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Blue Thunder 2X4 Intake Experience?

6.1K views 9 replies 4 participants last post by  turbo2256b  
#1 ·
Anyone here have any experience with the Blue Thunder 2X4 intake manifold? I have access to one, and a couple of Holley 390 carbs to give it a go. From reading various posts online here and other places, there is the possibility of running lean on some cylinders while just using one carb as the primary, and having the second carb kick in later on. Is it better to go 1:1 on the linkage with the Blue Thunder intake to ensure better fuel distribution to the cylinders, or just using the rear carb as the primary while cruising? This is for a 289.
 
#4 ·
I run the Blue Thunder dual Quad intake on my 302. Linkage is set up 1 to 1. Highly modified carbs matched up by Nickerson to stage 5. I also ported the intake and it flows more than a mildly ported VrJr. Stock they flow about the same as a Performer RPM. It is much better material and casting than a edelbrock. According to Nicerson the carbs now flow 520 CFM each total of 1040 CFM.
 
#5 ·
I've read that the ports on the Blue Thunder are a bit on the small side and some work needs to open them up a bit, so that's not too much of an issue. I am more concerned about the linkage and how it's hooked up, and you've answered that question. By any chance do you have any pics available of your setup?
 
#6 ·
No pics at the moment as i just went to windows 10. The picture set up on this is a bitch. Cant seem to put the picks in different folders like the older versions like windows 7.
Can get some new pics tomorrow as I dont want to load my memory stick with about 2000 pics into one folder.
Understand it took me 2 weeks 6 to 8 hrs a night and a lot of time on a flow bench to get 215 cfm per port bolted to my ported DOOE heads. The slightly ported VrJr only got 180 bad port 190 good port. Stock the intake is improved over the Ford factory unit.

Some issues with plug readings different have to do with cooling issues and can happen with most any intake.
 
#7 ·
As turbo2256b mentions, the successful carbs are those that have been extensively modified.

It's unrealistic to thank you can put on two stock carburetors and have the same results. A 1:1 linkage doesn't allow for for any imperfections, a progressive linkage does allow for the carbs not being perfectly tuned to the intake and engine. Most builds fall into the "not perfect" catagory. Just sayin'.

Z
 
#8 · (Edited)
The linkage set up is a couple aluminum turn buckles from the local hard wear store a bit of stainless steel threaded rod. The ends are spherical rod ends. One end left hand the other right hand. The center threaded rod is RH thread. The turn buckles have to be one thread size smaller than the rod ends as they have to be drilled and tapped for the LH and the RH threads.
The ends have the ability to have a bit of play to very tight allowing almost 100% 1 to 1 but can be adjusted so the front or rear primary's can start to open first partly depending on which carb the throttle cable is attached to.

This set up also has cruse control and TV cable for the AOD.

The last pic I am pointing to a secondary throttle adjustment. Once I SET THE PRIMARY THROTTLE BLADE TO IDLE TRANSFER SLOT properly I use this to set idle speed without having to remove the carb
 

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