Hot Starting Issues

[Jeff Balazs]

Hank;

I will let you know if this modification works. I have a feeling it will.....but it will need to be road tested to be certain. I have essentially eliminated all the other possibilities by removing the mechanical fuel pump and rerouting the fuel line. Makes you kinda wonder if the problem others have had was actually heat sinking into the carb all along? Perhaps the old clothes pin trick acted like a low tech remote heatsink and lowered the temp just enough?

 

My friend Carlos assures me that this composite material has much better properties than phenolics. It is my intention to have this spacer extend out past the base of the carb flange a fair amount......maybe as much as 3" or so forward of the carb. By doing this it should act as a heat shield under the float chamber much in the same way the fuel pump heat shield works. The combination of an effective insulator and a heat shield should do the trick. That is my theory anyway.   We will see if it actually works.

 

It is sort of funny as I look back at this build.  When I first got this truck I considered repowering it. As I got further into it it seemed as if the only way I could preserve the true character of it was to stay stock. I started going straight down this path......but then as I began to consider how I really wanted to use it I started making mods. Those mods have continued throughout the build to the point that now it has many difference's from the stock beast. Just yesterday I added a third brake light to the back window.  I feel like I am slowly dragging this truck into the 21st century. Hopefully this final mod to the fuel system will once and for all eliminate the hard starting condition I experienced last week. If not.....I sure like what Charles is doing to his woodie. If only I had the bread......

 

Jeff

[55 Fargo]

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Edited March 7, 2014 by Fargos-Go-Far

[55 Fargo]

I have never had this problem. I do not have a heat shield on my fuel pump but I did route my pump to carburetor line ahead of the exhaust manifold.

 

i betcha your carb bases do not get as hot as the stock set-up, the hot carb base and bowl, most likely is the culprit in a lot of these scenarios..

[MBF]

On the slantsix.org  website someplace there is a picture of an aluminum plate mounted under the carburator and extending out past the outer dimensions of the carb used as a heat sink.  This may be something to consider if the composite plate doesn't solve the problem.

[Don Coatney]

i betcha your carb bases do not get as hot as the stock set-up, the hot carb base and bowl, most likely is the culprit in a lot of these scenarios..

That is a good possibility for 2 reasons. My carburetors do not sit on top of the heat riser box and they are elevated above the intake manifold.

 

[Jeff Balazs]

Mike;

That is exactly what I was thinking of doing. Carlos and I were talking about it when he suggested this composite material would probably do an even better job. Again we will see. If for some reason it doesn't then a combination of aluminum and phenolic material will probably be my next option. From what I understand this composite stuff does not hold the heat like metal will which may be beneficial? Either way I would be surprised if this installation does not make for a substantial improvement.

 

Don;

I think you are exactly correct......I am certain being directly above the heat riser contributes to the problem.

 

Jeff

[Young Ed]

On the slantsix.org  website someplace there is a picture of an aluminum plate mounted under the carburator and extending out past the outer dimensions of the carb used as a heat sink.  This may be something to consider if the composite plate doesn't solve the problem.

 

The later flatheads with the shorter carbs to accomadate the lower hood profiles had one of these stock. I think it was probably steel rather than aluminum but same idea. It went out infront of the carb a bit and then curved up.

[HanksB3B]

I had the opportunity to sort through Rods $5 NOS Carter 1949-1951 DTE1 Carburetor Kit today. This photo shows something I've never seen before included in any of the non-authentic aftermarket carburetor rebuild kits. It is called a flange gasket and sits between the carburetor base and the manifold. It had a middle layer of what seemed to be aluminum. What is supplied these days is a simple 1/8" thick piece of cardboard. I know that doesn't seem like much but you never know.   

 

 

Hank 

[Desotodav]

I had the opportunity to sort through Rods $5 NOS Carter 1949-1951 DTE1 Carburetor Kit today. This photo shows something I've never seen before included in any of the non-authentic aftermarket carburetor rebuild kits. It is called a flange gasket and sits between the carburetor base and the manifold. It had a middle layer of what seemed to be aluminum. What is supplied these days is a simple 1/8" thick piece of cardboard. I know that doesn't seem like much but you never know.   

 

Hank 

 

I saw some of those in the old kit that I'm bringing over for you Hank. Surely the percolating issue can't be solved that easily?...

