What kind of performance gains are achieved by this and does it affect the streetability?

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

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.   

 
 Steve Metzger       Tucson, Arizona

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!

Frank/Rebop

Bristol, In ( by Elkhart) 

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.


Lawrenceville, GA

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.


Doug T

The Highlands, Louisville, Ky.

Bill: Your are right, my intake is a truck unit, with a flat surface. Bought it by accident.

Paul

Bill/ Paul, when did they start to use that manifold on the trucks, 58 up?

Frank/Rebop

Bristol, In ( by Elkhart) 

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.

Glen Henderson



Freedom is not Free

Letohatchee, AL

Frank, over here i believe it was 59 f600,s on.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

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.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico