Engine runs poorly, help?!

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Model T Ford Forum: Forum 2016: Engine runs poorly, help?!
Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven G. Williams - Imperial, MO on Tuesday, March 08, 2016 - 05:22 pm:

We took our recently restored 1912 Torpedo on the Winter Tour last week.
new points on Coils and adjusted correctly; new Anderson Timer, timing set correctly; new round core Brassworks radiator (same as I put on our '14 which did last summer's Canada tour great!), carbon removed from valves and head, valve seats ground; pistons seemed ok (did not replace rings). Outside oil line installed; headbolts torqued correctly and when I returned the torque was still good. Discovered the magneto isn't up to snuff, so drove on battery. (discovered the charger did not give it a complete charge Monday night, which might have caused us problems on Tuesday). New Champion X spark plugs correctly gapped.

On Sunday discovered the car did not have enough power to take the gentle hills in high gear without retarding the spark and it was laboring a bit. The car cruised ok on level ground, but climbing those slight hills the engine did not have a lot of power. On the slight hills and sometimes on the level each day the engine would overheat, the motometer topping out for a bit, and when that started to occur I'd back off and coast until it cooled down. I did not have this trouble with our '14 in Canada. I drove with the spark advanced, until I had to retard it for the extra power needed going up those slight hills in Florida. I had fiddled with the dash carb adjustment for smooth running. Carb is a newly rebuilt Holley NH.

I had bought the T-Vac vacuum diagnostic gauge, and installed it today to get a diagnosis. With the engine running, and sometimes revved, it read consistently between 12 and 15, usually bouncing around 13 and 14 inches. The needle was not steady, but almost a violent vibration.

The chart with the gauge says 14-17" steady nominal reading "engine worn/fair- degraded rings/valves." "8-14 inches steady nominal reading incorrect valve timing."

The needle was never steady, and I know the timer is correct.

When I applied a screwdriver to each cylinder (spark plug top to head) there was no change on the 1 and 2 cylinders, but 3 and 4 reacted. Pulled the coil box head and all four coils had the points vibrating.

So, help? Thanks!


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A Bartsch on Tuesday, March 08, 2016 - 05:28 pm:

First, swap coils from 3-4 to 1-2. Next compression test. respectfully, jb


Top of pagePrevious messageNext messageBottom of page Link to this message  By R. S. Cruickshank on Tuesday, March 08, 2016 - 07:04 pm:

James has a good suggestion. I can't explain why one or two cylinders aren't firing but I do know that if you are running on battery, the coils may not run as set up for the high output of a mag. You may have to de-tune the coils to allow them to fire consistently. I learned this because my mag was week and I set the coils for a normal mag output and they would not run until I de-tuned the coils. Installed new mag and reset the coils and gained back the power I was missing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Tuesday, March 08, 2016 - 08:07 pm:

Steve, have you checked the compression on the two cylinders that are not firing? Swap the coils like James suggested and see if the problem moves to cylinders 3 and 4 and if 1 and 2 start firing. The problem is probably coil related.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Tuesday, March 08, 2016 - 08:09 pm:

Steve, have you checked the compression on the two cylinders that are not firing? Swap the coils like James suggested and see if the problem moves to cylinders 3 and 4 and if 1 and 2 start firing. The problem is probably coil related.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Berg on Tuesday, March 08, 2016 - 09:02 pm:

That needle is telling you something. Check compression on all four cylinders first. Should be roughly 50psi hand cranked. Next short each coil out to see if it works. Apply 6 or 12 volts dc to the battery post and then take a jumper wire from the timer post on the coil box to ground for each coil. Should buzz, be careful the engine might try to start, put the car in neutral or raise the differential.

Report back your findings.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Tuesday, March 08, 2016 - 09:12 pm:

When swapping the coils around, if the problem moves with the coil - well, it's the coil. If the problem stays the same - it could be carbon tracking or other less than optimum conditions in the coil box. If the compression is good I'd still suspect electrical issues. The Fun Projects kit for reworking the coil box is great. Replacing with wood can work but is subject to shorts and misfiring if/when the box gets wet. Time to make sure all connections are clean and tight. Using a 6 volt battery to power the coils will accentuate any weaknesses in the ignition. Seriously consider using a 12 volt battery to power the coils until the mag can be fixed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven G. Williams - Imperial, MO on Tuesday, March 08, 2016 - 10:38 pm:

Thanks for all your replies. I'll work on them tomorrow. FWIW, the coils all buzz, and when the engine is running I've removed the coil box cover and felt each coil vibrating. The coil box is new - new wiring, contacts, etc. Checked compression before going to Florida, and compression ranged from 40 to 50 depending on the cylinder. In Florida I swapped the coils, but it did not seem to make any difference.

