Are you running a low vacuum bypass, bimini? I've got a set of JDM SS cams sitting on the shelf, ready to go in this fall and I was told by Jim that it's very rare for them to need to run one with their cams.
Need help/advice on what to do about a vacuum issue after JDM cam install
- Thread starter FEARSNO1
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Bigger cams close exhaust valve(s) later and open intake valve(s) sooner, both of which will impact dynamic (realized) compression, idle quality and vacuum. But of course, all you guys know this already. We all love the sounds of a lumpy cam at idle, haha!
Just fooling around with a vacuum gauge and my blower (TVS) on the bench, it seems like you'd need at least 12-13 in. hg. to keep the bypass closed. If your vacuum at idle is less than that, you probably need some sort of by-pass actuator with a lighter spring. Should be able to get a visual on it to see if it's closing at idle too. L&M indicates you can't use the Whipple actuator, and eludes to the fact that the spring isn't light enough for their line of camshafts. No idea what Whipple's actuator needs in terms of vacuum, but it's $85 lighter than L&Ms.
Yes I'm running one at the advice of my tuner.
-J
Which one are you running?
I believe the only option for the TVS is L&M's bypass.
It looks the same to me. Only difference I can see is the way whipple plumbs the vac line to beneath the blower where the tvs takes vac from the plenum.
I'm 99% sure he sourced it from VMP. Tuner has a '13 Shelby with Crower stage 4s and he needed one so he ordered one for my car also.
Never tried without it, it was installed from initial start-up.
-J
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