Hey fellow camaro and firebird lovers! I am debating in purchasing this stroker kit and I am wondering if it will fit my 350 block. 3970010 is casting number. I know the block would need maching and clearance for the stroke . thanks help is appreciated. Want to build this for my 85z28 thanks

 

That would be what is known as a "383" (with a .030"-overbore).

If it is a real factory 400 crank, the main journals would have to be turned down to 350 size.

If it is a "kit", most likely it has 350 size mains.

It's pretty much a given that the oil pan rails have to be ground back a little to clear the rod bolts with a 3.75" stroke in a 350 block.

 

Cool ya well the guy selling it says its a stroker kit . Sounds like a good deal for $500

 

As mentioned above, an original 400 crank would need to have the mains machined down to fit in the 350's block. If you wanted to destroke a 400 with a 350's crank to make a 377, you would need to install bearing spacers in the 400 block to take up the extra room.

As a kit, the crank is probably already machined to fit into the 350's block. If it's like a 400 crank and is externally balanced, you'll need a balancer and flexplate/flywheel for a 400. If the crank is internally balanced then the neutral balanced balancer and flexplate/flywheel from the 350 will work.

The "kit" should also come with the proper length rods with pistons since the 400 uses shorter rods which can have standard 350 pistons installed on them. If you use the longer 350's rods, a special stroker piston needs to be used which moves the wrist pin higher into the piston.

As for clearancing the block, I've never seen an issue with a 010 block made into a 383 that needed any clearancing. It all depends on which rods and rod bolts are used. If any sort of clearancing is required, it's at the bottom of the cylinders.

Since your block would need to be bored out 0.030", have the engine built right and have a machine shop do all the bottom end work and assembly. Let them check all the measurements and clearances. You'll get back a properly assembled short block that you can the finish building with heads, intake etc. The block should not be bored out without the pistons because they need them to check the final size.

 

Thanks. I checked the motor and it is bored 060 over . Pistons stamped 060 and cyl measure the same . So now that kit actually doesn't work for me? Well the pistons at least cause there 030 It comes with 400 balancer and flexplate, balanced rods with pistons on them and a set of forged aluminium 030 as well

 

Time for a new block.

 

Nope, .030" over (4.030" diameter) pistons won't work too well in a .060" over (4.060") bore.

The "kit" might be available with the other size pistons though.

OTOH, if you've got a .060" over block and the bore isn't ABSOLUTELY FRESH (that is, you just now had it bored to that), then it's pretty much trash, not worth building a motor out of anyway, since it will not be possible to get a good seal on the rings. You'll have one of those motors you always hear about that has all these nice parts but just doesn't run anywhere near what it should, lives a short life, smokes unrepairably, and leaks oil out of every gasket and seal because of pressure in the crankcase from all the blowby. A 010 block like that is the single most common piece of automotive casting in the history of the known universe as far as I'm aware; nothing to shed a tear over anyway. If yours is already wore out, throw it in the trash and get another, they're cheeeeep and plentiful; and then maybe you can even use the .030" over kit.

 

I also have a complete L82 350 same casting 3970010 original motor from 76 corvette I pulled out in summer . Needs rebuild as wellMay use that one then. Is it really trash at 060. It measures 4.0595.

 

The 060 motor ran great started it one morning and it had a tick I shut it down and pulled it from my 84 monte ss to find a bent rod .

 

This is the only damage that is obvious . Good thing I didnt keep running it

 

At 0.060" overbore in a factory SBC block, there's not a lot left you can do to it. The walls are getting thin. You could get it sleeved back to an original 4" bore but for the cost, it would be cheaper to find another block especially one that hasn't been bored out yet. Sleeving an 010 block isn't worth the money unless you have some special numbers matching block in a rare car however machining down the deck after sleeving will grind away any stamped in numbers anyway. Sleeving a $3000 aftermarket block is worth the money.

If you're pulling any engine for rebuild, you're going to want to pull the heads to see if it has any sort of overbore. At 0.060", it's not good to push it out more. At 0.030", you could do a cleanup overbore of 0.040" but generally it will go out to 0.060".

A machine shop can say if your 0.060" overbore block can have new 0.060" pistons back into it. If the cylinders have distortion, taper etc then they can't be simply rehoned for new pistons.

As for aftermarket blocks, my BBC Dart block has been punched out from 4.500" to 4.625" and the cylinder walls are still at least 0.250" thick.