First shake down run around the block

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Sep 16, 2007 | 07:23 AM

JimG1098

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From: Eastern shore,Salisbur,MD

First shake down run around the block

Hi gang, Have had a preety busy summer and have not been on the board in a while. But I have worked on the truck every once in a while. I replaced all the brake lines and rebuilt all whe wheel cylinders. Had the boster rebuilt in Oregon.

Took it out last weeekend for the first time around the block. Truck starts very well. Points and cap are clean. Idles very well. (54 f-750 fire truck)

I have to pump the pedal once ( It goes down a lot ) but by the second pump it stops. Not sure what that may be. Perhaps some more bleeding is necessary, or mayby some more brake adjustment. Please let me know what you think. I am using Dot 3, per mfgs warentee on the booster

The second isue is that I believe the carb is loading up, Cant get much above 30, starts to sputter untill I back off ( 2 bbl Holly) with a governor)

Any sugestions would be appreciated. Mayby I'll work on it again today

Thanks gang, good to be back on the board

Jim G

Sep 16, 2007 | 09:08 AM

ALBUQ F-1

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From: NM

The brakes sound like an adjustment problem, if they hold tight on the 2nd pump.

I wouldn't assume the carb is the problem with the higher speed running, although it could very well be a bad calibration (wrong jets). What size jets are they? Is the power valve new? Does it have a vacuum rating stamped on it?

Check for vacuum advance, too.

Sep 16, 2007 | 12:34 PM

JimG1098

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From: Eastern shore,Salisbur,MD

Albuq F1

I realy dont know squat about carbs. What should I be looking for in the ratings. Nothing has been done to the carb since I 've had it.

How does one change a power valve.

Thanks for the inpit

Sep 16, 2007 | 12:41 PM

Truxx1956

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From: I live in Leitchfield, KY

On drum brake vehicles, the adjustment of the shoes is critical! Sounds like you have them a tad too loose. You should have just a little drag as you turn the drum. That keeps the wheel cyl from having to move so much, also you might want to install a residual pressure valve in line to the brakes, if you're runnin the original master cyl under the floor. The RPV is kind of like a check valve and keeps a constant amount of pressure10# for drum, 2# for disc on the the line. That way when you hit your pedal it is ready to activate the shoes, with no play. As for your carb, I'm not a carb man at all. I just buy new Edelbrocks and adjust the idle screws and go! I know alot about brakes as I do alot of that stuff.

Later and GOD bless

Sep 16, 2007 | 04:50 PM

JimG1098

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From: Eastern shore,Salisbur,MD

Truxx1956 Thanks for the reply.. How would one do that and exactly where would I be placing it. Have a under floor MC and booster. Is it placed after booster? Thanks for the info I will be rechecking my adjustment of the brakes asap

thanks
\
JimG

Sep 16, 2007 | 05:11 PM

Truxx1956

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From: I live in Leitchfield, KY

If you do decide to install an RPV, you'll need one for both front and rear I think? You need to talk to the folks at Godman brakes, or The Right Stuff? They are the place I get stuff from time to time. They should be able to tell you for your application. I'm not entirely sure with that old type of booster, but I'm 99 percent sure it'd be after the booster, like real close to the axle, on the front and rear? I know most that's where they need to go, but when you do get a hold of them, you can ask them. They are very knowledgeable

Sep 16, 2007 | 05:21 PM

WALFORD'S 56

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From: oh

truxx --my 56 F600 has new brakes also,and they work good,except the 1st pump they do very little--2nd is a descent pedal and 3rd pump is great. How do I adjust the brakes? thanks Bill

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Sep 17, 2007 | 01:09 AM

wmjoe1953

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From: Oregon

If the brake system is stock, you don't residual brake valves. There is a one way check valve in the power brake slave cylinder. If you are having a pedal issue, you need to adjust the brakes, and bleed them some more. I have an excellent pedal on the fire truck whenever I hit the brakes. To adjust the brakes on a Big Job, you should find a hex slot in the backing plate. Use a 3/8" allen, and adjust them. As for the carb, you chould have three air fuel adjustments. There should be one on the back of the carb below the fuel inlet. (assuming it's the tea pot carb that should be on it). If it's the original tea pot, there aren't any power valves. Truxx is correct that there should be light drag on the drum/hub assembly when you spin it. Be careful, the Big Jobs are easy to over tighten, and difficult to loosen back up, and hard to tell when you have it just right, especially if there is any rust on the drum surface. Seeing as you just rebuilt the whole brake system, readjust the brakes, and try it again. On the bigger trucks, especially for hauling weight, you need to have the rears a bit tighter than the front, or you can have a heavy load flying all over the road when you hit the brakes. Just my input on the Big Job brake subject, as they are not anyhting close to a typical pick up set up

Sep 17, 2007 | 07:33 AM

#10

Truxx1956

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From: I live in Leitchfield, KY

Quote:

Originally Posted by WALFORD'S 56

truxx --my 56 F600 has new brakes also,and they work good,except the 1st pump they do very little--2nd is a descent pedal and 3rd pump is great. How do I adjust the brakes? thanks Bill

Depending on what rear end you're using? You just jack it up, and look at the bottom of the backing plate there should be an elongated hole wit a rubber plug remove the plug and you'll see a star shaped adjuster nut? with the weight off the vehicle turn the nut til there is a slight drag on them. Like the one cat said, the rear need to be a tad tighter than the front.But I'm very sure that's your problem, if the brakes get better by the 2nd or 3rd pump, and the pedal don't go down.Hope this helps

Sep 17, 2007 | 09:10 AM

#11

f100kid1936

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From: Spartanburg, SC

Looks like the one finger typing gremlins hit me or my 2 live brain cells weren't in sync. My post was assuming you had an under the floor master cyl and it was lower than your wheel cylinders. In that case, with a mix of disc/drum or disc /disc, you will need residual valves. If your master cyl has built in resid valves, as mine does, you won't need them.
Naturally, drum/ drum or stock brakes don't need them.

Sep 17, 2007 | 12:29 PM

#12

Truxx1956

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From: I live in Leitchfield, KY

Quote:

Originally Posted by f100kid1936

I'm not sure, but I think all vehicles with the under the floor (lower than firewall) can benefit from the RPV's I'm not totally sure about your guys trucks, as I dont do anything stock. I always use a vacuum booster, so I don't know much about those old hyd boosters. I know they must do pretty well as they still use them on certain cars, and you can still buy them from places like Godman, and The Right Stuff. Let me know how it turns out? I think most of your problems are adjustment of the shoes?

Sep 17, 2007 | 07:30 PM

#13

JimG1098

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From: Eastern shore,Salisbur,MD

I will be getting to adj the brakes the next time I get a chance. As far as the RPV, I believe there is one in the booster. i remember seeing a description in the parts break donw for the booster in my parts CD

Thanks for the assist i will post when I work on it again

Thanks

Jim G