Background: I blew a head gasket on my 87 7mgte with 125K ish on the odometer. It was a stock Toyota head gasket that was put in at the Toyota dealer at 88K miles (receipt from previous owner). Taking things apart, I saw that it was only a coolant-exhaust leak, with no signs of transfer to the oil passages. So my plan was to put in a MHG with ARP's and get back on the road.
I pulled the head and took that to the machine shop to get it milled - He took .007" off to get everything straight (Toyota never touched it with the first BHG repair), and I lapped it to get it from 45 to 30 RA finish for the metal head gasket. On to the bottom end, I started scraping the old head gasket and cleaning up the top of the block and discovered some minor pitting around the water cooling passages. After the slew of cuss words, I'm thinking it's time to pull the motor and get the top of the block surfaced as well. Better not to cheat fate, and to do it the right way now before everything is back together again and it just starts leaking again.
Here's where my mind is at: As long as the motor is out of the car, and as long as a machinist is going to cut material off the block, I was thinking of doing a basic freshening up of the bottom end as I probably wouldn't trust it to be burr/chip free and clean enough after decking. And what the hell - It's got 125K on it and the block is out, right? I really only have the $ to do something really simple: New bearings, new oil pump, new rings, re-use the stock pistons and rods. I think the stock Toyota bottom end is realistic for my power goals, too - Basic Performance Upgrades. I'll probably never go any wilder than an upgraded CT with 550's and supporting fuel mods.
So here are the questions: What should I have the machinist do to the crank and the block? I've searched on some people's build threads, but haven't been able to find exactly what I'm looking for.
I still have visible cross hatching in the cylinder walls... Do I ask to have the cylinders honed and re-cross hatched? Am I buying myself anything with this, or is it just cutting out precious material when I am planning on re-using my stock pistons? If so, do I need to find a torque plate if the machinist is just honing / cross hatching?
Should I have the crank nodes polished, or leave them alone if they look OK and meet tolerance?
Should I have the block hot-tanked and go for new freeze plugs and new oil pump drive bearings? I have read that it's better to clean with other methods, (http://www.supramania.com/forums/showthread.php?t=5631) but what if hot-tanking is the only method available? Go to another shop in a bigger city? I already trust this machinist - He did really nice work with my head and my buddy's DSM block/head work. I mean - Is it better to hot-tank it, or clean it in my driveway with a pressure washer? It's probably going to be too expensive for me to do anything else. (Also - If I need to suck it up and save more money, that's good feedback too.)
For basic performance upgrades, is it OK to re-use my stock fasteners, or should I be thinking ARP's for every bolt that is going to get used? I know it's always better to use new hardware, but is this an OK spot to "skimp out"?
Any help / advice is appreciated. Thanks!
Dango
I pulled the head and took that to the machine shop to get it milled - He took .007" off to get everything straight (Toyota never touched it with the first BHG repair), and I lapped it to get it from 45 to 30 RA finish for the metal head gasket. On to the bottom end, I started scraping the old head gasket and cleaning up the top of the block and discovered some minor pitting around the water cooling passages. After the slew of cuss words, I'm thinking it's time to pull the motor and get the top of the block surfaced as well. Better not to cheat fate, and to do it the right way now before everything is back together again and it just starts leaking again.
Here's where my mind is at: As long as the motor is out of the car, and as long as a machinist is going to cut material off the block, I was thinking of doing a basic freshening up of the bottom end as I probably wouldn't trust it to be burr/chip free and clean enough after decking. And what the hell - It's got 125K on it and the block is out, right? I really only have the $ to do something really simple: New bearings, new oil pump, new rings, re-use the stock pistons and rods. I think the stock Toyota bottom end is realistic for my power goals, too - Basic Performance Upgrades. I'll probably never go any wilder than an upgraded CT with 550's and supporting fuel mods.
So here are the questions: What should I have the machinist do to the crank and the block? I've searched on some people's build threads, but haven't been able to find exactly what I'm looking for.
I still have visible cross hatching in the cylinder walls... Do I ask to have the cylinders honed and re-cross hatched? Am I buying myself anything with this, or is it just cutting out precious material when I am planning on re-using my stock pistons? If so, do I need to find a torque plate if the machinist is just honing / cross hatching?
Should I have the crank nodes polished, or leave them alone if they look OK and meet tolerance?
Should I have the block hot-tanked and go for new freeze plugs and new oil pump drive bearings? I have read that it's better to clean with other methods, (http://www.supramania.com/forums/showthread.php?t=5631) but what if hot-tanking is the only method available? Go to another shop in a bigger city? I already trust this machinist - He did really nice work with my head and my buddy's DSM block/head work. I mean - Is it better to hot-tank it, or clean it in my driveway with a pressure washer? It's probably going to be too expensive for me to do anything else. (Also - If I need to suck it up and save more money, that's good feedback too.)
For basic performance upgrades, is it OK to re-use my stock fasteners, or should I be thinking ARP's for every bolt that is going to get used? I know it's always better to use new hardware, but is this an OK spot to "skimp out"?
Any help / advice is appreciated. Thanks!
Dango
