Use a gasket that matches the carb base plate as a template - and make sure there aren't any edges sticking out into the airstream.

The latest issue of the YBM does have an article on carb spacers and shows exactly how much power particular spacers are worth on the aluminum intakes.  Some of that information is transferable to the ECZ-B iron manifolds.  That issue is just now making it into the subscribers hands.

As a general rule for the ECZ-B intakes, the 1” height is preferred over the ½”.  For lowend torque, use a four hole and for upper rpm performance go with either a dual oval or open type spacer.  How the intake is modified will determine just how well a particular spacer will perform.  I'll add that the 'tapered' style of spacers (four hole on top and open on the bottom) still tend to show performance improvements on everything they are tried on.  If the intake is a four hole, then maintaining the spacer as a four hole typically gives the best results but even the tapered spacers tend to work on the four hole intakes even with the hole mismatch that's present.  If the intake holes have been elongated, then there are some advantages with other spacer designs that will come to the forefront.

Having heck of time finding new 4 hole base plate gaskets to fit the Holley and ECZ-B, Holley shows them for around $20, I need 2, that ain't right and I'd cut them myself from paper stock. Anyone know a source?  Found it at NAPA, $1.53, had to go to RockAuto to get part #, then back to NAPA, NAPA site sucks.

Want to plug the exhaust crossover, seems I read thin aluminum under gasket on head side is that correct?

Thanks for the help. Gotta do search to sign up for Y-block Magazine. Found this one also, check in mail.

Here’s a link to a previous discussion regarding the tapered carb spacers.

http://www.y-blocksforever.com/forums/Topic67347-3-1.aspx 

And here’s another picture of the bottom side of a tapered carburetor spacer showing more detail of how this particular spacer transitions the air flow from the carb to the intake.

Here’s a picture of just a few of the carb spacers that have been tested.

It almost seems to me, after reading doen through the thread - that there is a particular length of straight tube that needs to exist under the butterfly shaft. The combination of that uniform passage - and then the "diffuser" opening below does the deed? Looks like the section of straight tube must be something equal to (or slightly over) the full diameter of the butterfly below the pivot centerline?

The tapered spacers do tend to work best in those instances where the engine is under carbureted.  The tapered spacer straightens out the air flow by reducing flow eddys under the carb itself thus permitting more air flow through the carb.  As a general rule, the better the heads are, then the more a tapered carb spacer tends to benefit engine performance in a particular rpm band.  There was thirty plus horsepower gain on my roadster engine in just playing with spacer designs.

I have Gary’s 312 stroker on the dyno right now and it’s in the process of testing nine different single four barrel intake manifolds on it.  All are ported differently.  With what’s been tested so far, it’s becoming clear that there is no particular spacer that’s going to be a fit all.  Certain intakes simply like certain spacer designs or spacer heights.  Once all the intakes have been run, then it’s a matter of sorting out the data and making some sense of it.

I think I know the answer to this, but to be more certain, here's the question; I plan on using the "B" manifold on a street, supercharged 331 cu.in. motor. So, would you elongate the holes into ovals and use a 1" spacer that was open or with holes?

Thanks,

Rono

Here’s my two cents worth.  Anyone else is free to comment.

That’s a yes for elongating the carb holes into slots.  With the slotted intake you can go either way, four hole or open but my particular choice in this case would be an open style carb spacer if simply choosing from these two designs.  Because maintaining a separation under the carb (true dual plane) with the supercharger isn’t as important as in a normally aspirated scenario, then reducing any restrictions under the carburetor by using an open spacer would have its advantages.  Another option that would help to smooth the transition going into the ‘slotted’ manifold and still maintain a true dual plane design would be a spacer with dual slots that matches the intake holes.  Here are some more pictures including the dual oval or slotted spacer.  All these spacers are upside down and viewed looking at their undersides.

You asked for more input, and here's mine.  I tried a slotted front-to-back intake on my race car with the Paxton.  Ran .1 to .15 seconds slower with the slotted one compared to the stock F code manifold.  No other changes were made.  It uses the stock phenolic 1/2" 4 hole spacer under the teapot..

http://www.summitracing.com/parts/QFT-300-4150-1AL/

Rono

John.  Thanks for the real world input.  Supercharging just seems to make its own rules.  What works for normally aspirated engines just doesn’t cross over cleanly to ‘blow thru’ stuff.

Wayne.  Here is a summary of what was dyno tested on a pair of iron intakes.  On a ECZ-B four hole intake, the 2” four hole spacer had lower peak and average numbers than when using a 2” tapered carb spacer.  Transitioning into the intake at the carb holes does not seem to be the key here. Running that same intake without any spacers had lower numbers than what was seen using spacers.  The intake just likes spacers.

