[velle307]

hello all
i have just received a block from a friend who says its a 350 but the castings conflict block castings(3970024)...307.. well all pulled apart (rod-knock) it has 350 pistons a 4.000 bore and a 2.484 stroke and crank castings(3932442) my question is can you bore this block to a 350 safely? in another forum i seen only one person who said it could be done with the block i have.

thanks for all the help..

[DoubleVision]

I`ve heard the 307 blocks have enough meat to bore to 4 inches, however, I wouldn`t attempt it unless I had the bores sonic checked to assure there was enough cylinder material left after the overbore.

[velle307]

the guy who had it before me had it running for years he said and he didn't touch the motor only when he took it out to change it cause of rod knock. must have been the guy before me
and how much allowable play should be in the rod bearing/crank it is about .002 now on all. rods good or more less?

and how about overheating i didn't ask him about that should i get a thermostat that is higher or lower temp? and how about the radiator cap wont that lower the temp of fluids by pressurizing the coolant how much difference will the cap be if i go to a 20lbs cap...? from a 16lbs?

[fast68]

my first chevy engine ever was when i was 16 i bought a 68 chjevy c-10 long fleet pickup for 2200 bucks at a local chevy dealer, in 1994, it was the 307 2bbl and 3 speed column shift SM326 and the 12 bolt non posi 3.73 with coil spring trailing arm rear suspension

i would definitely have the block water jackets cheked for thickness

but i would just go grab a 4" bore block

they are dirt common especiall the 3970010 and 014 blocks and were both 2 and 4 bolt and many were high tin and nickle content(010 and 0120 cast in bellhousing area and timing cover area). the 307 blocks werent either thing and noen were 4 bolt either,

soend same money on a 4 bore block and you can do alot more with it for the same $$$$$$$

350, 327, and 302

all same blocks, '68 and '69-'79

[cobalt327]

Originally Posted by velle307

hello all
i have just received a block from a friend who says its a 350 but the castings conflict block castings(3970024)...307.. well all pulled apart (rod-knock) it has 350 pistons a 4.000 bore and a 2.484 stroke and crank castings(3932442) my question is can you bore this block to a 350 safely? in another forum i seen only one person who said it could be done with the block i have.

thanks for all the help..

It's certainly possible to have enough meat in the bores to use a 4" piston. The failure rate was more because of sand pits and inclusions than a too-thin bore thrust surface, in my experience.

As long as you don't need to bore your block, I'd continue to use it. It isn't going to "like" an overbore to larger than 4", though.

BTW, the stroke is 3.48", I think you have a typo in your first post.