So here we go again with this ford 460 If i get on the highway when it is cold it will usually make the shift point at 5500 w/o missing a beat, but as soon as it gets up to temp 185 degrees it starts to pop and miss pretty bad. Engine is running a edelbrock 750, straight from the box, adjusted both screws for highest vacuum reading and then reset to make each equal as edelbrock said to do. Engine is 71 block, d3ve heads,edelbrock intake, headers, 2.5 in exhaust to 3 in stacks, stock duraspark 2 system, all new including new accel coil, stock ignition control unit, and cap and rotor, wires are accel as well and im running autolite xp25 plugs. i have a holley 140gph fuel pump mechanical, removed all electric pumps in tank, and im running a holley pressure regulator set to 5 psi as the edelbrock. I run 50psi oil pressure when at temp of 185. Engine is stock elsewise, Checked compression from 1-8 here it is 155,150,145,150,150,150,145,150. vacuum reading in at 20hg, timing is as follows all in at 3000 and is 36 degrees, 26 mechanical and 8 degrees initial, i have tried 10, and 6, with no luck as i said in the beginning if it is cold it seems to not do this. The way it acts it seems electrical, just not sure where to start and what i should look for. Fuel pressure does not drop and this will do it from the beginning, if you have it in park or going down the road if you bring it up fast or slow to 4000-5500 rpms it just runs like ****. Vacuum advance is currently plugged and disconnected to test for timing issues. Any ideas?

 

You may want to post into the 385 forum, as they will be able to better help you.

Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460) - Ford Truck Enthusiasts Forums

 

I would guess the stock Duraspark box is going south. I would borrow one from a friend and try it.

I had an Mustang that would do a similar thing. Ran great cold but once it got warmed up it would run like crap in the the upper rpm ranges. I switched to a MSD ignition and it solved the problem.

 

Any thoughts on whether a tester on that unit would be able to tell if the box is bad when its cold or should i heat it up and take it off and promptly have it tested?

 

I doubt it would do it cold since it's not doing it cold when on the truck. But, it worth a shot. They might let you "test" a good one on your truck?

 

replaced it with a new one and no change.....I also got to thinking well i filled it up with gas rear tank only, so i thought maybe i got some bad gas, put gas in the front tank and some seafoam in the rear, it felt good for a min and then it came back, i was thinking ok if its coming and going it has to be something electrical and i mean the rpm range was getting lower and lower and it would only do it once at operating temp and if you were on the highway thru it in neutral and let it coast down the hill then hit the bottom put it in gear and stomp it, it would handle it thru the gears once, then would come back, i was under the hood and the coil felt hot so i tested the coil primary circuit was 1.8 and secondary was 12.5k i think the secondary is bad so i put the old coil on because i upgraded to an accel coil, as far as i know the accels are a reliable coil. It seems to hit each gear, here is the weird thing, i have 26 degrees mechanical 6 degrees initial and my vacuum advance adds like 27 to 12 depending on where its adjusted, i just cant find anywhere it likes that and pops like crazy, do i go full manifold like i got it or ported, how much vacuum advance do i go with, whats a good way to test it

 

I run 12* initial and run the vacuum line from the distributor to the "timed spark" port on the side of the stock Holley carb, it's the port on the passenger side, up near the fuel bowl sight window.

Check all of your grounds also.

 

Hook a temporary fuel pressure gauge up and see what it your FP does when the truck is acting up.

 

I have an inline fuel pressure gauge, both inline filters stay close to full and the pressure never drops below where i have it set at 5 psi. i am running an edelbrock is why it is set to 5, edelbrock recommends 4-6 psi anything higher and you will overflow the metering rods and have carb fires.

 

Sounds good, just wanted to rule out the fuel pump acting funny when hot.

 

Maybe return fuel line orifice is plugged up. Motor doesn't like the hot gas since the return system is plugged up not keeping cold fuel coming in.

 

I threw that whole return orifice system out the window, im running it like the old days manual pump electric pumps removed and a hose set 1/2 off bottom of tank in place of pump, inline filters and the holley fuel pressure regulator

 

you might want to look into it. it's called the "hot fuel" option. did you run your truck last summer without it?

 

i think a lot of people are misunderstanding what the engine has on it now, It is a 71 ford 460 motor, no smog d3ve-a2a heads d1ve-a2b block, stock motor NOW running a edelbrock aluminum intake, edelbrock carb Holley manual fuel pump, NO electric pumps in tank. No hot fuel option is on this truck all new lines have been ran to do away with this HUGE mistake ford made. It also has a holley pressure regulator to bring the fuel pressure down to 5psi for the edelbrock carbuerator. It seems to be really hard to time out, i have tried 6, 8, 10, 12, 13 and i have even gone as low as 4 degrees intial and the curve is all in at 3500 rpms, anywhere from 32-36 at that rpm but it is a real dog and hates any sort of vacuum advance after that off ported timing or full manifold

 

Best advice I can give it just recheck all of your wiring connections and grounds. Also maybe try to borrow a another stock distributor and see if that does it.

The timing does not sound right. With it at idle the timing should not move at all until you give it some gas, then the ported vacuum should start advancing it. Total timing should be all in by 3000 rpm.