I suspect it may be a combination of things, electrical and mechanical. I'm wondering about the rings on the pistons, if I shouldn't have replaced them.

I have two more rebuilt coils that I'll use after trying the swap and checking cylinders with them. And will check compression.

I'm no mechanic, yet LOLOL like most of us who own Model T's, we learn, thanks to the Forum.

FWIW I bought our '14 touring in 2002, and it never drove well on mag, so I always drove it on battery. 4 tours, one thru the Rocky Mountains (Search for the Mohicans tour) and after that tour drove it to the top of Pike's Peak. Drove it in Canada this past summer. Never had a lick of trouble with it until the engine developed a problem knock in Canada. Sent it off to be rebuilt, and discovered there was no magneto in it! %^$#* Yet I had no trouble driving that car! Go figure. It will have a magneto, needless to say. And when I get the '14 back together, I'll pull the engine on this car and have the magneto worked on. I want a T to drive!!!

Thanks for the guidance, going to be busy tomorrow!


Top of pagePrevious messageNext messageBottom of page Link to this message  By keith g barrier Savannah Tn. on Tuesday, March 08, 2016 - 10:48 pm:

If your coils have not been set by a hand cranked coil tester or strobe o spark it will never run as good as it could. KGB


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven Thum on Tuesday, March 08, 2016 - 11:49 pm:

His coils were set on a Strobo Spark. They a firing good and the car was tested with a known set of good coils


Top of pagePrevious messageNext messageBottom of page Link to this message  By David L Corman on Wednesday, March 09, 2016 - 08:09 am:

A fellow T member had a nice running car which he decided to detail the engine. Afterwards it would hardly run, although it had compression, fuel, and good coils. Turns out, He had poorly grounded spark plugs since he cleared the head bolts and expoxied the head getting expoxy in the spark plug threads. Sorry you could not enjoy such a great Winter Tour, hope to see you in Crystal River next year.


Top of pagePrevious messageNext messageBottom of page Link to this message  By G.R.Cheshire on Wednesday, March 09, 2016 - 09:12 am:

Steven: the violent vibration in the vacuum gauge would have me checking the valves to make sure one of them isn't sticking or in need of re-seating. do another compression test after obtaining a good reading then squirt a little oil in the cylinder then check again if the compression goes up (it will do this even with good rings) all is ok if there is no change I would check that cylinder's valves. Good luck :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By jeff cordes on Wednesday, March 09, 2016 - 09:26 am:

I would check the front intake port for a leaking gasket. That will make 2 cylinders run bad and give erratic vacuum gauge readings,


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Wednesday, March 09, 2016 - 10:06 am:

Sounds like the head gasket is blown between #1 and #2. Compression check is the next thing to do.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John f. wilson on Wednesday, March 09, 2016 - 01:12 pm:

You might check the actual spark coming to the plug sometimes there is a short between the coil and the box thus stopping the spark to the plug. the coil will still vibrate but the spark might arc somewhere besides the plug. Good Luck


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven G. Williams - Imperial, MO on Wednesday, March 09, 2016 - 05:48 pm:

Before reading the last six posts, I worked on the car. (And David, we enjoyed the Winter Tour very much! Drove 2.5 days in T, rest in modern). I'm guessing we drove almost 150 miles in the T.

Could not get the car started today. Went ahead and did compression test. Prior to the trip, compression was between 40 and 50 on the four cylinders. This time compression was between 0 and 15. When I squirted a couple squirts of oil on top of the piston heads, compression rose to between 15 and 28 in the four cylinders.

The head gasket was brand new, installed just before the tour.

I'm guessing my next step is to pull the head and replace the rings and check the pistons and the valves.
Thanks all!


