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need help deciding how to build a 383 V8

RockinChevy

RockinChevy

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Guys, my friend may be giving me a bored .030 over 350 V8 block (no pistons, no crank, no cams, no valvetrains) for free, that's right, FREE...if I can show him where I want to go with the build. He needs to find out what year design the block is based off of first and wants to make sure I don't junk the motor by building it half-assed with mix-n-match parts. I have NO experience in this field though I have done 350s before but never with aftermarket parts.
Well, he asked what direction I want to go, whether it be a 355 or a 383 stroker... well, I'd still like to drive the truck like always and still do rockcrawling in the future. So I'm thinking 383 stroker but not convinced yet, I'd like an all around kind of power and torque for wheeling and highway driving... Any tips from the 383 gurus out there who really know the math and parts will be greatly appreciated and I'll follow through the thread closely. I'm a real dummy with camshafts and cranks and such so help me out...

BTW, my original 350 is losing lots of oil, approx. 4 qts but I don't see blue or black smoke from the exhausts, no puddles below the rear oil seal or oil pan, no leaks at the valve covers and none at the heads....:dunno: All I can do is keep topping off the oil and do oil changes. The motor has 192K miles on it so it is time to do an engine swap anyway...
Thanks
 
Drop off the block , since you need to have it clearanced anyway . And while your there ask them how much to do the bottom end with 5.7 inch rods and Speed pro pistons . A nice dual pattern ( better way to go than an old rv cam , or too much performance cam ) cam for the rpm range we use . Roller timing set , etc . Just a nice solid bottom end .

Then compare that to the cost of the kit , and doing it at home . Not quite as cheap , but worth it if you don't have the place to do it .
 
are you saying that taking it to a shop to do the bottom end would be cheaper than a kit and doing it at home?

i too am wishing to builid a 383 for my project truck and also need to be schooled on this.
 
Not always cheaper . However , I am never trying to clearance a block at home with hand tools ever again .

For this kind of build , let them do the bottom end for you . And then just bolt some parts on to it when you get it home .

Now my .060 OVER 350 ( that WAS going into my Chevelle ) is just underground and bored stock stuff . That kind of build can be done at home in your sleep .
 
dyeager535 said:
You'll need some more money to get that 383 to work right with TBI.
Click to expand...


Mine runs with just an aftermarket chip. It is temporary until I get the money to upgrade TBI and get a real chip from TBIchips.

Aside from a bigger TB and a chip, what else should be done? I dont trust myself with tuning it and dont know anyone in my area that can do it.
 
If going with a 383, then you'd probably want different injectors, and as you mention, complete re-tune. Either do it yourself, or go to someplace that dyno tunes. (depending on usage, the 454 throttle body might be necessary, the 350 probably doesn't flow enough to support a high RPM 383, but that's a guess)

The problem is that you can't tell if an engine is lean or rich based solely on how it runs, nor can you tell what the injector duty cycle is, or WHEN the setup is running lean or rich.

This post (pay particular attention to the AF ratio graph, but the HP/TQ graph also plays a part) without a doubt shows why you MUST tune when modifying EFI setups:

http://coloradok5.com/forums/showthread.php?t=163920&highlight=454

More than likely (don't want to put words in his mouth) Burt could have run that engine as-is, and only when he holed a piston would he have known something was wrong. It probably ran like a champ before tuning.

TBI/TPI when open loop (and/or) startup, cold, or heavy acceleration/load has no idea if the engine is running lean or rich. It runs on pre-programmed values which when used on a modified engine, will never be right...until the time is spent to see what exactly is going on when it's running. The narrow band O2 sensors used in these setups are ONLY accurate at 14.7:1 AFR, which is not correct for a cold engine, nor for an engine that is working hard. Since the O2 is not accurate outside of 14.7:1, GM figured out for EACH drivetrain combination (transmission, gears, chassis, camshaft, heads, exhaust and so on) what kind of fueling was needed based on other numbers (RPM, TPS, and so on) and those are "hard coded". Any time the engine meets the criteria, the O2 sensor is essentially ignored, and those hard coded numbers come into play. A 383 at WOT obviously needs more fuel than a 350 in the same conditions, but with the tune/injectors for a 350, the engine will run lean.

