Backfire and loss of power

[COOTER]

Trying to get this old heap running again is getting on my last nerve. It all started with a loose set of points, then a cam gear disintegration, to fan clearance issues...and now to backfiring and loss of power, mainly in 2nd gear.

First question, when setting timing, I know the rotor should be pointed at the #1 terminal. Moving CCW, should it be set when the leading edge, the center, or the trailing edge of the rotor is lined up with the terminal? It's currently timed at the center.

The Les Andrews book says it could also be a condenser, coil or fuel problem. I put in new gas and a wee bit of Seafoam, in hopes that it was just old gas causing the problem.

Maybe just need to clean out the carb?
Advice?

[gweilbaker]

Does this help?

http://www.abarnyard.com/workshop/timing.htm

[COOTER]

Yes, but would the difference between center and trailing edge be enough to cause backfiring and loss of power? It falls so hard on it's ass, I can't even get to 3rd.

[denniskliesen]

Find the place in Les' book about using a test light to time your engine. Before I time mine, I always turn it to a location where the points are at a high spot on the distributor cam. Set them at .018" gap. Next rotate engine to check gap at each contact point with the distributor body. I've seen these with some points having a large gap and one with no gap. Proceed to finding top dead center using your pin in the front cover. Connect a test light to the arm of your points, spark advance lever all the way up. As you pull down on the lever 2 notches and the test light should go out at about that location. This is all explained in better detail starting on page 2-18 of Les Andrews volume 1.

[Tom Wesenberg]

Originally Posted by COOTER

Yes, but would the difference between center and trailing edge be enough to cause backfiring and loss of power? It falls so hard on it's ass, I can't even get to 3rd.

I would hold the coil wire 1/4" from a head nut and check for a hot blue spark.
If the spark is good, then I'd check for good fuel flow to the carb and through the jets.

[100IH]

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Do you know that there 2 top dead center positions? The one you need is at the end of the compression stroke, the next time around it is at the end of the exhaust stroke, then back to the TDC that you need to set the cam to open the points. Use the timing pin to EXACTLY locate the crankshaft and camshaft, then move the distributor cam to begin to open the points with the spark lever in the up position for full retard. The rotor will be where it needs to be.

[Y-Blockhead]

Originally Posted by COOTER

Yes, but would the difference between center and trailing edge be enough to cause backfiring and loss of power? It falls so hard on it's ass, I can't even get to 3rd.

I don't understand why people are concerned with the position of the rotor in reference to the distributor body contact (as long as it is pointing to #1 terminal)..

Set the points to .018 - .022". With the timing pin in at TDC on the #1 compression stroke rotate the point cam CCW so the points just open. Spark occurs when the points open and the magnetic field in the coil collapses.

[COOTER]

Originally Posted by 100IH

Do you know that there 2 top dead center positions? The one you need is at the end of the compression stroke, the next time around it is at the end of the exhaust stroke, then back to the TDC that you need to set the cam to open the points. Use the timing pin to EXACTLY locate the crankshaft and camshaft, then move the distributor cam to begin to open the points with the spark lever in the up position for full retard. The rotor will be where it needs to be.

So, you're saying even though the timing pin is in the cam gear dimple, that's not necessarily TDC?

[Bulligen]

If you are using the gear dimple that should be TDC

[COOTER]

Then it sounds like my timing is correct.
Fuel flow to the carb is good. Carb internals may be gunked up a lil since it's been sitting for nearly a year now. If the spark seems strong, I guess, I'll clean out the carb.

[denniskliesen]

Before you take your carb apart, check the flow from your gas line at the carb.

[COOTER]

Already did. I drained the fuel tank at that connection. Flow was strong.

[Dick Steinkamp]

Originally Posted by COOTER

Yes, but would the difference between center and trailing edge be enough to cause backfiring and loss of power?

No. The rotor has a fairly broad leading edge. Any part of that can be opposite the #1 terminal in the dizzy body when the coil fires when the engine is timed correctly.

[TinCup]

Without knowing the full background of the motor we can only offer up suggestions at this point. Another culprit could be valves. If valve clearances are tight then the motor can be starved for air fuel mixture. I recently just did this on a very expensive rebuild after 4k miles and the car was losing power. I found most of the intakes had closed to 6-7 thousandths versus 12 where it should be.

[COOTER]

I understand that these are just suggestions. That's what I'm looking for.
As far as background...
Nearly a year ago, although a bit tired, the motor ran pretty smoothly until the cam gear blew apart. Other than changing out both the cam and crank gears, nothing else has changed.I reset the timing, emptied the old gas and added fresh gas. It's a little harder to start than before but seems to idle nicely. It's not until I get it moving that it starts to stumble. Can the coil and/or condenser go bad from just sitting for a year?
What would cause the valves to close up?

[TinCup]

Valves close up due to wear of the valves and the valve seats. On one of the first cars I found this solution it behaved just as you are describing which makes me suspect valve timing. Your statement that the car ran fine before you lost the cam gear no make me suspect that the timing gear is off. Are you confident that the cam and the gear line up accordingly?

[COOTER]

Unless the timing marks were incorrectly marked, yes.

[heneste]

Was the timing done last year the only occurrence that you timed the engine? If the motor has a B timing cover, the hole for the timing pin is not in the same spot as it is for the A timing cover so TDC won't be when the timing pin is inserted. You can check visually to see if the piston is at TDC with your pin inserted in the timing cover to verify.

[Bruce of MN]

I had my engine die today and the problem turned out to be that the float valve seat in my Tilly unscrewed itself. Someone must have not done a good job screwing it in in the past. After doing it right, it ran fine all the way home - 45 miles.

