Rochester F.I. Replacement

[Gary S.]

I have a dilema with my '58 fuelie car. I restored my car some 8 years ago and have enjoyed it a lot. However, in the last year or so she has left me stranded a few times. The problem seems to be warm start ups (perculation?). My first thought was to go to a carb set up and just have fun with it.
The engine is a numbers matching (but not original to the car) 283 ci with low hp F.I. Early on, I because of a smoking problem I opted for Pro Comp aluminum heads with 2.01" intake and 1.75" or so exhaust valves and 63 cc combustion chambers. I run it with non-ethenol fuel. It runs well until the temp approaches 180. As long as your moving it stays below 170.
There is a fellow that remans "clone" 245 and 270 hp 2x4 carbs for our year car. Considering the heads upgrade, does anyone have some good advice as to which setup would be best for our car? I'd hate the thought of not driving my car in the summer.

Thanks to all,
Gary Sparks

[Darryl D.]

Re: Rochester F.I. Replacement

I have a 383 stroker engine in my 57 with aluminum heads and 270 h.p. clone carb it is about 450/475 h.p. I got the carbs from Fuelie Dave although he is retiring and may have a deal on carbs for you. I guess to answer your question I would think that with your engine you would want the 245/250 h.p. clone carbs.

The only other solution would be to run pure racing fuel in your F.I. car to stop the perc.


To me it would be a matter of how many miles I plan on driving the car during my ownership to compare the cost of the fuel verses the cost of converting to the dual quads. My car came to me with a single carb on it and the cost of the manifold, carbs, air cleaners, linkage with assorted springs etc. and installation was $2500. You can buy about 250 gallons of racing fuel for that price. Pure racing fuel is expensive and I would want to buy it by the drum to fuel at home unless I was fortune to have fueling available close to my home.

[Jim L.]

Re: Rochester F.I. Replacement

I have a dilema with my '58 fuelie car. The problem seems to be warm start ups (perculation?).

Gary, what's your hot start and drive off procedure? Short of a catastrophic internal failure, an FI unit won't leave you stranded. It might embarrass you in front of your friends when the engine coughs and sputters after a hot restart. But restarted properly, it won't strand you.

Jim

[Gary S.]

Re: Rochester F.I. Replacement

Thanks Darryl, you pretty well nailed the conversion cost, as I have figured it. Is the difference the 245 and 270 carbs primarily jetting or is there something more?

[Gary S.]

Re: Rochester F.I. Replacement

Hi Jim, Thanks for your response. Since I'd never had a F.I. car, I read as many articles on them as I could find. The hot start up topic came up often. The most frequent method I found first was appling half throttle failing that, full throttle. That didn't seem to work so well. I live near an airport community here and a friend asked to check out the car while I attempted to start her up. He held he throttle closed or just cracked open and that seemed to work the best. If you don't get it fired up on the first try, you just have wait until it cools a little more, 45 minutes or more. We live in Florida and go to cruise-ins every Friday and sometimes other nights year round. It's more than embarrassment, there no coughing and no starting, just frustration and stranding albeit temporary.

[Todd H.]

Re: Rochester F.I. Replacement

Gary,

Maybe you've read about what some FI owners are doing that they say solves the percolation issue. I have not tried this yet with my '57, but I hope to get it done in the coming winter months here.

Insulating the fuel line from the fuel pump all the way to the inlet on the fuel meter has solved the issue for some. In addition, I plan to remove my plenum and spider and place a thin layer of insulation between the baseplate and the spider. That heat can't be helping the problem. Again, some claim just doing the fuel line has solved the problem for them.

If I find those posts I'll post a link. Perhaps Jim or the other FI experts here will comment. I don't believe racing fuel, avgas or a carburetor should be necessary.

[Darryl D.]

Re: Rochester F.I. Replacement

Gary,

Maybe you've read about what some FI owners are doing that they say solves the percolation issue. I have not tried this yet with my '57, but I hope to get it done in the coming winter months here.

Insulating the fuel line from the fuel pump all the way to the inlet on the fuel meter has solved the issue for some. In addition, I plan to remove my plenum and spider and place a thin layer of insulation between the baseplate and the spider. That heat can't be helping the problem. Again, some claim just doing the fuel line has solved the problem for them.

If I find those posts I'll post a link. Perhaps Jim or the other FI experts here will comment. I don't believe racing fuel, avgas or a carburetor should be necessary.

I don't think ANY of the above will help. Read the info in the link below from Jerry Bramlett especially the section MODERN PUMP GAS ISN'T GOOD ENOUGH. This kept me from buying a 1965 F.I. car less than a year ago.

https://jerrybramlett.net/tips.html#nogood

[James G.]

Re: Rochester F.I. Replacement

I don't think ANY of the above will help. Read the info in the link below from Jerry Bramlett especially the section MODERN PUMP GAS ISN'T GOOD ENOUGH. This kept me from buying a 1965 F.I. car less than a year ago.
https://jerrybramlett.net/tips.html#nogood

Thanks Darryl. Very good article. JERRY BRAMLETT knows his Rochester FI systems well.

As an old road racer of Rochester Fuel Injection Corvettes, I agree 1000 %. The ''REED'' pressure of the old gasoline was entirely different in the 50's and 60's. Even Regular gas in the this time period will run better that todays modern fuels. I use to see 50-70 more hp on my race motor with 100 % racing 110 octane race gas. And idle speed increase by 300-500 RPM over 700 with the old race fuel.

Gary, you may consider calling Jerry and sending him your unit. Once corrected you should have many good miles driving your Corvette. Valve lash, Cam design, point adjustment / and or electronic service parts can greatly affect the way your car runs. Where do you live? We FI guys may know of a good ROCHESTER FI tech close that can join you at a friendly dyno shop to make proper adjustments to your unit.

