I have an 85 t/a with the LG4 engine.I plan on building up an 84 305ho from a t/a.I'm well aware this engine is a "paper weight",so lets get that out of the way right now.doing .030 over with port/polish 416's with 1.94,maybe slightly higher comp. ratio.i wanted to put a mild cam in it,probably a generic grind,around 260 or 268.would i be able to use my 85 dist with stock ecm,or would i need the 84 ecm,or would a mechanical dist be the best route.any info or suggestions would be great.

 

Welcome aboard thirdgen.org.

Any particular reason for the overbore? Unless you have excessive cylinder wear, it really doesn't help anything, and is money down the drain performance wise. The HO pistons will provide very adequate compression ratio - pop-top pistons would be an unwise move for the street.

The stock carb, distributor, and ECM are very capable performers. An aftermarket coil and ignition control module (7-pin), and tuning for the secondary rods and hangers, assuming the carb is in generally good shape, is the best street performance system out there, in my opinion.

It's what I'm running, and what I also ran when I had a juiced-up 305 in there before the 350 shortblock went in.

A Comp XE268 cam would be a very good choice, assuming valve spring upgrade while the heads are being worked (new retainers to eliminate the exhaust valve rotators also a very good idea).

 

i was thinking of the overbore just because i dont know how the engine ran in the original car.the owner said it ran well,but you can never tell.so you think i should have the machine shop give it a once-over for a rebuild?the carb is in good shape,but could probably stand a rebuild as well.my boss used to race 350s,and he suggested using a vacuum advance hei dist,something like accel,for durability and adjustability.as far as the cam,i was leaning towards the comp 268's,which they sell as a kit including springs,rocker arms and all the goodies.this project is in the infancy stages,so im just trying to gather as much info as possible

 

Computer and non-computer carbs and distributors work with their kind only. You can't use a vacuum/mechanical advance distributor with a computer controlled carb, and vice-versa.

In a race-only application, a Holley double pumper with a mechanical distributor could be argued to be the slightly better combination. Even then, you can use a computer distributor with a non-computer carb in a race application, set the total timing, and it would be at least as good if not a better distributor than the mechanical advance unit.

The weaknesses of a factory distributor are the control module (7-pin) and coil. The aftermarket has you covered there.

A compression check on the engine before it is disassembled would give you the best information about its condition. If a 305 needs to be bored, it makes more sense to find a 350 core to rebuild. Even putting the 305 heads on it after the work you described would make for a better final product than a rebuilt 305.