base circle samller on new cam
06-10-2007, 02:07 PM
#1
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base circle samller on new cam i need some help on figuring out which pushrod length to run. stock the base circle was 1.55" and the 228R from TSP measures 1.45" so thats .050" with the .080 preload, i would loose that .050"!!!! so im asking if i should go with a 7.45" pushrod, or just bit the bullet and have the heads milled .045".
cam is 228/228-.588/.588-112, would i have any valve clearance issues with this cam and a head milled .045"
cam is 228/228-.588/.588-112, would i have any valve clearance issues with this cam and a head milled .045"
06-11-2007, 12:43 AM
#2
I just went out to measure my cams, I just had a dial caliper handy.
The stocker measured 1.550" and my XER273HR measured 1.485".
In spite of this, Comp say that a stock length 7.400" pushrod should be applied. I think the reason is because of the higher valve lift. To keep the rocker tip sort of centered on the valve tip, with higher lift, the pushrod end of the rocker should sit a bit lower than stock when on the base circle, as it will sit higher than stock at peak lift on the lobe. If the base circles were the same between the two cams, then a shorter pushrod would be necessary to correct the valve stem tip contact (sweep path).
The stocker measured 1.550" and my XER273HR measured 1.485".
In spite of this, Comp say that a stock length 7.400" pushrod should be applied. I think the reason is because of the higher valve lift. To keep the rocker tip sort of centered on the valve tip, with higher lift, the pushrod end of the rocker should sit a bit lower than stock when on the base circle, as it will sit higher than stock at peak lift on the lobe. If the base circles were the same between the two cams, then a shorter pushrod would be necessary to correct the valve stem tip contact (sweep path).
