Anyone familar with Electric fuel pumps on a 68. I have had so much problems with vapor lock from the heat in the engine bay and header heat that it vapor locks and I have to wait until it cools off to be able to start it again. An Electric fuel pump Vrs. the Manual one sounds like the best way to solve this problem. I have everything insulated, fuel lines, fuel pump etc. but I still have this problem. So thought moving all this to the rear under the gas tank may be the best way to go.
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
There are a few things contributing to your problem. You mention headers. They are terrible for adding to underhood heat. It would help some to wrap them, but it sure is ugly. Modern gas boils a lot easier, adding to the problem. Part of the solution is to try to minimize heat with tuning, insulation, and air flow; but the only thing that will really help is to recirculate your fuel. The ultimate solution is an electric fuel pump with a bypass type of pressure regulator that flows excess fuel back to the tank to keep it cool. Put the regulator as close to the carb as is possible. Even if it builds heat while parked, you can turn on the fuel pump and cool off everything up to the regulator. A final thought is a heat barrier under the carb. The best kind uses a large sheet metal shield, with an insulator on top of it. That keeps heat from radiating up the outside of the carb, and reduces heat transfer through the carb base.
Hello There fellow 1968'er, I installed a Holley model 125 Electrical Fuel pump on my car and it is working great. I went electric to get away from the excessive heat that my high compression motor makes. Having a high flow mechanical pump just inches from my 1 7/8" header pipes made me worry. The Holley #125 pump will support up to 700 horsepower and according to Holley it doesn't need a regulator, for safety I used on anyway. I installed the electric pump of the frame rail below the fuel tank. I then took a number 6 A/N (3/8") stainless line and slid it over the fuel outlet on the tank, it goes to a inline fuel filter and comes out and feed the "Inlet" side of the pump. Before the line connects to the fuel filter I have a fuel shutoff (ball valve) so I clean filters easily downstream. The "Outlet" side of the pump goes into a #8 A/N (1/2")and then into a 1/2 inch flexible aluminum fuel line material. The fuel line goes down the inside of the frame rail along the right hand frame up to a point near the windshield washer bottle location and then it comes up into the far right of my engine compartment and into a bracket supporting it and then a #8 A/N stainless hose feeds the Holley carb type Fuel regulator(a type 803 regulator I believe). This regulator has two outlets and is mounted on the Carb studs, one #6 A/N hose on the right feeds the primary side of my Holley and the left outlet feeds the secondary side of the Carburetor. This systems works great on my car and I have never had any vapor locking of this engine. Once I had fitted the fuel lines I removed the whole system and installed a D.E.I.Aluminized Convoluted Tubing over the entire length of the fuel line. I also used other short sections of D.E.I. tubing insulation to protect the hoses in the engine bay and around the exhaust. No place other than the engine bay will my fuel lines get closer than 10-12 inches. To power the pump get a Painless Wiring Kit# 764-50102 or equivalent, this is the best and simplest way to wire it up properly. I put the relay and the circuit breaker in my center compartment behind the seats. When choosing a pump find a good gerotor gearset pump over a vane style pump. The difference is Noise, lots of noise. The Holley I used was called a HP125 and it flows 110 Gallons per hour at 7psi. I have been very happy with this system. The Holley website has instructions for designing the fuel systems and it might help you get some ideas. Be sure that your pump is below the level of the bottom of the fuel tank. Stay away from the "Bypass" regulators as our fuel tanks don't have any returns built into them . My tank has an extra tube on the top for venting but I don't think I would use that for anything other than what GM designed it for. I hope that this helps a bit, Fuels systems have to be designed carefully but it is sure nice to have a solid 7psi at each float needle with full fuel bowls all the way to the end of the track.
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
I converted all the steel lines to 6 AN braided lines and put a Holley Blue pump back by the fuel tank(no return line - only a feed line). Ceramic coated headers - not wrapped. I also have a 1/2" phenolic spacer under my carb to reduce the conduction of heat from the intake manifold.
Drove the car all summer including some stop and go traffic - not a single issue.
____________________________________ LukesVette Homepage Veteran of Operation Iraqi Freedom
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A quick note on the use of the Ceramic coatings on all headers or conventional manifolds. After having two sets of Hedman Headers with the "Ceramic Coatings" fail and turn all rusty and having the coating actually flaking off on spots I spoke to a gentleman at one of the premier Coating companies and he explained to me why coatings fail.
The first reason is they get too hot and this does irreparable damage to the coating and they discolor or fall off.
The second reason is more likely the most common cause of coating failure. I was told that if you park your car for several weeks/months on an exposed concrete floor that the allows moisture to rise and get on the ceramic coating. The chemicals that go with the moisture from the raw concrete or cement floor will destroy a good coating in just a couple months.
Both of my sets of headers were on a Corvette parked on a new Cement floor and neither lasted more than 1 winter. I tried to polish out the discoloration, I did everything I could and they still looked worse than ever. Hedman replaced my headers under warranty the first time and they have offered to do it again. Instead I have chosen to have them done by the company who does the coatings for Hedman when they are on a professionals car or a high visibility application.
On the premium headers they use a temperature insulator which will protect against higher temperatures (roughly 200 Degrees F) and take the temps from 1200 to roughly 1400 degrees. The coating is also a different composition and will stay bright and more reflective longer.
Keep your coated headers away from Concrete/cement floors and if you have to park it on Cement use some cardboard or a rubber mat, just something to go under the car to keep the moisture from getting on the headers.
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