Timing Question

[76K20]

When I put my engine together I put in a Comp Cams double roller timing gear set.  This set allows you to set your cam 4*  advanced for horsepower or 4* retarded for torque.  I chose the torque setting.   My question is do I want to set my timing at the stock setting of 6* BDC or since it's already 4* retarded do I want to go to say 10*?    Thanks for the help, Alan

[Irish_Alley]

the cam timing effects your lifters not the ignition timing. i would try 10° and see how that feels then maybe bump it up to 16° and compare the two

[bd]

When I put my engine together I put in a Comp Cams double roller timing gear set.  This set allows you to set your cam 4*  advanced for horsepower or 4* retarded for torque.  I chose the torque setting.   My question is do I want to set my timing at the stock setting of 6* BDC or since it's already 4* retarded do I want to go to say 10*?    Thanks for the help, Alan

If you "retarded" the cam timing in an attempt to boost low end torque your headed for disappointment.  Retarded cam timing shifts the engine's power curve toward higher RPM... advancing the cam timing shifts the power curve lower.  Regardless, bear in mind that cam timing changes result in a trade-off.  Although advanced cam timing may strengthen low RPM torque and responsiveness, high RPM power will proportionally suffer as a consequence.

IMHO - Except in general terms, not all engines respond exactly the same to changes in cam timing.  Influencing factors include carburetion, intake and head flow characteristics, combustion chamber and piston crown design, developed compression pressure, and exhaust flow characteristics.  Hence, unless you have a tailored purpose in mind that deviates from daily street transportation, a factory or near factory cam grind will provide the best compromise, overall, with the timing gears set straight up.  Otherwise, be prepared for some experimentation to dial it in.

As Irish stated, adjust ignition timing independently of cam timing with one caveat - changes in cam timing often affect the amount of ignition timing an engine will tolerate without detonation.  So, pay close attention to avoid engine ping.

[76K20]

When I put my engine together I put in a Comp Cams double roller timing gear set.  This set allows you to set your cam 4*  advanced for horsepower or 4* retarded for torque.  I chose the torque setting.   My question is do I want to set my timing at the stock setting of 6* BDC or since it's already 4* retarded do I want to go to say 10*?    Thanks for the help, Alan

If you "retarded" the cam timing in an attempt to boost low end torque your headed for disappointment.  Retarded cam timing shifts the engine's power curve toward higher RPM... advancing the cam timing shifts the power curve lower.  Regardless, bear in mind that cam timing changes result in a trade-off.  Although advanced cam timing may strengthen low RPM torque and responsiveness, high RPM power will proportionally suffer as a consequence.

IMHO - Except in general terms, not all engines respond exactly the same to changes in cam timing.  Influencing factors include carburetion, intake and head flow characteristics, combustion chamber and piston crown design, developed compression pressure, and exhaust flow characteristics.  Hence, unless you have a tailored purpose in mind that deviates from daily street transportation, a factory or near factory cam grind will provide the best compromise, overall, with the timing gears set straight up.  Otherwise, be prepared for some experimentation to dial it in.

As Irish stated, adjust ignition timing independently of cam timing with one caveat - changes in cam timing often affect the amount of ignition timing an engine will tolerate without detonation.  So, pay close attention to avoid engine ping.

According to Comp Cams retarding the cam 4* is for torque and advancing is for horsepower.  I went by what their instruction sheet and technician told me.

[bd]

Retarding cam timing (aka, phasing) shifts the engine torque curve toward higher RPM.  Advancing cam timing shifts the engine torque curve toward lower RPM:

http://www.enginebuildermag.com/2011/11/cam-drives-and-timing-components/

http://www.hotrod.com/how-to/engine/mopp-1211-degreeing-a-camshaft/

http://www.crankshaftcoalition.com/wiki/How_to_choose_a_camshaft#Phasing_the_camshaft

    ...Check with Comp again to get clarification.

[bd]

Here's another from the Comp Cams website.  Pay particular attention beginning about 1:20 in...

http://www.cpgnation.com/forum/threads/comp-cams-technology-explained-video-cam-timing.6143/

Edit: spelling