Hard warm starting

[50mech]

20 minutes ago, soth122003 said:

How thick is your carb base gasket? If it is a thin one you might be getting more heat transfer than normal. I think the ones with a carb kit are about 1/8" thick. Something to look at maybe?  I've also heard of people cutting a riser/spacer out of phenolic about 1/2" thick to stop the heat transfer.

That being said, Mine has a harder time starting hot. The shop manual states to start a hot engine, press the accelerator to the floor and let up about 1/4 of the way and then start.

 

Joe Lee

Yes it's one of the little 1/8inch that came with the carb. 

I'm not sure the shop manual starting procedures will apply the same way since it's now a 75-82 Carter yf carb. The linkage on it is such that for cold starting you have to depress the pedal once to reset the high idle cam....hot,  Im not so sure of, in this case it won't start regardless of throttle position. If it's been off more than a couple minutes. Otherwise fires back up no problem.

 

I would think this carb would be designed to handle the ethanol fuel...so a spacer may be in order like you say. If it still has an issue after some of the previous suggestions have been done.

Edited March 2, 2020 by 50mech

[50mech]

Hot starts were problematic with the BB as well though they got much worse after replacing the fuel pump...which had a failing check valve that finally stopped working all together.

[Sam Buchanan]

1 hour ago, 50mech said:

Hot starts were problematic with the BB as well though they got much worse after replacing the fuel pump...which had a failing check valve that finally stopped working all together.

 

So you have to "hand choke" to start the hot engine? Sounds like a fuel delivery problem...may be vapor lock due to a fuel pump that can't tolerate heat. These cars came with a heat shield above the fuel pump to inhibit vapor lock. Also, make sure your fuel line is not really close to the exhaust manifold. Winter blend ethanol-contaminated gas has a high vapor pressure....doesn't take much to make it boil.

Edited March 2, 2020 by Sam Buchanan

[kencombs]

Could be spark, as a rich mixture will light off much easier than a lean one.  Since open throttle doesn't help and hand choke does?.

 

Slow cranking is a key piece of info.  Back in the early 60s when I was doing a lot of stuff in Dad's salvage/garage, warm restarts due slow crank was a common issue as a lot of our customers where still 6V.  Cables, battery, voltage regulator adjustment, dirty grounds etc are all suspicions.

[50mech]

29 minutes ago, Sam Buchanan said:

 

So you have to "hand choke" to start the hot engine? Sounds like a fuel delivery problem...may be vapor lock due to a fuel pump that can't tolerate heat. These cars came with a heat shield above the fuel pump to inhibit vapor lock. Also, make sure your fuel line is not really close to the exhaust manifold. Winter blend ethanol-contaminated gas has a high vapor pressure....doesn't take much to make it boil.

Yes.  Only if it's sat for about 10 minutes while hot though.

After putting a pressure guage inline just before the carb I've found I'm not ever losing fuel pressure. Also a glass filter that remains full. Right now that very hot carb has me suspecting it.

 

 

[50mech]

12 minutes ago, kencombs said:

Could be spark, as a rich mixture will light off much easier than a lean one.  Since open throttle doesn't help and hand choke does?.

 

Slow cranking is a key piece of info.  Back in the early 60s when I was doing a lot of stuff in Dad's salvage/garage, warm restarts due slow crank was a common issue as a lot of our customers where still 6V.  Cables, battery, voltage regulator adjustment, dirty grounds etc are all suspicions.

Definitely have to go over all that too, as it being a little slower when warm seems odd for a properly functioning system, though still slow that doesn't currently stop it from firing up within 2-3 minutes of shutting it off... If that means anything?

[50mech]

Also, closing the choke plate is not enough. I must completely seal the throat.momentarily

Edited March 2, 2020 by 50mech

[greg g]

Might also look into a half inch phenolic spacer between the carb and intake.Langdons Stovebolt has them for around 15 bucks.  You might need longer carb studs the vendor should have those also.

[50mech]

Looking at a diagram of the yf, is it possible the fuel is vaporizing under the diaphragm, thus the float is full ( presrving fuel pressure) yet no fuel can enter the idle circuit? Or any circuit... until I create a very high vacuum situation.

Edited March 2, 2020 by 50mech

[1949 Wraith]

13 hours ago, 50mech said:

Looking at a diagram of the yf, is it possible the fuel is vaporizing under the diaphragm, thus the float is full ( presrving fuel pressure) yet no fuel can enter the idle circuit? Or any circuit... until I create a very high vacuum situation.

 Your carb is vented so there should be no pressure build up in the float bowl.

[50mech]

10 minutes ago, 1949 Wraith said:

 Your carb is vented so there should be no pressure build up in the float bowl.

I mean the bowl stays full, keeping the valve closed so there's pressure in the feed line. 

[50mech]

I was able to confirm that the riser valve is stuck in the heating position. Counterweight touches the manifold so splitting that is on the list for this weekend.

Edited March 3, 2020 by 50mech

[Dartgame]

I'd fix the heat riser or remove it altogether, your choice, and retry. Your comment about the carb being hot makes sense logically.

Edited March 4, 2020 by Dartgame

[50mech]

Gutted the heat riser. Installed copper sheet blockoff plate... problem solved.

[50mech]

Also big thanks to @Bbdakota for this thread.

https://p15-d24.com/topic/51270-need-a-carburetor/?tab=comments#comment-544576

 

The yf carb is a notable improvement in performance and driveability over the BB  ( even with the electric choke) and goes on like it was made for it. I paid $65 for a new one, wish I would not have bothered rebuilding the BB in the first place. 

