Hey guys I am new to the Big Truck world... I am seeking some advice from you guys. I picked up a 1988 F700 24' Box truck (24,600 GVW). When I went to look at the truck it had been sitting for some time and had about 2 gallons of old old fuel in her. I asked the guy to get some good gas so we could test drive it. We added 5 gallons of fresh fuel and when we were driving it was back firing pretty bad and 2 times out the carb... needless to say the Power valve diaphragm was blown out and she was leaking a good bit of fuel Also noticed that the vacuum port under the carb on the back side was not hooked up I think that is for the secondaries?? So I pulled the carb wend to NAPA and ordered a new one put it on and it still leaked for some reason all around the gasket... it was the same size as the old one but not as thick. So I decided to do something I would not normally do I used RTV on both sides of the gasket and let it sit upo over night to dry. It worked and did not leak.. I had to get this thing off the street and back home to Wy... So I loaded up all the stuff from my storage unit and hit the road for the 9 hour drive to wy. The truck drove fine but on hills it would slow down to like 35mph on the longer ones and like 45 on the small ones... and on flat ground it would speed up to around 68 and then just stop and then slow down to 63 or so and then start pulling again. I had a long 10 mile slow but solid climb up hill were I pretty much had it in 3rd gear doing 35... I noticed that if I kept lifting my foot and kinda pump the gas pedal it would accelerator better and if I kept my foot down on a hill in 5th gear to maintain speed it would act like it was loading up on fuel and then have a light backfire when I let off. Sorry about the long write up but I want you guys to know what is going on so you can advise best. I noticed that when I was messing with the carb that there is no adjusting it that I saw.. I believe since I put the RTV in there that I will need to rebuild the carb but my question is should I just put a new 600cfm carb on it or rebuild the old? I am going to be driving this beast from Wy to FL soon and then it will be mostly storage.

 

Replace the carb, the original carb has a built in governor mechanism and they not worth
rebuilding. Buy a new 600 or 750 cfm Holley and a new carb mounting gasket, make sure
you get the original thick one.. The universal Holley carbs 600 cfm (list #1850C) and 750
cfm (list # 3310C) are resonalbly priced and work well, I run a 750 cfm on my 429..
You will have to make the throttle linkage work but it isn't a big deal..

 

If I install a aftermarket carb on it will there be a home for all the Vacuum lines or do I have to modify the vacuum lines? I know there were 5 that I remember hooking up..

 

Also does anyone have a vacuum diagram they could post up?? I have a lot of leaking and dry rotted hoses...

 

You can find factory vacume diaghrams and factory service manuals at Fleabay for reasonable prices.
Sinice its been running so rich you might need a set of spark plugs and possibly a wire set as well.

 

I'd do a flow-test to see how well the fuel pump is pushing fuel. It sounds like you might be running out of fuel under load. If the gas was really old, the pickup in the fuel tank is probably clogged, or crud stuck to it, fuel filter, fuel pump, lines, you name it.

Of course, it could be running overly rich. Check to see if the plugs are black or white.

 

Yeah I got a new fuel filter for it (could not put it on since it was so tight..had to wait till I got home to my tools) and put a can of seafoam in the tank... I also have the plugs and will change them as soon as the snow melts off some.. Do you know what the gap is on them?

 

Set them .045 you'll be okay....

 

So I pulled the plugs and they all looked good... they were all newer other than the ones on the passenger side where you have to pull off the heat manifold thing.. they look much much older but were still in good shape.. the very back plug however was not plugged in at all so I was running on 7 cylinders! Also I changed the fuel filter and it was puking brown stuff out like crazy... do there have a fuel pump filter sock on them and if so it is hard to get to and what do you have to do to clean or change it?

 

Just got the new part for the carb it worked so no more RTV in the carb... Fixed all the vacuum leaks hooked up the AC (It turns on for 2 seconds the turns off then turns back on 2 seconds later??) Truck is still slow but found out my tires are good so I pumped them up to 100psi (they were at 70psi hualing 25K pounds..) I think the truck will just be slow going up moderate hills.. I want to change the manual transmission fluid and the rear end.. Anyone know what kinda oil and how much for each?

Also have some questions for you guys that drive these a lot... Is the brake system on these ok or way under powered (I will going through Tennessee? I want to install a Tac to watch my RPMS what is the max RPMS for these 429's? What is the best time to shift gears in these for optimum gas millage?? What kinda engine oil type and weight should I run in this beast (I will be in FL for good after the move)

 

The brake system isn't underpowered. At least I wouldn't call it underpowered..

As far as oiling the boxes, all you've got to do is fill them until the oil comes out. Nice and easy. As far as what type of oil. That can be kinda tricky. Best to call the dealer for that one. Or im sure if you can get the models of the transmission and rear diff that someone around here can figure it out. Could be 50w could be 80-90. Good bet the rear end is 80-90. Tranny's probably 50w, but it may be ATF or 80-90 aswell?

If you get a chance, could you tell me how many quarts of oil your engine takes when you change the oil? My dipstick is MIA. just filled with 2 gallons. Not sure how close I am. Prefer to know..

 

Ok Thanks and yeah I have been calling everywhere and they either say put ATF in it or use 80-90W..

As for the amount of oil.. A bit of a tricky situation there.. When I bought the truck I changed the oil before I drove off with it however I could not get the oil filter off by hand so chose to leave it on and change it when I got back home.. So with that being said I drained all the oil out and except the filter and had to put in 7 1/2 quarts then when I got home I pulled the old filter off and put on a WIX high capacity one and had to put in another quart and a half...so I would say if you use the big oil filter it is going to be right around 9 quarts total. Sorry hope it helps.

I am going to get the model of the tranny today and post it up hopefully someone will chime in fast cuzz monday I am going to hit the road!

Is it ok to just use normal engine oil or do I need to use a special oil for these trucks?

 

Ok so the magic numbers are.... Model# FS4005B It is a Fuller 5sp made by Eaton. I did see that Eaton says that in some of there tranys you dont need to change till 500,000 miles would this be part of that list?

I put a Tachometer on the truck So I could set the timing could you guys tell me how to do it on these trucks and what to set it to?

Also What is the max RPMs on these trucks So I know when to shift before.

 

With the big oil filter it holds 10 quarts, shorter filter, 9