Square-bore vs. spread-bore?
IF your using a spreadbore to a spreadbore, below is what you want.
Depends on if the engine will like the extra plenum to start with. Also, the contour of the adapter (wide to narrow) to the contour of the intakes plenum (a square carb pad to how it enters the plenum and then into the runners) can be a crappy thing as well. Lastly, engine combo & drive train w/the cars weight have an effect on how the whole system works because of the above. If the car is heavy and has Hwy gears & it runs OK or boarder line, but the. Runs crappy with the spacer.....
IF your using a spreadbore to a spreadbore, below is what you want.
