Fuel problems when hot

[62 Dart Convertible]

My dual quad 413 always has and continues to run hot in stop start traffic, even when ambient weather is not that warm (like 75 deg F). Ignition timing is correct. I rebuilt the motor a few years ago and also replaced thermostat, water pump, hoses, coolant, and 13 lb rad cap. I had the 22" 3 row radiator apart, it was clean as a whistle. I recently replaced the viscous clutch on the 7 blade fan, and added the factory shroud. This made not a lick of difference. Today I fitted a 160 deg thermostat and drove it around town. I saw on the temp gauge that the engine temp is a little cooler for quite a while as it warms up (like gauge at a 1/3rd scale), but eventually even with just constant cruising at steady speed, the temp still climbs up past half way.

What else can I do to keep this thing cool? Am I just expecting too much of my radiator?

This leads to the second major problem of fuel vaporisation/vapor lock. When it's not too hot, she runs like a swiss watch. As the underhood temp climbs past half way on the gauge, then starts the erratic running, chugging and stalling. I limped home from todays test drive and parked on the drive, temp gauge just past half way with the engine coughing and farting and barely able to run and quickly ripped off the air cleaners. As suspected, the rear (primary) carb was bone dry - nothing from acc pump squirters. The front carb was able to squirt a little, but not much. The carbs were restored when I did the engine and they are still like new. I've checked the fuel pump pushrod and the new fuel pump I fitted a few years ago, they are both fine. All my problems are heat related. Last year I tried covering all the steel lines in rubber insulation - it made no difference. I added extra insulator gaskets under carbs, made no discernible difference either.

Is it likely the fuel is boiling in the lines/fuel pump/fuel filter or in the carbs?

All I have left to try is fitting 1/2" wooden insulator under the carbs.

I'm guessing an electric fuel pump near the tank and a fuel return/reticulation line would be the answer?!

Help?!?!?

 

[HT413]

Do you have a fan shroud? If so, the fan blade needs to be half in / half out of the shroud for maximum airflow. Regarding fuel boiling, I agree, carb spacer should help. I had a similar problem and a 1" spacer cured it (though I didn't try a 1/2").

 

[65-440]

are you using the newer valley pan gasket, with the heat risers blocked off ? And I also agree on the carb spacer, just not the wood ones !

 

[Dennis H]

Use a laser temperature gun to be sure. Ethanol laced fuel can boil at 173 degrees. Wrapped fuel lines and spacer will help. My fan clutch was bad and did not know it for a while. Not easy to diagnose. Spin it cold, warm etc. When replaced with a Hayes, the temp creep issue at red lights and idle went away.

 

[lewtot184]

the stock type 2 valve fuel pumps can be a problem. i use the white edelbrock heat spacers for the dual quads. i double them up and remove the center gasket material (basically create an open gasket). using a vapor seperator and a return line to the tank would help. i think todays fuels here in the u.s.a. start to boil at 130f; real problem! i have a 440 in my '69 r/t with a 22" 3 row radiator and there's nothing that can be done or be tried to prevent it from running hot. i've tried everything! my 65 coronet has a 22" 4 row and won't run hot if you drove it thru hell.

 

[62 Dart Convertible]

Thanks for your thoughts guys. I am nearing my whits end.....

I already fitted these 1/8" insulators -


Yes I fitted a fan shroud months ago and fitted new fan clutch too - made bugger all difference. Engine does have exhaust crossover blocked. I bought a pair of these Edelbrock 8723 and will fit next -


I'm sure if I had 1962 era fuel, this would not be happening. I'd love to know the boiling point of our fuel here today, but I don't know how to measure it safely... in a pot on the stove with a thermometer would work but probably not a good idea...

I am going to borrow our laser thermometer from work and take some readings...

How can I add a vapor separator and return line? Any good links?

 

[lewtot184]

wood insulators are very good. phenolic may be the best. i use those edelbrocks stacked and they did help.

 

[khryslerkid]

The 8723 spacers have all four holes measuring the same as the secondarys. The primarys in the carb and the intake are 1 9/16 (smaller). Does it effect the flow?

I want to use 1" under mine and am thinking about machining the intake primarys to match or making a sleeve for each bore. (origanal 2x4 cast iron intake)

- - - Updated - - -

I'm wondering which Water pump you might have. I know there are differences between them and depending on what application you have, one is better than the other. (impellers)

Coolant flowing too fast won't have the time in the radiator to cool. Too slow overheats. There is a difference between the impellers on air condition cars and non air condition cars. I don't remember what one to use at the moment...