[Jeff Balazs]

Well you know Hank it is just possible that a gasket like that could make a difference. I could easily see it working better in regards to heat than what I have in place now. And after all we are talking about the boiling point of fuel.....and a few degrees will make a difference.

 

I have been thinking that I probably aggravated this situation with another "modification" I have made as well. I have insulated the living daylights out of this truck. And it would not surprise me at all if the under the hood temperature is higher as a result. I used Hushmat Ultra on the both sides of the firewall and on the underside of the entire hood assembly. One layer on the engine side of the firewall and 3 inside the cab. That was followed by 2 layers of doubled foil insulation and a rubberized sound mat and then the upholstery panels. Pretty much no heat is getting into the cab from the engine bay. With all this insulation I might win the prize for the coolest and quietest cab......but the heat that was normally going through the firewall has to go somewhere. This may be a case Dr Frankenstine being bitten by his own monster.

 

jeff

[TodFitch]

Well you know Hank it is just possible that a gasket like that could make a difference. I could easily see it working better in regards to heat than what I have in place now. And after all we are talking about the boiling point of fuel.....and a few degrees will make a difference.

 

I have been thinking that I probably aggravated this situation with another "modification" I have made as well. I have insulated the living daylights out of this truck. And it would not surprise me at all if the under the hood temperature is higher as a result. I used Hushmat Ultra on the both sides of the firewall and on the underside of the entire hood assembly. One layer on the engine side of the firewall and 3 inside the cab. That was followed by 2 layers of doubled foil insulation and a rubberized sound mat and then the upholstery panels. Pretty much no heat is getting into the cab from the engine bay. With all this insulation I might win the prize for the coolest and quietest cab......but the heat that was normally going through the firewall has to go somewhere. This may be a case Dr Frankenstine being bitten by his own monster.

 

jeff

I doubt that the insulation in the cab or on firewall make much difference but putting it on the underside of the hood assembly may well have made a big difference.

[HanksB3B]

I doubt that the insulation in the cab or on firewall make much difference but putting it on the underside of the hood assembly may well have made a big difference.

 

Unfortunately, I kind of agree.

 

(not so   ) about it, Hank.

[Jeff Balazs]

Yes......but the truck is sooooooo much quieter with it......I am not really sorry I did it. I will actually be able to enjoy a stereo when I get around to putting one in. I will deal with the fall out of this installation as I have no choice at this point. Once Hushmat goes into place it isn't likely to come off.

 

Jeff

[JJs 1948]

I found the easiest solution for vapor lock was just hold the gas pedal to the floor and push the starter pedal with your left foot. Starts right up everytime after very quick.. I always worried about taking my truck out, even for a casual drive, and now I don't worry about it one bit. So many people make this such a difficult problem when actually it's a simple fix. I do have a heat shield installed on my engine but they don't prevent vapor lock. Try it out.

Jeff E.

[Jeff Balazs]

Hi Jeff;

I have a bad left knee and I am sure I don't want to risk it on this maneuver. It does not do well with unusual side to side movements. It is OK with the normal day to day stuff.....but it has it's limitations.

 

Besides there has to be permanent fix for this condition. I will just keep at it until I find it.

Really when you think about it......it should probably not be getting so hot that the gas percolates in the carb at any time. Even if it did not cause hard starting it can't really be a good thing. Also a cooler fuel and air mixture produces better power than an overheated one.

 

Jeff

[Merle Coggins]

I've done the two feet together starting thing a few times. It does work, but it's awkward. An easier way is to press down on the throttle pedal and pull the hand throttle knob to set about 1/4 - 1/2 throttle. Then crank the engine and be ready to push the throttle knob back in as soon as it starts. That way you only need your right foot.

 

Merle

[Young Ed]

I do that too except I've upgraded to pushing the gas with my left food and the starter pedal with the right to avoid the awkwardness.

[Jeff Balazs]

It sure sounds like no one has really gone after the root of this. Maybe it's not too big an issue in different climates or in regions that use a better fuel formulation? Not sure. I just know it could get quite annoying here. It gets pretty darn warm and stop-n-go driving is unavoidable. And since this is going to be my daily driver it will see frequent stops when running errands, etc.

