@sctrailrider is 100% correct here. If you have an Optimizer or P-400 than you have an engine worthy of the expense of a true rebuild including machine shop work for the block and heads. Cost will exceed the value of whatever it's in except if it's a HUMMER or RV. Looking at the cost of NEW diesel pickups and SUV's that are emissions strangled a near $8,000.00 engine is pocket change. I point out some new stuff is reliable and some are attempting to take the Olds 5.7 diesel hand grenade trophy away. So expensive new and unreliable. Rust end game is a consideration applicable to where you may live.
So the new long blocks offered are a good value. If you can get them apparently.
One big consideration. Most of the vehicles these engines came in are antiques now. 1982 to around 2000 with some marine stuff still going out the door and even 10 years of parts gets us to 2010. It's only due to the military that we have a cheap source of engines. The 10+ year production body style has used parts and LMC truck.
For the GM cast iron: "overhaul" and that's a small engine economic "overhaul" of just parts above the wrist pin. As we discussed GM 6.2 and 6.5 cast blocks are scrap in the PER world. (Professional Engine Rebuilding) So who cares if you cut corners on a throwaway engine? After all it merely needs to start halfway reliably and go down the road. So the answer be: you. Just set your expectations accordingly.
The military manual only has one oversize 0.20" documented. (Read into that whatever you want.) Fix what broke and hope you didn't miss any show stopping cracks. If the GM block needs to be punched out oversize it starts to add up quick to not worth it. For example Heads are $250 each at the machine shop plus parts like valves and NEW springs. Block is like $1000 to punch oversize. 6.2 pistons are inexpensive surplus, but, 6.5 Pistons are $500.00+. New cam bearings that take special tools and skill, Rod bushings and big end resizing... We were at $2000.00 of just the select numbers I threw down and haven't even added bearings, $80 * 8 for new precups because yours are going to be cracked, new oil pump, gaskets and assuming nothing comes back scrap due to cracks. Injectors are a cheap $500 or so a set for good ones. The IP is also up for a refresh with a new head and rotor...
So getting a low mile surplus engine, cleaning the cylinders up with new standard size rings is a frugal option because it doesn't require all the machine shop work from wear. Some day the crankshaft is going to fall out of the cracked 6.2 block of mine. Meanwhile I have had a running 3/4 ton truck with lots of cash I didn't have left on the table. If I had a choice at the time I would have replaced the block when I had to pull it out and noted the mains cracks.
One last thing. Your labor to pull an engine is worth around $1000.00. Keep this in mind when skipping having the block checked for cracks because if you miss them the engine is coming back out and wasting gaskets and other parts that can't be reused.
So the new long blocks offered are a good value. If you can get them apparently.
One big consideration. Most of the vehicles these engines came in are antiques now. 1982 to around 2000 with some marine stuff still going out the door and even 10 years of parts gets us to 2010. It's only due to the military that we have a cheap source of engines. The 10+ year production body style has used parts and LMC truck.
For the GM cast iron: "overhaul" and that's a small engine economic "overhaul" of just parts above the wrist pin. As we discussed GM 6.2 and 6.5 cast blocks are scrap in the PER world. (Professional Engine Rebuilding) So who cares if you cut corners on a throwaway engine? After all it merely needs to start halfway reliably and go down the road. So the answer be: you. Just set your expectations accordingly.
The military manual only has one oversize 0.20" documented. (Read into that whatever you want.) Fix what broke and hope you didn't miss any show stopping cracks. If the GM block needs to be punched out oversize it starts to add up quick to not worth it. For example Heads are $250 each at the machine shop plus parts like valves and NEW springs. Block is like $1000 to punch oversize. 6.2 pistons are inexpensive surplus, but, 6.5 Pistons are $500.00+. New cam bearings that take special tools and skill, Rod bushings and big end resizing... We were at $2000.00 of just the select numbers I threw down and haven't even added bearings, $80 * 8 for new precups because yours are going to be cracked, new oil pump, gaskets and assuming nothing comes back scrap due to cracks. Injectors are a cheap $500 or so a set for good ones. The IP is also up for a refresh with a new head and rotor...
So getting a low mile surplus engine, cleaning the cylinders up with new standard size rings is a frugal option because it doesn't require all the machine shop work from wear. Some day the crankshaft is going to fall out of the cracked 6.2 block of mine. Meanwhile I have had a running 3/4 ton truck with lots of cash I didn't have left on the table. If I had a choice at the time I would have replaced the block when I had to pull it out and noted the mains cracks.
One last thing. Your labor to pull an engine is worth around $1000.00. Keep this in mind when skipping having the block checked for cracks because if you miss them the engine is coming back out and wasting gaskets and other parts that can't be reused.