On an ECZ-B intake that had the carb holes slotted, the 2” tapered spacer outshined a 2” HiFlo (4 holes into 4 squares), a 2” Offy dual slotted, and a 1” HVH dual slotted spacer.  No spacer at all had the lowest values of all.  It would appear that it’s hard to go wrong with the tapered carb spacer design on the ECZ-B intakes.

Hadn’t thought of trying the tapered spacers upside down; holes on the bottom instead of the top.  Down the road when there is a four hole intake back on the dyno, I’ll give that scenario a whirl.  At this point, I’m even thinking two tapered spacers with the open cavities matched up together and the holes themselves at the carb and the intake.  Lots of possibilities here when talking about combinations.

Rono

Ted/John, just thinking about the blowthrough scenario, could it be that being open, the manifold is slightly charged but when the valve opens the air has to search for that open valve and you have the air going all sorts of directions fighting and bumping into itself to get to whichever valve is open. whereas in a direct 4 hole combination, each runner has a full charge and is ready to enter the cylinder as soon as the valve opens? I guess an 8 hole (2-4bbl) would be optimal if it was the case.

Rono

On the other hand - I sure can see the advantage of smoothing the edges of the air entry into the manifold too. Seems like you need two transitions - one out of the carb - and one from the open plenum into the manifold passages.  

Rono.  You’ll need to slot the four hole gasket so that there is no unsupported gasket material under the carb or over the intake opening depending upon which way you install the spacer.

Billy.  Boosted applications are completely different when it comes to air flow requirements.  While I’ve reams of data for naturally aspirated carb setups, I’ve only a smattering of information on some of the various blow-thru applications in regards to spacer demands.  Because many of the engines I test with superchargers already have fixed carburetor setups, there’s not much opportunity to test a variety of carb spacers on those.  There are undoubtedly some learnings to be had in that area but the complexity of many of those setups prevents their owners from spending the time on the dyno to test some of the variations in those setups.

Chuck.  Here’s a picture of the tapered spacer and looking at it from the bottom side.  The general idea is to have the four hole portion at the carb base which eliminates some of the flow eddys that form which in turn inhibits flow through the carburetor.  These spacers work really well on the smaller sized carburetors in that the flow through the carb is increased simply due to the reduction of the turbulence that occurs under the carb.

(1) Is the above picture inverted to the way the spacer goes under the carb and shown this way for clarity?

(2) Assuming so, would it then simply discharge onto the the carb mounting surface of the manifold (slots in particular)? Does the center divider get reduced - removed to certain depth  - "sharpened" edge - what sort of manifold match?

 I drive mostly on the street and this spacer is somewhat more forgiving at Idle and off idle. I didn't notice much loss in acceleration but I have not tried it on the track. The BT has a medium size "window" between the oval holes, if that window was not there the idle would probably be even better. 

been looking at HVH website,  surprised they say plastic/phenolic spacers not for street only drag/marine use!

ally for street/strip use  why ...any coment please. i would have thought plastic would have been a better heat blocker

stuey

(2) Assuming so, would it then simply discharge onto the the carb mounting surface of the manifold (slots in particular)? Does the center divider get reduced - removed to certain depth  - "sharpened" edge - what sort of manifold match?

I’ve experimented with the iron intakes in dropping the center divider down and those efforts end up hurting the lowend torque values regardless of the spacer design being used.  The Mummert aluminum 4V intakes have a preference for a measure of open plenum between the intake and carb and that’s what the tapered spacer provides.  On the other hand, the Blue Thunder intakes tend to prefer a carb spacer that is more segregated in design or has less openness between the sides.  Said another way, the BT intakes prefer a spacer that keeps more true to the dual plane design.  Doug’s observation mimics what I also see with the BT intakes.

With both intakes being so similar in overall design, then that begs the question “Why the different spacers?”.  Here’s my observation.  The Blue Thunder intake has a crossover slot at the secondaries while the Mummert aluminum intake does not have that slot.  Unless proven otherwise, this would be a contributing factor why the two intakes prefer different spacer designs when all else remains equal.  The verification for this would be to test the Mummert intake with and without the aforementioned slot and verify that is indeed what is driving the carburetor spacer difference.

Here are a couple of pics of some of the spacers that were recently tested on a variety of Y intakes.  The left picture is the carb side of the spacers (top) and the right picture is the intake manifold side (bottom).

you just stopped me from making another mistake

stuey