350 to 305 TBI

[48rat]

So I may have a dumb question! I have a 48 Chevy that I put a 350 tbi in, well that one went bad and I put a 305 tbi in it because I had it laying around. Now I'm to the point of setting the timing, I unplugged the wire set the timing, shut it off then plugged it back and the timing goes way high. It idles way to high, any thoughts.

TIA

[Mikebtte]

You can drill out the alluminum plug in the drivers side of the TBI and you will have a idle speed adjust screw. Factory covered it for some reason.

Also remember to reset the idle air control valve on the passengers side of the TBI.

Let me know if you need anything else, I did this same set up in my 59 Chevy.

FYI, 305 and 350 have different injectors, if running the 350, use the 350 injectors.

305 flow less.