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Author Topic:   cam timing
johnlj68
Dirt Roller

Total posts: 22
posted March 26, 2003 03:06 PM
I just installed a new cam in my 355. the adverttised duration is 292and lifts are 488 with 1.5 rockers. i will be running 1.6 rockers and would like to know where the timing would fall at with these changes?
This is a chevy with a 500 cfm hollley 2 barrell on a 3/8 mile track with 12 degrees banking.
Thanks, JJ

rico 08
Dirt Freak

Total posts: 372
posted March 26, 2003 06:56 PM
1.6 rockers won't change when the valve opens and closes,it only increases the lift and duration under the curve.So if it's been degree'd you're ok.if you are refferring to spark timing that too should be fine.

johnlj68
Dirt Roller

Total posts: 22
posted March 26, 2003 07:42 PM
would the advance timing mark on balancer still be 8 btdc? This is a 3 speed tranny. Thanks, JJ

rico 08
Dirt Freak

Total posts: 372
posted March 27, 2003 01:24 PM
That is mostly for stock timing,use total timing to be more accurate,i'd try something in the range of 32-36,i'd borrow a timing light from someone if you don't have one that has the degree knob to set it this way.

dode
Dirt Freak

Total posts: 417
posted March 28, 2003 09:02 AM UIN: 13209501
Using 1.6 ratio rockers will not change when the valve comes off of the seat, but it will change the .050 point. As to how much, that will depend on the lobe profile. On the intake valve opening for instance, the .050 intake opening event will occur at .002" less valve lift. How many degrees that is will depend on your cam though.

John

quote:
Originally posted by rico 08:
1.6 rockers won't change when the valve opens and closes,it only increases the lift and duration under the curve.So if it's been degree'd you're ok.if you are refferring to spark timing that too should be fine.


rico 08
Dirt Freak

Total posts: 372
posted March 28, 2003 09:18 AM
That was my simplified explanation,basicly we both said the same thing.

bncars10sen
Dirt Roller

Total posts: 13
posted April 02, 2003 12:05 PM
If your running as stock timing gear, check the crank gear, out of the factory they had them retarded. Look closely, turn it around and you will see that it will advance the cam approximately 2-3 degrees. Good Luck

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