[pittbull7934]

I am planning on doing a drum to disc conversion (in the front) on my 68 ELKY, I want to run power brakes but I was told that when you have a big cam the booster won't work properly. I was also told to look into a hydro boost.

Below are my cam specs.


Should I get the brake kit with the booster or is the booster worthless?

Should I get a hydro boost?

Should I go with discs but without the booster?

I have never heard of a hydro-boost, so now I am a bit confused as to what I should do.





Specifications: * Advertised duration: 288 intake/296 exhaust * Duration at .050 in. cam lift: 234 intake/246 exhaust * Gross valve lift: .497 in. intake/.504 in. exhaust * Lobe separation: 112 degrees * Recommended compression ratio: 11:1 * RPM range for 350 level four: 2000 to 6200 rpm * 11:1 compression ratio recommended

Recommended components for level 3: * Lifters: CRO-66000 * Valve springs: CRO-68301-1 * Hydraulic lifters: CRO-66000 * Retainers: CRO-86032 * Kit (includes lifters springs and retainers): CRO-84000 Recommended components for level 4: * Valve springs: CRO-68390-3 * Retainers: CRO-87048 * Seals: CRO-86072 * Kit ( lifters springs retainers and seals): CRO-84102 (for rpm over 7000 plus. Limited street use.)

Designed as a level 4 cam for 350 engines this cam has a definite lope at idle and is best suited for dual purpose Hot Street/Drag Strip Hot Marine and Oval Track applications. These grinds produce strong mid-range to top-end torque and horsepower. The requirements for this cam are headers dual exhaust large cfm carburetor aftermarket ignition and compression of at least 11:1.

[speedydeedy]

I can't tell you if you need hydro-boost or not but I can tell you what it is. Instead of relying on vacuum to operate the power booster there are 2 extra lines coming off of your power steering pump that boost your brakes with hydraulic pressure. And of course it does not use the same booster,it has a special hydraulic booster at the master cylinder. I first saw these back in the 70's when they first put diesel engines in cars and light trucks.In my opinion you don't need it with that cam,but I am not an authority on that.Hopefully someone who is will chime in. Hope this helps.

[SSedan64]

That cam will be borderline with a vacuum booster. I'm using HydroBoost myself. The Mid 80's Chevy Astro and GMC Safari vans are good candidates for Hydro donors. Just make sure they don't have ABS.
A little Info. >
http://www.vancopbs.com/category_s/114.htm
http://www.performanceonline.com/sto...28&cat=0&page=
http://www.brakeandfrontend.com/Arti...t_systems.aspx

[cobalt327]

Often, all that's needed is a vacuum reservoirs can, to hold a supply of vacuum that can be used when and if needed to operate the vacuum assisted power brakes. This is the least complicated (of power-assisted systems) and least expensive, too.

Another option is to use an electrical vacuum pump that works off the car's battery.
Yet another alternative (my personal favorite) is to use manual disc brakes.

And then there's the "hydro boost"- a hydraulically assisted system that usually requires the vehicle to have power steering, as that is where the "hydro" of a hydro boost system comes from. There are systems that use stand-alone hydraulic pumps for their power, but to me, this defeats much of the advantage in being able to tap into an existing system to do other duties.

Sometimes, work has to be done to the PS pump or valving to get it to work correctly w/the PB system. This is prolly the most expensive of all the different set-ups. But if it is done correctly, it will work very well, and the PB unit up on the firewall is small, so there's an advantage in clearance.

[joe_padavano]

Originally Posted by cobalt327

And then there's the "hydro boost"- a hydraulically assisted system that usually requires the vehicle to have power steering, as that is where the "hydro" of a hydro boost system comes from. There are systems that use stand-alone hydraulic pumps for their power, but to me, this defeats much of the advantage in being able to tap into an existing system to do other duties.

The stand alone systems go by the brand name of Powermaster and were used in mid-1980s GM cars like the B-bodies and the turbo Buicks. The have a small electric pump and accumulator built into the master cylinder and actually use the brake fluid as the hydraulic working fluid in the booster. Otherwise, in concept they work exactly the same as the hydroboost that uses the PS pump. The Powermaster units have gotten a bad rap because usually the accumulator goes bad. This can be replaced, but the price of new accumulators seems to be outrageous for some reason (I have a friend with a GN). The advantage of the Powermaster is that it IS standalone. All you need to do is hook up a couple of electric wires and the normal two brake lines. No vacuum hose, no PS hoses, no mods to the PS pump or reservoir.

[pittbull7934]

I had power brakes in my 72 chevelle, and it had a big cam (i don't know what size) and the brakes stunk! I put a resivoir on the system and it helped a little but not very much.

I always thought the booster was bad (at the time i didn't have the money to replace it) but after hearing a big cam could cause low vacume for the booster, I had an "aha" moment.

Does anyone know for a fact that power brakes with a resivoir will work with my cam?

[SSedan64]

Difficult to say for sure. Some have very good results with vacuum reservoirs and some don't. Electric vacuum pumps are noisy, but work. I'm not sure about a Manual disc setup either, an old Elky is pretty heavy.
buddy of mine has a 81 TA with 4-wheel disc brakes and a cam smaller than yours + vacuum reservoir and crappy brakes. All brake parts are new.

