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By PF Arcand - 13 Years Ago
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Want to do a mild street port job on a "B" intake. What tool will work best to cut the carb mounting base from 4 holes to two ovals? Just trying to grind it away with a Die grinder doesn't seem efficient. Thanks..
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By Glen Henderson - 13 Years Ago
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I used a cutoff wheel and a air hacksaw to cut out most of the materal, then cleaned it up with a die grinder.
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By charliemccraney - 13 Years Ago
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x2 on the cutoff wheel.
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By Doug T - 13 Years Ago
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I have done several using an electric die grinder and 3/8" straight tungsten carbide tip. Grind stones are much slower rotary files are useless. The hack saw does make the center material go away faster. Once you get the oval shape be sure to radius the sharp edges into the roof of the runners. Then reach down into the down sloping runner and increase the size of the passage entering the left and right lower passages. There is a real pinch point here. Save the metal shavings and mix them with an Epoxy glue to fill the flange face. Be careful of the chips which are small and sharp, eye protection is essential.
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By PF Arcand - 13 Years Ago
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Thanks to all that replied.. Doug, I'm not quite sure what you mean when you say to "fill the flange face?" Are you referring to the rough vertical cut areas?
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By pegleg - 13 Years Ago
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Paul, He's refering to the carb pad. The area that is relieved in the casting around the carb entry holes. Make sure you file that flat when you're done so the carb will seal.
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By GREENBIRD56 - 13 Years Ago
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It ends up looking like this when the holes and slots are cut - the "air gap" of the original gasket face is interupted. 
In some cases, guys have simply milled them flat. 
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By PF Arcand - 13 Years Ago
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Thanks Frank & Steve. I should have pulled the intake down off the shelf & looked at it again, before asking the last question. Some how I got a picture in my mind (such as it is!) that the surface was flat...
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By aussiebill - 13 Years Ago
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PF Arcand (8/26/2011)
Thanks Frank & Steve. I should have pulled the intake down off the shelf & looked at it again, before asking the last question. Some how I got a picture in my mind (such as it is!) that the surface was flat...Some of the B intakes do have a flat surface, maybe truck and full size cars?
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By pegleg - 13 Years Ago
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Bill, I suspect different castings are early versus late production stuff. I have one here with no firing order on it. It's early............i think. b
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By Y block Billy - 13 Years Ago
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What kind of performance gains are achieved by this and does it affect the streetability?
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By GREENBIRD56 - 13 Years Ago
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The main idea is to make the "B" manifold - which has small bores that match the OEM Holley 4150 type carb - more closely fit the throttle plates of other carbs. A garden variety Holley 600 cfm, model 1850 has bigger primary bores than those holes and others (Road Demons) are worse. If you just mount the bigger carb on there with a gasket or two so the butterflies will swing - open the throttle and have a look down the primary bore  Yep, big 'ol step hanging out in the airway. At low throttle angles - the butterfly can darn near seal off with the manifold bore edge below.
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By pegleg - 13 Years Ago
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Billy, does not affect the streetability at all. I doubt if anyone ever measured the hp gains. most of the time the newer carb works so much better than the originals that it doesn't matter!
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By charliemccraney - 13 Years Ago
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When I did it I noticed a little more power at the top end. Low speed, it didn't seem to do a whole lot. Driveability was as good as it was before.
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By Doug T - 13 Years Ago
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The "B" manifold modifications I suggested will support over 325 HP in a street engine as I found when I dyno'd my engine back in '98 with the modified iron manifold. I don't know what the stock manifold would do but David Vizzard's book "performance with economy" suggested that the radiusing the straight bore under the throttle plates was an important part of this mod and produced substantial improvement maybe in the range of 3-5% on other V8 manifolds.
I had some conversations with John Mummert about the modifications he used to do to iron B manifolds back before the Blue Thunder. He did the "oval" holes, radiused under the flange, and cut away the pinch point at the lower lateral runners. John wasn't specific but I came away with the impression that he also radiused the juncture between the lateral runners and the fore/aft runners. This was more than I wanted to try with the tools that I had.
Frank is correct about filling the carb flange.
BTW Steve M Was that a JPG that I posted looking down into the Oval holes? It looks just like one I took but I can not find it on the computer I am using tonight.
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By PF Arcand - 13 Years Ago
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aussiebill (8/26/2011)Some of the B intakes do have a flat surface, maybe truck and full size cars?
Bill: Your are right, my intake is a truck unit, with a flat surface. Bought it by accident.
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By pegleg - 13 Years Ago
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Bill/ Paul, when did they start to use that manifold on the trucks, 58 up?
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By Glen Henderson - 13 Years Ago
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I can't find it now, but I think some of Ted's dyno test (heads or exhaust) used a modified B intake. If I remember correct, it made pretty good numbers.
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By aussiebill - 13 Years Ago
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pegleg (8/28/2011)
Bill/ Paul, when did they start to use that manifold on the trucks, 58 up?Frank, over here i believe it was 59 f600,s on.