 

I compared both after this fix and the yf is superior and looks better IMO.

 

I eliminated the oil bath filter in favor of a 4" chromie  for normal driving and made a similar adapter to his for the oil bath just in case.

 

[Dodgeb4ya]

Those 4" paper filters generally need to be replaced in a year....even sooner in dusty areas.

Hardly any filtering surface area.

Learned that on my 51 Cranbrook when I was 16.

The car wouldn't hardly accelerate and got horrible gas mileage.

Saw the filter was partially sucked in.

Went back to the good ole oil bath...

Still on it 50 years later?

Edited March 8, 2020 by Dodgeb4ya

[50mech]

Elements are $3. $6 for a washable reusable one. 

 

Kerosene is $4.50 

Edited March 8, 2020 by 50mech

[Plymouthy Adams]

it has been reported her a number of times that these small 4 inch element are too small for the application to the flathead and results in restricted air flow.  Report of stacking two of these resulted in better/ample air flow.  Edmunds knows this and markets a special tall filter...  When running at the lower end, cleaning/changing intervals increase as stated given it is suitable for correct flow to begin with.   Washable units are nice given the fact that it is often so hard to find a replacement element for these aftermarket cleaners.  This is a major aspect to consider when buying one of these, finding new elements.  Other areas may be different but in my area (yes repressed for sure) its tough finding either at times.

Edited March 8, 2020 by Plymouthy Adams

[50mech]

Didn't think about it but yeah.

Standardair filter formula;

218x3600rpm/25500= aprx 31sqin required at full power.

 

Only apprx 25sqin on a 4x2 filter.

 

Technically it needs another 1/2 inch height to be adequate for full hp. Although, according to same the oil bath filter is actually less adequate.. at only 23sqin entry area or so.

Maybe I'll stack one.....for another $3. Idk it's not far off....for a cruiser. Makes it adequate to 3200rpm ish and that's at the end of it's service life.

 

They are more convenient than the oil bath. Which I did keep if ever I want to use it.

 

 

 

 

 

 

Edited March 8, 2020 by 50mech

[Tooljunkie]

Glad you solved the issue. I guess im fortunate that the heat riser on my engine still functions as it should. Considering it was last registered in 1965. 

[50mech]

13 minutes ago, Tooljunkie said:

Glad you solved the issue. I guess im fortunate that the heat riser on my engine still functions as it should. Considering it was last registered in 1965. 

Very!  3 of the four bolts holding the manifolds together were already broken. 1 stud broke in the block (very front) and of course the flange bolts had to be cut.

[50mech]

Update: 

Hard warm starting came back with a vengeance. This time not until a good 30-40min drive though instead of 10.

 

The car exhibited the same problems as @BloodyKnuckles thread here.

https://p15-d24.com/topic/25525-odd-problem-with-fuel-pumps-thats-plural/#comments

 

Seemed to be boiling the fuel at the pump bowl onward and it could be seen in the glass filter at the carb doing the same.

 

After a lot of chasing I found 3 issues in the fuel system.

1. I had installed a brass hose nipple in the tank but it did not go deep enough to compress against the flare on the pickup line. Once fuel dropped under point it exits the tank, I was sucking air from inside the tank. I fixed this with a ball from a compression fitting.

 

2. Pinhole in fuel line at the frame right under the crank pulley.

 

3. The brass hose nipple at the inlet side of the pump would allow air through the threads....but only when hot. Teflon tape resolved that.

 

Now I don't get fuel bubbles or air but that did not fix the hot starts.

 

I checked the spark and it was now weak when hot. I replaced the wire from ground+ to the coil and changed its position to the battery cable lug on the head. ( Pertronix so coil is wired with the ignitor on the neg side into the dizzy. Bass ackwards from the points wiring)

Also cleaned that spot and replaced that battery cable.

 

Problem fixed. I figured if I went over enough of you guys' suggestions id find it out. Thanks all!

 

Also I think I'll drop to a 1ohm coil. If 1.5 is this sensitive to a ground that really wasn't too bad looking and worked until it was hot,  and the ignitor needs a .45ohm minimum I think being more in the middle of the range of correct operation is a better bet.

 

Edited March 15, 2020 by 50mech

[DJ194950]

Have you checked voltage to the coil when motor is hot and hard starting??

 

DJ

[50mech]

1 hour ago, DJ194950 said:

Have you checked voltage to the coil when motor is hot and hard starting??

 

DJ

Yes, it was only getting about 4.3 during cranking....now 5.5

No longer hard to start hot, and cranks faster as well.

Edited March 16, 2020 by 50mech

[50mech]

Spoke with pertronix tech support and they state the module needs 5.2v with a 1.5 ohm coil in line. Not a large margin considering healthy cranking voltage is 5.5.

They didn't recommend running any lower resistance coil.

However I asked about running a .7ohm coil with a ballast resistor and cutting out the ballast resistor while cranking.

They said that would be perfectly fine.

 

Only hitch here is that the way the ignitor is wired in a pos ground system the wire running from the starter terminal to the coil, forward of the resistor will need a diode. Otherwise key on it would try to run the starter through the coil and smoke some stuff.

 

So I think in the future I will be changing to that setup just to give a larger margin of error to the system. For now , it works so it will stay for a while.

 

Like this quick sketch.

Or, I may be able to wire from the solenoid trigger instead.

 

Edited March 16, 2020 by 50mech