Carburetor Issue, Extended Crank When Cold

[seely]

Hi everyone,

I am having an issue I am wondering if you all might be able to help me diagnose. I did a bit of work to my 75 Bronco and got it up and running, tuned the carb and replaced a few things (fuel pump, harmonic balancer, water pump, timing chain, and distributor). It's been running great, but as of late it is having a difficult time catching when I turn it over cold. Essentially, I need to crank the engine for so long the battery starts to get weak, then eventually it catches. After I run it, I can fire it right up again after I cut the engine, as long as it doesn’t sit too long.

My assumption is that the float bowls are emptying while it sits and I am cranking the fuel pump to fill them up before it will actually ignite. I don’t see any fuel outside of the carburetor, so I am wondering if it is leaking down into the manifold. My reason for thinking this is that the first crank fires up immediately for a split second, then the engine dies and the long crank-time begins before finally starting.

Any ideas on where to look to fix this?

Carburetor is a Holley 1850-2

 

[DirtDonk]

Could be what you’re saying, but it could be a choke adjustment issue, or a spark timing issue, or just a weak spark.
First thing to do I would think would be to pull the air cleaner off and look down the carburetor. First when it’s warm, then later when it’s cold.
When hot do you see fuel dribbling down inside?
When cold is the choke open fully, then when you roll the throttle back slightly by hand does it close fully?
And then when you first try to fire it up does the vacuum pull off pull it open slightly?

Those will be my first checks anyway.

 

[DirtDonk]

Forget what I said about the vacuum pull off. Your Holley 1850 would not normally have one of those I don’t think.
Not familiar with the -2 part, but usually the Holley four barrel‘s have the typical standard automatic choke.

What is your normal starting procedure?
And since you’ve had this difficulty have you tried checking for lack of fuel as well as too much fuel both?
For lack of fuel you simply pump it a few times before you try to start.
For too much fuel you push throttle all the way open slowly and keep it there while you’re cranking until it kicks.
As you would do if flooded.

If you haven’t yet, give those two methods a try to see if it changes anything.

 

[m_m70]

I need to crank the engine for so long the battery starts to get weak

how old is your battery?

 

[1970 Palmer]

I would back track on your recent many repairs, since that's when this issue started.

For example, it's easy to get a cam chain one tooth off. Yes, it will still run, you would likely need to crank in some additional initial timing to make up for the late, or early cam timing depending on the direction it might be off. One of my shop mechanic's got a Kawasaki Jet Ski cam one tooth off during a shim under bucket valve adjustment and it was really hard to figure it out.

You need to check the timing with a timing light to see exactly where it is firing currently.

Pull the air cleaner off in the morning before you try to crank it. Look down into the carb and you want "to see" two nice solid squirts from the accellerator discharge nozzles when you move the throttle linkage.

You can confirm if the Holley has any fuel in the float bowels by simply loosening just one of the bottom float bowel screws. Just loosen, with a rag under the screw, if it had gas in it will run out. If you get no gas, it was dry.

Have you set the float levels to the sight glass holes?

Have you checked the fuel volume flow, and also the fuel pressure?

Just some ideas,
John

 

[seely]

Thank you all for your suggestions! To answer a few questions, the battery is about 10 years old I think. For the choke, I know I have a manual choke that I can control through a cable that I pull at the dash console. I typically don't use this very much. I have been trying different ways to start it including pumping and flooring the throttle. I have been getting better luck with pumping, but still only after a considerable amount of time cranking the starter (unless the engine has been run recently and then it starts right up without any finesse either way).

For the recent work I've done, prior to that I couldn't get it started very much at all. The issue was with the timing/distributor and the other maintenance was done before I knew what the problem actually was. I replaced the timing chain because I suspected it jumped a tooth, but tried to make absolutely sure I didn't put it on a tooth off.

After which, I retimed it to around 12 BTDC, set the float bowls until gas was just below the sight holes, and then set the idle mixture/speed and it was running great until over time it has started taking longer and longer to crank when cold.

I am fairly confident the battery is still good as I am getting pretty strong spark, but could still check the fuel pressure as well as looking down into the carb to see the fuel being squirted in by the throttle.

 

[DirtDonk]

Weather of battery is good or bad is not indicated very well by the spark. Get it tested.
At 10 years old that battery is nearly aged out. Must be a good battery though, or it would’ve aged out five or six years ago.
Of course you would know when cranking if it’s dying too soon. If you can get good cranking for five or six minutes then the battery is still good.
If it starts slowing down after only 20 or 30 seconds though, it’s showing its age.

Doesn’t matter what position the timing chain is in to ignition timing. Once the ignition timing is set and is steady, that’s where it is.

Use your choke!
Things can change in other areas that necessitate the use of the choke.
Whether you used to use it or not may not matter. If it’s not starting easily, then try the choke if you have not already.
As part of your testing have you started using the choke?
If not, push the throttle slightly and pull the choke knob out a little. See where the choke plate is as a reference and give it a shot.

Are you familiar with manual chokes? If not, then if when you pull the choke knob out the engine fires but starts to grumble in rumble and literally “choke” then it’s too far.
Open it slightly until the idle smooths out.

Good luck