Advancing cam w/bushings

Discussion in 'Engine Topic' started by Dogwater, Nov 25, 2015.

  1. Dogwater

    Dogwater Veteran Member

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    Chevy 357cu. in. W/Comp Cams XE268H
    Everything runs great but I'd like to move the power band or when it comes on cam just a bit lower in the rpm's. Right now I have Comp Cams black bushing on the timing sprocket, this put the Cam straight up. If I use the 4° bushing (advancing) will this bring the power band down a couple of hundred rpm's? Right now it comes on cam starting at 3500 rpms. I've never used timing bushings before. I know I will loose some top end power buts that's OK for now. I've read that changing to a 2° didn't do much, thought I'd try a 4° first or should I go more than 4°?
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    Think I'd call Comp Cams and ask them. Advancing the cam should lower the power band, but... Have all engine, drivetrain, and vehicle info available when you call.
     
  3. middleagecrisis

    middleagecrisis Veteran Member

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    Advancing the cam 4 degrees isn't going to make a noticeable difference in your engine's performance range. Did you degree the cam (with a degree wheel) when you installed it? I ask because that cam should come on a lot earlier than 3500 rpm. That cam should be off-idle up to 5500. I've had name brand timing gear sets that weren't even close to straight up, never would have known if I hadn't been using a degree wheel.
     
  4. Damon

    Damon Veteran Member

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    I'm with middleagecrisis on this. That cam should be hittin' pretty good well before 3500. Ignition advance curve (centrifugal advance) can have a big effect on low rpm torque. And, of course, if the carb ain't tuned up very tight.....
     
  5. hhott71

    hhott71 R.I.P 11/19/18 Lifetime Gold Member

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    Been there and done that.

    Couldn't tell a difference driving it or in the time slip.

    Save your money.
     
  6. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    I know for a fact that when my sbc was built the Gm#140 cam was installed with a 4 deg bushing just for the life of me my CRS :whine: can't remember if it was installed advanced or retarded !!! :confused:
     
  7. Dogwater

    Dogwater Veteran Member

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    I have been running the timing a bit on the retarded side, 32°. This is a newly built engine, only have 650 miles on it. No, I didn't degree it but I did put no. 1 all the way up in the cylinder before putting on the heads an timing cover. This is how I set the timing pointer with the balancer on the crank an adjusted the pointer to TDC on the balancer, both stamped 0's on both crank & cam gears facing each other. I know, I should of degreed it. I haven't played with the timing at all besides checking if it has moved any. I'll start advancing the timing until it starts pinging then back it off, I'll do that first.
    * I did forget to mention that this cam is a 112 LSA*
     
    Last edited: Nov 25, 2015
  8. Dogwater

    Dogwater Veteran Member

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    Drove the Camaro around a bit to get it up to temp. Checked the timing before doing any thing, it was at 29°. Bump the initial timing up to 36° then ran the rpm's up to 2500 an got 60°. So I back out some of the vac advance an got it down to about 52°. Vac advance was adding 12° knock it down to 8°. Took it for a quick drive an as I start to get above 2500 rpm's I can hear a real fast rattle, its real faint though, can barely hear it. Didn't sound nothing like ping. Scared me, drove home calmly. Maybe it was ping. I'll back off a degree.
     

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