THis winter I am planning on pulling the head ('78 200, never opened up, about 55K miles on it) to milled it (and to open up the carb inlet port a bit). Several of the lifters take a while to pump up and since I have a solid lifter Clifford cam w/ about 30K miles on it from my previous 170 I am considering putting it in at the same time (assuming that the lobes/lifters are still good). Are there any issues to consider when converting from a hydraulic cam back to solid lifters? Solid lifter ticking is not an issue with me - I grew up with the sound.
What are the typical compression ratio break points for ocane levels of 85, 87, 91? And as a follow-up question, about how much will the head need to be milled? I am just trying to get a ballpark idea and know that I will need to check the existing chamber volume when I pull the head. I have a Bridgeport and plan on rough milling the head and then having the machine shop Blanchard grind the head for the finish.
I tried to go this route when I rebuilt my 170 a few years back. Along the way I made either a calaulation error or measurement error. I planned on a 9.3:1 CR and the 170 head was milled by a total of 0.135 inch (it had probably seen one or two light resurfacing prior). Still during the break in phase (at 192 miles) I seized the engine after less than 10 miles of freeway driving at no more than 70 mph. I do not want to go down that route again.
Your thoughts? TIA.
What are the typical compression ratio break points for ocane levels of 85, 87, 91? And as a follow-up question, about how much will the head need to be milled? I am just trying to get a ballpark idea and know that I will need to check the existing chamber volume when I pull the head. I have a Bridgeport and plan on rough milling the head and then having the machine shop Blanchard grind the head for the finish.
I tried to go this route when I rebuilt my 170 a few years back. Along the way I made either a calaulation error or measurement error. I planned on a 9.3:1 CR and the 170 head was milled by a total of 0.135 inch (it had probably seen one or two light resurfacing prior). Still during the break in phase (at 192 miles) I seized the engine after less than 10 miles of freeway driving at no more than 70 mph. I do not want to go down that route again.
Your thoughts? TIA.