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Cam duration
#1451593
06/11/13 11:57 PM
06/11/13 11:57 PM
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Joined: Jul 2004
Posts: 12,812
Tulsa, Oklahoma
Wagonmaster
OP
I Live Here
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OP
I Live Here
Joined: Jul 2004
Posts: 12,812
Tulsa, Oklahoma
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Longest duration to still make enough vacuum for power brakes?
10.5/1, aluminum heads, forged crank, looking at roller cam kits.
I know, lots of particulars involved, just opinions/thoughts, please.
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Re: Cam duration
[Re: Wagonmaster]
#1451594
06/12/13 12:08 AM
06/12/13 12:08 AM
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Joined: Jan 2007
Posts: 7,664
IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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Displacement matters a lot. On a 496 with 243@.050 cam, 108 CL (not vacuum friendly) I get 13" at idle. Just enough vacuum for PB to work without noticeable issues and assist devices in my book. That's after tuning. Before it was under 10". Increasing initial advance to 20 degrees and tuning idle mixture helped a lot.
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Re: Cam duration
[Re: ahy]
#1451595
06/12/13 07:55 AM
06/12/13 07:55 AM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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LSA plays a big role too. I had a 220/230 duration cam on a 114 LSA. pulled 14" of vacuum at idle in a 318, then a 222/228 cam on a 107 LSA in a 360, idles at 9"
with my stick shift transmission, the 9" at idle is not a problem for my power brakes. blip the throttle a little after starting the engine, and I get enough vacuum built up that I can manuver around in the driveway without having a hard pedal. downshifting the transmission while slowing down creates enough vacuum that I can get 3-4 full pumps of the master before vacuum is depleted.
with only 9" of vacuum in the last 4000 miles of driving, not once have I had a problem where my brake pedal was too stiff
**Photobucket sucks**
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