Hot Starting Issues

[Jeff Balazs]

Ralph;

These are interesting threads. I particularly like the authors comment  " I think I may have outsmarted myself ".

I think every time we make a modification we run the risk of this. My own observations are It can be a very humbling experience.

 

It was particularly interesting to me that this occurred using an aftermarket dual carb manifold which I would have thought would run cooler than the stock set up. The composite insulator/ heat shield I have made is very similar to the metal shield he fabricated when he made it into two pieces. The only real difference in the shape is I have not extended it towards the head as much as I too was concerned with creating a hot spot.

 

It also sounds like I will need to fit a regulator just to be safe.

 

One contributing factor that I think I am going to need to address is the under hood temperatures. I have lined the entire hood assembly of my truck with Hushmat ultra and have removed the mechanical fan. This makes for a very quiet runner which I really like..but it has probably raised the under hood temps significantly.

 

I installed a fresh air kit on my truck and I have been thinking about adding a tee with a blast gate to the ducting that runs near the carb. Introducing air flow in this location might help keep the temps down some. The blast gate could even be operated with an extra cable control I have. I don't know if anyone has tried something like this but it is just possible that cooler air flowing into this area might have a beneficial effect.

 

More to think about here.

 

Jeff

[JBNeal]

if you have lined the hood with insulation, your heat shield between the carb & manifold may be ineffectual.  If heat is not allowed to radiate upwards & outwards while there is little air flow through the engine compartment, then a 'cloud' of hot air will surround the engine fuel supply & induction components.  This could reduce the charge air density and lead to performance problems.  AFAIK the flatheads were changed little in the heat shielding department in the four decades these engines were produced.

 

Looking at more modern cars, they have fuel lines that are uninsulated, with injection manifolds that mount atop V-block engines  Underhood insulation works best on these cars to keep them warm to assist in emission control, but their induction is usually designed so that the air inlet is far away from the heat source of the engine to increase charge density.  These engines rely on computer controls to reduce air flow & increase fuel delivery dependent on air pressure & temperature conditions.  On the flatheads, the choke & throttle controls were manual for years, relying on the operator's experience to best judge how to maximize performance.

[TodFitch]

Slightly off topic but this does touch a little on things mentioned in this thread. . .

 

I took a look at my parts books to determine when fuel pump heat shields were first used. There are none listed in the '28 through '33 Master Parts list nor in the 1934 preliminary parts list.  So heat shields were introduced sometime after 1934. The '36-'48 parts list shows heat shields from '36 up. So either '35 or '36 was the first year.

 

But what I found most interesting was a couple of columns next to the heat shield in the '36-'48 parts book under part type codes 14-84-1, and 14-84-5 through 14-84-25.

 

14-84-1 is a "Auto Pulse Fuel Pump and Bracket Package" that came in either 6v or 12v varieties with the same part number listed for all years '36-'48. Curious that they offered a 12v electric pump package for cars that all left the factory as 6v.

 

14-84-5 (Fuel Pump Booster Bracket) through 14-84-25 (Fuel Pump Booster Cable Terminal) confuse me. I think they are parts for mounting and connecting the above "Auto Pulse Fuel Pump" into the car but they mention "Fuel Pump Booster" instead. They consist of brackets, insulator, wiring and tubing. Looks like it gets power from the fuel gauge terminal. On my car that would be the one place to get switched power from the ignition switch, so I am guessing that is why they connect there.

 

Main take away is that pulse type electric fuel pumps were available from the dealer way back when and there was enough perceived need for the factory to supply them.

 

 

Edit: Based on a quick web search, it looks like the old Autopulse fuel pumps were pretty rugged and that rebuilding services and parts are still available. Possibly an interesting option for someone looking to put an electric pump on their car and still remain original. Or at least original as in the factory sold that setup even if they did not deliver it on new cars.

[Young Ed]

Slightly off topic but this does touch a little on things mentioned in this thread. . .

 

I took a look at my parts books to determine when fuel pump heat shields were first used. There are none listed in the '28 through '33 Master Parts list nor in the 1934 preliminary parts list.  So heat shields were introduced sometime after 1934. The '36-'48 parts list shows heat shields from '36 up. So either '35 or '36 was the first year.

 

But what I found most interesting was a couple of columns next to the heat shield in the '36-'48 parts book under part type codes 14-84-1, and 14-84-5 through 14-84-25.

 

14-84-1 is a "Auto Pulse Fuel Pump and Bracket Package" that came in either 6v or 12v varieties with the same part number listed for all years '36-'48. Curious that they offered a 12v electric pump package for cars that all left the factory as 6v.

