BBC header size

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bbboswell
Southern Airboat Member
Posts: 78
Joined: Sun Jun 17, 2012 10:51 am

BBC header size

Post by bbboswell »

What size primaries are y’all running on 550’s hp big blocks?
crazycoonass
Southern Airboat Member
Posts: 64
Joined: Mon Apr 16, 2012 1:01 am
Location: Franklin, La.

Re: BBC header size

Post by crazycoonass »

I'm having a 540ci bbc being built right now. I plan on going long tube 2'' primaries with 4'' collectors.Big engine, big tubes to get the hot gases out.
Also I'll be making about 740hp.
bbboswell
Southern Airboat Member
Posts: 78
Joined: Sun Jun 17, 2012 10:51 am

Re: BBC header size

Post by bbboswell »

crazycoonass wrote:I'm having a 540ci bbc being built right now. I plan on going long tube 2'' primaries with 4'' collectors.Big engine, big tubes to get the hot gases out.
Also I'll be making about 740hp.
Thanks for the input.

454 @ 540hp and I have always run 1-3/4 primary 3” collector but engine builder wants 2” primary long tubes. I always thought the smaller tubes aided scavenging to help tongue but he thinks they are over scavenging and pulling still burning fuel into the exhaust which was causing my header glow issues.
crazycoonass
Southern Airboat Member
Posts: 64
Joined: Mon Apr 16, 2012 1:01 am
Location: Franklin, La.

Re: BBC header size

Post by crazycoonass »

Header glow? Hmmm. That sounds more like a timing problem. Or possibly a lean carb.
bbboswell
Southern Airboat Member
Posts: 78
Joined: Sun Jun 17, 2012 10:51 am

Re: BBC header size

Post by bbboswell »

crazycoonass wrote:Header glow? Hmmm. That sounds more like a timing problem. Or possibly a lean carb.
Plug color was good and no run on after shut down
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