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By John Mummert - 13 Years Ago
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As I recall we dyno'ed a 314 in Y-Block before the Blue Thunder was available, around 1999. It made around 355hp with the modified B intake and 325hp with an unmodified B intake.
I did considerable work to the intake going into the runners from the head side and blending the intersection where the carb runners meet the cross runners from head to head.
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By PF Arcand - 13 Years Ago
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While grinding on the "B" intake, I noticed that two areas have diaganal ridges in the bottom of the runners. I first thought they were casting defects, then concluded they were directional ridges to help the fuel mixture go to the long side runner. Is that a correct assumption? If so I assume they should be left as is?
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By John Mummert - 13 Years Ago
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Paul, there is a ridge that appears to keep too much fuel from going to Cylinder #2. Probably shouldn't be removed completely for street use but I have smoothed them over for high RPM use.
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By PF Arcand - 13 Years Ago
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Thanks John... I've been experimenting with a modified drill bit extender (shortened & machined down) to reach into the inner port areas. However, due to the single speed of my electric die grinder, imbalance of most the stones is proving to be a problem. Still experimenting with that situation. Another thing I noticed is, that the front upper port floors at exit, are slanted to the outside somewhat. Was that done for a reason or is it just a casting defect? Having the fuel mixture tend to the outer side of the port, doesn't on the surface of it, appear to be benificial. Yes, no?. And would it be a good idea to try to flatten the floor somewhat?. Checking the intake port exit openings against the intake openings on a set of "G" heads, it appears that Ford deliberately made the intake exit openings smaller than the head opening, to avoid interference. On a basically stock street engine, is it just as well to leave the intake openings as is, rather than opening them up to port match?.. I think that's enough questions for now.. Thanks - Paul
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By PF Arcand - 13 Years Ago
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Folks; My previous post accidently gives the impression that it was intended just for John Mummert. If anyone else has input on modifying the "B" intake that is helpful, feel free to post it.. Thanks
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By Rono - 13 Years Ago
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Okay, I just picked up a "B" intake over the weekend and plan on going ahead with the mods discussed in this thread. One thing that wasn't covered was the tube near the base of the manifold. I remember it had a purpose, but can't remember what that was. So, do I plug it or leave it as-is. Below are a couple of pictures. There's a screw on one side and the tube appears open on the other.   Rono
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By Hoosier Hurricane - 13 Years Ago
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Rono, that was the heat supply for the automatic choke. Often the tube rots out and the choke gets filled with exhaust carbon. Also leaks exhaust out the inlet end of the tube.
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By Don Woodruff - 13 Years Ago
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With regard to the problem with the single speed electric die grinder, there is a device called a Variac. this varies the output voltage of the output side of a variable transformer. As die grinders are series wound this limits the speed of the grinder. You can easily con trol the speed. I like to use a 1/4 wooden dowel with wet or dry paper wrapped around it for final smoothing and polishing. DW
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By Y block Billy - 13 Years Ago
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For variable speed I have used old sewing machine pedals, put a male plug on one end and female on the other and can be used on different tools.
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By PF Arcand - 13 Years Ago
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Don & Billy; Thanks for the grinder speed limiting info. If I can't find either of the items mentioned, could a light dimmer switch in an electrical box, with a duplex plug, suitably wired, be made to work?.. John F., I think you have enlightened me re the choke heat setup. My 4 Bbl intake is the same as Rono's, having a single hole on one side of the crossover & an offset hole on the opposite side of the manifold, which is not the same as some other Y intakes, as to placement of the choke heat tube setup. (if I'm getting this right?) This had me scratching my head some. I was under the impression that all heat tubes took in air at the bottom "button" on the crossover & the tube curled upward & exited to the choke supply tube, on the same side. So, there were two layouts used?
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By Rono - 13 Years Ago
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Paul; So back to my original question, did you plug your choke tube in some way or just leave it open? Thanks, Rono
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By yblockpinto312 - 13 Years Ago
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A lite dimmer works great for varying the speed of a die grinder. I`ve used the same setup for 25 years with no issues.
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By PF Arcand - 13 Years Ago
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2nd shot at a reply.. last night the page froze, again!!
Rono: First, as John indicated, not a good idea to leave it open, in case the tube has a hole in it. But, what to do about the choke operation? I'm intending to use an Autolite 1.08 carb, which I have. Will try to ascertain if my manifold's tube is usuable? If not, it's back to the drawing board. Might be able to get an electric choke setup, but some have indicated they don't like them to much. Also, is another draw on my Generator system. However, am advised that Ford supplied Heat stove conversions, they come up on e bay now & then. But, from a photo it looks like an ugly setup. Also, I think it requires drilling the exhaust manifold.. don't like that idea to much. So am left with ???.
Greg: Thanks for the confirmation re using a Dimmer switch as an electric grinder reostate.
