Posted By: rave_12000
biggest 340 cam and still have power brakes? - 05/03/11 04:50 AM
wondering how big of cam I can put in a 340 in my 70 challenger and still have power brakes???? Comp cams.
biggest 340 cam and still have power brakes?
Posted By: dOc !
Re: biggest 340 cam and still have power brakes? - 05/03/11 04:53 AM
I say RUN whatever you want ...NO WORRY ... just get a vacuum-storage-cannister 
Posted By: Mr340
Re: biggest 340 cam and still have power brakes? - 05/03/11 12:31 PM
Posted By: Coronet-R/T-Rag
Re: biggest 340 cam and still have power brakes? - 05/03/11 12:53 PM
I've run the canister with my 340 and you get about 2 pumps at idle then no more vacuum. I would stay under 240 degrees of duration at 50. Actually, I would put on manual brakes and not worry about it.
Posted By: ahy
Re: biggest 340 cam and still have power brakes? - 05/03/11 01:15 PM
I'd guess 220 deg @.050 would work and 230 a big maybe depending on compression, lobe seperation and other details. PB seem to work OK with 12-13" or more vacuum.
Tuneup also has a big impact on vacuum. Bigger cams like plenty of idle advance and careful mixture adjustment.
Tuneup also has a big impact on vacuum. Bigger cams like plenty of idle advance and careful mixture adjustment.
Posted By: thedriver
Re: biggest 340 cam and still have power brakes? - 05/03/11 03:13 PM
i use a XE285HL comp hydraulic on my 340. my car operates generally in 4000ft-6500ft DA. Power brakes still work, but tuneup is definitely part of it. 
Posted By: rave_12000
Re: biggest 340 cam and still have power brakes? - 05/03/11 03:26 PM
had 268/280 224/230 .477/.480....thinkin about bumpin up to 274/286 230/236 .480/.491. comp cams. any advantage here? 340 six pak approx 9.5 to 1 compression.
Posted By: 70Cuda383
Re: biggest 340 cam and still have power brakes? - 05/03/11 03:31 PM
no matter how big the cam, when you lift on the throttle and the engine is still spinning 1500-2000 rpm, it will "charge" the vacuum booster, and you'll get one or 2 pumps of the brakes. stop and go traffic is different obviously...
but, you could get a vacuum canister to store up extra vacuum, get an electric vacuum pump dedicated to the brake booster and hidden under the fender out of sight, or go with manual brakes.
but, you could get a vacuum canister to store up extra vacuum, get an electric vacuum pump dedicated to the brake booster and hidden under the fender out of sight, or go with manual brakes.
Posted By: thedriver
Re: biggest 340 cam and still have power brakes? - 05/03/11 05:19 PM
Quote:
had 268/280 224/230 .477/.480....thinkin about bumpin up to 274/286 230/236 .480/.491. comp cams. any advantage here? 340 six pak approx 9.5 to 1 compression.
you would notice a slight hp increase with that cam. However, i doubt it would be worth the money (and labour)for the increase in power over the 268. like maybe 15hp?? i would recommend spending the money on something else.
I used to run the comp 268 cam in my 340, i had iron heads, 10:1cr headers etc. I decided on the cam change (285HL, like i previously mentioned) but also went with edelbrock heads. power increase was substantial. but looking back, it was probably mostly due to the heads.