I'm back with my '26 Coupe this summer and looking to confirm that the engine, magnificently rebuilt by J & M Machine in 2016, is fully run-in. The regime is to run the engine at an idle for increasing periods of time, keeping the water temperature below 80C. Last year I managed 45 minutes below 77C, so I thought I was well on the way.
I'm having trouble keeping the engine cool this year, however. My question is what is the right spark advance setting for this exercise. That diagram we sometimes see on the forum has the spark and throttle advanced about 3 notches each for idling. I found that heats the engine very quickly indeed, and am experimenting with a more advanced spark. Today I tried about 15 notches - i.e. the lever horizontal, about half way down. But the temperature was pretty high with this setting - I could run for only about 8 min before reaching 80C. Any suggestions? What IS the right spark advance for idling?
(I have the fuel mixture at one turn. It starts to run rough at about 3/4 turn, so I think I'm running fairly rich and this is probably not the problem. I also got a lot of white smoke today, though little of this in my test run yesterday. I think I'd better check the head bolts.)
Just drive the thing
for now, spark advance is: advance until speed ceases to rise purely by spark rod
every T in the world is going to overheat sitting at idle for too long
let me revise: every T in the world is going to run very hot sitting at idle for too long (and some will purely overheat)
Scott is right...just drive it. Mine rebuilt engine ran hot for about 90 mines of gentle driving then broke in. Once that happen the temp dropped back to the low side of the normal range and has been there ever since.
If you do idle it, use the spark advanced until the engine will not speed up any more with the spark lever or until it begins to run rough then back off a little. A richer fuel mixture will run cooler than a lean mixture. Also the idle should be fast enough to splash oil onto the cylinders so would be a fast idle. Drive it for about 5 minutes then let it cool off, drive it a little longer next time and then just drive at about 25 mph and keep on going unless it begins to overheat, then let it cool off.
Thanks, Norm. I found it sped up at around 2/3 spark down.
Actually, I do think it's ready to drive. Thanks for the encouragement. Now for the other 1/2 dozen things that need attention before I can pull out of that garage...
It was ready to drive the day you started it the first time.
Edit. 176 degrees Fahrenheit=80 degrees Celsius? Wonderful! Just warming up!
Over 100 Celsius (212 Fahrenheit?), I'd be upset.
Jack is right too, along with everyone else.
Get it sorted and go beat it up a bit and enjoy it. True. :-)
My 18 was very fresh up on top (pistons, rings and valves) last summer when it found and chose me. NO miles since work way back when.
It overheated at the drop of a hat. Couldn't control the overheating/boiling.
Put the water pump back on. Worked OK then and now he hardly heats up at all after some miles or putzing around the yard.
I'm about ready to take the pump off. :-) I took him out and let him run within his parameters. :-)
Yup, set that spark lever as far as one dares without the engine knocking worse or letting you know it's too far.
You lucky bugger, you have a fresh engine all round.
It'll let you know if you listen. :-)
Hah! The 18 here likes a horizontal timer lever too! But he's a knocker downstairs. Bad.
Do not be afraid to fiddle with the fuel mixture at idle and then again at speed if your carby isn't perfect.
It can very helpful out on the road to be able to hear the engine as it beats.
Hint. IF you need to get THAT far about hearing the engine "pick them off" whilst running, take the muffler apart and leave all the rearmost bits off. Not too loud.
I did that for a few miles and loved it as I'm used to it with my other T!
Then I left the innermost workings of the muffler in the parts bin, and put the rear section and outer bit of the muffler back in but I'm deaf as a stump.
Works for me.
Keep us up to date Tom!
For first start and 'break-in' is for me a check of all the systems, looking for odd noises or fuel or oil leaks, and checking carb throttle, and spark advance and retard, looking over the running motor. This is best with the T parked before first drive.