 

I am going to try and completely eliminate the possibility of this being a regular occurrence by addressing the heat that is transmitted to the carb. I got a sample of the composite material on Friday and it is a full 1/4" thick. I am going to cut it to extend about 4" ahead of the carb base and at about 1 1/2" out on the other 3 sides. I think this should prevent some of the heat from the manifold from reaching the fuel in the carb. Maybe I can get my hands on a temperature meter and get some before and after readings.

 

Jeff

[55 Fargo]

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Edited March 7, 2014 by Fargos-Go-Far

[TodFitch]

. . . I betcha this was a problem way back when, and owners got used to dealing with the issue. . . 

Maybe. Maybe not.

 

Reading the Gasoline FAQ and some other source indicates that there has been a drive over the years to reduce the amount of higher temperature boiling point components in gasoline because they cause a disproportionate amount of pollution. Also interesting is that the usual blends for aviation fuel end up with a lower final boiling point than automotive fuel so it sounds like heat related issues could be worse if you decide to use aviation gas.

 

Anyway of the 500 or so different hydrocarbons that are or could be in gasoline, some boil at temperatures as low as 28°C (82°F). So heat related issues, vaporizing fuel in pump leading to lack of pumping (vapor lock in by book) or fuel percolating in float bowl after stopping when engine is hot leading to a hot restart issue, is highly dependent on the mix of hydrocarbons in the the gas.

 

Since nearly all cars on the road today are fuel injected with high pressure manifolds delivering fuel to the injectors, gas does not need to be optimized for a high boiling point. So the oil companies may not bother. But back in the day when all cars had mechanical pumps in the engine compartment and a carburetor sitting on top of a hot engine and no concern for smog they were certainly optimizing for different things.

[deathbound]

Jeff,

 

All things being equal, My heat riser has never worked (broken spring) and I was told in this warm climate it would not really make much of a difference. During 2014 I've been busy improving and solving all kinds of stuff and have not yet really operated my truck for any length of time on a long trip with the correct fuel filter and hard line from the fuel pump to the carburetor I now have. I've also added a heat shield. There supposed to be a thick cardboard insulating gasket 14-34-2 between the carburetor and the manifold that is supposed to be there that I assume you also have installed Jeff. For now, I will carry that can of WD40 until yours goes into production and I can get one. 

 

 

Hank 

 

In this diagram, it looks like there is an insulator (14-33-5) between the 2 bodies.

[Desotodav]

No problems with the left and the right feet on the starter and gas pedals here in Oz with our right hand drive vehicles - left foot across on the starter and right foot on the gas.

 

Have a read of this link from the Carolina Rover Club about vapor lock. It seems that they are a strong believers of the wooden clothespin theory (paragraph 4) ... http://www.carolinarovers.info/croc-stuff/tips/365-how-to-cure-fuel-line-vapor-lock . 

[55 Fargo]

Here is 1 British based BP article explains how the boiling point of modern fuel differs from yesteryears formulas,

 

http://www.bp.com/liveassets/bp_internet/australia/corporate_australia/STAGING/local_assets/downloads_pdfs/f/Fuel_news_modern_petro_vintage_engines.pdf

[Jeff Balazs]

Since I already removed the mechanical fuel pump and rerouted the fuel line I think we can remove this from the equation. Other than the carb there is nothing left to hang clothes pins on or insulate. I had thought that this would be enough to eliminate the problem. Obviously I was wrong so the issue has to be at the carb.

 

I have ordered an infrared temperature meter and I will focus on the temperature as seen at the carb. One of the areas I will look at closely is the heat riser and it's effect. I plan on taking readings with it in it's normal operating position and wired off. I really want to see what the difference is. It could be significant. Once I have enough readings to form a baseline I will then install the composite insulator/heat shield and see what difference it makes.

 

Jeff

If all this doesn't work then maybe this old ram will be the first to get a "Shaker" hood scoop.

[Merle Coggins]

Interesting article Fred. Thanks for posting it. 

I suppose that since my truck isn't a daily driver I've just learned how to deal with it, and I just deal with it. Since Jeff's truck is intended to be a daily driver I can understand his need to reduce the symptoms as much as possible. I will await the results of his spacer/heat shield modification.

 

Jeff, Look for Heat Sensing Tape for testing. This stuff comes in various temperature ranges. You stick it on and operate the vehicle. As it gets hot it will change color depending on the highest temperature measured. It would be interesting to find the results of this type of test too.

 

Merle