Don't flame me. Looking for backfiring assistance.

[signsup]

So, had engine running a few years ago and then put the 27 Depot Hack away for body restoration. Bringing it back to life as WWI ambulance and want to get running chassis as good as I can before all the wood work.
Reconnect everything, engine mounted coil box, throttle and timing rods connected and combination priming choke rod and lean adjustment rod connected. Initial attempts indicated fuel pouring out of gaskets in Holly NH carb, so replaced all the gaskets and gave carb good cleaning but not a total rebuild.
Current attempts cause backfiring at carb on a regular tythem stroke. I tried to read a little about back firing causes and I get lost.

Is it all adjustment combination related and if I don't burn the shop down first, I'll trial and error the adjustments? Or, is it a valve remaining open and ignition getting back to carb instead of staying in cylinders? I will gladly pull the head if I have to, but don't want to if we think there is another direction to go in.

I can have the wife go down and take video if that helps ID the issue, but I really don't want to run this too much in this condition.

I'll monitor post and respond to any questions and will gladly report back results of further testing or correction.

Thanks in advance.

[Charlie B in N.J.]

Check the ignition timing just to be sure. As to a stuck or leaking valve: DO NOT PULL THE HEAD. You need to do a compression test to really see what's going on inside the engine. A dry then wet test will indicate the rings and the valves condition. Pulling the head before you do this will tell you exactly NOTHING. Actually you might see a stuck valve that might have freed up using a bar or lever to push it back down without pulling the head. don't jump. Ask and diagnose properly.

[Norman Kling]

When you say "Backfire" do you mean it is spitting through the carburetor or firing through the exhaust system?
First thing I would do would be to do a compression check on the engine. That will indicate whether your rings and valves are sealing correctly. They should be the same or nearly the same on each cylinder and around 50 psi with a standard stoke and head. The altitude of your location makes a difference. It would be lower at higher altitudes.
When that is determined to be correct. check the timer or distributor timing for retarded spark after dead center. Usually the crankshaft pin in the front pulley would be around the 10:40 clock position viewed from the front looking toward the rear of the car.
Next would be to check for a spark at each spark plug. Try pulling the plugs and laying on the head and rotating the crankshaft with a crank and the ignition set on battery. You should get a spark at each plug in timing order 1,2,4,3. If this is correct and the wires are in the proper order at the timer. Your ignition system should be correct.
Next thing is to check the fuel system. You should be able to get gas to flow from the carburetor bowl if you open the valve at the bottom. This should be a constant flow. Save the gas and pour back into the tank. The gas should not overflow the carburetor with the valve at the bottom closed but stop filling when the float valve is closed by the float level. Now if the engine starts, set the spark about half way down and adjust the carburetor needle clockwise till the engine starts to misfire. Then back the valve till it starts to misfire. About half way between is the correct setting. When the engine warms up, you might meed to adjust the needle again.
Spitting through the carburetor is usually caused by too lean and popping in the exhaust is usually caused by gas going through the exhaust valve and then firing when it hits a hot manifold. Also a vacuum leak in the intake manifold can cause some cylinders to be lean while others are too rich. So check for input leaks on the manifold gasket.
That's about all I can think of.
Norm

[speedytinc]

Whats a "regular tythem stroke"??
Gaskets?? Does the carb leak fuel now?


You can do a quick Mexican compression test by manually cranking the engine expecting to feel even drag/compression @ each cylinder on the compression stroke.

[J1MGOLDEN]

The most probable cause is the rotor turns the other way an #2 and #3 spark wires reversed.

Remove those two spark plug wires and start it on two cylinders to see of the backfire is gone.

[DanTreace]

attempts indicated fuel pouring out of gaskets in Holly NH carb, so replaced all the gaskets and gave carb good cleaning but not a total rebuild.
Current attempts cause backfiring at carb on a regular tythem strok

Likely the carb is the issue. If leaking, the float may be too high, and the gas puddle isn't right or the valve mixture is off.

For at least a good in repair NH, initial setting is 3/4 to 1 1/8 out. Too lean with cause backfire, or sputter on starting.

IMG_3361 (700x503) (580x417) copy.jpg (146.92 KiB) Viewed 2546 times

[John kuehn]

Good info from Dan on the carburetor adjustment! Most every T is in that range of adjustment or pretty close to it but not all are the same. This is an important point to learn when learning about Model T’s. I have 3 T’s and each has a slightly different adjustment but they are somewhere between 1 1/8 to 1 7/8 turn but that’s my cars others may be different.

[DanTreace]

John, that's true. Some carbs have worn down needle or seat, that can make a larger range needed.

Also, important instruction by Ford is to secure the nut on needle valve shaft, or your adjustment can walk away on you!

Helped a fella couple weeks ago, his nice '22 from is grandpa is now his. So learning was needed. He claimed it started up fine but now runs real bad. So I took a look after starting, and let the motor warm up some. Yep, ran a bit rufff!

