working on my cousins kids truck the last few days its a 71 f250 360 435np only modification to motor is an aluminum 4bbl intake and holley carb and the trucks motor sounds good no misses at all when its not under power, you can rev it up and it never misses a lick but once you get it out on the highway it misses and cuts out and lose's power.... we have replaced dizzy (still does it) changed carb's (still does it) changed coils (still does it) changed plugs and wires (still does it).........i have searched and searched but cannot find a single vacuum leak... i have looked in the dark for any wires grounding out or sparking and replaced all wires that could have possibly been bad from the firewall forward........ the truck smokes a bit when you take off first in the morning or if you let it set for a while (i assume valve guide seals are bad did leakdown test and compression test and all was good only one cylinder was 7 lbs less than expected)......and then he tells me he ran it out of oil 2 miles from home a couple weeks before problems started and limped it home with no oil pressure..... so am i right to assume that he might have wiped his cam lobes a little bit causing this entire fiasco? would the cam cause this effect? whats your feelings on this fellas i have troubleshooted all the other possible problems i think

 

You didn't say anything about checking fuel press. to see if it's keeping up. Cheaper than a cam and lifters.

 

its not lack of fuel 6.5 psi at carb at idle.....and we have adjusted and adjusted timing back and forth and can choose whether it will miss out more at higher rpm or adjust it the other way and it does it at lower rpm

 

think we got it figured out...... we had replaced all the wire from firewall forward well he brought it over and i looked inside the cab and found a place where the no-longer existing grommet was the wire was old and brittle and i assume it was grounding out against who knows what under the dash (explains why we didn't see any sparks under the hood) and i removed the little angle plug that hooks up to the coil and used a new connector and 1 long piece of wire (instead of 3 splices) and the truck hasn't done it since that we can tell so thanks fellas