[John D.]

Re: Rochester F.I. Replacement

Gary, In your hot climate you are going to have issues with perculation especially when you are using pump gas. You have heard and read enough here and other forums to know that. Step up to Racing Fuel or 100LL AV and give that a try. Don't cut any of those fuel. Use it 100%.
But I think you have other issues besides fuel.
One time long ago Dennis Clark aka Dip stick came up with a funny solution. He said take the hood off and put it up in the attic. Lot of truth to that.
Open the hood to let the hot air blast out for a few minutes. Longer the better. Then hood the gas pedal to the floor and keep it there. Turn the key to the start positon and crank the engine until the engine fires. Then you are going to have the pump the pedal to get some cold fuel in.
Does your '58 have the 1/8" (almost) thick one piece gasket between the FI and the baseplate (intake)?
Do you have a siphon breaker solenoid installed. Make sure the copper nozzle lines are not touching the hot plenum.
Gary Chestnut has mentioned insulating the fuel line (mentioned above). He gave us the name of the company that sells that material.
Fuel line between engine fuel pump and the FI inlet fitting.
Your car does not have a choke. FI chokes didn't come out until '62. But we nickname it a choke.
If it working properly? Remove the sheet metal fuel meter shield. Between it you have the power stop and the economy stop. Look in shop manual. Corvette Service guide if you don't know what I am talking about.
If you enrichment pin is stuck or bent (little pin) that isn't helping. When you start the car cold just stand there and after about 5 minutes open the throttle a tad. Then you should see the ratio lever swing from the power stop (rear) to the economy stop (facing the headlights) Make sure that is working.
Have you tried another ignition coil? How about the condenser?
I get complaints like yours all the time being the NCRS fuel injection contact person. Gary it's the fuel that is the main problem. Read Jerry Bramlett's web site.He highly recommends racing fuel.
Empty your gas time. Put 5 gallons of racing fuel in. Give it a try. John

[Gary S.]

Re: Rochester F.I. Replacement

Hi Todd, I have that insulated fuel line you mentioned, not installed yet, planned for cooler weather. I should have mentioned i use 100LL fuel akso. Thanks for your input and I'll get that fuel line on ASAP.

[Gary S.]

Re: Rochester F.I. Replacement

Jim, y'all are right, Mr Bramlett sure knows his stuff! Thanks for you input. I have that insulated fuel line mentioned above and plan to install now that the heat is calming down some. I live in North Central Florida. Thanks again.

[Gary S.]

Re: Rochester F.I. Replacement

John, I can't thank you guys enough for taking time to think of solutions to my problems. To answer your questions to me; I am using 100LL fuel, I installed the thick one piece gasket, at cruise-ins and shows I do release the hood latch (but not open the hood), I sent a siphon breaker to Kenny Hansen to install during rebuild (wasn't installed). My car has a "choke" of sorts, electric cold start assist I think they call it. Cold starts are not a problem other than a "long" cranking time which I've read is to be expected. I must say my car runs absolutely great until the temp rises to about 180 and above. Even at about 40 mph on our hottest days the temp stays below 170. It seems it's the "heat soak" issue I've read about after the car is shut off that's doing us in. I have tell you I'm a bit nervous about taking things off the unit. I'll give those things y'all have mentioned a try and hold off on pulling the F.I. for a carb setup. Many thanks to all! Gary

[Richard T.]

Re: Rochester F.I. Replacement

John,
Where can I get the fuel line insulation you mentioned? I'd like to give it a try.

[Jim L.]

Re: Rochester F.I. Replacement

Hi Jim, Thanks for your response. Since I'd never had a F.I. car, I read as many articles on them as I could find. The hot start up topic came up often. The most frequent method I found first was appling half throttle failing that, full throttle. That didn't seem to work so well. I live near an airport community here and a friend asked to check out the car while I attempted to start her up. He held he throttle closed or just cracked open and that seemed to work the best. If you don't get it fired up on the first try, you just have wait until it cools a little more, 45 minutes or more.

I recommend the following starting procedure:

Hot starts: Hold the accelerator to wide open throttle and crank until the engine fires. As soon as the engine starts, start driving. The engine will instantly smooth out and run normally.

Warm starts: This is an ambiguous situation. The engine isn't cold but it's had time to cool so neither is it "hot". So what do you do? This: Set the accelerator to wide open throttle and crank the engine. If it doesn't start immediately, it's telling you it needs fuel. So, close the throttle completely and crank the engine. It will fire although it might run a little roughly. If so, start driving immediately and it will smooth out instantly.

John's suggestion to open the hood and let hot air escape is extremely effective. Decades ago my bride and I drove our FI '60 from CA to CO for a regional. We would open the hood any time we shut off the engine.... rest stops, fuel, restaurant.... anything. It looked like we were having car trouble, but when we re-fired the engine, it ran smoothly right from the moment the engine lit off.

Fuel Injection has some quirks and you, the owner, just have to learn what they are and how to work around them. Set up correctly, it is a reliable mechanism which won't leave you stranded.

Jim

[Duke W.]

Re: Rochester F.I. Replacement

I recall there is an old adage among experienced FI owners that goes something like "90 percent of FI problems are the ignition system". Don't overlook this. Get some long test leads and set up a dwell and/or volt meter in the cockpit. Check that cranking dwell is 30 degrees and full cranking voltage at the coil, at least about 10.5. Pull a plug wire and connect to a spare spark plug that is grounded to the engine, and look for a strong blue spark during hot cranking. Even if the indications are okay, check the related wiring, especially all connectors.

Duke