iroc stangs

Hi well im thirteen and i just got into all this car stuff about 4 months ago and well I was just thinking to my self how is the transformation of a 350 to a 383 done?

I was thinking it was just porting and boring but is this simpily all you do? What tools do you all need to do this? How long does this usally take to just to do the transformation ( sorry i couldnt think of the word)? On adverage how much power do you usally get if everything is done very good and if all the correct parts are used? Im referring if you are starting from a 350 chevy block.

So please give me all the info you pro's know. And anything I should be aware of if I attempt of making a 383 from a 350 in the future. Thank you all!

InfernalVortex

iTrader: (4)

It's not hard but requires some specialized work.

1. The crank has longer throws on it, this means your rod bolts can hit the sides of the block at the bottom of the bores. So these spots need to be clearanced. You can do it yourself if you want but I'd probably leave it to a machine shop.

2. The crank has longer throws on it, this means your rod bolts can hit your cam shaft lobes in some situations. Would require different rods, a small base-circle cam to compensate, (I'd avoid those) or you can grind on the rod bolts to clearance them. I think the last option is considered acceptable but Im not sure I'd do that. The small base-circle cams are fine but if you go flat tappet I'd be concerned about longevity. A lot of people use them and they work just fine, but a lot of these are drag cars and weekend cars that dont get 10k miles a year put on them either. But perhaps my concerns are unfounded.

3. You need to figure out whether you're doing a 1 pc or 2 pc RMS crankshaft (depends on block) and whether or not you want it internal or external balance. Those two things affect what flywheels/dampers you need to run. This can have other repercussions, if you ever want to use a T56, it's a lot easier to use a 1 pc RMS, internal balance flywheel, otherwise you'll need to pay $400 or so for a conversion flywheel.

Porting isnt necessary, but you will need to watch the compression ratios. With regular 64 cc heads (any decent modern factory 350 should have 64 cc heads) your comrpession ratio will be fairly high, so you'll either need some deep-dished pistons or some 72cc heads.

ZONES89RS

iTrader: (2)

A 350 is a 4 inch bore, a 383 has a 4.030 bore. A 345 has a 3.48 stroke and a 383 has a 3.75 stroke crank.

A 350 standard bore with a 3.75 stroke crank ia 377 cubic inches. So boring to 4.030 makes the extra 6 cubes. .060 over will make 388 cubes.

Now, if you install a 3.85 stroke crank in a 4.030 over bore 350, you get 396 cubic inches.

From there you get into different rid lengths to help with the application like racing or towing.

Z

AlkyIROC

Old school 383 isn't hard to make but OEM parts are getting hard to find.

Start with a 350 block. Typically the 010 casting is used but any 4" bore, 2 piece rear main 350 block will do. Using .030" over 350 pistons, have the block bored for the new pistons.

Now the hard part. Using OEM parts, you need a crankshaft and con rods (plus flexplate and balancer because it's externally balanced) from a 400 SBC. Since they stopped making them in 1979, finding one in the junkyard is getting difficult. The 400's crank has larger mains so they need to be machined down to fit into the 350 block. Assemble the 350 pistons onto the 400 rods and install everything into the 350 block and you have a 383.

If you do find a 400 in the junkyard, it's better to build it than strip it down for parts to make a 383.

Now with aftermarket availability, there are plenty of different routes to go. You can get a cast or steel crank. A crank for a one or 2 piece rear main seal block. Internally or externally balanced. You can use longer con rods which will require different stroker pistons because they will move the wrist pin higher in the piston.

There are many ways to make a 383. It depends if you want to do it super simple with OEM parts or if you want to use better aftermarket components.

AC

iTrader: (3)

All said above is great info and accurate. One other thing to consider is that you have a EFI or fuel injected engine and computer that holds the tune for that engine. Putting in a 383 will need some amount of tuning done to have it run right. I don't want to hijack your thread any more that this but be aware fo this part as well as the mechanical aspect of just building the 383. They're nice engines, I just finished building my 3rd 383 this week.

ziggy89

my way was a cake walk. take a 350 block to a machinest have it punched .030 over and cleared for the stroker kit. (slight clearencing on bottome of cylinders) as stated above. then buy a stroker kit/ rotating assembly from jegs or summit. mine came with crank, rods, pistons, rings, bearings, oil pump, harmonic balancer, double timing chain and gear set, and a flexplate,. have the rotating assembly balanced, take it home and put it together. i did mine pretty simple and pretty cheap. cast crank, eagle i-beam rods, and speed pro hyper pistons and when i brought everything home i had a short block to put together for a grand. i did it pretty good

AC

iTrader: (3)

I'm building my 3rd 383 right now. I did this as a first: bought a 383 1pc rms block from summit for just a few $'s over 700 delievered to my door! GREAT quality. I inspected evertyhing, all bores, clearances etc, really great quality. After I gave it a good wash I just started dropping everything in and torquing fastners. This block compared to my other one which I paid over 1500 bux in machining work alone to get it to the same level this Summit block is. BTW, the summit block is a GM 4bolt block.

AlkyIROC

Buying a shortblock assembly can be much cheaper and better than trying to piece one together plus the added cost of machine work.

toolegit86

so if i have a 010 block already and the block has been .030 over flat top pistons and the stock rods. and i have a 400 crank that is turned down i can just drop it in??

i have the 400 fly wheel and blancer. the main question is will the .030 pistons and rods work??

AlkyIROC

The .030" over pistons will do fine but you'll also need the shorter 400 rods for the 400 crank. Using the longer 350 rods on a 400 crank will push the piston out of the cylinder unless you use aftermarket stroker pistons which positions the wrist pin higher on the piston and closer, if not into, the oil control rings.

ziggy89

i agree with stephen. just buy sum stroker pistons. probably your cheepest bet

five7kid

iTrader: (14)

I'm still trying to figure out how you make a FALSE 383. . .

ziggy89

gm kinda does it.

that 383 short block is different.
its a 4.000 bore with a 3.80 stroke. not the typical way but none the less its 383 cubic inches

five7kid

iTrader: (14)

So, which is the "TRUE" 383?

It could be argued that the only "true" 383 is a Mopar. . .

ZONES89RS

iTrader: (2)

Very true, ask an old school guy that never stroked any chevys and say 383, they will say,"Dodge 383?"

ziggy89

yea i can see that.
only one i can think of from the factory.

that 6.2 liter gm has to be pretty close though. i think 383 is 6.3 or sumthing

racing geek

iTrader: (5)

Where are some places to by a completed short block?

AC

iTrader: (3)

Summit, nice and easy. Other than that your Googling speed shops around the country.