 

14-84-5 (Fuel Pump Booster Bracket) through 14-84-25 (Fuel Pump Booster Cable Terminal) confuse me. I think they are parts for mounting and connecting the above "Auto Pulse Fuel Pump" into the car but they mention "Fuel Pump Booster" instead. They consist of brackets, insulator, wiring and tubing. Looks like it gets power from the fuel gauge terminal. On my car that would be the one place to get switched power from the ignition switch, so I am guessing that is why they connect there.

 

Main take away is that pulse type electric fuel pumps were available from the dealer way back when and there was enough perceived need for the factory to supply them.

 

I've never seen proof but I have heard that some export cars as early as 39 were already 12v.

[Jeff Balazs]

Brian;

There is little doubt in my mind that insulating the hood was not the best idea I have had. But it is done and would be a real pain to remove. Also the truck is very quiet with this insulation so I want to keep it.

 

I am going to have to work up some sort of fix for this situation as I am positive at this point that it has raised the temps under the hood. Today I ran my tests with the hoods open just to see what would happen and the difference in the readings are very dramatic. I have a spare 6 volt fan in an old heater that I may try and rig up as a heat extractor. If I draw the warm air down from the area directly below the hood and exhaust it out under the cab then that could make a huge difference. The fan would probably only need to operate in heavy traffic conditions.

 

Jeff

[TodFitch]

At one time there was a fad to add louvers to hoods. . . . Time to bring that back?

[Jeff Balazs]

At one time there was a fad to add louvers to hoods. . . . Time to bring that back?

Tod;

That was one of my first thoughts. I had a few sports cars years ago and I found that louvers really work at keeping things cool under the hood. Thing is I have fresh paint and the Hushmat right where they would want to go.

 

I think I will try building a heat extractor system first. There is plenty of room under the hood and if I fit a venturi type fitting on the trailing end of the ducting somewhere under the cab it could be very effective. I think I may also add a wye fitting and blast gate to my 4" duct on the fresh air system ducting. It could easily be pointed directly at the carb and manifold.

 

Jeff

[Don Coatney]

Heat out, rain in

[Jeff Balazs]

Don;

Well not really. The air intake on the trucks fresh air system is quite a bit lower than the heater and the associated ducting. It is actually a very well designed option. I honestly can't really ever see it blowing water up into the ducting.

Besides......what rain?

 

Jeff

[DJ194950]

Jeff after rereading all the posts on the subject, is your only proberm restarts and not any other overheating sitting with  engine running  in stop and go traffic?  Restarts after a good run with no traffic issues?  A minute or two after getting home? Engine left running at idle for some time after home?

 

Understand you have installed a pusher electric fan, size compared to the radiator?  does it cover it?  Shroud?  Single or dual fan?

 

How about adding a time delay controller for the fan so that it runs for a short time after the engine is shut of like the new autos?

 

Just thoughts off in a differant direction to solve this issue.

 

Many posters do not realize the temps Ca. gets to (110+ d.summer) and the stop and go on top of that for a daily driver you want.

Problem you got can only get worse this summer.

 

All the other conversations are certainly the root problem areas of concern but what? else  also may be contributing factors? if any.

 

Best

 

Doug

[Don Coatney]

Don;

 

Besides......what rain?

 

Jeff

Sorry, I was not thinking there for a moment

[Jeff Balazs]

Hi Doug;

Well.....I do think that it gets a warmer under the hood than it should. And it seems to run on the warm side when the weather is warm. Now that I have the infrared gauge this condition is being verified not just guessed at. In retrospect I wish I had not got ahead of myself with the hood insulation......but what is done is done. I would be willing to bet that it is one of the quietest examples of these trucks out there. I have probably made myself some extra work getting it to this point ....Oh well......it wouldn't be the first time.

 

I have a single 6 volt 16" pusher fan with no auxiliary shroud. No controller either. The fan is controlled by a separate switch with an indicator light on the dash. Today with the temp in the mid 80s and with the hoods open the radiator tank temp was 157 after idling for 20 minutes. It seems to me that the fan is probably up it's job......but I need to improve the venting of heat that collects in the engine compartment. That may be all that is really needed?

 

So far I have avoided installing any modern electronic devices like controllers etc. It is my goal to keep the operating systems in this truck as close to totally "analog" as is possible. My attitude towards automotive electronics may cause me to go to extraordinary lengths to get the truck where I want it......but that is fine with me. At this point I am fairly certain I will be able to get it straightened away without resorting to a bunch of circuit boards.

 

Jeff

[TodFitch]

I've noticed a variety of cars that have thermostatic fans that seem to be for keeping things cool after they are parked. This evening the Porsche that was parked beside my car as I came out of the market had a fan running in the engine compartment as I walked up. Turned itself off as I unlocked my door.

