88 F250 w/460 runs rough w/ black soot

[Pete33Vt]

I have an 88 f-250 w/ a 460, std trans, 4x4. I have changed the timing chain and have the base timing set I think. By hearing and starting ease. The emission decal is missing so I am looking for the actual timing numbers. Also the engine is acting like it did before change. Very rough idle, stuttering at some speeds, sometimes and alot of black soot coming from tail pipe. I have 202,000 + on the body and unsure on the engine, swapped before me. Hate to give up on her but need to get alittle better mpg. Any thoughs?

[Pete33Vt]

More info on this problem!! I am still looking for the timing numbers!! The running problem only happens once in a while. Most of the time it on a warm day after vehicle sits for a while. I am thinking its the egr valve. But I would like to have my timing right first. There must be someone on here that would have some timing numbers for a 460??

[jtmerritt]

Engine firing order is

Assuming the timing is set correctly at about 8 BTDC with the distributor vacuum advance disconnected and plugged. I would look at the carburetor power valve sounds like it may be ruptured or the choke is not unloading or both. Also, check the float levels to be sure they aren't set too high.

John

[Pete33Vt]

John, Thanks for the info. I should have mentioned that my 460 is fuel injected. Is 8 BTDC still the right number? Thanks Pete

[jtmerritt]

Since it is 8 with a vacuum advance, I would set it at 8 with the spout connector on the distributor removed. With the spout connector I would guess it is about at 10 degrees BTDC. If you are still having the rich running problems after setting the timing let me know.

John