so last week I bought a new to me 1978 f350 supercab Camper special with a 460, Performer 460 intake cracked and JB welded, Carter AFB 750 which leaks, The previous owner had lost the metal Gas line between the fuel pump and carb and just replaced it with rubber hose. It had a miss when I test drove it but still ran strong enough for me to buy it. It has true gages installed and So I drove it home about a hundred miles. It did fine but the longer I drove the hotter it got. Never over 210 but when it would push 200 it would begin to surge and I figure it was vaporizing the fuel. Strangely I got 13 mpg on the way home. Once home I dug into a basic tune up. Plugs (autolight Plat), Wires, Cap and Rotor. The plugs that came out all looked good with the exception of number 8 which was just a little dark but not oily. The timing sweep was so small that I pulled the motor to TDC of number 1 and the distributor was stabbed wrong. So I restabbed it and while it will start and run the idle is still rough and the timing sweep is very small. Also when I go to start it the motor feels like it is out of time, my guess now is that the timing chain is off a tooth. By the way most of the emissions equipment is gone I assume. No smog pump or EGR there is a a PCV hooked to a Vacum port. But that is about it. I don't have to pass any emissions but want it to run clean and cool.

Things I know I need to do:

1. New intake that isn't jb welded.
2. Rebuild the Carter so it doesn't leak.
3. find a metal fuel line from the pump to the carb. I have put pipe insulation around the rubber for the meantime.
4. New timing set and water pump???

I need to some input on my thought process.

Also the Autoparts store said that the stock thermo was a 195 degree and that seems way hot for Arizona in the summer



thanks

Sam

 

How are you checking the temp? The thermostat is correct at 195 if you are running hotter look to the radiator and/or shroud. 3 or 4 row? If you look inside at the core is there any corrosion or buildup? That cracked manifold could have let it run lean.

Double check your firing order and wire routing. Compression test?

Timing sweep? Your results in degrees?

Make sure the Vac advance canister holds vacuum and the manual adv mechanism has free movement.

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When I got my new to me 77 F250 460 it had similar running conditions as yours. Vacuum gauge reading was low and rapidly fluctuating indicating week valve springs/sticking valves. Did you check vacuum readings? I set the timing with a quality light (was off and had to r&r distributor to correct). Repaired a leaking vacuum hose, leaking carb base gasket and replaced brake booster that had a blown diaphragm. Not much change. Replaced factory carb with a known good used Holly and it's a whole different truck. Starts easy, runs smooth, twice the power and vacuum is high and steady.
You may have a combo of things wrong but fix your known intake and carb problems first.

 

thanks Guys,

The previous owner had installed a 3 gage set of mechanical Gages (temp, Oil, and Volts) So not the stock gages. The Radiator is a 4 core from the Camper special super cooling setup. It doesn't seem to be clogged or have a lot of build up. Shroud is epoxied together (a common theme) but it is still intact. I have wondered if maybe a new fan clutch is needed though. And I believe that the crack in the manifold is in a water jacket as it is very close to the thermostat housing.

I have not done a compression check yet but it is on the list when I can borrow a tester from a friend. I've checked the firing order twice and it is right. As for the sweep, what i mean is that there is very little movement available in adjusting the distributor advanced or retarded before it begins to stumble. I cant remember what the numbers were but I will get them.

I hadn't thought about the vacuum advance but will check it. The mechanical advance seems free.

Thanks for the input.


Thanks, I will absolutely do that. I have pretty much settled on the Weiand Stealth Intake Manifold 8012, I can get one for about 205 new shipped to my door. Is there a better manifold you would recommend for about the same price? A rebuild kit for the Carter is on the way as well.

 

Weiand Stealth Intake Manifold 8012 is what I would get if I needed a manifold.

I should say that the vacuum readings I had did not match up to any diagnostic chart exactly but were closest to valve/valve spring issue.
How to Use and Interpret a Vacuum Gauge

Maybe it was some kind of internal carb vacuum leak. Being your manifold is cracked visibly maybe it is also cracked or warped where you can't see.

 

Thanks for that link I just did a search and found out that my Carter is a 625 CFM with EGR provision. Not a 750. Should l sell this one and find a 750?

Everything I've read about the stealth 8012 is really good for my application. And I think you could be correct that the current manifold may have other hidden problems.