...Trying to imagine what would happen to the timing belt and cam sprocket if the head is milled and the block is decked...
Imagining process:
- crank and cam would be closer together
- which means even with correct valve timing the t-belt would slack
- and cause the cam sprocket to rotate counter-clockwise a bit in order for the belt to be tight
- which advances everything in and on the head
- valves open and close sooner
- spark also comes sooner
Alright, depending on how much was milled and decked, you may have to retard the cam sprocket one tooth (this means rotate it 1 tooth clockwise looking from the driver's side) then compensate with the distributor and/or the adjustable cam sprocket to obtain ignition timing of 18 degrees btdc. The only way you can know for sure if you need to do this is to get a reading with a timing light while your adj cam is at zero. If you find that you have to crank the distributor all the way to the firewall side just so you'll get 18 degrees btdc, it could mean you might have to do what I described. Once you obtain 18btdc while having the distributor positioned closest to the center of its adjustment, this will be the best starting point to make further valve timing adjustments. You can now open the valves sooner or later and still have room in the distributor travel to fix ignition timing.
Yes, anything other than ideal valve and ignition timing will cause a hard cold start.
Disclaimer: I've never tried to tune adj cam gears. (uhh which one of us has a chassis dyno right) This is just how I perceive the dynamics to happen in our 4 stroke engines.
EDIT: forgot about the jerry-rigged obd0 dizzy. You will have to further the jerrying to get more adjustability out of it.
Imagining process:
- crank and cam would be closer together
- which means even with correct valve timing the t-belt would slack
- and cause the cam sprocket to rotate counter-clockwise a bit in order for the belt to be tight
- which advances everything in and on the head
- valves open and close sooner
- spark also comes sooner
Alright, depending on how much was milled and decked, you may have to retard the cam sprocket one tooth (this means rotate it 1 tooth clockwise looking from the driver's side) then compensate with the distributor and/or the adjustable cam sprocket to obtain ignition timing of 18 degrees btdc. The only way you can know for sure if you need to do this is to get a reading with a timing light while your adj cam is at zero. If you find that you have to crank the distributor all the way to the firewall side just so you'll get 18 degrees btdc, it could mean you might have to do what I described. Once you obtain 18btdc while having the distributor positioned closest to the center of its adjustment, this will be the best starting point to make further valve timing adjustments. You can now open the valves sooner or later and still have room in the distributor travel to fix ignition timing.
Yes, anything other than ideal valve and ignition timing will cause a hard cold start.
Disclaimer: I've never tried to tune adj cam gears. (uhh which one of us has a chassis dyno right) This is just how I perceive the dynamics to happen in our 4 stroke engines.
EDIT: forgot about the jerry-rigged obd0 dizzy. You will have to further the jerrying to get more adjustability out of it.
