C2 fuel injection - practicality

[Thomas S.]

[Duke W.]

Re: C2 fuel injection - practicality

If it doesn't detonate now it won't detonate with FI. How about vapor lock and percolation? Are you experiencing either or both now? I'm not sure if the Rochester FI system is more prone to percolation than the AFB, but there have been many threads on how to mitigate vapor lock and percolation like installing insulation sleeves on the fuel lines and insulating the FI "spider".

If you're looking for a "correct" '63 system including the ...375 FI unit, air cleaner, distributor, and unique '63 FI radiator support you're probably looking at $20K worth of parts if you can find them all and significant refurbishment may be required. At 1000 miles per year is it really worth it?

Consider that the AFB is pretty simple and reliable, and the FI system will only add more power about about 5000 revs all other things equal.

Duke

[Joe M.]

Re: C2 fuel injection - practicality

In central Nj, 327/350, dealer original purchase by me, engine never apart. original t-10 and 3:36 posi. Run 63 FI in my 63 coupe for years. FI rebuilt by Bramlett. Run shell 91 or 93, runs smoother on 93, every once in a blue moon some AV gas. Haven't had any restart problems or problems in general. Did break a drive cable. that's why you need to carry a spare or two. Love that FI! Love a carb too, but FI is over the top. Follow hot start instructions and must drive often, as a maintenance procedure. Cars don;t like to sit idle in the garage. Top notch FI guru sets up your FI and you are good to go! DSC_3715.jpg

[Thomas S.]

Re: C2 fuel injection - practicality

I think not driving these older cars on a regular basis is a universal problem, but maybe more so on a fuelie. Nice car and thanks for the feedback.

[Thomas S.]

Re: C2 fuel injection - practicality

The 63 AFB runs like a new Rolex, no plans on changing anything. I'm considering an additional car. The only issue I currently have is hard starts during the very hot summer months if the car sits for a few days after a drive. I've learned to live with it.

The Fuelie is a "bucket list" thing and I probably would not buy a 63 with that option. So, it sounds like fuel availability would not be an issue but there would be an additional level of complexity if it needed service and I chose to do it myself.

[Michael J.]

Re: C2 fuel injection - practicality

I have had 4 fuelies, 3 '64s and one '63. I consider the '64 to be a superior fuel unit to the '63 due to improvements made and the better cam in '64+. The '65 is the same as the '64. If you want a fuelie go for a '64, much cheaper than a '63 or a '65 and just as much fun to drive. FI properly rebuilt, set up, and adjusted is as good as any carb, maybe better. The more you drive them, the better they run. I use 91 octane ethanol free, but I live at 7000 feet, and have never had any pre-detonation issues. I would suggest a rear end ratio of 3.70 or higher, as the FI engine lacks low end torque and needs a better ratio to launch in a "spirited" way. Good luck.

[George J.]

Re: C2 fuel injection - practicality

In central Nj, 327/350, dealer original purchase by me, engine never apart. original t-10 and 3:36 posi. Run 63 FI in my 63 coupe for years. FI rebuilt by Bramlett. Run shell 91 or 93, runs smoother on 93, every once in a blue moon some AV gas. Haven't had any restart problems or problems in general. Did break a drive cable. that's why you need to carry a spare or two. Love that FI! Love a carb too, but FI is over the top. Follow hot start instructions and must drive often, as a maintenance procedure. Cars don;t like to sit idle in the garage. Top notch FI guru sets up your FI and you are good to go! [ATTACH=CONFIG]113486[/ATTACH]

Joe is 100% correct!

[George J.]

Re: C2 fuel injection - practicality

I have had 4 fuelies, 3 '64s and one '63. I consider the '64 to be a superior fuel unit to the '63 due to improvements made and the better cam in '64+. The '65 is the same as the '64. If you want a fuelie go for a '64, much cheaper than a '63 or a '65 and just as much fun to drive. FI properly rebuilt, set up, and adjusted is as good as any carb, maybe better. The more you drive them, the better they run. I use 91 octane ethanol free, but I live at 7000 feet, and have never had any pre-detonation issues. I would suggest a rear end ratio of 3.70 or higher, as the FI engine lacks low end torque and needs a better ratio to launch in a "spirited" way. Good luck.

I'll echo Michael's experience. I have been running my car for 25 years. I rebuilt the fuel unit 20 years and 20,000 miles ago, and am doing it again. The reason for the rebuild is that the ratio lever walked off of the linkage, otherwise, it would still be running fine. They can be finicky to get set up, and each one is different, but once done they run well. I have used Shell 93 for the last 20 years, plus. I think many of the problems people have are that they use cheap gas and let them sit too long. I try and start mine, in the winter, at least every 8 weeks. I am running a 3:36 rear, which does require some clutch slipping when starting, but boy does she like to run on the freeway. 90+ is fun with the sidepipes.

