My son and I just bought a small block Chevy 400 cu. in. engine for him to
rebuild and install in his '79 El Camino. He's heard that .030 is the max.
you can overbore this block. Haven't got the heads off yet and we don't
know if it's standard bore or not. Anyone know if this .030 max. overbore
information is true? Thanks for any help.
Make sure your cooling system is rock solid. New radiator, flush the block
etc. As was mentioned, no water passages, then if you start upping the HP
you start making more heat, and these are not known as cool running motors.
My son's going to have it boiled out, line honed and bored with torque
plates. Already has a new radiator on the El Camino. He really wants to get
everything done right. However, I can't understand why all the aftermarket
overhaul kit suppliers that we can find only offer .030 oversize pistons.
If .010 or .020 would clean it up after we get the heads off Monday, that's
what he'd like to to.
Um I am thinking ya'll need to check your info a little more. I am running
one in a 78 cheyenne right now that is .06 over. That is the max that you
can take them. I don't suggest it but you can get pistons for that bore.
Partsamerica.com has a set of .06 for 104.99. I suggest you change your
rods to the 5.7 instead of the 5.565 stock rods. This will cure some of the
over heating problems. You also have to change the pistons to match the
rods though. Also look at Northernauto.com. They have lots of parts that
are harder to find. .03 is your basic kit you can get for a 400 sb.
Thanks for the input. We read this .030 max. overbore deal in a Chevy small
block overhaul book and from a Car Craft article about Chevy small blocks.
A couple fellows my son knows also told him this. I'd like to think it's
not true. I do think the longer rods are a good idea, also. I'll check the
TRW makes standard cast pistons in Std, 20, 30, 40, and 60 over. Part number
400NP. And, forged pistons in Std, 30, 40 and 60 over. Part number L-2376F.
They also have the rings for all those combinations, and about any other
part you will need.
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