Top of pagePrevious messageNext messageBottom of page Link to this message  By John T. Tannehill III, Hot Coffee, MS on Wednesday, March 09, 2016 - 06:56 pm:

I think it would be strange to have decent compression although low and then have almost no compression in a
all cylinders, sounds more like a valve issue to me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Wednesday, March 09, 2016 - 08:51 pm:

Sounds like it slipped cam timing due to a stripped fiber gear.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Wednesday, March 09, 2016 - 09:58 pm:

Note, I started this a few hours ago, but got interrupted. Several posts since might seem a bit incongruous.

A lot of good advice above. One thing I would add to, compression checking.
Yes, do a compression check. BUT sometimes it will give false information and throw you in the wrong direction.
You said you have done minor work on the valves? Are the stems tight? Or loose? What type of lapping or cutting was done?
There are several things that can make make a valve return slowly. Iron cuttings or lapping grit gets onto the valve stem or in the guide hole is one. A slightly tight stem or mis-matched stem in the guide is another. Squirting oil into the stem may help? Or it may not (if this is the problem, you could try it?).
What happens, is the valve may close okay at under a hundred rpm, which is where hand cranking and starters fall in. The compression check might say things are okay when in fact they are not. At idle (about 300 rpm), it may or may not work okay, or not at all. At higher speeds, what happens is that the cam turns, the lifer itself may or may not drop down, but a piece of grit in the stem will cause it to hang up just enough that it does not drop completely before the cam comes around to lift it again. It does NOT matter whether it is an intake or an exhaust valve, or some of both both.
If the exhaust valve hangs up? The intake stroke will be very weak and there will not be enough to compress and fire well. If either or both valves hang up? Neither the compression or power stroke will work properly. Both will lose some of their effectiveness out the hung-up valve. On top of that simple fact, is a slightly more complex one. If an intake valve hangs up enough, long enough? But closes enough for an intake charge to compress a little and fire, the higher pressure explosion can partially exit back out the hung up intake valve and vacate the intake manifold enough to affect its paired cylinder by clearing out some of the gasses it is waiting for. This is a common cause of backfiring (back out through the carburetor) on freshly rebuilt engines. The valve stems are tight, oil hasn't worked its way in everywhere yet. And the tight surfaces haven't had any time to wear down yet. On well done tight engines, this problem usually corrects itself in the first few hundred miles.

Actually, MOST of what I was writing still works.
Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven G. Williams - Imperial, MO on Wednesday, March 09, 2016 - 10:55 pm:

I will pull the engine tomorrow, and start to work. Got books and tools, and have arranged for a very mechanically minded friend to come check all my work after I return from Chickasha. He will also rebuild my magneto for me...it works, but not well, and he's done a lot of this before. I'm going to make a list of your suggestions, and thus check everything before I put it back in the car. Gotta get it running before the Easter Concours show at Forest Park here in St. Louis.
Thanks all!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, March 09, 2016 - 11:06 pm:

If you have a fiber timing gear, take Royce's suggestion and check it out. You may not need to pull the engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John T. Tannehill III, Hot Coffee, MS on Thursday, March 10, 2016 - 07:06 am:

Agree with Royce & Steve, remove the timing gear cover and inspect your gears.. Let us know what you find.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Thursday, March 10, 2016 - 11:51 am:

Just FYI: In my back to basics (1960's style) Encyclopedia a rapidly fluctuating needle indicates worn intake valve guides. Rapid vibration when accelerating is bad valve springs. Vac gauges aren't the best way check for problems. Indications are a bit muddy from eng. to eng. This book also says 17 to 21 steady is good/OK.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven G. Williams - Imperial, MO on Saturday, April 02, 2016 - 11:04 pm:

Thanks for all your help. Here's where I am now. Pulled the engine. Long story short, aluminum pistons (like what's in the car now) no longer made and can't get rings for them. Pistons slop in cylinders, gotta get them bored .80 over, with new pistons and rings. Getting a valve job. Block planed. Magneto was shorting out, got a new field coil. Clutch was worn, could be removed by hand, got a new Turbo 400 on order. It was one surprise after another. Valves weren't all seating, so problems there.

Good news, have a great machine shop to do the work. Bad news is I'm about 5 weeks from getting it back, as they are so busy. He's done other Model T engines, which is good. I have help from St. Louis club members, which is even better.

So, thanks again for the guidance on the forum.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez-Templeton, CA on Sunday, April 03, 2016 - 11:53 am:

You might want to check the spark timing to #'s 1&2. It's mighty easy to have the wires reversed.


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