Could someone explain the how the 4 hole and open spacer differ?
4 hole helps with throttle response and low end torque, open increases plenum volume and tends to favor upper rpm power. Divided wall basically mirrors the plenum on a dual plane intake. You can take a section out of the divided wall spacer that will give you a small open channel that will also increase your power band down low.
Any spacer will give more plenum volume due to raising the carb, but the different designs serve different purposes. The 4 hole by far will help your low end and mid range as well as your booster signal which will increase your throttle response as well. They will also help with fuel percolation caused by heat transfer to the carb from the intake.
I understand the help with fuel percolation caused by heat transfer to the carb from the intake, but if you cut out a section of the divided wall on a dual plane, why have a 4 hole spacer, I thought that the purpose of the 4 hole was to divide the left ports from the right… What am I missing? and thanks for helping
I was referring to making a channel on a divided wall spacer, not a 4 hole.And on the divided wall, I’m not talking about taking out the hole divider, just a small section. Check out the air gap line of intakes. For reasons unknown to me that small channel on the divider seems to promote stronger low end for some reason. Read it in an article and thought to myself “I have a divided wall spacer on my two plane. I think I’ll make my own little air gap and see if it is real, a marketing strategy that is perpetuated by a magazine on the take (read paid advertisement instead of real deal shootout), or just nonsense. So I did and it worked. For some reason the signal increased. I would have thought that it would have defeated the purpose of a dual plane intake and been exactly opposite due to the same logic (you’re opening the divided wall and in some small effect making a tiny single plane above a dual plane). Keep in mind the channel I’m talking about is maybe 3/4” long. As a matter of fact the low rise Performer Caddy intake for the 500 has the divider wall sectioned a little on the intake itself. Was the difference measurable in my car? Absolutely. And trust me, with my tiny little small block, anything I can do to make it stronger down low is worth a try when the mod is free and reversible (have a stash of carb spacers on the shelf).
I guess I should have been more clear on that one. I wasn’t talking about taking the entire center out of a 4 hole, I was talking about taking a small section out of a divided wall spacer. Sorry. Sometimes my head gets ahead of my typing.
Thanks for the education, never too old to learn
I would have never dreamed the whole air gap thing would have done what it did. Go figure. I learned something as well.