bigboo_1962

hi, i have a 1962 c-10 with a 305 i just put a new vacuum advance, cap and rotor, and still have the same problem. runs fine 1st though 3rd but when i shift to 4th i get some hesitation and it (for lack of a better word) lunges and i loose speed when i shift back down it'll do the same thing but not if i come to a stop and then speed back up, until i get back to 4th. if anyone has suggestions they would be greatly appreciated. thanks

therewolf

Hi bigboo_62,

Welcome to the Chevy Forums.

The 305 engine was built from 1976 to 1992. If the engine is original, it's not a 305.

If it's not original, assuming you were correct in your first post(you probably are, as the larger trucks tend to burn up a smallblock over time, not to mention some people put in a smaller engine some times for better fuel economy for their business vehicle) have you determined what year and factory your 305 came from?

Sight unseen, I would have to guess your problem is from putting the newer engine in the older vehicle and not linking the vacuum controls and the transmission up properly. Is it the original transmission, or did it come with the 305?

old dog

it's a 305 v-6 ? usually only seen them in gmc's if not maybe the mechanical advance in the distributor is shot . is it a standard point type dis or hei type electronic ?for the v-8.

bigboo_1962

i think it's the original trans but the motor is out of a 80 something Camero i don't know how to find out what year it is or where it came from. i think it might just be my timing (messed with it rand a bit better) but i can't find the marks only the one on the harmonic balancer and it has hei and it's a v8

therewolf

If you set that with a timing light, and it's not running right, you may want to set it by ear. The Harmonic Balancers on the older small blocks tend to slip with increased mileage, which can give you a bad timing setting, if you use the mark on the balancer.

For a long time, the OEM had a romance with nylon timing gears, which tend to snap a tooth or two under engine duress or prolonged wear. The telltale sign of worn gears and chain is if the timing mark tends to jump around under the timing light. In the event you can't get your timing set, to level the playing field, you may want to consider changing to a brand new set of metal double roller timing chain and gears, if you're going to keep the vehicle awhile.