Cranking

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Model T Ford Forum: Forum 2014: Cranking
Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Elliott on Friday, May 16, 2014 - 12:40 pm:

Another dumb question for you guys. My recent '14 purchase was fired up for the first time last week. Seemed to run fine after I found the "sweet" spot on the mixture adjustment and ran/started well on mag after it was warmed up so that was a relief but it sure took some time to fire up. However, it sure seemed to crank different than my 1916 T. On my '16, the upward pull at 9 o'clock position is rather stiff - I feel really good resistance and can get a good crank from a lower position than 9 if I wanted to. It usually only takes one or two pulls to get a good response and start up. On the '14 it sure seems the resistance is too light and I can only get a light pull at the 11 o'clock position and it takes several turns to get a chug. Forget about any other dial position for a crank - only 10 or 11 o'clock. Consequently, if it doesn't start right away it gets rather tiring when you have only one position that takes a crank and you're cranking a lot because of the lack of resistance. The motor on the '16 was rebuilt and the '14 engine hasn't been touched as far as I know. Do all T engine's crank similar, or are they all different? Dumb question, I know.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Friday, May 16, 2014 - 12:45 pm:

I'm no expert, but it sure sounds like your '16, having been rebuilt, has a lot more compression than the '14. I think I'd do a compression test on it and see how it measures up.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Elliott on Friday, May 16, 2014 - 12:51 pm:

I just did a comparison test and with the '16, when I start the upward pull I get resistance build up until I reach near the top, then it turns over. With the '14, I don't get much resistance build up so when I reach the top, the turn over is less dramatic. Does that make sense?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Elliott on Friday, May 16, 2014 - 12:52 pm:

BTW, how do you do a compression test?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Friday, May 16, 2014 - 01:03 pm:

You need a compression tester, which is a dial gauge with a hose and a fitting that screws into the spark plug hole. When you turn the engine the gauge shows how many pounds of pressure the cylinder is producing. Decent compression for a T is 40 pounds or more, but more important is for all four cylinders to be about the same.

The problem with most testers today is that they're made for high compression engines, and have a scale measuring hundreds of pounds. For a T it's best to use one that doesn't go over 100 pounds.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Friday, May 16, 2014 - 01:09 pm:

By the way, your description of starting the 16 sounds right. If the 14 has low compression on all cylinders I would guess worn piston rings. If there's a wide difference among cylinders, I'd think valve problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Friday, May 16, 2014 - 01:19 pm:

You can get an inexpensive compression tester (pressure gauge) at most auto supply retailers for $20-$25. In your case I'd just get one that has the rubber end.

I'm not too good at this, so if someone can give Bill better instructions, PLEASE DO!!

Remove the spark plugs, then one hole at a time just hold the gage in the hole firmly and turn the crank. (This will take 2 people, one to hold the gauge and one to crank.) You may need to give it 2 full revolutions per cylinder because you only get a reading on the compression stroke. A healthy engine should produce around 50+ PSI.

I'd do this on both engines. That way even if your testing is flawed you will be able to see a comparison and know if the '24 is weak.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Friday, May 16, 2014 - 01:21 pm:

I mean know if the '14 is weak....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Elliott on Friday, May 16, 2014 - 02:06 pm:

Henry

Do I remove all plugs first, or just one at a time as I test them?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Friday, May 16, 2014 - 02:59 pm:

Here's how I would do it, others may suggest variations:

1) Warm up engine.

2) Shut off engine (key off).

3) Shut off fuel supply to carb.

4) Remove all spark plugs.

5) Set throttle to wide open.

6) Press compression gage firmly into #1 spark plug hole.

7) Have assistant crank engine over 3 times, record maximum reading of compression gage.

8) Repeat step 7) with compression gage in #2 spark plug hole - be sure assistant cranks engine the same rate and same number of times for each cylinder.

9) Repeat step 7) with compression gage in #3 spark plug hole - be sure assistant cranks engine the same rate and same number of times for each cylinder.

