my car originally came with a 2 barrel rochester. i recently upgraded to a 4-barrel edlebrock performer intake and edlebrock 600cfm carb. i want to put a pontiac Q-jet on there but i find it hard to find the correct one(1968) how would my perfomance be affected if i put one on their that is not from the correct year???? i.e. 1970 455 Q-jet??? please give some suggestion and advice! (my car is an original 350 2V 265hp)
One of the other guys is looking at doing a similar thing, and it sounds like you both may be looking at the same carb on eBay. Check with DavidATX. Make sure you don't get into a bidding war.
To answer your question, though, unless you also make some cam changes to take advantage of more airflow, you won't be using the Q-Jet to its full potential, but it will work.
I don't have the Rochester specs on the small-valve 455 carb, nor the 68 350 4-BBl carb, so I can't be certain, but It probably will need to be re-jetted and tuned to work on an otherwise stock 2-bbl motor.
