jimlab

Like the subject says, vacuum pump or vacuum canister?

I'm dropping from a 260/266 @ 0.050" 0.650"/0.650" 112 lsa cam to a 242/248 @ 0.050" 0.625"/0.625" 112 lsa cam and wondered if I really need a vacuum pump or canister to store vacuum for my power brakes (not an F-body, but the need for brake booster vacuum still applies), or if the new cam is small enough that I don't need to bother.

I'd rather save the expense, wiring, and noise of having a pump, if possible, so a canister would be the best solution if I need help for my brakes. It can't hurt, can it?

Any help is greatly appreciated.

SStrokerAce

Jim,

I think you have enough Compression where it will have enough idle vacuum for your brakes. Especially since it's a SR on a 396.

Bret

jimlab

Thanks Bret. I think a vacuum canister wouldn't hurt, and I'll need a check valve anyway, but I really didn't want to add another electrical device or the noise of a vacuum pump.

stealthblack

i prefer a can over pump, i run one now, even though my cam is tiny-its ground on 110.Ive run big solids with tight centers without vac assist before and the problem wasnt that you couldnt brake coming to stop[as revs were off idle] it was that the pedal sucked when the motor was idling.
IE stop and go traffic was a PITA and you had to rev it in the staging beams to get enough pedal to stall the converter.
If i read right that youre going DOWN to 24x, i dont think it will be big deal, but couldnt hurt if you have room.
just my opinion.

Denny McLain

I wouldn't expect you to have any problems at all. I've ran bigger cams and didn't.

That sounds like a great cam for a high performance street stroker. I've got one pretty close. Let us know how it works.

jimlab

Let's just say that way back when, I had a really bad experience with a 306/306 (advertised duration) cam (in a 350 with a Weiand Team G miniram) in my '67 Camaro and a complete lack of brakes at high speed.

I just want to make sure I've got the right stuff.

Thanks. One of these years, I will.

CCCCCYA

Jim - You know, when you think about it, if you have the room for a canister then it just makes sense to go with one. It's definately cost effective, and for 60 bucks (what I paid for mine) plus plumbing it makes no real sense NOT to use one with a larger cam. I've got a plain old 847 in my 383, and I have a canister. It's just too easy/cheap to put it on there and helps in the peace of mind department.

Dave C.

Mindgame

"242/248 @ .050 lotalift/lotalift 112º lsa"

Ya kidding jimlab.

That cam would pull 10" Hg (or better) in a 350 ci @ ~900 rpm. You won't have any vacuum problems with that in a 396.

Good luck.

-Mindgame

jimlab

I figured as much, but wanted to be safe rather than sorry. I was going to use the vacuum pump with the 260/266, but wasn't sure if the smaller cam would require anything, since I knew it would pull quite a bit more vacuum.

jimlab

Yep.

Mindgame

BTW jimbo, got any new pics of that monster RX7 of yours? Hadn't heard much from you in a while.

Did see a video of a guy who shoed an LS1 into a last-gen RX7. Pretty solid high-ten second car. Looked darn good too.

-Mindgame

jimlab

I've gotten a few things taken care of, but not many pictures posted. I finished the Cobra 8.8" IRS swap, I'm about half way done on the headlights, just finished cutting down the original set of fabricated valve covers to mount coil packs on, and I'm just about ready to start on the headers. Bret's helping me get my valve spring issues worked out, and I've got a new cam (as mentioned) to get in the engine.

Might have been Brian Hinson, but there are a couple others in that range now, still getting things sorted out. Hinson has a new twin turbo setup that should be pretty potent. Even Jordon has an RX-7 conversion in the works.

96speed

Jim: I recently swapped back to power brakes from manual brakes. No problems so far. However, I only put about ten city miles on it. Idle is set at 1100. Cam is a ~25x/26x. Lift is under ~.610".

Ryan

jimlab

Thanks Ryan. I know Jordon used to daily drive his car with a solid roller in my range, so it can't be that bad, but I'll go with a vacuum canister anyway, just to be on the safe side.

bunker

I just tunned the car so I don't need one Yeah sure laugh tune brakes you ask.

Pretty simple, I messed around with the IAC follower tables so when I let off the gas while driving at any speed my RPM is at 1500 to create enough vacume for my brakes, just upped the IAC tables and observed the RPM while coasting, now it worked out so if I'm coasting to a stop in my 6 speed even in neutral my RPM is 1500 until I come to a complete stop meaning 0 MPH, even at 2mph the rpm is still 1500 then once 0 hits the idle drops to 1000 which is what I idle at, this improved my braking 10 folds because with more RPM = higher vacume, no need for canister