Whats it take to build a 383?

[sled_dog]

Ok I'm thinking about buying another truck. Its an 88 1500 short bed, think i can get it REALLY cheap. If I do I will either fix it up and sell it or fix it up and rock it around town with SAS swap and some 38s.(I miss driving something that turns heads) Anyway if I keep it I would want to rebuild the motor and probably go 383. I can get a 383 1 piece rear main crank on Ebay for like $150 so I figure why not. I know I would need a chip(though who knows maybe the K5 wants some TBI and the short bed wants a nice carb. What do I need to run a 383? I've always heard 400 balancer and such but what the heck is this? I've never been clear on this stuff.

 

[fad2blk99]

A 3.75" (or 3.80) stroke crank is the best thing that ever happened to a small block!
To build the 383 you'll need to first know about your crank. A while back most people were taking a crank out of a 400 (which is a 3.75" stroke) and sticking it into a 350 (replacing the stock 3.48" stroke crank). In order to use the 400's crank you'll have to machine the main journals from 2.65" to the 350's main bearing journal spec of 2.45"
However, now that 383's are popular, crankshafts with 3.75" stroke and 2.45" mains are easy to come by and are often cheaper than buying a 400 crank and having it turned down.
Now in order to the achieve 383ci with a 3.75" stroke crank in a 350 block, you'll need to bore it .030" over. Or if you are lucky enough to score Chevy Performance Parts new(ish) 3.80" stroke crank, you can get 383ci on the 350's standard 4.001" bore.
All that being said with the 3.75" stroke crank you will need a harmonic balancer and a flex plate from a 400. I'm not sure about CPP's 3.80" crank.

 

[pauly383]

You forgot to mention that with a 400 crank and most others that you need to clearance the oil pan rails to clear the crank throws. And with some rod and piston combos some cams will hit the rod bolts and these need to clearanced also.

 

[fad2blk99]

Good points...
I know I left out a few important details, but I wanted to give the key info before he bought the crankshaft.
You can also avoid having to clearnace rod bolts by running a small-base-circle camshaft (if necessary).
The best thing to do before buying anything is to find a good machine shop with experiance building 383s to assemble the bottom end. They'll know what components are required with certain kits and can reslove any clearance issues. Building a 383 is not like freshing up a bone stock 350, and not something I would try to tackle in my garage. Not on the initial build up anyway.

 

[Beast388]

You will have no choice but to purchase a 383 crank with a one-piece rear main seal. 400's were all two-piece, so you cannot have one turned to fit your 350 block.

I built my 388 in my garage. I did all of the clearancing too. It took many test fits, but worked out fine. I used a set of H-beam rods that use cap screws instead of regular rod bolts so that I did not have any cam clearance issues. But, those rods required more clearance at the bottom of the cylinders and oil pan rail. I had to dent my oil pan in a few select locations as well.

You will need to use an externally balanced flywheel/flexplate and harmonic dampner and have the engine balanced. Most aftermarket stroker cranks require it.

You can use the 5.565" long 400 rods and reuse the factory pistons (if the bores are good) but I would recommend 5.7 rods and aftermarket hypereutectic pistons. 6.0 rods are popular, but with the 3.75 stroke, the pin locations are well up into the oil rings. For longetivity reasons, I chose the 5.7's.

Good luck with your build up, research your parts and have fun with it! /forums/images/graemlins/thumb.gif

 

[sled_dog]

Thanks guys, I went and looked at it again, its rustier than I remembered(they always are), so I know what I'm gonna do, just gonna fix up my Burban and sell it then use that money to put a down payment on a newer(96 or newer) 2500 pickup. I had a 95 which was TBI, the only thing it was missing was a little more power so Vortec it is.