Hi,

I've been asking questions on similar threads, and have learned that doing that is impolite - "hijacking" someone elses thread is what its called I guess. Sorry for that, I will start a new post for my questions

1. I've been failing emissions testing and generally have a poor running engine at idle and no power on acceleration. It passed last year with the stock set up. I changed over to a weiand intake and edelbrock 1705 shortly after. with a open 1 inch spacer, then the fun began.

2. Its a 76 F-250 trailer special, 2wd, 460, C6 transmission

3. After putting in the new manifold & carb, it ran extremely rich and lousy.. I reset the timing & went through setting mixture again. no change. i set timing by disconnecting vacuum to advance and plugging it. then set timing at 12btdc and reconnect vacuum to ported vacuum (this is what works on my truck, don't want to get into ported/manifold vacuum debate, if I connect to manifold after setting timing, the timing jumps to 30btdc - so its not correct for this truck, ported is)

i set fuel mixture by putting a vacuum guage on manifold vacuum, then turning in the mixture screws all the way in, one at a time, then out till i get maxium vacuum.

4. got some advice on this board to get rid of that open spacer. did that- changed it for a 4 hole- noticeable improvement- but still not a 460. Also followed the advice to run it a bit leaner than the way I'm setting up the mixture.

5. Still no go. decided to pull the plugs for the heck of it, even though they were less than a year old. 2 of them were black and arched together- so was getting no/little firing in those cylinders. bingo- ran alot better, till it didn't.

6. took her on a test drive and around 5 miles down the road, it started surging, or pulling, like it was running out of gas. then it died. I pulled the fuel filter off the fuel pump and noticed it was empty. filled it with clean fuel, truck started right up. Did same thing around 4 miles down the road.

Also, it pings on acceleration. I can't get rid of that, its driving me nuts. What was the recommended octane for these back in 1976? I'm running mid-grade 89. I have a rebuild stock distributor (motorcraft), vacuum advance is not adjustable on these.

So- any suggestions? I was thinking the fuel filter on the sending units could be clogged- they are the original units. But both socks were not on the sending units when I pulled them today . Or, my fuel line comes up by the PS pump, near the exhaust manifold - could I be boiling the fuel and causing fuel starvation? And the pinging?

 

An aftermarket electric fuel pump should solve the vapor lock problem..

 

Black fouled plugs usually means you are getting way too much fuel. I'm not familiar with an Edlebrock 1705 and you did not state if the carb was new or used. I've heard of new carbs not being good out of the box and may require some fine tuning and if it was used well then it might have some plugged up jets.

My guess is that your motor is a low compression 460 and will probably run fine on regular gas if its in a good state of tune. However if you have lots of miles on it and its been running rich for a while then you could have lots of carbon build up and sometimes higher octane will help with the pinging. If it pings hard on moderate acceleration / load then you probably have too much timing and will need to back off a few degrees. Do you have any problems starting when hot? That is usually a sign of too much initial timing.

There's a very good chance that you simply have 38 years of crap in your fuel tank and fuel lines and its time to do a nice cleaning with some new filters. I am going through that on mine. You probably can pop that carb off and take a peek at the float bowls to see if you have some sediment in there. If so you might have some plugged jets. Again, not knowing how well your truck ran before this 'upgrade', I'm guessing here.

You might find something in this article helpful.

FORDMUSCLE webmagazine: Timing is Everything - Distributor Curving for Maximum Power

If you have the factory type of fuel line plumbing then I doubt your boiling the fuel. On my motor, the hard line makes a nice bend from the fuel pump and comes along the timing cover so its not near any exhaust heat. If yours is running next to the exhaust manifold, then you should move it asap.

I would not jump to an electric fuel pump just yet. The old mechanical units are just fine for just about anyone running a "street" motor.

 

This single issue must be addressed before you can troubleshoot the rest as KICKUP has posted .. Running the bad fuel through the carb may warrant cleaning it out as well .. Any air leaks in the fuel line from the fuel pump back will cause it to loose it's prime and may not show up as an actual fuel leak .. A simple test put a fuel can on a stool on drivers side front wheel well and run a rubber fuel line to it from the pump and start the motor .. If it runs well then your problem is from the pump back ..

 

If you switched your SmogCarb for a NonSmog carb, switch most are nonSmog, you will not ever get it running correctly. There are vacuum lines that you had to disconnect and probably just plugged, thinking that its ok.

One of those lines will be to your charcoal canister. If you plugged that line, and still have the Smog fuel cap on, the one that seals, i am sure that you are not pumping gas correctly. If anything, you can try a vented cap.

You cant just change an intake and carb on a smog vehicle and think that it will run correctly.

 

Great points .. The distributor is also set up for an emissions motor and must be addressed also, recurved ..