BBC 4-2-1 Headers

[earntaz]

I have a 433 BBC going into a 71 Nova -- 95% HP street. Has anyone used 4-2-1 headers on a BBC? How did they work?

Thanks

The TAZ

[earntaz]

No one has any info on 4.2.1 headers for BBC?

[67 Nova Boy]

What are 4.2.1 headers?

Dave
67 Nova Boy

[markjohnson]

I'm a big fan of exhaust scavenging theory and have used Belanger Tri-Y's (or 4-2-1) on my Z06. I've always liked Tri-Y headers and they're supposed to be superior to conventional headers, especially street-driven cars, but they're hard to find because they're more time-consuming (more expensive to manufacture). Doug Thorley or Belanger Bros. manufacture them but mostly for small blocks. I have a set of the Flowmaster Scavenger collectors that I'm going to use on my next BBC project. The Flowmaster collectors basically convert a typical 4-into-1 header into a Tri-Y header by separating the exhaust pulses away from each other and are great for building mid-range . . . .you know, right where the tach likes to drop to after every gear change! Anyway, you have to join the proper cylinders together for them to function properly= 1 and 5, 3 and 7, 2 and 4, 6 and 8. Most of the time with the Flowmaster collectors, you need to swap a primary tube or two with each other so you can can pair up the correct cylinders into the scavenger collectors. One more quick note . . . if you happen to have one of those 4-7 swap camshafts that are so popular these days, then you need to do different cylinder pairings than the ones I listed above.

[earntaz]

Thanks Mark -- the Nova will be 95% street and I am looking to enhance the torque in a 433 BBC. I have also heard you will have more ground clearance compared to a conventional 3.5" collector. Sounds like this may be something to play with.

Again -- thanks ... The TAZ

[earntaz]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 67 Nova Boy</div><div class="ubbcode-body">What are 4.2.1 headers?

Dave
67 Nova Boy</div></div>

See Mark's explanation above ...

[markjohnson]

They will usually help with ground clearance because instead of having four large primary tubes bundled together and hanging down under the car, you will only have two before they merge into the collector.