 

And I recall the Toyota Landcruisers of 20 or so years ago had a vent on the side of the fender with a duct and fan setup to blow air on the carburetor.

 

You might want to simply blow air from your fresh air ducting directly onto the carburetor with a small fan and let the air exhaust where it will after it flows by the carburetor bowl.

[Jeff Balazs]

Tod;

At this point it seems like my first move should address the heat that collects just below the hood assembly. I can't help thinking that if I can get the excess heat to exhaust properly the rest of this issue may just go away. Or at the very least it will be much easier to solve. If I were not so far along I would consider adding louvers as I know they work and they are a trouble free solution. I really need to give the problem some more thought.

 

Jeff

[Desotodav]

Jeff, I was at a car show recently when I spotted this nice blue FJ Holden (GM) ute. Check out the 'port holes' in the hood sides.... would something like that work for you? They should be somewhat effective in circulating air under the hood. They had similar things on the old Buick's from memory. I suppose that they would be somewhat directional so as not to allow rain in?

[Jeff Balazs]

Hi Davin;

Nice truck!

Something like that might work at speed......but I think it would be more effective for what I am concerned with to have it vent at the highest point. I am not sure anything on the sides of the hood would do that much when stuck in traffic on a hot day.

 

I wonder what a couple of low profile finned aluminum hood scoops turned around to face the windshield would look like?    If I could find a pair the right shape and small enough......that could be finished in black....... I think I would be inclined to go that direction. Not the great big Hillborn type item.......but maybe something kinda retro looking? I suppose even a boat type bilge vent scoop might be pressed into service.

 

Jeff

[JBNeal]

I knew it, this whole thread has been a prank 

[HanksB3B]

Hi Davin;

Nice truck!

Something like that might work at speed......but I think it would be more effective for what I am concerned with to have it vent at the highest point. I am not sure anything on the sides of the hood would do that much when stuck in traffic on a hot day.

 

I wonder what a couple of low profile finned aluminum hood scoops turned around to face the windshield would look like?    If I could find a pair the right shape and small enough......that could be finished in black....... I think I would be inclined to go that direction. Not the great big Hillborn type item.......but maybe something kinda retro looking? I suppose even a boat type bilge vent scoop might be pressed into service.

 

Jeff

 

Jeff, If you'd go to that extreme why not take the hood off and drive around while you're thinking about it. What to do...take the hush mat off Sometimes fumes can loosen glue-bonds..or they still got more of that paint formula down at the paint store don't they?

 

Hank 

[Jeff Balazs]

Well it is not a prank. Perhaps a bad joke...caused by my quest to have the quietest Pilothouse....but definitely not a prank.

 

I don't know if anyone else has thought about what improving the under the hood ventilation might achieve? I feel like it should be considered. It is a fairly obvious way to potentially eliminate or address a whole host of issues. My two days of "warm weather" (mid 80s) testing has shown me that it may be possible to lower the engine compartment temps by around 20 degrees. That kind of difference is probably enough to eliminate hard starts and overheating........ and it would probably have a positive effect on how well the engine runs and even what sort of mileage it could get.

 

Would I fit a scoop? or vents? or whatever? to get these potential benefits? You bet. I really don't see it as any different than fitting radial tires or disc brakes. If I think it will make the truck a more reliable daily driver then I am all in. No one who has spent any time driving around LA in the summer can say that they have not been stuck in traffic. Or that they have never seen some poor smuck with his hood up....steam rising.... and getting screamed at by all who were stuck behind him. If I can do something to prevent this then I am not going to be that guy.

 

It has always been my goal to make this truck into a decent daily driver. There is a lot more to this than one might think.  In the end I don't care as much about what it looks like as how well it functions. To this end I have made a ton of modifications. Some small and others quite a bit of work and expense. I have never worried that it isn't a hot rod. It has enough power to keep up with traffic and it stops well now. The ride is decent and the interior is comfortable. I admit I went crazy with the sound and heat insulation.....but it is very quiet and cool so that was worth it. And I will probably keep tweaking it as I go. It is the last vehicle I will ever buy.....so we are stuck with each other.

 

Jeff

Hank......insulation stays.......heat goes bye-bye

[55 Fargo]

Surely this " hot start issue"' is not related to all Mopar flathead 6 cylinder engine owners. There are plenty who live in areas outside of the LA area who experience major hot weather, even in the northern climates, albeit for much shorter duration 90f is 90f , 100 f with a 115 humidex is the same in Georgia, as it is in St. Louis.

This issue is not unique to the Mopar flattie world, many carburated gas engines suffer these hot weather hot starts from many different manufacturers.

