauges that will mount off a "T" fitting near the carb. Here is what i've come up with so far:
(http://i223.photobucket.com/albums/dd31/sencraig/c3e9bced.jpg)
Everything to the left of the gauge and "T" fitting, which both came in on wed, is what i found laying around in my parents' garage from a previous project----looooong story. i don't even remember if i made it or the shop i eventually went to constructed it. The shop was actually Malcolm Durham's. Anyways, to the far left, we see a part of stock line which was cut into leading to the rubber connectors and so forth. All i need is a 3/8 barb and something that will screw into the inlet nut on the carb.
As for a permanent gauge, when i get time to research it and do it right, i would ultimately like an electric gauge that can stay inside the cab as opposed to on the hood which is cool, but this is a street driven truck, not a racer, so i feel inside is better. And then, of course, i feel that the best way for the gauge to feed off of(get signal) would be to slightly bend the stock line so that there is space between the tubing nut and the inlet nut and then appropriate adapter nuts/fittings can be used to join the two with a "T" fitting in between. This way it's leak free and safe as stock.
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1) OK, so now i'm completely confused.
a) At this point, could somebody provide a part# that will accomplish what i'm trying to do? A/N or whatever is fine as long as it works.
2) If all GM's pretty much use the same fittings, i may try the salvage yd. route and use compressed air to blow out the small shavings.
3) No, this is just a temporary line for testing the pump and any other occasion when i would need to test a pump. i got one of those liquid filled Jeg's brand mechanical gauges that will mount off a "T" fitting near the carb. Here is what i've come up with so far:
(http://i223.photobucket.com/albums/dd31/sencraig/c3e9bced.jpg)
Everything to the left of the gauge and "T" fitting, which both came in on wed, is what i found laying around in my parents' garage from a previous project----looooong story. i don't even remember if i made it or the shop i eventually went to constructed it. The shop was actually Malcolm Durham's. Anyways, to the far left, we see a part of stock line which was cut into leading to the rubber connectors and so forth. All i need is a 3/8 barb and something that will screw into the inlet nut on the carb.
As for a permanent gauge, when i get time to research it and do it right, i would ultimately like an electric gauge that can stay inside the cab as opposed to on the hood which is cool, but this is a street driven truck, not a racer, so i feel inside is better. And then, of course, i feel that the best way for the gauge to feed off of(get signal) would be to slightly bend the stock line so that there is space between the tubing nut and the inlet nut and then appropriate adapter nuts/fittings can be used to join the two with a "T" fitting in between. This way it's leak free and safe as stock.
Go to Home Depot or any hardware store and ask for a 3/8 tube fitting
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I think I'm lost...what are we trying to do here?
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Steward,
You can get the flare nut at any parts store. Just ask for a small section of 3/8 line with nuts. They sell them (like brake line) in all kinds of lenths. You'll get two nuts and the line with double flares.
Steve
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Ok, thanks for the link; It looks like the brake line idea will work.
85MM, i will get a picture up as soon as i finish the project, maybe a picture can explain it better than words.
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i got 24" of 3/8 brake line at advance auto last night for $2.50, so a big thank you to steve.
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Your welcome sir