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Discussion Starter · #1 ·
Building a 427 with Brodix Track 1 heads at 221 CC intake a 67 combustion. The cam has 256 intake and 266 exhaust at .060 Lobe separation is 111.5. Lift is .423 intake and .426 exhaust. Hydraulic flat tap. I will have a vacuum pump on there to keep my brakes working.

FiTech states I've got to have a minimum of 6" of manifold vacuum. Comp Cams had trouble telling me what they thought it would be. Does my vacuum pump help with manifold vacuum? Think I will have trouble with the FiTech?

Thanks all!!
 

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It's a custom grind comp cam
You sure you have the cam specs right??
It seems very odd....

256/266° @.050" lifer rise is a pretty big whopper for a hydraulic flat tappet.....but .423"/.426" valve lift is miniscule for a duration that big....not really any bigger tha stock .410" valve lift.
Is this a circle track lift rules type of cam or something of that nature?? Or a bull nose/ball nose cam??

I ask because normally on 427" SBC stroker engines with 256/266° @.050" we would be expecting to see lift figures of .525"+ for hydraulic flat, .550"+ for solid flat or hydraulic roller, and over .600"+ for a solid roller cam with that kind of duration.

On top of nearly never seeing a cam with that small of lift in a 427 stroker...

if those specs you posted are correct, that low lift is certainly going to limit power potential.

it's just my opinion, but I'd expect it to make between 7-8" of vacuum at 1000 rpm idle.

Comp Cams would have trouble finding their backside with a map and a flashlight as far as tech help goes, if you aren't a well known race team or engine builder the tech you talk to is just a flunky.
 

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Discussion Starter · #7 ·
You sure you have the cam specs right??
It seems very odd....

256/266° @.050" lifer rise is a pretty big whopper for a hydraulic flat tappet.....but .423"/.426" valve lift is miniscule for a duration that big....
Is this a circle track lift rules type of cam or something of that nature?? Or a bull nose/ball nose cam??

I ask because normally on 427" SBC stroker engines with 256/266° @.050" we would be expecting to see lift figures of .525"+ for hydraulic flat, .550"+ for solid flat or hydraulic roller, and over .600"+ for a solid roller cam.

On top of nearly never seeing a cam with that small of lift in a 427 stroker...
 

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Discussion Starter · #8 ·
You sure you have the cam specs right??
It seems very odd....

256/266° @.050" lifer rise is a pretty big whopper for a hydraulic flat tappet.....but .423"/.426" valve lift is miniscule for a duration that big....
Is this a circle track lift rules type of cam or something of that nature?? Or a bull nose/ball nose cam??

I ask because normally on 427" SBC stroker engines with 256/266° @.050" we would be expecting to see lift figures of .525"+ for hydraulic flat, .550"+ for solid flat or hydraulic roller, and over .600"+ for a solid roller cam.

On top of nearly never seeing a cam with that small of lift in a 427 stroker...
 

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Oops! Lift is .676 and .681.
Then it obviously ISN'T hydraulic flat tappet....that kind of lift is strictly solid roller territory, or maaaybe a big hydraulic roller but that is getting awful dicey for a hydraulic roller to keep control of.
The spring to control .676" lift is beyond what a hydraulic roller lifter will handle.

So what have you actually got?
 

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Really need the detail cam data Comp must have sent you a timing card with the cam.

No a vacuum pump is of no help in building manifold vacuum, it is strictly a gadget to assist vacuum assisted power accessories like power brakes, vacuum windshield wipers, vacuum headlight doors, vacuum switches on air conditioning systems. The pump has no relevance to manifold vacuum .

Manifold vacuum will be a function of displacement, compression ratio, and of course the elements of the cam timing. These will include duration and lift, plus intake center angle to the crank, intake to exhaust lobe center angle (LSA) and it’s relatives overlap degrees and intake closing angle to crank degrees. All of this is either stated on the timing card that came with the cam or can be calculated from that basic information.

I’m truly surprised that Comp doesn’t have a relative close enough to your custom grind to get you in the ball park. I guess I’d have to question why the custom cam? Who in this process of configuring the engine knows enough about the subject of camshafts to select a custom grind over something off Comps shelf?

Bogie
 

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You've built a whopper of a motor and now you're onto a budget EFI system?

Go Holley and never look back. It will be an extra $500 over the FiTech and worth $2000 more than that FiTech garbage. An if you're genuinely serious about going fast at the track then look into a Haltech.
 

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Discussion Starter · #14 ·
You've built a whopper of a motor and now you're onto a budget EFI system?

Go Holley and never look back. It will be an extra $500 over the FiTech and worth $2000 more than that FiTech garbage. An if you're genuinely serious about going fast at the track then look into a Haltech.
Agree! FiTech is out. Holley most likely the winner. I'll look into Haltech. Thank you!
 

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Hmmm...some of FiTech's kits are listed as "625HP Dual EFI", "800 HP Mean Street" and "1200HP EFI 8, Boost/Nitrous"
The FiTech software is not user friendly.
I am not an expert, but having installed all of them at least once, and based on what experts tell me, the Holley stuff is the best value for a hotrod. If it's a race car, get FuelTech.
 

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Discussion Starter · #18 ·
Really need the detail cam data Comp must have sent you a timing card with the cam.

No a vacuum pump is of no help in building manifold vacuum, it is strictly a gadget to assist vacuum assisted power accessories like power brakes, vacuum windshield wipers, vacuum headlight doors, vacuum switches on air conditioning systems. The pump has no relevance to manifold vacuum .

Manifold vacuum will be a function of displacement, compression ratio, and of course the elements of the cam timing. These will include duration and lift, plus intake center angle to the crank, intake to exhaust lobe center angle (LSA) and it’s relatives overlap degrees and intake closing angle to crank degrees. All of this is either stated on the timing card that came with the cam or can be calculated from that basic information.

I’m truly surprised that Comp doesn’t have a relative close enough to your custom grind to get you in the ball park. I guess I’d have to question why the custom cam? Who in this process of configuring the engine knows enough about the subject of camshafts to select a custom grind over something off Comps shelf?

Bogie
 

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Discussion Starter · #19 ·
Then it obviously ISN'T hydraulic flat tappet....that kind of lift is strictly solid roller territory, or maaaybe a big hydraulic roller but that is getting awful dicey for a hydraulic roller to keep control of.
The spring to control .676" lift is beyond what a hydraulic roller lifter will handle.

So what have you actually got?
Yeah not a hyd flat. My bad. That's why I'm grateful for everyone here. Still learning
 

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