Question about rebuilding a very new engine

[jdavis968]

Hello All- I'm new to the forum (first post) so if I've done something incorrect, kindly point it out and I'll make good.  I have a 350ci sitting in an '83 K20 that I had built for my son. He ended up not being an old truck guy (to each his own I reckon) and now I have a mostly new engine (< 1500 miles).  I am going to reuse the block, crank, and rods- replace the heads and pistons, cam, etc. My question is this- do I need to have the block bored being so new, or is simply honing the cylinders enough?

Appreciate the help!
-joel

[bd]

Welcome to the site.  That's kind of a loaded question that begs a lot of assumptions.  What is your intention for the "new" motor?  What did you have done 1,500 miles ago?  What happened to the motor in the meantime that you want to replace major components?  If all you are trying to do is freshen the motor, why new pistons?  It's difficult to provide a useful answer without sight of the entire picture.

Pistons need to fit their bores with the proper clearance.  At the very least, you should carefully measure the bore diameter, runout, taper and deck height then compare the measurements to the new pistons and rotating assembly you are planning, and machine accordingly.  While its apart, check for cracks and have the line bore checked.  You might even consider clearancing the block for a 3.75" stroke in case you later get the bug.

[jdavis968]

Thanks @bd. The engine was a new build, not rebuilt and there's nothing that happened specifically to the engine. It's just not spec'd the way I want it- low compression (dished pistons) and 194 heads (new, not pre-mid '70s).  The intention here is a rebuild that will yield enough power to turn 33s and not feel sluggish, which the stock build just doesn't do.

[zieg85]

BD is the perfect help on this.  A new stock 350 shouldn't be sluggish so there are some questions to answer.  What is sluggish?  What gear ratio and transmission is in the truck currently?  What is the timing?  Being a K20 you should have 4.10's that should move that truck quite well. 

[SomeTexan]

BD is the perfect help on this.  A new stock 350 shouldn't be sluggish so there are some questions to answer.  What is sluggish?  What gear ratio and transmission is in the truck currently?  What is the timing?  Being a K20 you should have 4.10's that should move that truck quite well.

It comes down to perspective. I've never driven a stock, low compression 350 that I didn't think was a sluggish dog of an engine. Even tuned well and putting out well above the rated output. But I've been running built engines for years, and well built for their application.

[Engineer]

After having a 454 all small blocks are sluggish. Hehe.

[SomeTexan]

After having a 454 all small blocks are sluggish. Hehe.

I don't know about that. I had a GM sb bowtie block at 454ci and it blew my old 540 bb out of the water. 50 more hp, 60 less ft lbs of torque but 200lbs less weight. Then I learned about the LSx, more hp, more torque and less weight. Now I'm going to go stare at my Dart LSNext2 billet block and dream about the day when the rest of my parts come in... My 118mm turbo should be in the mail in the next few days too.