Parked in the garage without air flow to the radiator that provides the cooling of the engine, you have to add substitute cooling. One way is with a big fan blowing into the radiator, other, a bit wet, is to flow water constantly into the radiator with the drain cock open. Otherwise you may have overheating on a new motor, with a parked T.
I likes Dan's water method...
Sometimes, on a modern vehicle, I'll remove the thermostat, set a water hose in the top of a radiator but disconnect the top hose and attach a washing machine drain hose to extend it to the ground. The drain cock is closed. With the engine running, it's flushing out the entire cooling system of debris but for your application it serves dual duty.
I'll agree with Jack Putnam. Ford didn't idle the new engines for 45 minutes - they started the car and drove it off the line; the dealer didn't idle the thing either. Just drive it easy for a few miles, then it's ready to go touring.
A new or rebuilt engine has had all the machining done so that the bearings are set where they need to be. There is no break in of the bottom end. Valves set up correctly are sealed and require no break in either. The only break in required is to generate lots of heat and pressure on the rings so that they seal. New rings look like saw teeth to concentrate the friction to a small area thereby smearing the ring smooth forming a seal.
Once I have run them for a minute to ensure I don't have any oil leaks, I run the crap out of it. You guys that worry about taking it easy on them are not doing it any favors. Talk with someone that has ever broken in an airplane engine.
Gary - Thank you for posting that! I feel strongly as you do that seating the rings properly is important, and as far as I'm concerned, you only have one chance to get it right,....and prolonged idling is "NOT" the right way to do it!
As you say Gary, the surface of many brands of new piston rings have what look like very "VERY" fine screw threads on their surface, which are designed exclusively for quick seating of the rings. Each one is pointed (like pointed ridges) as you say so that they will quickly wear on the cylinder walls, which, in a properly rebuilt engine, will have been honed in such a way as to leave a fine crosshatch pattern on the cylinder walls, which is also designed exclusively for the purpose of initial break-in.
The surface of the cylinder walls, combined with the surface of the new piston rings work together to ensure that the new rings seat (and seal) properly as the almost microscopic rough surfaces wear together as the high points of the crosshatch cylinder walls, and the high points of the contact surfaces of the new rings quickly wear each other down toward a smoother surface for hopefully, a nearly perfect seal. And here's the important part,.....this happens during the very first running of the engine when the rough (microscopically speaking) cylinder walls and sharp pointed ridges of the new rings wear together. During this first short period of running time, it is important that the new piston rings should be forced against the cylinder walls as much as possible, and this is most effective if the engine is working hard, and cylinder pressures are as high as possible. A new engine should certainly not be abused (neither over rev'd or lugged) but it should be working hard, at varying speeds,.....AND NOT IDLING!!! Maximum cylinder pressure by working the engine hard is important,....like when accelerating or climbing a slight grade.
Sorry for the long-winded post here, but it's otherwise hard to explain the importance of correct break-in of new rings and cylinders, and that maximum cylinder pressure, forcing the rings hard against the cylinders when the newly rebuilt engine is firs started is important,....and in my opinion, idling is a big mistake, and you only get one chance for that very first break-in time to quickly and adequately seat the new rings,.....FWIW,.....harold
P.S. To help clarify, I should mention that this is why it is so important when just installing new rings, to never just install them in the always "glassy-smooth" worn cylinders, and why honing the glassy smooth cylinders to produce a fine crosshatch pattern is so important for break-in and proper seating (sealing) of new piston rings.
Gary and Harold are correct. Drive the damn thing.
Prolonged idling below operating temp is a recipe for glazed cylinder walls and rings that lose their ability to seat, which will lead to oil consumption.
Sorry John, you said it first. Should have given you credit too
I'll add, the goal of a break-in is good ring seal, not only to keep oil consumption low but for performance.
John, Gary and Harold are Right! Idling a brand new engine or one with new rings is not recommended!
The rings need pressure to properly seat. This is best done during the first driving by several full throttle and full closed runs. It's best to avoid long steady rpm runs when an engine is new. This is true of brand new modern cars as well.