Shann

Hi all, after months of searching I finally found the perfect corvette for what I am looking for! It's a 72, 350 (low horse variant), 4sp (#'s matching), and to the best of my knowledge the engine has never been opened. It's a lot of fun as it, but my dads and my plan is to drive it around for a bit to enjoy it, before we take out the engine to turn it into a real fun car. He is very keen on the idea of booring and stroking it out to a 383, which presumably would have a higher potential power output than keeping it a 350, and hopes to get 400-450+ hp. I like the idea, but I don't know everything there is to know about the whole process besides a good bit of research online. If anybody has done it before, or knows about the process, what are the benefits and drawbacks to it? And I know the basics, but what are the specific changes that have to be made to it? Also, if there are any quirks involved that would not be obvious to the first 350 to 383 builder, what are they? Any input would be greatly appreciated, and if you think that the change is an awful idea, I'd be happy to hear why as well!!

stumpshot

Depends on lots of factors. Can you do the work of clearancing the block for a stroker? Will a shop do the boring and stroke work? Lots of critical stuff going on that you or a shop can screw up if you don't have experience with small blocks.
I'd recommend a crate motor, something that has heads, cam, etc that work with a 383 in horsepower range you want. Probably lots cheaper in the long run too. Don't get too hung up on horsepower-----torque is what I look for in a fun street car. Horsepower is good for bragging and dragging but torque is great for fun.

jb78L-82

IMO, if it is numbers matching, I would either remove it and store it or build that motor into a 355 with no block decking, if possible, preserving the matching numbers, either way.

The 383 crate motor is the easier route and cheaper potentially, but you always get what you pay for in terms of out right performance, reliability, and quality.

My OEM L-82 355 and others on the forum with 355's are more than a match for most crate 383's so I would not get too caught up on the cube difference. Unless you are going to build your 350 into a 383 using top components, the TQ difference with a crate 383 is about 15-20 ftlbs, BIG MAYBE, at 300 RPMs lower, which is hardly noticeable on the street. I built my OEM 350 into a 355 focusing on mid range torque as the goal utilizing top aluminum cylinder heads, roller cam, and approximately 10:1 compression (runs on 89 octane fuel with zero ping). With my 1 3/4 inch headers, I seriously doubt you could notice any difference between my built 355 and a crate 383 on the street.

BKbroiler

If you reuse your original block you're going to have to bore it, so you need new pistons. Maybe you can reuse your original crank, maybe not. If not, a 383 crank costs the same as a 350 crank. You can reuse your stock connecting rods in a 383. Aside from the minor issue grinding for rod clearance, there is no downside to building a 383. Everything else being equal. it will make more power than a 355, free power.
I have a mild 383 in my 77 - Qjet, Vortec heads with auto trans and 3.73 gears. I bracket race it a few times a year. There are usually a few other C3s racing. I have run 12.15 at 110, usually 12.30s in warm weather. None of those 350 powered C3s run within 5 tenths of what my car runs.

drwet

"There is no substitute for cubic inches." All things being equal, the 383 will make more power, and as BKBroiler pointed out, the cost difference between a 350 and 383 nowadays just isn't that great. Just make sure you use quality parts regardless which way you go. I built my 383 with a cast crank. Won't do that again.

jb78L-82

You are absolutely correct that all things being EQUAL with the SAME caliber of parts, the 383 with 28 cubes more than a 355 will make more power. As I have said many times now, that is not always the case. A 383 with fair heads, 9:1 compression and mild/moderate flat tappet cam will get spanked badly by a 355 with AFR heads, 10-10.5:1 compression and roller cam with aggressive lift and moderate duration...every day all the time. 28 cubes will NOT make up for those deficits..it is not just about the cubes. Car engines have been made forever with different cubes in the same engine series with smaller cubes making more power due to better component parts in the smaller motor...not a new concept....It's hilarious these absolute statements................

