The D.C. P15 Update

[knuckleharley]

On 4/22/2019 at 1:02 PM, Plymouthy Adams said:

on heat soak....with modern fuels the alcohol has a lower expansion temperature and well the engine is going to run x degrees.....the cure at times is lesser fuel in the bowl by adjusting the floats.  The very odds that you are going to outrun the fuel in those twin carb bowls against filling with an electric fuel pump is SLIM SLIM SLIM.   Another easy overlooked item is the heat of the very coil itself...these cause hard start more than most fuel probs.  Next occurrence...verify that your spark voltage is not weaker when hot.  I cold pack about the coil for testing will be a quick and easy test.

Excellent point about the hot coil,Plymouthy,and one I hadn't even thought about! One possible solution to that MIGHT be to mount it on the firewall instead of the engine.

[knuckleharley]

On 4/22/2019 at 2:26 PM, HotRodTractor said:

 

I'll certainly test the coil next time it happens. I didn't really give that a thought as it seemed to me that it was fuel starvation related.

Does anyone know what an acceptable temperature is for a 6 volt positive ground coil?

[knuckleharley]

On 4/22/2019 at 8:30 PM, HotRodTractor said:

After doing some poking around it appears that phenolic carb spacers that should work on these carbs are readily available for some other brands. Most notably available for Chevy inlines. 2-15/16 stud spacing, 1.7" bore, and available at least in 1/4" and 1/2" varieties off the shelf, probably more if I look harder. I need to double check a couple of things to see if I can get away with 1/2" without a lot of fuss with the linkage - but that will have to wait until I am back home. Off to Michigan tomorrow, then to the Carolinas later in the week.

 

It seems like this should be an easy test - I might even borrow the thermal imaging camera..... drive it around and get it good and warm under the hood. Pop the hood and take a thermal image immediately before shutting it off. Take a thermal image say every 5 minutes for 20 or 30  minutes making sure just to pop the hood long enough to image. Repeat the same test with the spacers installed.

I,for one,will be very interested in reading your report,

[knuckleharley]

On 4/22/2019 at 9:46 PM, Don Coatney said:

As I mentioned earlier I never had that problem. And I drove the car on some very hot days. What changed? The  electric fuel pump?

Don,if something is borderline to start with,it doesn't take much to push it over the line. Could it be he deals with more humidity than you,or maybe even a different ethanol blend?

 

One thing we all know for certain,this was sometimes a problem even when these cars were new,and were getting real gas with lead,so we are kinda fighting a problem the original engineers never even considered.

[Plymouthy Adams]

Knuckle, I am not going to say there is not a chart of some manner out there in cyber space with the operational parameters of the oil filed ignition coil depicted.   However, these coils are set up to operate with x voltage/current limitations.  Most operate efficiently in 3-5 amp range input for the proper output.  This is the limiting factor of the supplied voltage and dwell which is the saturation or on time and how that changes for given number of cylinders.  At no time should the coil ever draw more than 8 amps.    Consult the owners manual for the Mopar flathead operation of 6 volt battery, running current draw is approx. 2.5 amps.  With the engine off and points closed to complete the circuit, amp draw of the coil should be approx. 5 amps.  These values are not hard to measure with a VOM if capable of direct amp input and these are usually limited in hand held meters to 10 amps max and then only for a short test period.    That is why it is important when going to 12 volts to tweak the voltage by proper selection of the dropping (ballast) resistor.  Rule of thumb is that if the coil is reading 1.7 ohms on the primary, select a 1.7 ballast so that 1/2 of your supplied voltage is dropped across the resistor and the coil will consume the other half.   This works for most any setup for street use.  If you are racing and running a bit closer to upper limits..you will want to tweak this for proper current draw so to get the max output secondary voltage.  As you get higher in RPM band the racing coils will have a lesser ohm value for quicker saturation and then again, tune for proper current with correct ballast.  To keep the voltage input on the coil higher than needed is to also heat your internal coil temp higher than needed, this can result in expansion causing internal wear of coils and also this expansion of oil can crack/burst the case.  First signs of this is the secondary coil tower.  The oil is to help maintain/regulate a proper heat for consistent voltage output.    This is why I do not like the GM coils with internal resistor, it has been proven that the input voltage remains higher than it should for a longer period than necessary as this resistor are temperature active.   While on the average this DOES NOT necessary mean you are going to overheat the coil, it is just that you have greater voltage on the point contacts for a period longer than needed and shortens their life.  

Edited April 24, 2019 by Plymouthy Adams

[Don Coatney]

A few years go a forum member sent me the pictured coil and stuff. I installed it and went for a drive. Engine ran great until I had to stop for a red light. The engine died as if I turned the key off. I hit the start button and the engine fired right up. Drove home and removed this stuff and never had that problem again.

 

 

 

[Plymouthy Adams]

interesting, make a quick look on the internet for the wiring of this system...could not find a schematic or instructional on its install.

[T120]

I like knuckleharley's reminder to carry a fire extinguisher in our cars - if not for us, then perhaps for another motorist in trouble...

[55 Fargo]

Here is a pic of a Holley 1920 1 bbl carb on my Slant 6. Note the phenolic spacer.

Could it be the answer for the flatheads hot carb issues?

In my Slant 6 vehicles never ever noticed an issue starting in suoer hot weather with hot engine and high underhood temps.

