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Old 01-30-2003, 09:04 AM
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Post please help..... annoying warm start problem

Hi all Great site!

Let me first start by saying I am a mechanic and hobbist for 20 years. More specificly I am a Engine Performance Specialist by trade.

Well........ I recently aquired a 67 Barracuda. Nice car and runs great but very difficult to start when warm. Here is the deal.....

Thing runs fantastic!

Cold starts are great and hot starts are great.

Problem is, it's a ***** getting started after sitting 10 to 30 minutes. Still plently warm, choke wide open, great spark, plently of
fuel............ just takes 10 to 15 cranks to get it to fire......... that's not right, something is wrong.

All my other carb V8 cars (GM) were tuned to perfection and fired right up at the tap of the flywheel. It's not like I haven't figured out how to start this specific beast yet (car personality thingy) because I'm past that stage, it's been 4 weeks and have tried everything.

What I have is.........

-late 60's early 70's 318
-12 to 15k on re-build
-10.5:1
-30 over
-mild street cam
-headers
-Edelbrock intake & carb
-new: (correct) plugs, wires, cap, rotor, quality points/condenser, balast resistor, oil, belts, bla bla bla.

-Dwell 30.5
-Timing correct
-carb in very good working order
-200 HC & 2% CO @ idle and half that at 2500 RPM

Has great spark while cranking warm but not starting..... WTF?

Here is where I'm at........

Possible heat soak problem:

Voltality of the fuel manufactured this time of year (winter) will vaporize under heat much quicker than summer fuel. Coolant stops flowing & fuel stops flowing after shut down. Fuel in the carb get very hot as engine temp starts
to rise. (no spacer plate to reduce heat) When you go to re-start fuel is vaporizing stightly out of accel pump, even more in intake, and next to nothing is left before it even gets to the combustion chamber.

Problem with this theory is if you have somebody give you a "test squirt" during cranking it seems to have no affect. And when it does eventually fire there is a slight indication of load-up, which indicated plently of fuel.

Possible valve lash problem:

Does the early 70's 318 have adjustable rockers? Hydrolic lifters? If so, and if not adjusted properly, when the engine gets hot the clearence is less, and will cause hard hot-starts. This was an issue with a Typhoon we built for over 500HP. But I seriously doubt that is the problem.

Possible fuel PSI or float adjustment:

Edlebrock specificly states you can have no more than 6 PSI. (5.5 optimum) I have not checked mine yet, but reguardless that would cause a "running" problem more than a starting problem. If I had too much PSI pushing fuel past needle & seat I would have idle problems. This car idles great with excellent burn. (200 HC & 2% CO)

I best educated guess at this point indicates there is too much fuel.

If you start it withing a couple minutes of shut down there is no problem. Has to sit at least 5 to 10 minutes. And will act the same after sitting 30 minutes.

This means there has to be time allowed for "something" to happen or a "rich condition" to take place.

Thinking maybe the fuel is overflowing and or dripping after shut down. But there isn't an overwhelming smell of fumes. And if you pull a plug after tring to start it they are dry.

Basicly......... it "acts" like a dripping carb when you look at the starting symptoms, but evidence shows the plugs are dry and when it eventually fires it's not struggling, blowing black smoke, or acting loaded up.

It would have to take an aweful lot of fuel in the intake & combustion chamber to prevent a perfectly tuned engine to struggle like that. But there is not an idication of that.

It's a very annoying problem.

Suggestions or ideas?

I'm running out of ideas.............

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Old 01-30-2003, 09:18 AM
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The old Chryco coils were liquid filled and notorious for giving problems when hot, a Ford coil interchanges and does not have this problem.

I would check this first.
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Old 01-30-2003, 09:26 AM
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I live in California, and have been experiencing this EXACT problem with a 292 Ford Y-block engine equipped with an Autolite 2100 2 barrel. My thought process followed your pretty closely.

Then I tried removing the air cleaner lid, and starts after a "hot soak" were much improved. My thought is that winter fuel was volatilizing too readily. So as an experiment, I obtained an old air cleaner lid at the wrecking yard, and drilled two holes in the top to accomodate fuel line. I basically connected the hoses to the bowl vents and extended them through the lid. roblem "solved".