Common complaint, engine starts great when cold, or when weather is cooler, warm starts on hot days, becomes an issue.

Hotter engines and under hood conditions, hot intake manifolds, fuel lines exposed to high heat, carbs heated up to above normal temps, this all results in modern gasoline doing strange things, like expanding, causing flooded carbs, boiling and what is a condition of boiling "VAPOR", which impedes fuel to flow through and an area where there is now vapor, rather than liquid gasoline, much like any water type pumps losing prime.

This problem and discussion goes on in many different vintage vehicle forums, from cars to planes, and maybe even old trains, but in all of those cases it does not happen to everyone.

Engine cooling temp, unless being excessively high, do not seem to be the entire culprit, 180 or 160 t/stat, the engine will go to it's normal running temp with either, the t/stat only opens to allow coolant to flow to the rad at a lower temp, but eventually it will arrive at it's normal operating range, running a 160 or a 180, could give you  the same 175-185 engine temps on warm days, 160 begins to open around 155f, and it fully open at 180 anyway, a 180 opens at 175, and maybe fully opened at 200, but would regulate closer to 185 perhaps . So a 160 t/stat does not guarantee an engine temp of 160 on a 90 above day, it only allows the flow to start sooner, thats all.

The intake and exhaust manifold arrangement, has a lot to be desired, these intakes can get real hot, allowing carbs to boil, THIS IS ESPECIALLY TRUE IF THE HEAT RISER FLAP IS STUCK IN THE WRONG POSITION, for any reason, exacerbating the situation buy a 1000% on a hot day.

The under temps, modern fuels, that boil easier, winter blend fuels that do this type of thing in warmer weather.

Members on both boards need to chime in on here who drive there flathead vehicles on hot days, in hot weather and on a regular basis, those who do not, really cannot offer much insight into this problem and it's solution.

My 55 Fargo with a 251, has a stuck heat riser, makes a real hot carb, is a real pain for hot starts on hot days with hot under hood temps, I now have a donor set of manifolds  to fix that problem.

A carb and fuel pump must be in good order, ignition too, with coils and condensers in particular. If a cooling system is not in good shape, this of course makes high underhood temps and need to be addressed also.

12 vol systems IMO, start much faster and easier in the heat of the day, not saying anybody has to convert, but I have had both, and it is a big difference.

Look forward to others chiming in with there success hot start solutions and stories.....

Edited March 11, 2014 by Fargos-Go-Far

[Jeff Balazs]

You are right about temperatures being what it is and where it is. And we know that it is the main culprit when it comes to most hard starting issues that occur after the engine is hot. I also have to agree with you about the manifold design and excess heat that may be present due to the heat riser. Certainly I have made the problem worse by insulating the hood assembly. I am certain that by adding insulation that I have in effect raised the under hood temperatures. Now if I were the only one that experienced the hard starts when hot problem I would really have egg all over my face.

 

But I am not the only one. And I am very interested in solving this. If I stop and consider contributing factors and potential fixes .....one thing seems clear to me. If I am able to lower the under hood temps the chance of having this problem is reduced. And it would be great if the fix for this did not involve any additional electrical devices.

Heat rises and if it has a good path to escape it will. With the hood design that we have to work with the only way for heat to escape is to radiate through the sheet metal. What I did practically eliminated that path. And if the problem exists with this at say 85 degree weather I can only imagine how severe it will get when it really gets hot. Now if I come up with an effective way to "vent the hood" does this either eliminate or dramatically reduce the hot starts problem ? I think so. Of course there really is only one way to find out.

 

Jeff

 

Jeff

[TodFitch]

. . . And if the problem exists with this at say 85 degree weather I can only imagine how severe it will get when it really gets hot. . .

Don't forget that which of the hundreds of possible hydrocarbons they decide to mix up will affect the initial and final boiling point of the gas. And they change the winter/summer gas formulations based on the calendar not based on the actual weather. I think California is still on the winter blends which could be affecting things for you.

[jeffsunzeri]

Before you re-engineer the entire truck, put a fuel regulator in line before the carburetor set at about 3 psi. Total cost for an adjustable unit made by Spectre is about $30.

[JBNeal]

maybe ya don't have to remove all of the hood insulation, but at the very least perforate the insulation with holes in the 2" dia. range...another route is to remove the insulation on the hood wings from the air cleaner forward, thereby providing some sound insulation just ahead of the cab firewall.  just my opinion, but if ya start adding gadgets & gizmos to reduce the under-hood temps, theny yer gonna have a Rube Goldberg contraption on yer hands that will be doing the same function as sticking a door stop wedge between the hood and the cowl

[Don Coatney]

I don't recall, did you lower the float level in the carburetor?