I'm intrigued by the 383 and have seen a couple pull on the chassis dyno at Carlisle. I love the broad torque band of this motor. They also seem to sound different to me. I'm not talking about cam characteristics or exhaust tone, but something more basic, just like you can tell a big block sound from a small block. Is that my imagination, or do they really have a different sound?

Besides a rotating assembly, what additional requirements are necessary to stroke a Gen 1 350? Assuming $450-500 for a cast rotating assembly, what machining costs are involved and or, other work and parts to complete a good 383 short block?

Assuming all other things were the same on a 350 vs a 383, what would the gain in TQ and HP look like on the 383? What does the stroke have to do with the HP and TQ curve, aside from a longer stroke increasing CID? What's the downside to a 383?

I know GM offers a crate 383. Does anyone know why GM never offered the 383 in a production truck or car?

 

GM never offered a production 383. Other than the proper rotating assembly, you will need to correctly balance it to suit the crank manufactures flexplate and balance combo. Some are internal but most cheaper rotating uses the external. Balancing is something you would do anyway. Converting to internal balance is more money. Either the crank is converted to internal balance or you will have to buy an external balancer and flexplate. Block needs some grinding at the bottom of the cylinders and some at the oil pan rail. No big deal though. My engine builder charges $40 to do this. If you go with a hi dollar or low dollar 383 you will be quite pleased with the torque output. I have built 3 for myself and loved every one.

 

Yeah, I knew that but GM Goodwrench does offer some nice 383 crate motor options.

The 400 small block was also externally balanced and if I remember correctly, had some problems with siamesed cylinder walls and the potential to run hot. I've read that you can use a 400 crank along with with certain sized rods (forget which) for one 383 combo, or you can get there with a different crank/rod combo. Apparently, one way has less of a rod angle and less block machining required over the other.

Did GM come up with the 383 bore/stroke combo or was this a aftermarket builders development? I don't recall hearing of this combo until maybe the last 5 yrs.

 

In my opinion, GM jumped on the bandwagon regarding the 383. The aftermarket is responsible for the 383 idea. I recall my uncle building a 383 as a child in the late 70's. 383's have been around a while. Not until about 10-15 years ago did the aftermarket develop a huge selection for us to choose from. Look closely at gm's 383. The stroke is not 3.75 if memory serves. They also use a connecting rod other than the 5.7, 5.56 or 6 inch. I believe it is 5.85. I am not knocking gm's motor. I have no experience with it. I do know I can build one with similar quality parts for much, much less. GM offers a warrantee though.I imagine the sell well.

 

In your opinion, which combo (bore and stroke) do you think is best, assuming you have a stock Gen I 350 to begin with?

I'm wondering about this conversion for my '93 Z71 ExCab parts chaser and occasional tow vehicle. It has the stock TBI 350 with auto OD. Great running, dependable engine but it's a bit weaker than I'd like, (160 RWHP & 245lbsTQ). I'm limited with mods because of the TBI system and the slow baud rate ECM. It would be nice to get it to 200-225 RWHP and 300lbsTQ, which is close to Vortec multi-port performance.

I've procured a set of L98 heads and had them mildly ported and polished. I've got a set of Tri-Y headers and an Edlebrock TBI intake along with an "RV" grind TBI cam, which is supposed to wake the engine up a bit within the limitations of the ECU and TBI system. All of this combined should get me around 40hp and Xlbs of torque. The engine doesn't need rebuilding but has 110K. I hadn't planned on rebuilding it BUT since I haven't started the installation yet....for a bit more work and a few more bucks....I could potentially rebuild it as a 383.

 

Do it. You won't regret it. But, it will be hard to wipe the grin off.

 

Duntov experimented w/ different strokes & determined 3.75 was the longest the SB was happy w/ for racing. He used a std. bore instead of the .030 over of the 383. He was looking for 400 C.I.
SEE How the Corvette got the BB on my website.

 

Duntov's 4.00" by 3.75" 377 first showed up in the Grand Sports at Nassau in December 1963. A .030" overbore yields 383.

Duke

 

3.80 with a standard bore.
Looks more like they went after the 383 name
http://www.gmgoodwrench.com/perfpart...on=ce&cat=9274

GM made a custom stroker rod for their 383

 

What do you guys think would be a fair price for doing a 383 stroker, just the short block?

Keep in mind this is for my truck, so the starting base motor is the stock 350 TBI.

I already have the cam and kit, as well as a new timing chain, yet to be installed. This engine will operate in the same RPM range as stock, never over 4500 rpms, so overbuilding it isn't necessary.

What would you recommend, (type & brand) for crank, rods, pistons, and flywheel etc?

Thanks for any input you can offer.

Any guesses on improvements in TQ and HP are welcome. The stock 350 engine is rated 210-hp @ 4,000 rpm, and 300 lbs-ft. torque @ 2,800 rpm.

I will be using cast iron L98 heads from a TPI Firebird, freshly rebuilt, CC'd and mildly ported and polished. The "RV" flat tappet cam specs are approximately:

SAE dur 278/288, .050" dur 204/214, --- .420/.443 lift w/1.5 rockers

I am replacing the stock intake with the Edelbrock model made for the stock TBI unit. I will also be running a set of Tri-Y headers.

The Goodwrench crate motor #12497317 HT 383 is rated at over 400 ft lbs of TQ and 340+ HP running a very mild roller, (196/207 duration at .050 with .431/.451 lift) and Vortec heads with a medium rise dual plan aluminum manifold and carb. As Brian pointed out above, GM's crate 383 has a standard bore of 4.00 and longer stroke of 3.80. The power band for this crate motor is very broad and comes on way low, maxing out around 4500 rpm.

I don't expect mine would get anywhere near that high, (nor do I need it to). But I would be curious how much more torque and HP a 383 stroker converstion would be worth vs the same mods, (intake, cam, heads) done on a 350.