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By Doug T - 13 Years Ago
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Paul, I have seen two B manifolds with an aftermarket choke stove that consisted of something like a 1/4" pipe plug thread with a large (say 1") hex instead of a square. This piece was about 1" long and had a 1/4" hole for the choke tube in the center of the hex. Around this hole were about 6 1/16" holes drilled at an angle to intersect the 1/4" hole. This was threaded into the exhaust passage of the manifold facing upwards. It could be installed without removing the manifold and would be covered by a stock air cleaner. The carb/choke vacuum would draw air through this piece an up into the bi metalic spring as before. I never used them and do not have them now but it might work for you if you can find one. I do think putting a SS or copper tube in place of the original would function better because it has more surface area to heat the air. Drilling out the original, pulling a new tube in with a steel cable and expanding the tube ends to fill the new holes shouldn't be too difficult.
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By PF Arcand - 13 Years Ago
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Doug: I'll keep your notes in mind, thanks..Today I tried to drill out whatever is in the lower hole on the drivers side of the intake, without success. Drilled in about 3/8". It's like someone drove a rod or something in there? The inner heat tube is definately gone from the choke side of the intake. Looks to have been cut off. I have two other 2 Bbl intakes here, and both have different heat source setups. A 9425-C intake has an open tube coming straight up from under the intake to the choke pipe fitting. The other is a 57 intake & the heat tube starts (as far as I can tell, as it's installed) at the "button" & curls up to a large nut like looking afare on the crossover, with the choke heat pipe coming out of it.The nut looks a bit like what you described Doug. Will take closer look at it tommorrow..
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By marvh - 13 Years Ago
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PF Arcand (11/6/2011)
Doug: I'll keep your notes in mind, thanks..Today I tried to drill out whatever is in the lower hole on the drivers side of the intake, without success. Drilled in about 3/8". It's like someone drove a rod or something in there? The inner heat tube is definitely gone from the choke side of the intake. Looks to have been cut off. I have two other 2 Bbl intakes here, and both have different heat source setups. A 9425-C intake has an open tube coming straight up from under the intake to the choke pipe fitting. The other is a 57 intake & the heat tube starts (as far as I can tell, as it's installed) at the "button" & curls up to a large nut like looking afare on the crossover, with the choke heat pipe coming out of it.The nut looks a bit like what you described Doug. Will take closer look at it tommorrow..Paul: The manifold with the large nut has had a aftermarket heat stove kit installed. They are about 2" long, hollow , sealed at one end with a self tapping thread to screw into your manifold. The original Ford tubes are about 5/16" OD, one end swaged to 3/8" OD and ~7 inches long with the centre area crimped to restrict the amount air passing through to your choke thermostat. This tube is exposed to hot exhaust gases inside the manifold. If your tube is burnt off inside your manifold the choke thermostat will suck these exhaust gases from the manifold exhaust chamber and the little piston in your choke thermostat will gum up and corrode from the exhaust gases it receives instead of heated clean air. If one uses an unrestricted (un-crimped) straight tube (my theory) is; too high a volume of air likely will reach the choke thermostat due to not having a restriction causing the choke thermostat to not operate properly due to the air supply not being "heated" enough to kick the choke off timely. The new tube is driven in from swaged side ( I think it is the brass elbow side) as the manifold is drilled one side 3/8" and the other 5/16" Here is a link to a tube on ebay for an example, Item number 190585605249 http://www.ebay.com/itm/1956-1957-Ford-Thunderbird-Mercury-NOS-dual-quad-2x4-intake-choke-tubes-pair-/190585605249?pt=Vintage_Car_Truck_Parts_Accessories&vxp=mtr&hash=item2c5fc98c81 You can buy them from other suppliers cheaper than these. marv
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By PF Arcand - 13 Years Ago
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Marv: Thanks for the additional info re choke heat parts etc... I was able today to finally drill out the rusted heat tube pieces, from both sides of the intake, and was able to pass a wire right thru both sides. Based on the info kindly provided by everybody here, I should be able to sort out getting a choke heat setup in place, before installation.. Thanks again.
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By PF Arcand - 13 Years Ago
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Repeating a previous question. The "B" intakes port floors in the front upper ports, are slanted downward to the front side somewhat. Was that a deliberate design, or is it a casting defect?. If a defect, should some effort be made to flatten them some?.. Also, because the Intake is going on a stock cammed engine, other than fairly extensive plennum work, (as recommended here) I've left the intake port sizes as is, (and un polished), except to open up pinch areas some, remove casting defects & smooth and round corners etc. And I've tapered the outer port openings some to approximate the gaskets. Am I on the right track?... Observation; Looking at photos of the Mummert intake, I notice that the grooves in the plenum floor are "across" it, not long ways like the "B" intake. On the surface of it that would seem not the thing to do, but I'm guessing that was done to induce turbulence..yes, no?.. Thanks
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