[G B.]

My opinion about FI fuel problems

The percolation problem with old FI systems is caused by the very low distillation (boil-off) curves of modern pump gasoline. A big portion of the gas in the distribution spider may boil at idle on a hot day, especially immediately after a hot re-start. The engine will still run okay if you keep the rpm above 1500, however.

All vintage Rochester FI systems have a spider pressure of ~0.3 psi at an 800 rpm idle speed. This isn't enough pressure to raise the boil-off temperature of gasoline significantly. This means the gas in the spider will start boiling enough to create idle problems if the spider reaches 160 degrees F or so. Most of the heat comes into the spider through the nozzles. Heat isn't a problem at higher rpms because the spider pressure increases with engine speed.

You can keep the spider cooler by using a '63 - '65 recirculating feed loop, or you can mount an after-market fan to blow ambient temp air over the spider hub, or you avoid driving your car on hot days, or you can remove your hood and pack dry ice below the plenum before leaving, or you can use a combination of spider cooling methods that you've read about on the interweb. But the only slam-dunk way I know to avoid percolation in '57 - '65 units is to run gasoline with a higher distillation curve than pump gas, such as VP110. It does have a high octane rating, but that's not why you need it. We're not trying to cure detonation, pre-ignition, or even vapor lock in the engine fuel pump.

These things won't help: lead gasoline additive, mixing diesel oil in your gas, richening the idle mixture, or altering your distributor timing curve. The only two things that I've found to help are cooling the spider or using higher boil-off gasoline. Personally, I just use racing gas like VP110.

[Mike M.]

Re: My opinion about FI fuel problems

Jerry: is the boil-off (distillation curve ) better with AV gas? mike mccagh

[Thomas S.]

Re: My opinion about FI fuel problems

Are you buying the VP110, in 5-gallon cans, 50 gallon drums and how are storing / dispensing it. I’ve considered VP 110, but always had a concern about storage an dispensing, spills, etc.

[G B.]

Re: My opinion about FI fuel problems

Mike, I know aviation gasoline has a higher distillation curve than pump gas, but I don't remember if it's the same as racing gas. I did all of my gasoline research and experiments about nine years ago. At that time the distillation curves for different gasoline blends were available on-line. They may still be, I just haven't researched it since then.

I do remember trying undiluted Shell(?) 100LL aviation gasoline in my 7380 test car during the summer of 2012. It still caused percolation for the first 10 - 20 seconds after a hot re-start on a 95 degree day after a brief heat soak period. Yeah... I do sound like a chicken**** for complaining about that. However, once I learned that racing gas completely eliminated percolation EVEN after a hot re-start, I never looked back.

[G B.]

Re: My opinion about FI fuel problems

I buy it in 54 gallon drums and store them upright. I pump it out with a generic automotive 12-volt electric fuel pump using 3/8" suction/discharge hoses and 14-gauge jumper wires connected to a car battery. I consume about 3 or 4 drums a year. Or at least I used to before I retired. The only spills I've had occurred when I tried to manually pour the last few ounces out of the drum.

[Mike M.]

Re: My opinion about FI fuel problems

jerry: thanks for the info. up here in the Appalachian mountains of western Maryland, I've never had percolation problems with our Rochesters. Thank god our temps up here come nowhere near those we all experienced at the ncrs national convention in Mobile the summer of 2022. Hope u are enjoying retirement. mike mccagh

[Eric P.]

Re: My opinion about FI fuel problems

Over the past 40 years I have owned many early Corvettes and always stayed away from F.I. cars for a few rather foolish reasons. In the past 5 years I made a "bucket-list" of Corvettes I would own before it was too late, and a Mid-Year Fuelie was on that list. I feel lucky to have found a '64 with the original L84 in March of this year. I live in Ohio and was having a hard time this hot summer getting this car to idle properly and re-start after it was driven and at operating temperature. I drained all the fuel out of the tank and refilled it with a mix of VP110 and 94 octane ethanol-free aviation fuel. I figure my mix is somewhere between 98 and 102 octane grade with no ethanol. The car now runs as it should and re-starts fine. It even starts easier and better at a cold start. My little experience with high compression, high horsepower engines especially those that have early fuel injection or more than one carburetor, is to find ethanol-free fuel, and if you have to mix it, get the octane rating up to what it was back in the period when these cars were built. REC 90 or any fuel with an ethanol blend just isn't the same and not what the engine wants or needs.

And by the way, I love owning my first Fuel Injected C2 Corvette!
Eric Patty