383 build with Rochester fuel injection

I'm looking to build a 383, using a '57 fuel injection unit. Will the fuelie unit handle the cubic inches? What cam, compression, heads etc. do I use?

I'd say that you'd be much better off using an electronic fuel injection systems as opposed to the OEM '57 Rochester mechanical system. I expect that you can probably increase your nozzle size to deal with the 35% increase in engine volume, but then you could well get into turndown issues needed for low rpm operation - the nozzle might not be controllable in the idle range. I'm not saying this is a given, but I think it might be more of a tuning challenge than you think.

One of the Great 8 cars at Detroit had an intake that was built to look exactly like the OEM injection system from '57, but was a modern EFI. That would be the best of both worlds, but not a cheap way to roll.

Considering that a correctly rebuilt Rochester fuel injection unit costs $10,000 or more, the unit offered by GMPP on their crate motors seems cheap. There are also some units available from Arizona Speed and Marine and others. Like Roger said, the electronic tuneable setups are way more practical and look similar to an early FI setup.

I have a rebuilt FI unit. I'm looking for advice for this application and I realize this is not common.

Since they only built 1040 fuel injected corvettes out of 6339 in the 1957 model year, a restorer would probably give his left brain to get his hands on a doghouse with the correct part number......and leave you with $$$$ to build a 383 type motor. I have owned several 57 rochester units but it was before they were valuable. Most folks removed them from their car because they were too difficult to tune and keep tuned. The stock Rochester will not work with a 383 without some major tuning changes.....100 more cubic inches to feed.

I have been a fan of the Rochester fi for 50 years got my first one in 1962 traded a 4 barrel Rochester carb an d cast iron manifold for it. I made it work really good but it was made to support 283 hp on a 283 cu. in motor and it has a tough time doing that as a mater of fact a properly tuned 4 barrell carb will carb will out perform them I have owned probably 20 different units over the years I only have about 3 late model flat top units left the flat top started in 63 thru 65 365 and 375 hp. I even owned 1958 Pontiac unit that I wish I still had I have a polished and chrome one on my 32 and have run them for years but as for performance is concerned your better off with a 4 barrel there are a lot of people a lot smarter than me that over the years have tried to make them perform the problem they are a cheap thin di cast part you can't port them to get enough air in. That said they are sure neat units and fun to run every place you go you will find young guys that have never seen one befor. But don't waste your money building a 383 because it will just run like a 283 so build a power pack 283 with a solid lifter roller cam and have fun so that's my 2¢ worth ......ted

robot and ted, thanks for your input. #7014800. S/N 2293. I am going to build a motor and use this unit.
They are rare and you just don't see them on hot rods.

OK---think I have an idea of your goal/intensions-----------------If you were a customer of mine I would recommend that you not go bigger than a 302---------------you can use a later year 350 roller block and a 302 crank---besides that, the 1/8 over 283s were the hot things back then.

jerry is right we use to go 0.60 to build a 292 and if we found a good block and punch them 1/8 to 4 in. that's a 301 and they really did run when they were cold but when the got hot and they really did have heating problems but a lot blocks didn't survive so jerry is right use a 4 in. block but I would try to find a 327 block and put a 283 crank and build a screeemer that's what chevy did in 68 with the z28 302 that turned out to be a legend.....ted

my suggestion was so he could have roller lifters because of todays oil-------

I agree with you jerry but that way you have a big main and rod block all 283 cranks are steel and vary good quality so either way you have a trade off but I would use high quality after market solid roller cam so you have the tappet sound and a small journal crank that you can buzzzzz the crap out of and it sounds like a siren in the lights and it's back to the future OH I wish I had time machine OH WELL.....ted

If you want to use a 283 crank, there is a spacer bearing to make up the difference plus also some precision spacers------or, use the 302 crank with the bigger mains-----------

Serial #1741 is on ebay right now for only $14,500

All the more reason to make this happen. Something you won't see every day. Thanks everyone for your input.

Friend of mine has run them on a few small inch Chevy's in street rods...last one he did the FI unit was all smoothed out and powdercoated same color as the engine...Randy has ran them a number of times so he's got the tune-up dialed in for them and his cars with the FI on them run like a champ! Last one he did was in a really light track roadster with an all moly frame, etc, so a very light car with a 283 bored .060" and a solid mechanical roller cam, had all the good nostalgia pieces on it, looked great and ran even better!!!! (Well, for a chebbie)

Kind of like a stick in the eyeball to the Vette purist dudes who are wishing they had one of the units, but sometimes things just turn out that way.;););)

I am in agreement that a 302 would be the way to go. Good luck with your project and let us know how it turns out.

if you do look for a roller 350 block---some are 2 bolt mains, some 4 bolt mains--and in the middle of that they went from 2 piece rear main seal to one piece seal---the one piece seal cranks take a different flywheel------

I'm going to buy a crate 350 and use my fuelie unit. If it doesn't work.....all I have to do is replace the intake with something else and throw the fuelie unit in the trash......

You could bolt a two-barrel onto a 400 and still get from point A to point B. Using an F.I. unit on a 383 may not be ideal from a horsepower standpoint, but the motor would still run and haul the vehicle around, wouldn't it?

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With a carb, the air flow will choke in the venturi's keeping the mixture pretty well constant, right? The engine will simply "stall" at the point where it becomes air flow limited. Is it the same with the old mechanical injection unit, that the unit will reach a point of maximum air flow, and simply not add any more power beyond that point? Seems to make sense, but then I could be off base, too - just wondering?? I mean, it can't really lean out, as it will become air flow limited, right?

Project has been running for about a year. Went with a early 90's 350. Roller rockers, roller lifters, Duntov grind 30/30 style cam with 461 heads. Pulling 18" vacuum. There is never any hesitation, even on startup. This is all thanks to my FI expert in Scottsdale. Installed in a 1952 Chevy 5 window P/U. 3 spd on the column, Borg Warner fully syncro overdrive.

Very kind of you to come back around with an update. Thank you very much.
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