It sounds kind of Mickey Mouse, but it works. I plan to run the engine this way until summer, when I'll remove my vent entenders and see if the winter fuel really is the trouble.
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Old 01-30-2003, 09:55 AM
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[quote]"The old Chryco coils were liquid filled and notorious for giving problems when hot, a Ford coil interchanges and does not have this problem. I would check this first."<hr></blockquote>

Thanks... but the car has plently of spark and starts fine hot. Problem doesn't seem ignition related.

Thanks for the details SteveB. Interesting fix, but if that was the case my car would fire upon instant "squirt" of outside fuel.

What I mean is...... if a partner provides a additional fuel source while trying to start it under those conditions it doesn't help.

If my fuel were volatilizing, and my car wasn't starting warm because of it, then any "outside" source of fuel would cause the engine to fire instantly.

This has no effect. If anything it makes the condition worse, causing additional load-up, which shows a rich condition when it does start. Basicly symptoms of too much fuel.
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Old 01-30-2003, 10:24 AM
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I'm not suggesting that the fuel is evaporating so much that the bowl goes dry. I'm proposing that the vapors are building up in the air claener and intake manifold to the point where it makes the car moderately hard to start because of a rich condition.

I have had my carb apart a couple of times checking for a loose power valve or high float level etc., but it all checks out. The 2100 is about as simple as carbs get! When I look down the throat of the carb when the engine is hot, it looks dry as the Sahara down there.

Try removing the air claener lid next time the car is good and hot and see if it makes a difference.
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Old 01-30-2003, 11:10 AM
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[quote]"I'm not suggesting that the fuel is evaporating so much that the bowl goes dry. I'm proposing that the vapors are building up in the air claener and intake manifold to the point where it makes the car moderately hard to start because of a rich condition."<hr></blockquote>

Ok.... I gottcha.

I was thinking of it backwards. That would explain the 'extra outside fuel source test' only making it worse.

To be honest, it acts the same with the lid on or off.

Just an annoying problem that's got me frustrated.
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Old 01-30-2003, 12:23 PM
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I've had a similar problem in the past. Maybe your carb is leaking. What happins is after you turn off the motor, gas slowly leaks out of the carb into the intake manifold and after a few minutes it's the same as being flooded, but if you wait 20 minutes or so the leaked gas evaporates and the car starts just fine and if you were to crank it over after only a couple of minutes it starts right-up because it hasn't had a chance leak enough to flood out
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Old 01-30-2003, 03:25 PM
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Have you tried installing an insulator gasket between the intake and the carb? About 3/8 thick.
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Old 01-30-2003, 05:34 PM
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Is it hard to start only after a waiting period following at least a 15-20 minute run on the freeway? Or will it also start hard after just being warmed up to operating temp? If it needs to get good and hot before it will do this, I would try the insulator gasket as mentioned above.

Also-I know the emissions are low, but how are the idle needles set? 1 to 1 1/2 turns out? Are they sensitive as they should be? I'm guessing you already know this, but if the idle needles must be turned in too far to idle right, you may have a leak (fuel source) feeding the engine.
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Old 01-30-2003, 06:52 PM
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Here's one that's a little out there,

Could you be experiencing fuel draining out the fuel lines while sitting?

I know that would/should be solved with a buddy and pouring raw fuel into the carb but maybe he's using to much and effectively flooding it.

What about cranking RPM? Fast enough to properly atomize fuel?

Try covering the ing. coil with a piece of sheet metal and see if that keeps the coil cool enough. Or just relocating it far enough away from engine heat.

Edelbrock carbs love to leak fuel below the throttle plates where it won't be seen. A sure sign the throttle body is cracked.

I would change carbs for a short while, Borrow one from a buddy or something and see if the problem is really in the carb.

I'm thinkin your gonna have to get out the test tools and follow thier recomendations. Scope, ing. analyzer pressure guage, temp gauge ect...
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Old 01-30-2003, 09:58 PM
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Thanks for all the feedback guys.....

