Power Brake booster..single or dual diaphragm

[Super Chief]

After my engine swap I lost enough vacuum to my brake booster to cause concern. This a 79 Cherokee with the stock brake set-up. Did J-20's come with a dual diaphragm booster and if so what would be involved with changing over? And would that even help? As usual, thanks for the input.

[River Beast]

If you do the partnumber X-reference between the 79 J20 single [came with single and dual]with a single of youy 79 W/T you will see that they match.... therfore the dual will be a bolt-in for you... :D

however....

I too lost vacuum with a cam install and brakes were scary... I did this same research on the boosters a while back but was concerned that the booster wouldn't solve my problems....

I now have a hydroboost unit installed from a 76-77 caddy Eldorado with MASSIVE braking power... Retro93 turned me on to it...it runs off the PS pump... no vacuum to worry about EVER!!! :D

I have a page on my site that explains it all... feel free to ask any questions you may have after reading the page...

[ArtsiFrtsi]

Todd, was just reading your site on the hydroboost... do a what??!!?? last paragraph just ends...?? tongue.gif

[Sitting Bull]

Nice write-up Todd. I like the Alfred Hitchcock ending tongue.gif .

"For a while to let the air dissipate from the fluid.
Once your full… and the air is dissipated… take it off the jacks And do a"

test drive? happy-dance? hibbidy-dibbidy?

What cam did you have that required the swap? I have the edelbrock performer cam and think I'm getting the same thing. This looks like a great swap!

If for some reason you lose engine power, how do the brakes handle (similiar to losing vaccum power assist)?

[Jerk]

I have the edelbrock perf cam too, I haven't had any brake problems I'm aware of though. my manifold vac at idle is about 15 to 16" with 17* initial advance and the truck warmed up in park. is this normal? Also- do you have a "missing" sound at idle too? curious - Matt
BTW I have no vac advance and no egr.

[ April 09, 2002: Message edited by: Matt W ]</p>

[Sitting Bull]

No missing sounds at idle. You may want to check for a small exhaust leak causing the sound. Does the RPM hold steady?

[River Beast]

thanks for the heads up on teh page error.... ;) I'll fix it tonite....

I have na older cam made by TRW... .447 lift .262 duration... only 12" of vac at best.

[Jerk]

<blockquote>quote:</font><hr>Originally posted by Sitting Bull:
Does the RPM hold steady?<hr></blockquote>

nope, neither does vacuum at idle.