When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The rubber fuel line running from the plastic filter across the heater hose and on top of the valve cover are all contributing factors in the fuel getting heated.
Build or purchase a solid fuel line from the fuel pump, up to the filter.
Replace the plastic filter with a steel or aluminum type filter with fittings.
Run solid line from your filter up to your carburetor.
Keep the solid line from your pump to the filter as far away from the engine block as possible.
Keep the solid line from the filter to the carburetor as far away from the head as possible and run the fuel line as far above the intake as possible while running the line somewhere between the valve cover and carburetor.
There are many threads on this forum, with photos, that show how others have plumed their fuel lines.
Look at as many as you can and you will see a pattern of how it should be done.
Replace the aluminum spacer between your intake and carburetor with a 1/2" to 1" phoenlic spacer which will better insulate the carburetor.
CHECK HOOD CLEARANCE!!!
Check your starter cables especially the grounds to make sure they are tight and in good condition.
Your starter could be getting weak and heat soak will effect the efficiency of your starter.
Have your starter checked, and if needed, replace it with a good, high torque mini starter and think about adding a heat shield there as well.
Thanks! Are there special made fuel lines specifically to ward off heat? Any suggestions on brands?
Unfortunately had to have it towed to the mechanic. Gave him the lowdown on the problem and told him I am relatively sure it is a heat/vapor lock issue.
Called me back and said I had an old faulty ignition coil that he replaced. He asked if I wanted to still check for the overheating problem, as he couldn't get it to not-start during previous attempts. I told him yes. I still think it is the vapor lock you guys describe. But is there a chance that the problem could simply be an old coil?
Follow what the folks here are suggesting regarding the phenolic spacer (see picture) and fuel line changes, and be sure to check hood clearance (clay method mentioned works well). It's all very good advice. Regarding getting more air, if you have the budget I'd recommend the K&N set up I have. The top is a filter as well as the sides which allows for more air flow (see picture). A bad coil could be part of the problem, but I don't think that will solve the problem you've described which most here agree it is fuel percolation/boiling. Also, a starter heat shield is a good idea. I made my own (see picture) however being in the aircraft/high temperature insulation business I have access to some specialized materials.
Last edited by 69monzacpe; 08-21-2018 at 12:53 PM.
Yes a faulty coil could add to your problems as they also break down when subjected to heat and you could have a couple of issues going that is adding to the percolation and non-starting.
Are you running the OEM points ignition system or have you converted it over to HEI or other aftermarket system?
If you are running HEI or aftermarket electronic ignition,
Ask your mechanic to check the voltage with the ignition on at the positive side of the coil.
It should read the same as battery voltage.
Have him turn the key to start the engine and read the voltage at the positive side of the coil while the engine is cranking over.
If the voltage drops below around 11 vdc, it could be that whoever installed the new ignition used the (usually pink) resistance wire to apply the 12 vdc to the ignition.
If you are using the pink resistance wire you will need to run a new independent wire from the fuse box to the coil so the voltage does not drop.
11 vdc is not sufficient to fire the coil for HEI or electronic ignition systems. It may work but you would be getting weak spark at the plugs and compounding the vaporlock issue.
A weak heat soaked starter will also draw needed voltage from the ignition system while cranking the engine to start.
The photos posted above is one example of a better way to plumb your fuel line from the pump to the carburetor.
Follow what the folks here are suggesting regarding the phenolic spacer (see picture) and fuel line changes, and be sure to check hood clearance (clay method mentioned works well). It's all very good advice. Regarding getting more air, if you have the budget I'd recommend the K&N set up I have. The top is a filter as well as the sides which allows for more air flow (see picture). A bad coil could be part of the problem, but I don't think that will solve the problem you've described which most here agree it is fuel percolation/boiling. Also, a starter heat shield is a good idea. I made my own (see picture) however being in the aircraft/high temperature insulation business I have access to some specialized materials.
This is extremely helpful! I'm such a newbie that something as big as messing with the carb scares me. But putting the phenolic spacer on looks pretty straight forward. On mine, I just would take out the aluminum one and pop in the phenolic, correct? I do want to get more air via a bigger air filter. Just unsure of how to create space.
Also, could you guys explain to meet how the air filter contributes to starting the engine? I know that the air cleaner unit brings in air to mix with the fuel while it is driving. But does it actually vacuum air in while parked in order to start the car? Just trying to figure how much of a difference a bigger air filter would make to this vapor lock problem.
