I'd like to get a blue thunder intake, but as long as I'm going to get rid of the stock I was thinking maybe I could take a stab at modifying it first and save the $ for other parts.    I've never done anything like this before, but it seems worth a shot.   I have access to a vertical mill, but was wondering if anyone had some detailed information about what should be cut / changed to improve it's performance.  Is it worth the attempt?  If mummert is coming out with a new intake that is better than that blue thunder, than this might buy me some time while that is developed.  I just don't want to wreck my intake and then be out.  all help appreciated.

- John

John: Lake Forest, IL



'57 Fairlane 500 - Looking better every day.

Speedway has a good and interesting 5 hour set of DVDs  that covers match porting of intakes http://www.speedwaymotors.com/HEADS-PORTING-and-VALVE-TRAINS-3-DVD-SET,7587.html

and a lot of other worthwhile information.  I have the material together to try match porting a set of heads and intake myself, but suggest practicing on some expendible parts first.  To match port the intake alone, and not the heads, wouldnt do any good.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

I don't want to mess with the heads.  That's beyond my ability and that would be real bad if I trashed a good set of heads.  Specifically w/ the intake, I was thinking of milling the top.  Opening up the holes to a similar pattern as the blue thunder.  does anyone have measurements?  any benefit to this? - thumbs up or down?

John: Lake Forest, IL



'57 Fairlane 500 - Looking better every day.

Slot the holes front to back, but do NOT remove the front-to-back dividing wall between the left and right throttle bores.  Won't work right.  Been there and done that.

John - "The Hoosier Hurricane"

I found it!

http://www.y-blocksforever.com/forums/Topic11190-3-1.aspx



In addition to slotting the manifold, open the throttle bore radius to mach the carb or spacer. You don't want a step in there.


Lawrenceville, GA

It's interesting to hear the recommendation about slotting the primaries to the secondaries. I ended up with two iron 4bbl intakes for the small valve (2.09) Clevelands. One has four holes, the other has the two slots. I was going to use the four hole intake, thinking that the slotted intake was inferior.



Does anybody know why the slotted intakes work better?

Best regards,



Paul Menten

Meridian, Idaho

Excellent - Thanks for the link.  I'll take a stab at it and post some feedback/pics when i'm done.

John: Lake Forest, IL



'57 Fairlane 500 - Looking better every day.

This is what you need to do.  Slot the holes together.  Then look into the right side hole no matter which end you look from and you will see an obvious restriction where the passage on the right side dives under the cross runner.  Grind on this to open it out. The left side is not so restricted and doesn't need much.  Radius the holes where they start at the flange so that the flow does not have to go over the sharp edges left over when the holes were machined.

This pic shows a manifold that has the grinding finished but it has not cleaned up by blasting.  After blasting fill the surface of the flange including the space between the slots with an epoxy glue mixed with the iron filings that you have saved from the grinding.  Grinding is not the right word because I don't use abrasive stones for any of this, I do it all with carbide tools and a high speed, electric die grinder.  Level the hardened glue/iron mix with a file. I also plug the hot air tube with a 5/16 bolt on both sides and I don't run the heat in the exhaust plenum,  However this means things are slooooow to warm up! 

I like a 4 hole spacer for slightly crisper throttle responce.  I used a manifold modified like this before the BlueThunder was available and had my engine dyno tested.  This manifold modification supported over 325 hp on pump gas normally asperated, so it does work.

Doug T

The Highlands, Louisville, Ky.

Paul,

         They don't always. Combination of plenum volume and mixture velocity issues decide that. In many cases people add HP with 4 hole spacers under the carb. My Windsor powered Ranger being one. It liked the 4 hole better on the original Wieand manifold. With the Edelbrock that's now on it, the reverse is true. (?)

Frank/Rebop

Bristol, In ( by Elkhart) 

Sorry for being dense.  What do you mean by "After blasting fill the surface of the flange including the space between the slots with an epoxy glue mixed with the iron filings that you have saved from the grinding"

Are you trying to create a smooth surface on the top of the flange