65mojoe

Edelbrock RPM Air Gap for the win. I absolutely love mine. Good mid to top end pull combined with the rest of my setup. I think the whole "cool air" theory isn't so much that it allows cooler air into the intake; rather, it allows for quicker dissipation of the heat thats already there so that the manifold isn't heating up the air going in.

THUMPIN455

Both help, keeping the intake cool means a denser charge to the cylinder, while not having heat from the radiator going into the carb is also advantageous. Air gap just keeps the hot oil off the bottom of the intake, Having a cover over the lifter valley and letting some air in there helps alot. Then if you block off or simply dont have the heat risers in the head, it stays even cooler. Okay remember back a while I said Pontiacs have a factory air gap manifold? Well blocking the heat passages that are intended for cold weather driveabilty will result in a .2 thats two tenths of a second gain in the 1/4. Then remember how Pontiac had RAM AIR on some cars? Well ram air means cooler air getting in the carb, and that is also worth .2 in the1/4 due to it being cooler, not so much that air is being forced in.

The EFI guys will put bags of ice on the intake between rounds, so there isnt as much heat in the intake, meaning more air in the cylinders. So yes they work, but will you notice .2 of a second while driving on the street? nope. not a bit. Is it a good manifold? hell yeah it is, so are the other two. So you get what fits your budget and your car, because not all of us want to run a 6" cowl to cover up a carb. Remember the 351W he is talking about is TALLER than a 302 is, so the intake sits higher, and therefore can create a hood clearance issue.

A taller air filter flows better than a thin one, so a 3" tall element will be less restrictive than a 1" filter, so keep that in mind while picking manifolds and carbs. Too short of a filter can put the lid too close to the bowl vents and create a lean or over rich condition depending on what carb it is, how much it afects the airflow to the carb, and how much restriction it is. So a tuning problem could be your air filter is too short and not big enough around.

An air cleaner base with smooth rounded entry to the carb will flow better than the cheap summit type ones that have square edges, or a simple one that is a flat piece that has a hole in it for the carb. Moroso has a nice base, so does K&N, have both on some of my cars. Some factory GM filter assemblys flow really well with two snorkles, and its easy to set up a simple ram air system. Dont be afraid of using a part that works well just because it isnt from your favorite manufacturer, you like holley or carter carbs right? Same thing with other parts..

and on that note, some chrysler 8 3/4" rear ends will bolt right under a mustang... just something to keep in mind..

65mojoe

Easy fix for this is a K&N Xtreme Lid Top, that has the filter element built into it. Also, drop base is a quick fix for clearance issues.

I wouldn't be quick to suggest clearance issues with the air gap though. While it does raise the manifold up slightly higher than the other two mentioned manifolds, there shouldn't be any clearance issues, even under a stock hood, unless you run a phenolic spacer without any kind of drop base air cleaner.

THUMPIN455

The 66 we put a W in back in 86 had some hood issues with a slightly tall intake.. Its the only reason I mention it, since back then we didnt have the Air gap or RPM.. and the guy wanted a single plane...

65mojoe

Thumpin do you know if the victor jr. manifs are taller than the air gaps by much?

THUMPIN455

not for a W.. I dunno. Havent had one of each in my hands. I do know my Cleveland will be kinda tight in the 67.. but that is okay. I wont need to lift the back of the hood or anything like I did on some cars in the past. you have that year, drop in a 351 buy the manifold, put it on and let us know how it works!

65mojoe

come May I might just be in the market, but not till I see what the 302 will officially run at the Kingdon track. I'm going to try to run it into the ground, that way I will have no choice but to go 351....(or the Roush 342 I've been eyein![:-])

Yonco

Every post i see that thumpin has made is a freakin book! And i love it, im learnin a lot from this site and from you guys, thanks! -Jon

THUMPIN455

May as well share the knowledge of 22 years workin on cars, what was learned in school, and read in magazines. If we dont share what we know, and give a reason for why it is that way, or some background to illuminate something, then it just dies with us. the world is a better place when we think of others before ourselves, and try to help them when we can. (Even if we dont like them..lol) I like most of you anyway... okay well some..

Yonco

well, once i have info, ill share also, for the exact same reason, but i dont see anyone bolting in a L67 into thier mustang... so i dont have much info to share yet on this forum. -Jon