problem with 253 vh

[vhbill]

i have a fault with my 253 v8. some times when starting from rest at say trafic lights. the engine has a small miss just at the start when up to speed all is ok. replaced the spark plugs all was ok for a while (when changing the spark plugs number six cylinder spark plug was black in colour) change spark plug lead for number six, little change. moved plug exchanged 5 and 6 problem went away again for a while by the way car runs on lpg. removed plugs from 5 and 6 cylinders and compression check about 150 psi each. the car blows no smoke or uses oil. can any one help????

[Nobody Actually]

check your air fuel ratio's

[GMMAD]

could be the oil rings i had i 253 that done the same thing but ran on petrol

[Bilbs]

ok, tell me if im correct, you have an omvl style converter dont you, with possibly a new gen mixer(looks like air cleaner on top of carbie) or a spud (spacer with pipe going in side on top of carbie, then std air cleaner). If i am correct in this setup, the problem is your sensitivity adjustment, you have 2 screws on the side of the converter, you need to adjust the idle screw so it is smooth, then bring it just above idle, if its an auto put it in gear, handbrake on, chock the wheels, but bring to just above idle till misses, then slowly adjust the other screw until the miss goes away, that is how to tune an omvl converter, if this is your setup, i hope it helps, if not, i have no idea, just that this is what my 253 used to do when on gas when in need of a tune.