I'm try to decided whether to build a 383 or 350 for my 81. I'm looking for about 400-450hp apx crank. i know the 383 will get me there easier but i'm still having a hard time deciding. So far i have picked a set of bowtie vortec large port heads (225cc intake) part# 25534446 and a gm low rise dual plane intake for the top end, not 100% sure on what cam i'm going to run, but i do know it will be roller. the difference in building the 383 will be about 400 over the 350. let me know what you guys think. the car has a 2004r and 3.08gears

 

Bang for the buck , Stroker engine always wins .
GMPP even makes a OEM one. Get the Cubic inches up there for reliable performance.
383's can make big torque so....A lowend grunt Cam to compensate for the 3.08 Gear. .
A Cleaned up and polished "performer intake" as opposed to a "Iron Vortec 225cc. , not because of the Iron, but of its large ports 225cc would hurt your Low end...

 

I was rebuilding the engine in my 68 a few years ago. When asking about options for adding power, friend of mine told me "it's never enouigh power". So here I am 3 years later thinking about adding power. If you are planning to buy a block and start building, I would find a 400 block and build 406, 415, 427, 434... If you are rebuilding your current block, I would go 383 or consider my first option of 400 block. If you plan ahead there is not much difference in price.

 

We have used alot of the Large runner V/B heads and they are a nice piece but your going to kill them with a dual plane intake!! There is not enough cross section area in those intakes like the single plain intakes.

The port match is not going to be very good thats for sure.

 

I'm assuming you're starting from scratch? Back up for a minute and give some information on what you want (power targets), what you have and how much you want to spend.

There's no question you want a 383. Period

Definitely a mis-match on the heads and intake, and unless you're shooting for 500 HP (with the budget to match) those heads aren't going to be happy on a mild or warm 383.

 

i had thought about running the small port bowties but figured they would run out of air at too low an rpm for a 383, i hadn't thought about the dual plane intake being a choke, what would you recommend for an intake that would fit under the stock hood? my budget is about 2500, i get a great deal on heads (445 a piece for the large ports and 10 less a piece for small ports), i also get most of my parts at cost though our shop. 500hp would be nice but i know that would be out of my price range to keep reliable. i'm looking a for a good street driver with about 450hp if i could get 350 at the wheels i would be very happy!

 

AFR 195's or a cleaned and Polished Performer intake . The performer fits nice under C3 small block hoods

 

In that price range, even with great discounts on parts, you'll need to be pretty frugal. Is your discount on Chevy/GMPP stuff only or on other stuff too? Do you get a discount on machine work?

IMHO your best bang for the buck in that range would be a late-model Vortec roller-cam engine. A simple performance overhaul with an upgraded cam is going to get you into the 375-400 HP range depending on what you can spend on heads.

More money opens up more options - but in that range I can't see much more than a good performance overhaul and a cam upgrade. A cast-crank 383 is still in the cards since new aftermarket cranks sell for about what a shop charges to turn the stock crank.

 

i get a discount on almost everything i need, i was looking at a eagle stroker cast kit and i get my machine work for free (if i do the work myself) I would like to run a set of afr heads but there not in the budget right now, maybe an upgrade for later on...

 

My experience with Eagle has been that they're always out of spec; most commonly in rod journal taper. They've also been surprisingly out of index. After going through 3 Eagle cast cranks, I only use Scat. Just one guy's opinion.

You're on the right path - I'd think about doing a straight overhaul of a Vortec long-block, including the heads since labor is "free". Go with the 383 crank, and spend a little time on the short radius of the exhaust on the Vortec heads. You'll end up with a torquey 383 that will run out of steam around 5,500 RPM...but with those gears, that's pretty much out of reach anyway.

You can't really hit your power targets without decent Tier II-type (AFR) heads...