So twisted the carb needle flange a bit, and the motor smoothed right out. Then tightened the nut for more resistance to drift.

[signsup]

I will get to some of this tomorrow in the following order:
I'll try to start on two cylinders.
I'll look at my needle setting and adjustment nut
I'll pull plugs and check for spark in correct order.
With plugs out, compression test dry and wet would be next

I'll have wiffe take video of current condition so that we are all seeing and hearing the same thing.

Thanks for all the great info. Relieved that pulling head is not up on the list.

[Charlie B in N.J.]

You were smart to come here first. Seen too many people come here after the head is off.

[CudaMan]

Just for reference, here is a diagram of the timer and coil box wiring on a '26/27. The firing order is 1-2-4-3.

[signsup]

You guys are great. When I titled this thread, you could sense my trepedation in thowing myself on my sword. Many other forums would start by chastising me for not reading the manual for years or putting vacuum gauges on every moving part and recording the barometric pressure of the garage in which it is stored.
A nice, thoughtful, respectful conversation about what makes sense and in what order is not only very refreshing, but much appreciated.
Will post video this afternoon. Unless the Model T elfs have been in the shop and cured all that ails. Fingers crossed.

[signsup]

Here is Utube link of attempting to start. Battery is 6v with 00 cables and good ground, so bogging down of starter feels like compression, not battery. I probably won't be able to do much testing until Saturday but I did disconnect 2 and 3 plug and no difference other than it did seem to spin more freely. Connected 2 back up and left 3 off and same as original condition.

https://www.youtube.com/watch?v=K6C0hFhbuZY

[speedytinc]

Check your retard. Acts like timing is advanced. Follow the 3:30/9:30 method of the crank pin. Bog down of the starter is from a too advanced firing.

You shouldnt need that much choke to start. One full revolution on full choke. At that point some fuel should drip out of the carb.
I notice your mixture adjuster friction tabs are bottomed out. Repop needle?
You may not be getting a good closed adjustment making for a way to rich mixture.
The needle must bottom out on the jet then open 1 1/4 turns. Mixture will be rich, but will start.

[speedytinc]

You are putting your generator @ risk if you run the motor with the generator output open.
Ground the generator out with a jumper wire from the output terminal to the case.

[Norman Kling]

On one of my T's I choked it and turned the crank a number of times then turned the key to batt. It still would not start. Then I tried to choke it again and found out the choke was not completely closed. So I forced the choke closed and it started up but couldn't get it to idle smoothly no matter how I turned the adjustment needle. I found out the choke would not open completely. So had to free up the shaft. Old gas dried in that location will gel and cause it to stick. After freeing the choke, the car runs fine.
Norm

[signsup]

All good things to check and I will install a wire on the generator, don't know why it does not have one.
Exchanging a few emails with Scott and I pulled the plugs and checked compression with just my thumg and the starter going. 1,2,3 great 4 nothing. So, probably stuck open intake valve on 4. Trying some MMO for a few days and then will open up the valve cover and try to work the valve open and closed and once that is working, trying again. So, on hold until the weekend.
But, I'l be back...

[Norman Kling]

You need a cutout at the top of the generator connected to the output. The screw in the front of the generator gets a wire from the ammeter so that The cutout is a one way switch originally it had a relay which would connect it to the ammeter to show charge. The newer ones have a diode which allows current from the generator to the battery, but not allow current from the battery to the generator when not charging. This might not fix the problem of no charge if the generator has been run for long without the cutout or wire from the ammeter.
Norm

[nicklm]

If you want to check the valves in #4, you can remove the spark plug to see if the intake or exhaust valves are not working. If the intake valve is not closing, #3 would not give any power as well.
This has happened to us when the #4 intake valve retainer failed. If either intake valve fail, both 3 and 4 quit working even though the other intake valve is ok.
If the intake valve is stuck, rotate the motor by hand and push down the stuck valve several times as you rotate with some lubricant and it should eventually start to work. This should be easier that opening the valve cover.
Nick

[signsup]

So, we were able to get back at it today. Pulled valve cover and gasket and, yes, intake on 4 was stuck open. I got the job of cranking and my son put a screwdriver blade between the bottom of the valve and I would crank it over and it would rise and not come down, then he would tap a wood dowel through the plug hole and tap it down, spraying liberally with penetrating oil each time. After about, what seemed, like fifty rotations, it would finally seat on it's own. Did not do a compression test, but the finger over the hole test all felt the same to me.

Buttoned everything up and gave it a electric start. Started on first crank. Turned off and grabbed video phone. Still need to tweek settings and yes, the wiring harness for the generator and the radiator, so not running but a few seconds. I'll keep hand cranking it over once a day until I'm ready to test fire again.

Thanks to ALL who helped hold my hand. I was getting worried and heading towards pulling the head, but you guys talked me off the ledge.

Here she is sounding better...

https://www.youtube.com/watch?v=k2Byep8xaOo