[caddor38]

I was curious to those who have a larger cam with power assisted brakes what you use for Vacuum assistance. Is there a cam profile lift, durations? that determines when to move from a Vacuum can to a pump assisted vacuum? I have the Competition Cam 308R Solid Roller with 575 lift 262 duration and have already installed a Vacuum cansiter, but was a little worried to the affects of stop light to stop light braking etc.

[JLMounce]

Remember, that the vacuum canister will hold vacuum based on your maximum achieved vacuum before being depleted. While the engine may only make 8-10" at idle, if it makes 16 at cruise, the vacuum can is holding 16" until it's depleted and refilled.

For the street, if you're playing light to light that can be detrimental because if you're hard on the throttle and need to get on the breaks, your vacuum can may have only seen a couple inches of vacuum at best. Can really put you in a sticky place. As a result if you are unwilling to go to manual or hydroboost brakes, on the street I would favor a vacuum pump.

Ultimately a well setup manual break system or a hydroboosted brake system for street use with a radical engine is going to be your best bet IMHO.

[caddor38]

Originally Posted by JLMounce

Remember, that the vacuum canister will hold vacuum based on your maximum achieved vacuum before being depleted. While the engine may only make 8-10" at idle, if it makes 16 at cruise, the vacuum can is holding 16" until it's depleted and refilled.

For the street, if you're playing light to light that can be detrimental because if you're hard on the throttle and need to get on the breaks, your vacuum can may have only seen a couple inches of vacuum at best. Can really put you in a sticky place. As a result if you are unwilling to go to manual or hydroboost brakes, on the street I would favor a vacuum pump.

Ultimately a well setup manual break system or a hydroboosted brake system for street use with a radical engine is going to be your best bet IMHO.

Hmmm, I actually threw away some manual brakes I had for the car back in the past. I will have to look into this some more. In the past, I had a fresh build on my 400 with a mutha thumpr cam and it also had a vaccum leak that caused very low vacuum at idle and I had a vacuum can and there was no issues, however the cam profile is different. I may call Comp Cams and see what they recommend aswell for this application.

[25stevem]

How many CID are we talking about here, because assuming the same Size combustion chamber a 455 will make 13% more vacuum then a 400 with the same cam.

[caddor38]

Just called comp cams, and they recommend a pump as well. Thanks for the advice. I will probably keep the canister and install an electric pump.

[64speed]

I went hydroboost and its awesome

[caddor38]

Originally Posted by 25stevem

How many CID are we talking about here, because assuming the same Size combustion chamber a 455 will make 13% more vacuum then a 400 with the same cam.

This is a 455 stroked to a 495.

[Schurkey]

How much vacuum do you have now???

With an engine that big, the FIRST thing I'd do is look at the fuel curve, and ignition advance. I bet that engine can be tuned so it makes better vacuum. It'd be more fun to drive, too.

[caddor38]

Originally Posted by Schurkey

How much vacuum do you have now???

With an engine that big, the FIRST thing I'd do is look at the fuel curve, and ignition advance. I bet that engine can be tuned so it makes better vacuum. It'd be more fun to drive, too.

The enginehas only been on the Dyno so I dont know?

[Schurkey]

Try it and see how it works, before you buy more equipment to stuff under the hood.

MAYBE it's going to be OK without the vacuum pump. Might depend on the size/configuration of your booster.

[imposter]

hydroboost for the WIN!

[1968GTO421]

Manual Brskes here. Simple, fewer problems, less costs.

[caddor38]

Originally Posted by Schurkey

Try it and see how it works, before you buy more equipment to stuff under the hood.

MAYBE it's going to be OK without the vacuum pump. Might depend on the size/configuration of your booster.

Sounds like a good plan. I will do that. It appears a good vacuum pump can be $400 shipped. I can be patient

[Schurkey]

I have actual experience with ONE vehicle that has hydroboost. A sample size of ONE is not much of an indicator...

...but the pedal "feel" with Hydroboost on my '97 K2500 is goofy. Brakes are bled, including using a scan tool to chatter the ABS solenoid valves. Friction material and iron in good condition. Brake hoses OK. Stops fine, but takes some getting used to compared to vacuum boosters.

[vertigto]

Originally Posted by Schurkey

I have actual experience with ONE vehicle that has hydroboost. A sample size of ONE is not much of an indicator...

...but the pedal "feel" with Hydroboost on my '97 K2500 is goofy. Brakes are bled, including using a scan tool to chatter the ABS solenoid valves. Friction material and iron in good condition. Brake hoses OK. Stops fine, but takes some getting used to compared to vacuum boosters.

If you don't mind, what does a 'goofy' pedal feel mean to you?

I'm having to try a hydroboost system from Right Stuff to replace their standard 4 disc conversion that would not adequately stop/lock up the brakes. Curious what to expect and this is the first negative feedback I've heard about hydroboost.

[Schurkey]

Dead. No feedback. Over-boosted. Are all Hydroboost systems like this? I don't know. Like I said--sample size of one.

Similar in concept to middle-'60s Chrysler power steering--no "feel", spin the wheel with the tip of one finger. Completely, totally numb. Heaps and piles of assist, entirely lacking in "road feel".

[Don 79 TA]

i run a v.pump from CVR
it's two wires, adjustable for altitude and has been working for 12+ years
i also have a 1" bore master, that had made a difference too
manual brakes certainly cleans it all up nicely
i can only imagine the pressure hyrdoboost would make,,, my only experience with them has beein in trucks, and if it works for them, can only imagine how it would do on a car

[Goatracer1]

I always used manual brakes on my street/strip cars. It's cheap and uncomplicated and it leaves lots more room.

[jonmachota78]

X2 on try it 1st! . Mine actually has too much assist butt has a dual diaphram booster from a 79 to clear the tall valve covrrs

[JLMounce]

Originally Posted by vertigto

If you don't mind, what does a 'goofy' pedal feel mean to you?

I'm having to try a hydroboost system from Right Stuff to replace their standard 4 disc conversion that would not adequately stop/lock up the brakes. Curious what to expect and this is the first negative feedback I've heard about hydroboost.

Having quite a number of mustangs in the past, they all had hydroboost on them. Compared to a vacuum booster they can feel mushy with several notches in the pedal throw as the hydraulic pressure is purged etc.

They don't tend to ramp as pressure as added, so they kind of feel the "same" regardless of the amount of pressure you are exerting. The hydraulic pressure dampens feedback through the pedal so it's hard to tell when the tires are on the limit.

Hydroboost is great for cruisers and hot street cars that want power breaks but don't need them for any type of real racing activity. You almost never see hydroboost on any serious auto-x or open road race vehicle specifically because there's almost no feedback for the driver.

If that's not a concern for the OP, I'd go hydroboost over messing with vacuum cans or pumps.