Relatively simple question. Rules allow an offset cam key to return timing to stock after the head is decked. A D16A6 motor in the Honda CRX has an integral key in the cam timing pulley. Does this mean the offset key needs to go on the timing pulley on the crank where the key is not integral to the pulley?
Timing correction offset key
- Thread starter Racer45
- Start date
the rules do not say where you have to install the key. it just says:
"An offset key may be used to return cam timing to the factory specifications."
but isn't the bottom pulley for the timing belt an integral key also? it seems like it is the bottom pulley for the alternator belt, etc. that has the separate key.
i would agree, file and shim or just forget it. many on this forum would state that file/shim/adjust is not what the rules say you can do. i think it meets the intent of the rule and would never protest on that. just make sure you get back to factory spec.
tom
who has been criticized for using an underpulley that was modified to have a single pulley when the rules only said i could substitute an underpulley with a single pulley.
"An offset key may be used to return cam timing to the factory specifications."
but isn't the bottom pulley for the timing belt an integral key also? it seems like it is the bottom pulley for the alternator belt, etc. that has the separate key.
i would agree, file and shim or just forget it. many on this forum would state that file/shim/adjust is not what the rules say you can do. i think it meets the intent of the rule and would never protest on that. just make sure you get back to factory spec.
tom
who has been criticized for using an underpulley that was modified to have a single pulley when the rules only said i could substitute an underpulley with a single pulley.
btw, just how do you figure about how much is needed to do this?
all numbers are for illustration purposes:
if i take off 0.005" to deck a head, how much do i need to take off the key?
if the bottom shaft for the pulley is 14mm (just a guess), then the OD is 1.732" and there is about 0.0048" per degree along the outer edge. so do you expect to take off about 5 mils on one side and then a similar shim on the other side to shift the pulley around the shaft?
i realize that you would more likely be using a degree wheel, etc. but am interested in how much do you figure we are off when we take some off the head or the block? and is it necessarily bad? i thought the honda's actually made more power when the cam gear was slightly behind the factory spec, i.e., is returning to factory spec the best thing to do? it does not say we have to.
tom
all numbers are for illustration purposes:
if i take off 0.005" to deck a head, how much do i need to take off the key?
if the bottom shaft for the pulley is 14mm (just a guess), then the OD is 1.732" and there is about 0.0048" per degree along the outer edge. so do you expect to take off about 5 mils on one side and then a similar shim on the other side to shift the pulley around the shaft?
i realize that you would more likely be using a degree wheel, etc. but am interested in how much do you figure we are off when we take some off the head or the block? and is it necessarily bad? i thought the honda's actually made more power when the cam gear was slightly behind the factory spec, i.e., is returning to factory spec the best thing to do? it does not say we have to.
tom