[pittbull7934]

I think I may just take my chances with power brakes and a resivoir.

he hydro boost set up, when all said and done is way too much money for me right now. seems like a cool system though

[ruffrida2005]

I'm in the same boat as you. I already have my power booster, but I'm running a little less lift then you. Best thing I can tell you is to call who made the cam and ask them. If you can get a hydro-booster, that would be the best way to go. I tried to get one but had no luck. If you get the power booster, try it and if doesn't work good get the eletric vacuum pump, easy to install.

[cobalt327]

One thing to remember, is a vacuum reservoir does not generate any vacuum itself- it can only save the amount of vacuum that's generated during closed-throttle deceleration, for example.

A "trick" to using vacuum-assisted PB OR a vacuum reservoir w/a low-vacuum cam, is to not "pump" the brakes as you make a stop- this will deplete the vacuum can or booster quicker than if the brakes are applied but not released fully until necessary.

Same deal as using the brakes on a PB car that has the engine stall or is shut off- you get a couple on-off on-off applications at most, then the vacuum is depleted. Then you get the ultra-hard pedal and increased braking distances w/less control.

[68-poncho]

couldn't you use an old hydro boost off an old late 70's and 80's gm diesel pick up truck?these were plentiful, there are tons around here,would these work on a gm car as well?

[cobalt327]

There were a few that used a vacuum pump, too (not originally for the brakes, though). Don't recall the exact make/model, but I believe some were Caddy.

[75gmck25]

You might take a look at one of the vacuum pumps described in this GM motor home article.

http://www.gmcmotorhome.com/tech/vacuum_pump/index.html

Bruce

[cobalt327]

The following parts list was from a gentleman who switched his 1981-’87 Chevy gasoline engined pickup
truck over to the Hydroboost system from a 1986 Chevy C10 Pickup, 6.2L 379cid V8 Diesel MFI VIN (C).

Steering: Power Steering Pressure Hose
GATES Part #357640 {Pressure Line Assembly 16mm Male O-Ring x 18mm Male O-Ring x 49"} Hydroboost To Gear $19.22 $0.00 1 $19.22
GATES Part #366630 {Pressure Line Assembly 16mm Male O-Ring x 18mm Male O-Ring x 52 1/4"} Pump To Hydroboost $22.79 $0.00 1 $22.79

Steering: Power Steering Return Hose
GATES Part #362190 {Bulk Power Steering Hose (4-Ft. Length) C.P.E. Return Hose- 3/8" x 48"} Gear To Pump, Cut to Length, 24" Hydroboost To Pump, Cut to Length, 32" $7.79 $0.00 1 $7.79

Brake/Wheel Hub: Hydraulic Hose
AC DELCO Part #18J295 {replaces 18032006 #18032006} HOSE, FRT BRK DURAST0P; LEFT HAND; 2 WHEEL DRIVE HOSE, FRT BRK DURAST0P; LEFT HAND; OPTIONAL W/DURASTOP
KIT 18032006; 2 WHEEL DRIVE; w/(JD3) or VACUUM PWR BRK SYS (JB5) or (JD5) or VACUUM PWR BRK SYS (JB6) or (JD6) $13.35 $0.00 1 $13.35
AC DELCO Part #18J2037 {replaces 18J114 #19169840} HOSE, FRT BRK DURAST0P; RIGHT HAND; 2 WHEEL DRIVE HOSE, FRT BRK DURAST0P; RIGHT HAND; OPTIONAL W/DURASTOP KIT 18031825; 2 WHEEL DRIVE; w/(JD3) or (JD5) or (JD6) or VACUUM PWR BRK SYS (JB5) or VACUUM PWR BRK SYS (JB6) $13.36 $0.00 1 $13.36
AC DELCO Part #18J2119 {replaces 18031765 #19173040} HOSE,RR BRK DURAST0P; 2 WHEEL DRIVE HOSE, RR BRK DURAST0P; (6.2,454); HOSE, RR BRK $11.93 $0.00 1 $11.93

Brake/Wheel Hub: Power Brake Booster
A-1 CARDONE Part #527248 {Hydro-Boost Reman.} w/JD3, JD5 w/Hydro-Boost; GM codes are on the "Service Parts Identification" sticker. $125.79 $55.00 1 $180.79

Brake/Wheel Hub: Master Cylinder
CARDONE SELECT Part #131863 w/JD3, JD5 w/Hydro-Boost; GM codes are on the "Service Parts Identification" sticker. $33.79 $0.00 1 $33.79

Disclaimers - The prices reflect what was found online in 2004. You may want to double check to make sure these part numbers are accurate before you start buying parts.

Note this list does not include the power steering pump. A 2000 Vortec 7400 engine was put in the truck, it had a hydroboost power steering pump on it already, so a pump was not needed. The #366630 hose listed above did not work with the 2000 Vortec 7400 engine's pump, so a custom house was made up for it.

Also, the hydroboost listed above has a six studs to mount it to the firewall. The truck's vacuum booster only had four. So 2 of the studs were removed to bolt it up.

The push rod that attaches to the brake pedal was also modified; the hole in the pushrod was bigger than the pivot stud on the brake pedal.

[SSedan64]

The easier Hydro swaps come from Mustangs & GM Astro/Safari van donors although the Safari has an odd size pushrod end.
I got a new Hydroboost w/Master Cyl. and adjustable pushrod on Evilbay for $120. Used a KRC pump w/external reservoir, cooler and made my own lines. Cheap if you shop around.
Another Diagram here. > http://www.performanceonline.com/sto...28&cat=0&page=