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Duck
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Group: Forum Members
Last Active: 10 Years Ago
Posts: 349,
Visits: 1.3K
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That all makes sense to me- the only problem is T-birds are prone to clearance issues with anything more than a 1/2'' spacer. The one I'll run is a 4 hole... /Duck
BOO- YA!!! 
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LM14
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Hitting on all eight cylinders
Group: Forum Members
Last Active: 15 Years Ago
Posts: 9,
Visits: 48
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The only way you will actually know about what spacer to use is with dyno time. We spent a bit of time on it during one dyno session (approx 550HP Brodix headed/Motorpsorts block dirt late model engine) and found that the HP and torque didn't change between a 1" open and a 1" 4 hole and a 2" open and a 2" 4 hole but the place those max figures happened moved. On another engine, we always ran a 2" spacer and saw about 7 to 10 HP. Didn't matter if it had 1 or 4 holes. Driver preferred 4 hole and could tell the difference by the way the car came off the corner under full throttle. I would encurage you to play with it and see what feels the best. We had one motor that actually preferred the Motorcraft 3/8" tall heat insulating spacer and that motor gained almost 20HP every time we went back to it after trying something else. Just a few thoughts, SPark
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Duck
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Group: Forum Members
Last Active: 10 Years Ago
Posts: 349,
Visits: 1.3K
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AZ28 (9/7/2009)
What sort of carb are you going to use? Both the 600 cfm Holley that used to be on mine - and the Road Demon - have their own PCV vacuum ports. And I've got that hooked up to a PCV valve at the original T-bird valley hole (the one for theroad draft tube).You got a new valley cover - right? How are you going to work the PCV? That set-up Dutchy showed us is the way to go I think - the pipe tapped hole into the galley. This picture is an old one - but - I really "funneled" the spacer openings under the carb to make all of the edges match up as smooth as possible. Between the 1/2 inch of phenolic material - and the air gap under it(this is an unmodified intake) - the carb stays pretty cool.  Steve- I had the Holley rebuild facility assemble a carb to the original appearance/ spec of the '57 T-bird. No PCV provision. The valley cover had a boss for a PCV grommet hole which I drilled for the proper size grommet. The hole is offset to the driver side though, so I'll have to bend up a short piece of steel line to make it all work.Other than that, "Bob's my uncle".... /Duck
BOO- YA!!!
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GREENBIRD56
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Group: Forum Members
Last Active: Last Year
Posts: 1.7K,
Visits: 102.7K
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What sort of carb are you going to use? Both the 600 cfm Holley that used to be on mine - and the Road Demon - have their own PCV vacuum ports. And I've got that hooked up to a PCV valve at the original T-bird valley hole (the one for the road draft tube). You got a new valley cover - right? How are you going to work the PCV? That set-up Dutchy showed us is the way to go I think - the pipe tapped hole into the galley. This picture is an old one - but - I really "funneled" the spacer openings under the carb to make all of the edges match up as smooth as possible. Between the 1/2 inch of phenolic material - and the air gap under it (this is an unmodified intake) - the carb stays pretty cool.
Steve Metzger Tucson, Arizona
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Duck
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Group: Forum Members
Last Active: 10 Years Ago
Posts: 349,
Visits: 1.3K
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Steve- With just the aluminum spacer in place on the intake, there's a noticeable "step" where it mates to the intake. No way to do any type of transition, the way I see it (?) it's as if the spacer's holes are the larger of the two. I believe the best I can do will be eliminate all the "steps" and hog out the 2 steps in the bottom (inside) of the intake.
BOO- YA!!!
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GREENBIRD56
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Group: Forum Members
Last Active: Last Year
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Duck - When these guys milled (or ground out) the slots between the manifold throttle bore openings - they also opened up the bores to match the opening on the bottom of the carb. The diameter of the holes in the "B" manifold is 1-7/16 - and the holes in the bottom of my Demon 525 are about 1-11/16. There isn't much of the rim around the hole in the manifold left if you get things opened up that far. Is there some meat in the spacer to allow creating a bit of a transition taper? I used a phenolic spacer and tapered/blended beneath the throttle plate to get that smooth transition to the manifold hole.
Steve Metzger Tucson, Arizona
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Duck
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Group: Forum Members
Last Active: 10 Years Ago
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"Kill the steps"- Got it. Thanks, Steve. I appreciate your help  /Duck
BOO- YA!!!
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GREENBIRD56
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Group: Forum Members
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There need to be no steps under the carb venturi - if you open the throttle wide open do you see a step at the spacer? and then a step at the manifold lip? My outfit has the OEM holes -so I made the tapered spacer I sent the diagram of. If you are using the OEM spacer - does it have holes larger than the carb base?
Steve Metzger Tucson, Arizona
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Duck
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Group: Forum Members
Last Active: 10 Years Ago
Posts: 349,
Visits: 1.3K
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Thanks, Steve; I've slotted the intake front to back,and left the middle divider. I plan on using the T-bird 4 hole spacer w/ the PCV provision. Maybe I read Doug's explanation wrong (?) I did notice when I put the spacer on the intake after I milled it (intake) that the rear-most portions of the slots (cast iron) show when looking down the spacer's rear holes. I presume these "ledges" will need to be filed away. I equated that to the "chamfering" of the upper, inside of the slots (?) hope this makes sense... -Thanks- /Duck
BOO- YA!!!
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GREENBIRD56
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Group: Forum Members
Last Active: Last Year
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Duck - I think what he's referring to are the sharp edges on the bottom of the carb deck. Where the machining has broken through the "ceiling" of the plenum. If you maintain the four holes -and don't cut slots - to try and keep the crossection fairly constant below the primary... say bore them oversize to match the spacer and carb if you will - then this would be "flaring" the exit on the bottom side. When slots are used, the trailing edge of the carb bore would be abrupt with an open spacer - could be eased with a four hole spacer flared to the rear on the bottom. But forward - the flare would be on the underside of the plenum ceiling.....I can draw this better than explain it - but need more coffee..... Did your finished job look like which picture? (two full slots or two holes joined) and what spacer do you intend to use?
Steve Metzger Tucson, Arizona
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