Edited April 27, 2019 by 55 Fargo

[HotRodTractor]

Well - I ran through the points again - fixed the dwell back out the 42* - double checked everything - didn't find anything that stood out to me..... I've been driving the car a fair amount the last few days off and on - and today I put roughly 120 some miles on it (drove it to work, went to lunch, left for home, stopped and got gas, stopped at the farm to fix a lawn mower, and finally back home). I didn't have any issues with it. I HIGHLY doubt that the short changed dwell I had was any cause for the issue.... perhaps I "fixed" something else or even had some bad gas or something..... in any case, it doesn't appear to have the heat soak issue I was having. And I drove it HARD today. When the thermal camera becomes available I will still take some pictures as I think it could be interesting anyway.

 

Car runs down the interstate at 80mph like it was meant to do it. Nice and straight with plenty of power.

 

I got the new headlights and front turn signals installed. Not sure if I like them, but they will be fine for now. Video HERE

 

Still lots of clean up to do - but its cruise ready just in time for cruising weather.

[T120]

Looking good!

[HotRodTractor]

Its been a while since I've updated anything. I've been driving the car when time allows and I have nearly 1500 miles on it now since I've owned it. Earlier this week I probably put close to 200 miles on it just driving it through the course of a "normal" day for me. It gets lots of looks, compliments, and discussions everywhere it goes.

 

I noticed that it was getting a little moisture buildup on the floor of the garage where the car is normally parked - but I wasn't able to determine the source until today when I noticed quite a bit of water/coolant and started looking close at things. I'd say I get to play with freeze plugs in the near future.

 

 

The thermal camera at work just came back from being repaired and calibrated - so I am hoping to do that test in the near future as well.

[Adam H P15 D30]

At least that’s an easy one to replace 

[HotRodTractor]

12 minutes ago, Adam H P15 D30 said:

At least that’s an easy one to replace 

 

Absolutely! No complaints there! If one had to leak... that is a pretty good one.

[Dodgeb4ya]

I'd install brass....seen way too many steel plugs fail way too early on the old flatheads.

Dorman and other brand plugs don't have much corrosion protection like the old plugs did.

[TodFitch]

Look carefully at the other welch/core/freeze plugs. On my '33 when one failed a close examination showed issues with the others. It's a lot easier to deal with that at home on your own time than by the side of the road.

[greg g]

I keep a couple temporary boiler plugs in my travel kit.

[HotRodTractor]

All good ideas.

 

I already know that I am pulling the transmission this winter to update the speedo gears. I've been debating pulling the whole engine for some paint and detailing...... I might just fix this one for right now, and plan on pulling the engine and doing a closer inspection of everything this winter with the engine out of the car.

[Adam H P15 D30]

I have HEARD flatheads use the same core plugs as an early HEMI and the aftermarket carries bolt in core plugs because HEMI's have a tendency to spit them out if you spank them a little.  I would check....  Wayfarer would probably have more info.

[Plymouthy Adams]

I knew of a HEMI that would blow #7 spark plug ceramic out of the plug base every run immediately when shifted into third gear....remarkable reoccurring problem and no matter the brand of plugs...spit it out every time....he also ran undefeated 95% of the time....

[Dodgeb4ya]

Usually the MoPar flat heads lower core plugs rust through because of a build up of sludge sitting against the core plugs. The upper plugs don't have this issue nearly as much.

Right from the factory..many engines have brass core plugs installed at the front and rear of the block so they never will corrode.

Edited August 5, 2019 by Dodgeb4ya

[HotRodTractor]

I popped my freeze plug out yesterday - there was an inch plus of crude in the bottom of the block that blocked up most of the hole and completely block the drain petcock right beside the plug.

 

I ran water through a garden hose until it came out clear and I think I got most of the crud out.

 

Sadly - none of my local parts houses had 1-5/8" concave plugs of any kind. I ordered some off of Amazon since that was the quickest and cheapest that I found to hold me over until later this winter.

 

During my ordeal I looked at a few other plugs and I found a couple that show signs of some corrosion right along the bottom. So I'm definitely pulling the engine and going to replace all of them this winter and freshen up the paint under the hood. It will also be a good time to clean up some of my wiring. It never made it into a loom before I started driving it.

 

Does anyone have a good source for brass plugs?

[Los_Control]

Good job, I was lucky and was able to find the brass welch plugs here in town.

 

What I read, is actually casting sand from when the blocks were made and left over ... surprising how much is in there.

I dunno, may not be true.

 

Then I read somewhere else, brass is bad?

Actually steel plugs will rust, and is the weak link and need to be replaced from time to time.

 

While brass will not rust, and in time because of dissimilar metals, the block will actually start to corrode  ?

The block becomes the weak link.

 

I dunno, I read it on the internet so I know it must be true  ? 

 

I doubt will happen in my lifetime, but thinking I may pull my brass plugs and replace with steel .... I need a hobby and stop thinking maybe?

Edited August 11, 2019 by Los_Control

[Dodgeb4ya]

Brass is best in marine blocks I think...steel core plugs today probably made in China with waste steel scrap.

[HotRodTractor]

18 hours ago, Los_Control said:

Then I read somewhere else, brass is bad?

Actually steel plugs will rust, and is the weak link and need to be replaced from time to time.

 

While brass will not rust, and in time because of dissimilar metals, the block will actually start to corrode  ?

The block becomes the weak link.

 

I dunno, I read it on the internet so I know it must be true  ?

 

I have dealt with corrosion issues before - specifically electrolytic corrosion like being discussed here..... so I did a little research. Apparently the plugs that I have purchased are zinc plated (we shall see when they show up). In the grand scheme of things - zinc is the least likely to corrode and the least likely to rust. Its probably the best choice all around.