Fuel Problem with my fuelie

[Vinny]

I live in AZ where the 10% E10 fuel is mandatory....MY F.I. 1960 doesnt like it! When its hot weather 85+, the motor barely runs after it sits a short while, 1. Does anyone have a fuel formula that will make the F.I. or carb motor run better with the unleaded crap? Will adding a lead additive work? How about products like sea foam or stabil? any ideas or products that worked would be helpful...Thank you for input, Vinny

 

[67vet]

I have heard that if you use Stabil in your tank, that you should use the Marine version instead of the auto version. It is said to have a much longer "shelf life".

 

[71hcc]

It's called Spider Perk!

I have a 62 Fuelie that I got fed up with the hot start problem and put a carb on, made it alot more user friendly. I really hated to do it, but now I'm really glad I did, it starts and runs great no matter how hot it gets. The ONLY option you have that will fix the problem is to run straight race gas. It has nothing to do with higher octane, but racing fuel has a higher boil off temp than the gas that is refined today. Even mixing it with race gas won't work, you have to run it straight. There is no additive that will change the boil off temp of todays fuel, at least that I know of or found.

 

[jim lockwood]

The ONLY option you have that will fix the problem is to run straight race gas. It has nothing to do with higher octane, but racing fuel has a higher boil off temp than the gas that is refined today. Even mixing it with race gas won't work, you have to run it straight. There is no additive that will change the boil off temp of todays fuel, at least that I know of or found.

This advice is spot on.

You can mitigate the percolation problem somewhat by modifying your driving habit, however.

If you start driving as soon as the engine hot starts, fuel pressure in the nozzle lines will rise high enough to instantly stop the percolation. The engine will immediately run smoothly.

This is completely counter-intuitive; I realize that. The natural tendency would be to start the engine and then work the throttle while the engine (slowly) smooths itself out.

Force yourself to start driving even before the percolation stops, however, and things get instantly better.

Jim

 

[71hcc]

The old hot start fuelie problem

This advice is spot on.

You can mitigate the percolation problem somewhat by modifying your driving habit, however.

If you start driving as soon as the engine hot starts, fuel pressure in the nozzle lines will rise high enough to instantly stop the percolation. The engine will immediately run smoothly.

This is completely counter-intuitive; I realize that. The natural tendency would be to start the engine and then work the throttle while the engine (slowly) smooths itself out.

Force yourself to start driving even before the percolation stops, however, and things get instantly better.

Jim

Thats what I had been doing and just got fed up with dealing with it. My situation was a little different, I have a 377 CI, 11:1 CR with vette alum. heads. It just didn't respond that well trying to drive and keep it running. I liked the fact that I had the original fuel unit on the 377 but it wasn't as big an issue as taking the unit off of an all original fuelie. But maybe the other fuelie owners will benefit. Thanks Jim

 

[Vettehead Mikey]

There's no miracle-in-a-can like seafoam, stabil, octane boosters etc. that will help with this as far as I know. As mentioned above the problem is with fuel vapour pressure, E10 being worse than with straight gasoline. Some owners have reported success with using 100LL Avgas although this is not street legal.

 

[Hib Halverson]

For 35 years, I had a daily driver with a Rochester injected SB V8 in it. The first was a 327 with a '58 injector and the second one was a 400 with a '64 injector. While the cars these engines were in were not Corvettes (they were either a '57 Chevy wagon or a '65 Malibu) the problems like the one you're having is not vehicle-specific.

First off, I can tell you that your problem is likely not E10 gasoline or even unleaded gas. The idea that E10 or unleaded fuel is more prone to percolation than the leaded fuels of the bygone musclecar era is urban legend.

Now it is true that some late mid/late-'60s and early '70s engine with compression ratios above 10:1, iron heads and aggressive spark curves will have trouble with detonation but, again, that's not related to percolation...and, thus, adding a "lead substitute" pour-in additive will not "fix" a percolation problem. Also, adding "fuel stabilizers" to try and solve a percolation problem ain't gonna work unless the gasoline is really old and, if it is, just drain the stuff out--it's no good, anyway.

What you can do is, first, follow Jim Lockwood's suggestion about driving habits. Jim is a long-time fuelie driver and his advice is exactly what I did on really hot days with my FI Chevelle. I'll add that percolation and the poor idle and light throttle performance which comes with it is chronic to Rochester injection and it's worse with the early units than the late units.

Secondly, you can go over your fuel system and make modifications to reduce the amount of heat getting into the fuel lines and the fuel meter on the injector.

Thirdly, Jim Thorpe at Fuel Injection Service Co. makes a special manifold to plenum gasket set that is said to resist heat transfer. Right towards the end of the 35 years I drove injected cars I bought parts and services from Jim and had good results. In fact, I had one of those gaskets ready to install just before I parted-out the car and sold the injector. I gave the gasket to the new owner.

Fourth, you could use some thermal reflective material--(Design Engineering makes the stuff I use)--to cut heat radiation into fuel system parts.