[Tom Wesenberg]

Just in case anyone has a question about timing the crank gear to the camshaft gear, here is a picture of them correctly timed.
Someone had pictures in some books showing them one tooth off.

The second picture shows exactly how the rotor should be located when the timing pin is in the dimple of the cam gear. If you go by this picture, you don't even have to worry about where the spark lever is located.

[TinCup]

Thanks Tom I was looking for those pictures and you already knew what to do.

[Chuck Sea/Tac]

I'd like you to verify top dead center with the piston up on compression,and double check dimple in cam gear.

[COOTER]

Originally Posted by heneste

Was the timing done last year the only occurrence that you timed the engine? If the motor has a B timing cover, the hole for the timing pin is not in the same spot as it is for the A timing cover so TDC won't be when the timing pin is inserted. You can check visually to see if the piston is at TDC with your pin inserted in the timing cover to verify.

How can I tell if I have a B cover?

[COOTER]

Originally Posted by Chuck Sea/Tac

I'd like you to verify top dead center with the piston up on compression,and double check dimple in cam gear.

I'll pull a spark plug and check for TDC. Wouldn't it idle badly if the timing was off?
Probably can't get back on this until the weekend, but will update when I can.

[Y-Blockhead]

Originally Posted by Tom Wesenberg

The second picture shows exactly how the rotor should be located when the timing pin is in the dimple of the cam gear. If you go by this picture, you don't even have to worry about where the spark lever is located.

So basically your saying you set the timing by the position of the rotor? Similar as to the way the Nu-Rex timing wrench does? The same wrench that others on here bad mouth?

What is the point gap? If you have your points set at .018" your ignition timing will be different will be different than if the points are set at .022". And the rotor will be in a different position when the points open.

[100IH]

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Cooter, while your away, think on this. You already know that the cam gear is twice the size of the crank gear. When the crank goes through all four strokes, it makes two revolutions while the cam makes only one revolution. The dimple on the cam gear can only align at every fourth stroke - top dead center on the crank as long as the timing gear is aligned correctly as the picture above. To verify which front cover you have, go to fordgarage.com and search for timing cover, A vs. B. Vince covers the subject with great pictures. See you next week.

[Tom Wesenberg]

Originally Posted by Y-Blockhead

So basically your saying you set the timing by the position of the rotor? Similar as to the way the Nu-Rex timing wrench does? The same wrench that others on here bad mouth?

What is the point gap? If you have your points set at .18" your ignition timing will be different will be different than if it is set at .22". And the rotor will be in a different position when the points open.

You're correct, but with my points set to .020" and the rotor as pictured, I'd bet I'm within a couple degrees of firing at TDC when I push the lever full up.

You can easily tell if you are real close to proper timing by moving the spark lever up and down. When it's up, the engine should run slow and steady, and as you pull the lever down the engine should increase in speed until about 2/3 of the way down. After that it will be too advance and no longer increase in speed and actually start to buck a little.

[Y-Blockhead]

Originally Posted by Tom Wesenberg

You're correct, but with my points set to .020" and the rotor as pictured, I'd bet I'm within a couple degrees of firing at TDC when I push the lever full up.

You can easily tell if you are real close to proper timing by moving the spark lever up and down. When it's up, the engine should run slow and steady, and as you pull the lever down the engine should increase in speed until about 2/3 of the way down. After that it will be too advance and no longer increase in speed and actually start to buck a little.

Thanks Tom. That is what we needed to know to go along with your picture, points set at .020". And a great trick to remember when out on the road.

Now I wonder if it is the same with a stock distributor cam as it would be with a Stipe "Racing" distributor cam that has more duration.

[Tom Wesenberg]

Originally Posted by Y-Blockhead

Thanks Tom. That is what we needed to know to go along with your picture, points set at .020". And a great trick to remember when out on the road.

Now I wonder if it is the same with a stock distributor cam as it would be with a Stipe "Racing" distributor cam that has more duration.

Yes, it should be because any added degrees of dwell are added to the trailing end of the lobe. If they were added to the leading side, they would upset the timing.

Just be sure any freeplay is on the leading side of the cam when setting timing. In other words give the rotor a light twist clockwise to be sure the slop is on the leading side. The plugs fire the instant the points open, and the rotor turns CCW, so if you are hand cranking the engine to find TDC and go slightly past the dimple, then back it up, be sure to go back more than just the dimple so you are coming forward again to find the dimple. This will keep the freeplay on the leading side of the points opening.

To check for wear on the distributor shaft tangs, just give the rotor a light twist back and forth to see how much it moves.

[Dick Steinkamp]

I'm not sure I have the entire chain of events, but IF the car ran great just before the timing gear broke, and IF the only think that has been done to the car since that is the replacement of the timing gear, THEN the timing gear is off by a tooth.

If ignition timing, point gap, carb, valves, or other parts were also replaced or adjusted, then all bets are off.

[1crosscut]

I agree with Dick if the only thing changed was the timing gear and it then ran bad then the timing gear is off.

One easy thing to check that I have not seen mentioned is checking the flexible wire under the distributor plate to make sure it is not frayed, broken or shorting out. This will cause loss of power and back fire under load.

[COOTER]

A bit of Seafoam in the gas seems to have fixed things up.???
It sat all week with a fresh gas and Seafoam concoction...started up and ran fine yesterday. I'm a happy camper. I really didn't want to pull the front of the motor apart again.

[Mike V. Florida]

Originally Posted by COOTER

How can I tell if I have a B cover?

http://www.fordgarage.com/pages/timingcovers.htm