Brake Vacuum on Triples

Turn & Burn

Club Member
I’m installing triple 45 TBs on my new engine build. I’ve got a Kameari inlet manifold that only has one tap-in for the brake vacuum, although there are castings that can be drilled on 3 of the other runners. There is no common link / balance line between the runners at present. I’m just wondering whether to open the other 3 up and make a manifold from 10mm tube to maintain enough vacuum for the brakes.
What’s people’s experience of their brakes with triple carbs?B62238B7-D0CB-4CA8-B51D-3F89F044675D.jpeg
 

jonbills

Membership Secretary
Site Administrator
I only have brake vacuum from cylinder 6 runner on mine, and its fine. adequate servo, no mixture problems for #6.
only problem I did have is that piston 6 seized when the master cylinder failed and leaked brake fluid down the pipe and into the cylinder. But maybe that was a win, in that I only had to replace one piston :)
 

Turn & Burn

Club Member
Yeah, reckon they probably are for MAP, but I’ll not need them for MAP as I’m on TPS, so if there’s any benefit to using them for the brakes I would consider opening them up.
 

Turn & Burn

Club Member
I only have brake vacuum from cylinder 6 runner on mine, and its fine. adequate servo, no mixture problems for #6.
only problem I did have is that piston 6 seized when the master cylinder failed and leaked brake fluid down the pipe and into the cylinder. But maybe that was a win, in that I only had to replace one piston :)
Now that’s unlucky!
 

Bazzateer

Club Member
I can't see any advantage in more than one vacuum feed for the brakes, more single points of failure with multiples feeds.
 

Turn & Burn

Club Member
Thanks folks, one it is. I’d just seen a few Aussie posts where lack of vacuum had occurred on some manifolds without any linked runners.
 
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