When you remove the carb to install the phoenlic spacer, completely cover the hole on your intake with the palm of your hand and crank over the engine for just a second and you will feel what we are talking about and why it is important to allow as much air as possible to flow through the motor.
Just remember that the motor is nothing more than an air pump.
Sucks air in and pushes it out.
Again, can't tell y'all how much this is helping me. I've gotten a lot of suggestions on the spacer. Do you guys have any suggestions on what kind of fuel lines I could potentially replace my old originals with? Would stainless steel be the way to go? And on top of that, how about sleeves? I'm looking at a few sites that have specially designed fuel line sleeves. An example is below.
Stainless steel, mild steel, or aluminum works.
Search for an article written by "Lars" who is a forum member and has an article on plumbing fuel lines and the best way to run them.
I've not read the article myself, however those who have, have nothing but good comments about how it helped them.
I've not seen the sleeves you are showing, but I don't think they would do anything to really help any more than all the suggestions I've seen offered in this thread.
Stainless steel, mild steel, or aluminum works.
Search for an article written by "Lars" who is a forum member and has an article on plumbing fuel lines and the best way to run them.
I've not read the article myself, however those who have, have nothing but good comments about how it helped them.
I've not seen the sleeves you are showing, but I don't think they would do anything to really help any more than all the suggestions I've seen offered in this thread.
I will give that a read. I did read earlier today that the stainless steel lines bring in the most heat though. No clue if that's actually the case.
I also found some heat shielding wraps. Would a wrap or sleeve around a steel line be the best way to go?
Got a new ignition coil. The mechanic claims he tried three times to get it hot and not to start, but failed. I took it back out of the shop. Three hours later it took 3 goes to get it cranked up. So I don't think the problem is solved. However, despite a bit of resistance, at least it HAS started.
I am not sure if this helps inform a potential diagnosis, but one thing I wanted to add about my engine's problem is this. Many of the threads and videos I have seen on vapor lock or fuel percolation say their cars run crappy after a tough start or stall out while driving. In my case, that doesn't happen at all. The drive is fine, even if I have a ton of trouble starting it. Does that help pinpoint the problem at all for anyone?
You are getting there and learning on the way. One point, if you remove carb for any reason be extra, extra careful not to drop anything in to the manifold (big hole under carb). A nut can go way into engine and be very hard to remove. If leaving car unattended after removing carb, cover manifold hole. Mark
Wanted to run a potential solve by you guys. The fuel line is currently touching this heater hose. I touched it to see just how much heat was coming off the hose. It's scalding! Can't be helping this issue. I don't know where I would reroute the hose, though. My only thought is taking out the old AC unit, which isn't functional nor do I have any interest in making it functional one day.
Hey guys! So I bought some aluminized sleeving to potentially stop the vapor lock problem, in addition to moving the heater hose away from the fuel line. Check out photos below. My only concern is the sleeving may slip around. Otherwise, you guys see any potential dangers or problems with having it that close to the carb?
If you are going to keep that non-original carb, you should do as others have suggested and replace that rubber fuel line with a metal one. Does not have to be stainless steel. Find a parts shop that will bend line for you, buy a new (factory replacement) fuel filter and have a metal fuel line bent to go from your carb directly to the fuel filter - in a straight, L-shaped path. That will keep it from touching the heater hose and will minimize the chance of fuel leakage and fire that you currently have. That heat wrap is a band-aid approach to solving your problem.
That's about what I deal with too. In the morning she will fire rite up no problem but after driving for awhile she is harder to start. Reading the comments hopefully will help thku
Does the engine NOT turn over or just not start? If it doesn't turn over, then it may be a starter or starter solenoid heat soak issue. (common on GM starters). Make sure the heat shield is mounted on the solenoid.
Yes, very much a problem back in the day. Not "turning over" vs the engine cranks over but will not start. Two separate problem areas.
I might add that perking the fuel in the carb is also different than vapor lock. Vapor lock often times develops in the fuel pump. The primary reason is the heat transfer is the greatest in that area because the pump is bolted to the block. High vapor pressure gasoline (winter gasoline) and ethanol blended gasolines can also increase the severity of the problem. It's the relationship of fuel volatility vs car sensitivity.
Vic
08-21-2018, 02:07 AM