[quote]Maybe your carb is leaking.<hr></blockquote>

That's pretty much where I'm at now with it.

[quote]Have you tried installing an insulator gasket between the intake and the carb?<hr></blockquote>

No, and was considering it because of how it was behaving. But was trying to avoid it because I have VERY little clearance left between the air cleaner and the hood. She practicly touches now, and didn't want to raise it at all.

[quote]Is it hard to start only after a waiting period following at least a 15-20 minute run on the freeway? Or will it also start hard after just being warmed up to operating temp?<hr></blockquote>

Don't have to drive it. Doesn't matter. All it has to be is at operating temp.

[quote]Could you be experiencing fuel draining out the fuel lines while sitting?<hr></blockquote>

Na, plently of fuel, pressure still in line, clear filter that you can visually see, accel pump works like a champ.

************** UPDATE *****************

Wanted to reply to your comments first.

New info!!!

Earlier today I decided to start it up and check it out some more. Been 2 weeks since I ran it, was due anyways. Stumbled across new evidence!

Did the usually start up, ran flawless from cold to hot, let it run a while, shut it down.

Let it sit about 10 minutes. When back to start it but before I did I decided to look down the carb for the 10th time just to make sure it wasn't nossle dripping or anything weird.

Usually the radio is on but this time it was quiet in the garage. When I looked down into it that's when I heard it.

Sounded like the pipes in your house when the toilet doesn't shut off all the way. I could hear the fuel gurgling. This means one of 2 things......

1) too hot, fuel is boiling, causing rich condition and hard to start

2) too much pressure in the fuel line after shut off forcing fuel past the needle & seat, causing rich condition and hard to start

If you had to guess, which one do you think it is and why?
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Old 01-31-2003, 03:00 AM
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[quote]Originally posted by 67cuda:
<strong>Thanks for all the feedback guys.....

************** UPDATE *****************

Sounded like the pipes in your house when the toilet doesn't shut off all the way. I could hear the fuel gurgling. This means one of 2 things......

1) too hot, fuel is boiling, causing rich condition and hard to start

If you had to guess, which one do you think it is and why?</strong><hr></blockquote>

This one gets my vote and is why I suggested installing an insulator between the intake manifold and the carb base. Good luck!
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Old 01-31-2003, 06:29 AM
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I find it hard to believe that the fuel is boiling in a carb this time of year during normal driving. I know I have driven cars in super hot weather hour after hour on the freeway, and have never had trouble like that.

So I think its time to check the float, needle and seat. Make sure the float doesn't have any fuel in it, which would make it slighty heavy.
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Old 01-31-2003, 08:49 PM
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Many thanks for the help guys!

Least got it narrowed down and isolated.

Plan on doing 160 stat, shroud, viscous fan & clutch. That should lower the temp some. Needs done anyways. If problem persists after that then I will consider a spacer plate.

I hear ya Steve. But remember that winter fuel has a higher voltality rate. So running at idle in a 60 degree garage really isn't a cold weather factor or condition. Will pull top of carb to check & adjust. Will also check fuel pressure to make sure it's under 6 PSI.

Thanks again, was much help talking it out.

If anything crazy happens or turns out to be something else, I'll post it.
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Old 02-01-2003, 10:21 AM
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[quote]Originally posted by 67cuda:
<strong>I hear ya Steve. But remember that winter fuel has a higher voltality rate. So running at idle in a 60 degree garage really isn't a cold weather factor or condition. Will pull top of carb to check & adjust. Will also check fuel pressure to make sure it's under 6 PSI.</strong><hr></blockquote>

I guess I'm still having trouble with the idea of fuel boiling off or volatilizing when the engine is merely warm. I could see it under conditions where the motor was good and hot though. How hot is it running anyway?? Anything under 190-195 and you should be OK-even after you shut down for awhile.

Be sure and post any new developments on this as I am still trying to figure my hot start trouble too. Those tubes stricking out of my air cleaner work, but they sure look weird! We may have to wait until summer to really figure it out.
Steve
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