Preping a block for rebuild
- Thread starter simonjrwinter
- Start date
Doc Watson
Lifetime Supporter
Hopefully the mains were left on the block and torqued to correct values before the rebore to prevent any warping of the bores. Also check that a chamfer is around the top of each bore 1/32 x 45 degrees is enough, this helps when the pistons go in.
See if you can get it pressure tested and crack tested. Also hot tanking is the preferred cleaning method, but make sure the cam bearings, oil gallery plugs and freeze plugs are out, as well as the mains bearings.
Check the head surfaces for flatness (less than 0.007" over the full length of the heads) and deck the block if necessary. Remember this will change your compression ratio, and if one head is out you still need to machine each one to maintain even compression ratio across both heads.
Chase EVERY thread on the block after hot tanking.... and then clean it again. Gun brushes are good for cleaning oil gallery holes. De rust all water holes.
Also has the bores been finish honed? it depends on the type of rings you use as to what pattern should be honed into the bores.
Finally clean it again and immidiatly spray it with WD40 all over.... place in a bin bag and await small block assembly.
I think thats it.....
What engine is it? and whats the vintage?
Andy
See if you can get it pressure tested and crack tested. Also hot tanking is the preferred cleaning method, but make sure the cam bearings, oil gallery plugs and freeze plugs are out, as well as the mains bearings.
Check the head surfaces for flatness (less than 0.007" over the full length of the heads) and deck the block if necessary. Remember this will change your compression ratio, and if one head is out you still need to machine each one to maintain even compression ratio across both heads.
Chase EVERY thread on the block after hot tanking.... and then clean it again. Gun brushes are good for cleaning oil gallery holes. De rust all water holes.
Also has the bores been finish honed? it depends on the type of rings you use as to what pattern should be honed into the bores.
Finally clean it again and immidiatly spray it with WD40 all over.... place in a bin bag and await small block assembly.
I think thats it.....
What engine is it? and whats the vintage?
Andy
Depending on the reason for the rebuild, you might consider having it Magnafluxed or dye penetrant tested before you drop a bunch of money on additional machine work.
Howard Jones
Supporter
I would have the parts you have selected for the rotating assembly, pistons, rods, crank ballanced then have the block line bored and new cam bearings installed before it comes back to you.
The crank grinder should select the bearings to be used on it.
If they do a good job then it all should go back together AND fit correctly.
Plastigauge everything and measure ring gaps carefully and you should have a nice ballanced and blueprinted shortblock.
Don't deck it if it don't need it. Decking SOME 302 blocks can cause more problems that it solves. Some of the later blocks are very thin.
Oh and when you get it back from the machine shop clean it like you are going to eat it. I used 4 cans of brake clean on mine before I was happy with it. Use those blue paper towels because they don't produce lint. No white paper towels from the kitchen. Make sure you really clean out all of the threaded holes after you re tap them along with the oil galleys. Do the best you can with the water passages so they don't dump something into the rest of your clean block as you rotate it as you build it.
Use brake cleaner do the final final cleaning of the bearing surfaces prior to installing bearings.
Finally blow it out with air and put in a plastic bag after one last light wipe down with new clean motor oil.
Good to go!
The crank grinder should select the bearings to be used on it.
If they do a good job then it all should go back together AND fit correctly.
Plastigauge everything and measure ring gaps carefully and you should have a nice ballanced and blueprinted shortblock.
Don't deck it if it don't need it. Decking SOME 302 blocks can cause more problems that it solves. Some of the later blocks are very thin.
Oh and when you get it back from the machine shop clean it like you are going to eat it. I used 4 cans of brake clean on mine before I was happy with it. Use those blue paper towels because they don't produce lint. No white paper towels from the kitchen. Make sure you really clean out all of the threaded holes after you re tap them along with the oil galleys. Do the best you can with the water passages so they don't dump something into the rest of your clean block as you rotate it as you build it.
Use brake cleaner do the final final cleaning of the bearing surfaces prior to installing bearings.
Finally blow it out with air and put in a plastic bag after one last light wipe down with new clean motor oil.
Good to go!
Don't buy the pistons untill the machine shop has made sure if it needs to be bored or not and if so how much. If you are going to assemble it yourself. You need some special tools, like a ring compressor, torque wrench, degree wheel, dial indicator, if hydrolic lifters, than 1 solid lifter to degree in the cam, etc. Also after the block comes back from the machine shop you need to clean it well. You need thread chasers for all the bolt holes as well as long brushes to clean the oil galleries. I'm sure I missed some stuff, but you get the idea.
Thanks guys,
The machine work is all finished on the engine.
It was a (fairly) low mileage roller block 302 where something had made it's way down the bore and scratched it (I posted before about re-sleeving it) I decided to have it rebored with new pistons/rings and had the whole rotating assembly balanced at the same time. The cam and bearings are like new, and as this is intended to be just a standard rebuild, I have kept them as-is.
I'm VERY keen to make sure the engine is SPOTLESS before rebuild as the last engine (a 331 stroker) had problems from the start (despite the use of the correct tool to prime the oil pump and get pressure up)
After that I promised myself I'd always get someone else to build my engines for me.......hope I won't regret going back on that!
Simon
The machine work is all finished on the engine.
It was a (fairly) low mileage roller block 302 where something had made it's way down the bore and scratched it (I posted before about re-sleeving it) I decided to have it rebored with new pistons/rings and had the whole rotating assembly balanced at the same time. The cam and bearings are like new, and as this is intended to be just a standard rebuild, I have kept them as-is.
I'm VERY keen to make sure the engine is SPOTLESS before rebuild as the last engine (a 331 stroker) had problems from the start (despite the use of the correct tool to prime the oil pump and get pressure up)
After that I promised myself I'd always get someone else to build my engines for me.......hope I won't regret going back on that!
Simon
Not a lot to add to the above comments Simon other than checking very closely with a dental type mirror the condition of the cam bearings, these have a history of delamination of the bearing metal & detaching from the steel backing particularly around the oil feed hole, more so on high mileage examples or on engines that have been run with Hi Vo pumps. Look for any sign of a surface crack in the brg metal.
Rather than WD40 or CRC I prefer to coat the bores & any bare machined surface with a ATF, but thats just my preference.
When using hot soapy water to wash down the block do not use common household detergent, it contains salt and other corrosive stuff that will turn your shiny cyls to rust before you have the chance to oil them up.
Jac Mac
Rather than WD40 or CRC I prefer to coat the bores & any bare machined surface with a ATF, but thats just my preference.
When using hot soapy water to wash down the block do not use common household detergent, it contains salt and other corrosive stuff that will turn your shiny cyls to rust before you have the chance to oil them up.
Jac Mac
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