Awakening a Holt 75 Engine from a Nap?

Thanks again guys.

I was trying to type up everything from the weekend while it was fresh in my head; thought I could make it... I will have to default to typing up posts in another software as suggested.

I was driving home yesterday when the thought about the plugs came from thin air. It would certainly explain why we would have spark on an adjustable open-air tester, but not across the spark plug electrode gap. Also why the spark seemed inconsistent and took lots of speed on the mag drive to generate anything. I will definitely pick up some solid-core plugs and try at the end of this week or over the weekend.

Talking with the guys at the club, the engine used to start and run OK by hand. It got progressively worse as time went on over the last 7-8 years. The last two years were spent not running. Now, the other lingering question is: did we do damage to the mag and/or coil by running resistor plugs for a couple years?

And... did we do anything by over-speeding the engine on the belt?

This has been a useful thread for me because I didn't know that spark plugs could have resistors, and I run Autolite 386s in my ponies - sounds like I should swap them out for the other plug mentioned. My ponies start well enough but this might make them awesome : ) I kind of wondered why the Twenty Two started so easily - it still has the plugs in it that it had from back in the '70s (previous steward didn't change them) so they're most likely non-resistor, if a resistor version was even available in that size.

Overspeed? How fast were you turning that engine? What duration? Look at the valve train - lifters, push rods, valve stems, valve springs. Hopefully nothing was bent or damaged. - No matter how fast you turn the engine, if you do not have reliable hot spark, it will not fire. Does the impulse on the magneto work? Test your wires and spark plugs on something that you know is producing hot spark from a magneto. Ensure you have good ground on the spark plug being tested. Gap the plugs, sometimes they need to be tighter gap and others wider, only way I have managed is by ensuring they are properly grounded and then watched as the intended magneto sends the power to them. May not be scientific but it works. The Model T Ford "buzz" coils were great to learn how the points affected the spark at the plug. One could adjust the "buzz sound" which greatly affected the spark at the plugs. Once you have achieved hot spark at the spark plug electrode, you and adjust the volume of priming fuel you are introducing. Hot weather, less priming fuel is necessary as it vaporizes much faster. --- cts

Overspeed: we were hoping that turning the engine at operating speed might get the magneto turning enough to get a steady spark. The tractor on the belt was a WD-45 Diesel running at about 1/2 throttle. Maybe 750-800 RPM? Much faster than what we wanted. And the operator didn’t throttle back once we got the engine rolling. Sustained speed was a couple minutes at most. I already opened the crankcase and inspected rods and main bearings; I will look over the top end next weekend.

We don’t have any other engines on-site that use the solid-core plug leads. The best I can do is to ohm-test the wires. I will add this to the to-do list.

I have new NGK AB-6 plugs. Once these are gapped a little tighter, I will install and try again at the end of this week.

Thanks again everyone!

Neil - learning has been the name of the game for this project. I am extremely grateful there are members here that are willing to spend their free time helping others with vintage iron.

Huge thanks to you, edb, cts, BruceP and the others who have read this thread and commented or given support. This project would have fizzled without a forum like this. Thank you!

BigSkyTR6 -- Do not let the project die now - you have come a long way. Those old engines are pretty forgiving in many regards. Yes, they can be very trying too, most often when one does something like overprime or forget to put fuel in them - yep, been there on both counts! - cts

CTS - the project isn't dead yet! The last post was trying to express gratitude towards everyone who has contributed to this thread. The forum here has been a HUGE help!

We have two weeks before our threshing bee/engine show. I'm hoping the spark plugs are the problem and we can get the engine to fire with the solid-core plugs. If not, I spoke with a member of another EDGETA branch who is willing to loan us an HK mag, just to run the engine during the show. One way or another this Holt will run in the next two weeks!

For anyone interested, the show is the Huntley Threshing Bee in Huntley, Montana. Show will run August 15-16. I would be happy to chat with anyone that can attend.

Please take video, everyone here likes pictures and video. We await the sight of smoke and the sound of the exhaust barking, but just maybe there may be some overshadowing noise - THE CHEERS of the people that are making it happen! ( the engine speed of the WD-45 is not the final factor in how fast the HOLT turned, depends on the RPM of the driving pulley and the ratio between it and what-ever the pulley was on the Holt.) - cts

One of the to-do items for this weekend is to refill the grease cups; the crankshaft cup closest to the radiator is empty. Is there a recommendation for grease in these cups? Do I need something with moly additive? Or can I use a generic NGLI #2 grease on everything?

Thanks!

I would not get too excited about special grease. NGLI #2 should be much better than anything they had when that engine was built or operating. I can feel the excitement building - there is not much that provides that rush than the first time an engine you have labored on, fires and comes to life. - cts