Yes, you can try to bump up the fuel pressure, but that is a "global" change, and the ECM bases injector pulsewidth on the flow constant of the injectors, which is rated at a certain pressure. Increase pressure on the same injector, it will flow more even though the pulsewidth is the same, HOWEVER, while the ECM can compensate (somewhat, it is limited here too) by reducing the injector pulsewidth when the engine is closed loop, when not closed loop, it will be running rich, while at higher RPM's, it could STILL be running lean. Without monitoring the A/F ratio (and when you get down to it, power and spark) under all conditions, you simply cannot know how the engine is actually running.

There is at least one old post on here where someone holed a piston in their brand new 383 because they used stock 350 injection stuff.
 
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I'll check around and see what they are charging these days. Thanks Pauly, pretty good info for me to start with.
 
dyeager535 said:
You'll need some more money to get that 383 to work right with TBI.
Click to expand...

I'm thinking of converting it to EFI with the Edelbrock kit but man, they are pricey. I'll need to know everything about what formula will work with whatever size cams, crank, how much stroke, etc... I have a lot to learn on this topic.
 
If you go with a "kit", then you probably won't really have to worry about it...Edelbrock has no doubt tested their heads, cam, and injection system before shipping them.

But you are right...the aftermarket injection systems are pretty pricey.
 
Wow, that was some good information there, dyeager535.

So would you guys choose a 383 stroker over a 355? My friend said both can be done on the same block, only the 355 has power, and the 383 has more torque. So that's where I needed help deciding which direction to go. I don't plan on jumping on this project right away, I'll only go along as money allows which could take a year.
 
Well if you want to do a 355 , I will GIVE you ( no one else , please don't delete , hes a friend ) a known good 350 crank . I am sticking the 400 crank in the block its coming out of . Spins free , looks nice .
 
pauly383 said:
Well if you want to do a 355 , I will GIVE you ( no one else , please don't delete , hes a friend ) a known good 350 crank . I am sticking the 400 crank in the block its coming out of . Spins free , looks nice .
Click to expand...

I have another 350 block in storage with a 350 crank also. My friend was sitting here and reading this with me, he just mentioned he has a 400 crank he'll throw in. I'm sitting here questioning him what does he really have? He's laughing and saying he can't remember every single part he has in his garage. I'm gonna swing by his house and check out the 383 and look around what else he can toss in. He's cleaning out and doesn't want anything anymore, that's why it's free. I think I'll take the 383 route...
 
aftermarket SBC stroker cranks and rods can be had new and cheap (IE scat) I'm not sure why anyone still bothers messing with old 400 stuff.

I just yesterday picked up a good 355 from a guy and have plans for an aftermarket stroker kit. This if for my '73 Z-28 though.
 
brian, i just got done converting the jeep from a 355 to a 383, it takes time and money to do it right and you hafta take in fact what you wanna do with it and how much you wanna spend, i got a smoking deal on a 383 from a board member with under 1500 miles on it for cheap, but only because he had NO use for it... If you want a good 383 combo for all around torque and still some top end this is what i would do

start with a good 010 block, preferably a 4 bolt main, but 2 bolt main will work, have it clearenced and bored for the 383 rotating assembly... get some good dished pistons for (6cc dish would be like 9.5:1 with the vortecs) then do some vortec heads with comp cams extreme 4x4 cam, this thing will make enough torque to pull a submarine out of the water and still be drivable every day... my 383 is the exact opposite, makes a lot of midrange and high rpm power but only cause it was built for it... if you need further help between paul and i im sure we can set you up with a great proven combo.... Nate
 
BTW, if your gonna go the 400 crank route, i would recommend taking it to basko machine.. he has done two of these for friends of mine and they turned out good.. me personally, i would buy the scat kit and be done with it.. have the block machined and throw it all together yourself as scat will sell you a complete rotating assembly that is balanced and ready to go... just make sure they use the 5.7 rods and clearance them for the cam... Nate
 
There are a couple different ways to build a 383. I could go into many details here but it would take too long. If you want my professional opinion PM me and we can talk.
 
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