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Has anyone got a hydroboost unit to fit on one of these cars easily. I was thinking one from the olds diesel cars front the 80s. Thansk
 

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I installed hydroboost in my 91 OCC. If I were to do it again, I would use the boost unit from a 2007 Tahoe, or similar. The booster fits the stock MC. The lines can come from an 80s Olds diesel. You can get them from Rock Auto. They bolt in, but if you have headers, I would put heat shields on them. The only modifications you need to do are; replace the mounting plate with a flat one from an early 90s Astro Van (also available on ebay for $25 + shipping), and weld the eye from the vacuum advance at 6 3/8 on center (mounting plate to center of the eye) to the cut off stub of the hydroboost. You need a special tool to remove the plate: Hydroboost Socket. The specs for the hydroboost wants a separate return port for the hydroboost to the steering fluid reservoir, but I used a "T" in the line, and it has worked without issue.

The hydroboost from the 80s diesel may fit the car as well, but you will be buying a new one for about $400. I got mine from a junk yard vehicle for about $30.

Some people have used the hydroboost from the Astro Van, but the MC is much smaller, and you loose some braking ability. You also must make new lines from the proportioning valve to the MC, and it is a PITA to make the lines, because they have tight curves close to the ends. The lines also have bubble fittings on the ends. It is far easier to only cut the eye off of the pushrod, then weld the one from the vacuum pushrod onto the hydroboost, and you must do that anyway. You do not even have to bleed the brake system.

The hydroboost will fill in about 5 seconds after starting the engine, and start working. Be careful with the brakes, because they will try to throw you through the windshield when applied heavily. This is a great mod, especially if you have a low vacuum engine like mine. It also makes the engine compartment look less cluttered. If you want to have custom lines made, you can mount the hydroboost unit upside down, and get even better access to the rear of the engine.
 
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