A recent example:

The GM V6 engine series involved 2.8, 3.1, 3.4, 3.8 liter V6 engines. There were 2.8L HO V6's that would smoke the 3.1 V6 and the 3.4L with 4 valve cylinder head would smoke the 3.8L V6 all day every day. The smaller displacement engine actually made more power than the bigger cubes due to better heads, higher compression, better intakes etc. The cubes/displacement is only 1 part of the equation, NOT the whole equation.

derekderek

and try to catch a real Z28 with a 302 in it with the same camaro with a base 350... Now, Shann, why do you need 450 hp? your cast bottom end 350 will do 350 hp pretty easy with cam-heads-intake-headers. you will be pretty pleased and many thousands ahead. very few of these 40 to 50 year old vettes are gonna get 100k more miles put on them. and even less are going to the track and being revved to 6500 trying to get into the 12 second bracket. you say it is a lot of fun as-is. i assume it isn't a smoking, knocking pig then.

fly_fishie

Blueprint 383

jb78L-82

Another example of a smaller Cube SBC V8 302 smoking the bigger cubes, and MANY other examples......I have said this before as well, unless you are looking for 450+ Gross HP from that SBC 350 with today's roller cams and great flowing heads , there is little reason to stroke a 350 to make a 383 , plus it is not a drop in despite what many profess, there is machine work involved, labor clearance checks, and there is more money involved.

cv67

No reason not to build the # matching block. They dont break real easy
That stamp means nothing excpet to the ocd purist who will want an ultra rare super low mi car only
There are shops out there that can deck it (CNC) and save the # if thats a big deal.

The guy that bought my # match 73 only did as he figured it hadnt been messed with...I did not get # match money cause it was a 73..nothing special
2 mos later it had rims, new paint a 383 700r...he doubled his $ a year later lol

fishinfool145

There is no replacement for displacement.

Build yours or buy a crate engine is the real question. If you build, you know exactly what goes into it. If you buy, you get a tested engine and maybe a warranty

I built mine to keep it numbers matching, although only the block is original. Every other part was upgraded.

jb78L-82

This article sums up the differences: note the key words...identically prepped

Will a 383 Chevy stroker give me big block power in a small block package?

To put it simply, no. This is a misconception a lot of people have and because of so many bogus magazine ads for wanna-be engines out there, you see the statement, "big block power in a small block package", and the truth is, you certainly won't get THAT much more power out of 33 extra cubic inches. Actually, we need to compare apples to apples here. A 383 is a .030" over bore and when comparing this to a "350" cubic inch engine, we need to compare it with a .030" over bore 350 as well, to keep a level playing field, and a .030" over bored 350 is actually 355 cubic inches, so a 383 is actually only 28 cubic inches larger than a typical / compareable 355, and you think 28 cubic inches is going to give you "big block power"? Hardly.

Let's use the standard, 1 HP per cubic inch rule of thumb, just for the ease of math here. So a .030" over 350 is actually a 355 cubic incher, and at 1HP per cubic inch, we would get 355 HP, and the same for a typical 383 using the same rule of thumb, so we are comparing 383 HP to 355 HP, which is 28HP difference. Certainly not going to give you "big block power", and when you are talking big blocks, you are talking "torque" rather than HP, and it's "torque" that you feel in the seat of your pants when driving around. So, if a typical 454 big block, (also at .030" over) makes 461 cubic inches, and at 1HP per cubic inch, we are talking about 461HP, which is quite a jump from 355HP. A heck of a lot more than the 28 extra HP a 383 would typically make in the same comparison. But keep in mind, we are only using the old 1HP per cubic inch rule of thumb. Of course it would be more like 1.2HP or so per cubic inch in reality, and on more radical engines, upwards of 1.3 -1.4HP per cubic inch in really nasty street / strip engines like what we typically build for most people.

So why choose a 383 in the first place? Because the extra cubes are all by stroke, not by bore. Although a 383 might be making the same 1HP per cubic inch rule as the 355, it will inherently make more torque per cubic inch simply because of the physics of increased cubic inches via stroke rather than via bore size. Stroke means "leverage" and leverage gets vehicles moving, especially at lower RPM's. So even though you might not get true "big block power" out of a 383, you will certainly feel the added cubes in the seat of your pants compared to an IDENTICALLY PREPPED 355 because the 383 will make much more torque.

Now, if you really want big block power in a small block package, we can certainly do that for you with one of our 434 small blocks, or one of our monster 454 small block strokers, but as with any serious stroker of this caliber, you are also talking a minimum of a $11,000+ price tag, so the much less expensive 383 is an all around way to go for the guy that wants a little more grunt than what a typical 350 (or 355) can give.