need help with figuring out my timing

[buffblazer]

I need some help, i have an 86 350 bored 30 over, 600cfm edlebrock carb, rv cam, stock intake, headers, and true duel flowmasters. all of the emissions have been removed also. now i live in southwest oklahoma, and i cant get the truck running as good as it should, i have the timing at 10 right now but when i run it up to about 3800rpm, and let of the gas, it will backfire really loud and at night you can see a little fire out the pipes. what timing should i be running and what could i do to make it run at its best. thanks

 

[resurrected_jimmy]

I believe your timing should be closer to 28* total advance. Have you pulled your spark plugs and read them? You may have some other air/fuel and ignition issues besides timing is why I ask

 

[buffblazer]

oh well when i say 10 i mean when you look down on the harmonic balancer,the littel jigsaw tooth thingy says 10, and the plugs are rt45 ac delcos and ac delco wires with ac delco cap and rotor. now i forgot to say you can time it and then when you drive it a couple of days and re-check the timing, it will retard itself sometimes down to 8 or when i was running 12 it would go back to 10. how do i figure out the total degrees of timing, i know you say 20 for the cap, plus the timing marks, then whats the other one? i was told my a guy that works on hot rods, that i should be running about 36 degrees total timing. is that true.

 

[resurrected_jimmy]

ok, now we are getting somewhere. Your timing is jumping, totally different train of thought than what I was on. Yes your advance could go as high as 36* I was starting with 28* to be on the safe side. The backfiring out the exhaust made me start thinking that you may be running rich and your plugs are fouled (could still be the case but as an effect, not the cause of your problem). How fresh is your motor? A worn cam or timing chain can cause your timing to move like that. When you tighten down the distributor bolt does it keep the distributor in place? Any chance its backing off and allowing the distributor to move?

 

[Jason4x4]

may be dumb, but are you timing it with the vacuum advance unpluged?

 

[Chevy305]

may be dumb, but are you timing it with the vacuum advance unpluged?

X2, I was thinking the same thing!

 

[buffblazer]

the motor has about 100k on it, and when you tighten the dizzy bolts, the dizzy will turn if you dont have a really firm grip on the cap. and when i time it i unplug the vacuum line that runs to the carb, then i plug off the vacuum advance on the dizzy. am i doing that wrong? or is that what im supposed to do? oh and im not shure but when i check the bolts, it may or may not be backing off, i would have to check again to see.