 

[khryslerkid]

Here's the differences between the water pump applications. Taken from Don Taylor's "Big Block Mopar Engines" (scroll up to see the chart on part #s)

https://books.google.com/books?id=F...nepage&q=don taylor mopar water pumps&f=false

You might even have this book. Let me know if the link doesn't work for you...

 

[hangn0ut]

Have you checked your harmonic balencer for top dead center? All dampeners need to be verified for top dead center. New,used especially original ones all need checking. No exceptions.

 

[bigmanjbmopar]

Guessing you are not straying from original radiator? have you pulled the water pump off to see if the passages are getting gunked up? it might be flowing but like a heart pump if there's plague it's not as good.

 

[1962polara]

Are you sure the radiator is not blocked? Did you have the top tank removed and all the tubes run through with a wire? After 50 years it could be gummed up with rust flakes.

 

[Gpuller]

I'm gonna say that the fuel line coming up by the exhaust manifold is getting hot and causing the fuel problems. Insulate that and see what happens.
I used to have a rubber hose running from pump to carb and never had a fuel problem. Switched to a steel line and it was nothing but problems. Got foam pipe insulation from the hardware store and insulated the steel line. Problem solved.

 

[Dennis H]

OP says 22" 3 row clean as a whistle inside.

 

[Lionized]

Have you checked your harmonic balencer for top dead center? All dampeners need to be verified for top dead center. New,used especially original ones all need checking. No exceptions.

I'm curious to know how this has an effect on his fuel issue? I'm honestly intrigued, not wanting to come off as some a$$.

 

[62 Dart Convertible]

Original style radiator - been opened up - certainly no blockages, looked like new still.

New harmonic balancer fitted a few months ago - timing is right.

Engine ran hot with OE water pump before rebuild - fitted Summit water pump during rebuild 3 years ago - no different.

Passages in block, heads etc were the cleanest I've ever seen in an old engine - no problems there.

I tried insulating the steel fuel lines with split rubber hose, didn't make a difference - I will be trying again with better rubber insulation...

 

[idrivemopar]

First thing I would do is relocate that fuel filter sitting on top of the valve covers to the front of the engine under the alternator and away from all the heat coming up off the exhaust manifold. If its in the front of the engine, at least it will get air more directly from the fan and hopefully keep the fuel cooler, and maybe try a plastic filter that does not absorb as much heat like the metal ones do.

 

[bigmanjbmopar]

I upgraded my OE fuel lines from 5/16" to 3/8" aluminum and located the filters one in line under the passenger side and another above the alt location, also uses this cloth stuff I got off ebay to insulate the lines from the firewall up to the filter.

You can find it in different sizes and lengths, this seller will work with you if you ask for a better deal.

http://www.ebay.com/itm/4OF-3-4-BLA...hash=item4d3f04fc79:m:mmRp8f7-7YSM-i6H-cVMzBw

 

[hangn0ut]

I believe that if you correct the overheating problem the fuel perc problem will disappear. I think there is nothing wrong or mismatched or missing from your cooling system. And it aint the weather. Or the fuel. I think your tdc mark is off. Probably behind where it should be. Mopar dampners and timing covers are all over the place as far as tdc marks go. Dont care if the book says its an exact reproduction for that car,one or the other (dampner or cover) is off. Or both. When dampners age the ring slips on the hub. Not much,but enough. Now your timings retarded. And it runs hot. I will take a shot and say the motor spins real good when starting. Retarded timing. I know you said new dampner. But that dont make it right. Get down and dirty, twist that distributor clockwise and see if it makes a difference. Dont be shy about it. The twisting that is. Mark the housing at the base first so you can put it right back. What you got to lose?

 

[62MAX]

Frank, I think you know what I have,similar other than cubic inch,10.2 comp,same carbs and intake,cam 222/232 at .050,complete 3" Max Wedge exhaust,original 22" three core,180* stat,fan shroud,fixed 7 blade fan and O.E.M. 6 blade A/C water pump and A/C to boot.This thing has never went over 195* under any condition.I'd start with timing and go in order and eliminate all causes of over heating one at a time.