10) Repeat step 7) with compression gage in #4 spark plug hole - be sure assistant cranks engine the same rate and same number of times for each cylinder.



What you want to see is a consistent reading around 50 psi for all four cylinders. If one cylinder is way lower than the others, it points to a valve sealing problem in that cylinder.

If all cylinders are low, it points to worn rings.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Friday, May 16, 2014 - 03:18 pm:

Bill,

Mark's procedure will give you what you need. Let us know how it turns out!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Friday, May 16, 2014 - 04:28 pm:

One last step, after the test, give the assistant a beer to help ease the pain of his/her sore cranking arm! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Olsen on Friday, May 16, 2014 - 06:32 pm:

Mark: Mine settled for a game or rummy over bowls of icecream.
I had all the plugs out and had her crank to the beat of a song to keep the speed consistent, and no carb at that point.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Friday, May 16, 2014 - 06:35 pm:

You're a lucky man, Chris! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, May 16, 2014 - 07:19 pm:

I don't like to warm up a T when compression testing because of it's relatively low compression. The (possible) higher comp on a warm T will give you a false reading concerning comp when starting cold which could be a reason for hard starting. A 5 Lb. difference between hot VS cold on a 150 Lb modern won't make much difference but on a T it could be murder. So here's my 2 cents:
1: all plugs out. Ignition off. Choke & throttle open fully.
2: Have an assistant hold the gauge on #1 cyl.
3: Crank until the comp doesn't rise any higher. usually 5 to 7 full cranks. You will not get a true reading unless the gauge stops going up when cranking.
4: WRITE DOWN THE RESULTS! don't rely on memory.
5: Repeat on remaining cyls.
This should give you a reasonable idea of the comp./ eng. condition If it's low: (or if you really want to know why it's low) Repeat the full test starting with #1. This time add about a teaspoon of motor oil to the cyl before cranking. You wrote the readings down, right? If the comp goes up it usually indicates worn rings.(the oil seals the rings temporarily) If it doesn't go up it usually indicates valves not seating. (the oil won't reach or affect them). Under 40: poor.
40 to 45 OK. 46/ 50 really OK but I'm betting you're at the lower end.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Elliott on Friday, May 16, 2014 - 08:03 pm:

Great - thanks again for all the good advice! Now I just have to hit the local auto parts for a compression gauge. I will keep you posted!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Friday, May 16, 2014 - 09:49 pm:

I'll bet all the local stores have will be gauges for modern high compression engines. You may need an online search to find one with a scale of 100 pounds or less.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison_Rice Minnesota on Friday, May 16, 2014 - 10:22 pm:

Well, I hate to disagree with you CharlieB but only in one point and I'll tell you what I don't agree with and why. But please don't beat me up. :-)

I believe you should test your compression on a warm engine. And the reason I think this isn't simply because a lot of my manuals say so but mostly because you want to test the engine at its normal "working" temp. That's when you need good compression. A cold engine won't give a true indication of your engines health. I also think part of the reason, and this might sound a little out in left field but the ring gap on a warm engine is as close to close as it's going to get.

So am I full of you know what or what are your thoughts.

Ok, I went back and read your reasoning for testing cold and have to agree an engine with low compression won't give an indication for hard starting. So yep, you get this one. After all his concern is hard starting.

Your thoughts?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, May 16, 2014 - 11:35 pm:

Mike that's exactly the point for cold testing but by my way of thinking it really applies more to hard starting low compression pressure engines. Like I said we're talking say 50/55 Lbs. as absolutely great but how many have you seen at that pressure and that wouldn't contribute to hard starting. Many disagree but you can't deny the logic. I doubt you'd see, lets say, a 10 Lb. difference in a T engine from cold to hot but what good is a hot engine increase when your trying to start a T first thing in the morning? They have lower compression pressure than most modern lawn mowers.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison_Rice Minnesota on Saturday, May 17, 2014 - 07:45 am:

Thanks CharlieB. I figured that was your reasoning and am in agreement.


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