 

i have heard that from others about eagle cast cranks, i have run a few scat cranks and had nothing but problems with them, the crank snout was always a little too long. the problems with the eagle stuff is what made me change my mind back to a 350, mainly because i don't have the money to have the crank balanced again, As much as i would like a 383 i think i may stay with a 350 I have a good 92 roller block core with a great crank and rod set. i could always upgrade later... I think a 350 with the small port bow tie heads would be a great runner and i would be plenty of power (i drive spiritedly and very seldom race) I'm just afraid of having problems with the eagle cast stuff, and i can't afford the forged stuff right now. I haven't even driven the car since i bought it so i think a stout 350 would be plenty of power

 

More background always helps. A roller 350 is a great engine, and the 185cc intake runners on the small port are just fine with the right cam.

Sounds like a good plan

 

Yes and I would think the next step is deciding what is the right cam? What would be a good lift for this setup?

 

Sounds like a good idea. Can't go wrong with a roller engine.

 

the cam was one thing i never really could deiced on, i know alot about them but had a hard time narrowing one down, i was debating calling comp or crower and seeing about having a custom one ground. I'm going to order parts tomorrow for the engine and start the build up. any suggestion on a cam would be really helpful. thank you for all the help up to this point!

 

The budget you are on, even with shop deals, Won't put you in a killer 383 IMHO. Over a third of your money is spent in the heads. Not sure if the price you spoke of is complete, or still need s springs and valves.
Now you have $1,600 or so left. A good set of pistons will take that total down some along with a good set of aftermarket rods. Price some Olivers , not that you'll need Olivers, but the best quality rods are expensive. Don't go cheap there. or pistons. Most engines I take apart died in that area. That's why you'll see six used rods at the swap meets often. Balanced engine is a must it you'll be turning many Rs. Even if you aren't it should be balanced.
The Eagle and Scat cranks, as others have said, have had some issues. A good Crank will eat up the rest of your budget, and ALL builds end up costing more before they are up and running.
All that is bassed on you doing the balancing youself. The 350 can be a little less expensive but not as much fun. Will take some additional work getting to your HP goals.

 

I wouldn't suggest going with a custom cam unless you're really ready to do that level of design. For this type of build, an "off the shelf" cam is going to get you within a few % of the power you'd get from a custom-ground cam.

The posted flow numbers for the 185cc Vortecs seems to top out around 233/144 @ .500 lift...so in a mild engine there's not a big reason to go a lot further than that. Given the gears and trans, the focus is on making low-end torque vs. high-end HP. Frankly, I'd take some of the $$$ you've got for the engine and put it into gears and a torque converter...because those 3.07's are not doing you any favors in terms of engine design.

My sure to be unpopular suggestion would be one of the CompCams Xtreme 4x4 cams - the X425HR (P/N 08-409-8). The cam leaves a fair bit on the table in terms of making good use of the heads - but it will deliver the torque you need to offset the gears.

Diffferent gears - way different cam choice.

I would absolutely call CompCams and other cam companies to get their thoughts - just make sure you give them ALL the information so they can help make a good choice.

I'm assuming since you're ready to order parts the block is clean, pressure-tested and mag'd...and you know exactly what overbore it's going to clean up at?

 

We have used the 185 V/B on alot of our circle track engines and these are 11:01 compression, Flat tappet in the 258 @ .050 and a 600 HP Holley and we have seen 540 horse with these heads. Int. valve is 2.000 and exhaust is 1.550

Don't base everything on flow numbers as the V/B has a raised intake and exhaust runners and a fast burn chamber and workes better then most heads out their.

There is such a thing as quanity of air and such a thing as quality of air and the Vortecs have quality air thats for sure.

 

blockman thats more potential than i expected i must admit! i knew air quailty was best but, i didn't know it was that good on the v/b heads.

I have been looking at cams and found two that look kind of promising, there comp cams part# 08-503-8 and 08-301-8 the 301-8 is a cam for nitrous but the numbers look good, i also liked the 113 lsa i figure it would help the idle a bit, i would like your guys opion on either of these two. i called my trans parts guy and he said he can get a 2500 stall for my 2004r so i can throw that in also, i was planning on running long tube headers and about 9.75 compression. i can always upgrade the gear in rear at a later time if needed

 

+2 for the 406 SBC. I've never understood the 383 attraction at all. 450 hp will me more easily obtained with the x-tra cubes. You could even use the factory nodular iron crank at that level and still be ok.