383 build using a '57 fuel injection unit

[sptrainboy]

I'm looking to build a 383 using a '57 fuelie unit. Anyone done this?
what cam, heads, etc.....will this unit pull enough CFM to handle the cubic
inches?
thanks...

 

[Tom Bryant]

Welcome to the CAC.

Considering that this unit was designed for 100 less cubes and that Chevy designed a bigger unit after using the smaller plenum one year on the 327 I'd say it would be marginal on a 383. Big valves and ports would not be a good match to flow of the early unit. If you are using smaller heads and camming for low to midrange rpm I think it would make a nice driver. I feel it would run out of airflow in the upper rpm ranges though. For cam selection I'd call my favorite cam company and give them all of my specs and how I intend to use the engine to get their recommendation.

Are you wanting to use the '57 unit to keep an original look in an early car or just because you have one in the garage? I know that's how certain components end up on my engines. If you don't need the look of the early unit I think you would be happier with a '63-'65.

Tom

 

[Hib Halverson]

I'm looking to build a 383 using a '57 fuelie unit. Anyone done this?
what cam, heads, etc.....will this unit pull enough CFM to handle the cubic
inches?
thanks...

Not even close.
You'd be totally wasting your money.

 

[kpic]

"MAKING A '57 FI UNIT RUN RIGHT The most difficult challenge in the Rochester repair world is getting a 4360, 4520, 4800, 4960, or 7300 FI system to work properly. It's only been in the last few years that I've become confident these units can be made to run right. To get them to that level, you must make several modifications to the original designs, install perfect reproduction parts, and ensure every single component functions flawlessly. You Do-It-Ur-Selfers have now been warned."
RAMJETS THAT RUN! - Corvette Fuel Injection Repair

I added the the bold and underline. If I was you, I contact Jerry Bramlett.

A Rochester FI requires special tools to adjust it, as they aren't available anymore you'd need to build them. Back in the day, due to the complexity, most mechanics removed them and went with a high rise and a Holley.

"WARNING: A 1957 - 1965 Rochester fuel injection system will not always work properly on a stock engine using modern pump gasoline. You must use undiluted 108 or 110 octane racing gasoline in your car after I calibrate your FI unit to get its best performance. If you're unable or unwilling to buy racing gas, please don't ask me to work on your FI system. I DO NOT WANT YOUR BUSINESS. I simply won't compromise my quality standards."

The bad news is you can't buy gas with the octane to make it work properly anymore. When these units were sold, you could buy 100 octane gasoline anywhere, those days are over.

 

[71hcc]

Been there, done that

I have a 62 fuelie that has a 377 with the original 62 FI unit on it. The motor is a 11 to 1 motor, 87 vette Alum heads with what I believe to be a copy of the old 30/30 cam. I bought the car that way in 2003. The car ran really strong with no problem feeding the motor but, It was a real PIA in the summer. It fired up and ran great when the eng was cold, after I drove it somewhere and tried to restart it while hot it was real hard to keep running long enough to get cold fuel through the lines under the plenum. As long as I didn't stop anywhere and shut it off it ran great or I let it set for 45min to an hour to cool down I didn't have any problem. A couple of years ago I finally got tried of dealing with it and pulled the unit and put a carb on. Car still runs great but I do notice that it doesn't seem to pull quite as hard as it did with the FI on it. It's the gas that is refined today, it has a lower boil off temp than the fuel that was refined in the 60's. Race gas has the higher boil off temp, that's why running race gas solves the problem. As soon as you try mixing it the problem comes right back.
That was my experience with my car, hope that gives you an idea what to except.

Jim

 

[sptrainboy]

Jim....
thanks for the input. I'm in the process of building a 383, .030 over, roller cam, roller rockers, World aluminum heads, 10:1. Also a comparable cam that will give me 12-15" of vacuum at idle. My plan is to mix a little 110 with 91 pump gas.....don't know until I try. Along with the fuelie unit, I have a '61 distributor. Did you mix your fuel or did you run straight 110.
...Chris

 

[71hcc]

Jim....
thanks for the input. I'm in the process of building a 383, .030 over, roller cam, roller rockers, World aluminum heads, 10:1. Also a comparable cam that will give me 12-15" of vacuum at idle. My plan is to mix a little 110 with 91 pump gas.....don't know until I try. Along with the fuelie unit, I have a '61 distributor. Did you mix your fuel or did you run straight 110.
...Chris

Hi Chris,
Believe it or not I run pump premium all the time with out any problems, now or when I had the FI unit on it except for the hot start problem. I tried mixing 110 with premium to help with the hot start problem, it made no difference until I ran straight 110. It's not the octane, it's the higher boil off temperature of the race gas that makes the difference. It would always start but I would have to set there and work the throttle with my foot to keep it running for 3 or 4 mins until it got enough fresh cool fuel thru the spider and all the lines under the plenum. It would make me not want to stop any where that I couldn't leave it running or stay for an hour for it to cool off. It was embarrassing to start it up and have people look at you like ( what a piece of S#$% ) because it ran so rough. I liked running it because it was something different that you don't see very many of but after several years I just wanted a more user friendly setup so I pulled it and put a performer manifold ( because it's the only thing that clears the stock hood ) and a 750 speed Demon carb. The early FI units are tricky to get set up right to say the least and they are restrictive on air flow at a certain point. The heads and cam in my motor don't flow enough to be a problem but to put this unit on a really good set of heads and cam would be like putting a restrictor plate on a NASCAR motor, same effect. I was lucky, my FI unit was working good when I bought the car so all I ever did was some minor tuning. With the heads and cam you have, not knowing the specs, I would guess that they will out flow the FI unit or will be right at the max it can handle. This is all just my opinion based on my experience with my car and am not trying to talk you out of doing it, just wanted to make you aware of what your up against.
Glad to help if I can

Jim