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Cam GM1408839 vs SP CS1103r....

3K views 3 replies 1 participant last post by  talisman51 
#1 ·
Ok...maybe it doesnt quality as a hotrod (SBC 327/300hp 4sp, OE iron intake, OE exhaust, AFB), but I am looking for max TQ without detonation. I originally was going ALL OE with the GM 1408839 (929 replacement) BUT....my SCR will be up around 10:1 and I am concerned about detonation as a result of high DCR and pump gas. So....I found a later closing ICA with the SP CS1103R. Both are 194/202 @ 50 but the SP has very lazy open and close ramps with an .006 of 268/278 compared to the 252/262 of the 839.

1. Will the SP CS1103R...perform well while being less prone to detonate?

2. Am I headed in the wrong direction...should I be going with a longer modern cam with steeper ramps...aka Voodoo or CC XE262?

Thanks
 
#3 · (Edited)
To ping or not....

3.36 gear and approx. 3300lbs. Note that the motor is a blueprinted all original...cast iron 461 62.2cc heads with the 1.94 and 1.5 valves....AFB carb on cast iron dual plane...wide ratio muncie 4sp (2.56:1 first gear).

As far as reducing CR...I could easily up the HG thickness, but I would rather not take my quench up from an existing .042. Polishing the head CC is another option, although the heads are machined and already assembled. Unfortunately, the cam manufacturers techs have not given me much confidence in their choices. Would be great to get an unbiased cam recommendation. The table below is an attempt to organize and compare some of the cam choices' highlighting valve timing and duration differences..

Note...I computed ramp rates to get a comparative between manufacturers. These ramp rates are calculated for both opening and closing ramps. That Voodoo is the obvious fast ramp choice. Since I am focused on durability and prefer using my new OE springs(80lbs closed, 256/inch)....the Voodoo is not a real option.

Although the choices are endless and I have read my eyeballs out over the past months...I really comes down to max TQ with pump friendly DCR.

Thanks in advance for you help!
JimV

 
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