Holland Hornet .051 - Never got it started

Chemman Thu Nov 02, 2023 11:27 am

Since I joined this forum I have been trying to solve problems that are decades old. Back in the mid 60's I bought a brand new Holland Hornet .051. I was so proud of it. I was probably 15 or 16 years old. I built a plane for it and took it out. I couldn't get it started. The glow head was ok. Over probably the next five years I tried to start it with no success. I always wondered if the backplate was sealed well enough when it was mounted on the plane. My engine did not have the attached tank like I see in my Internet searches. It just had a backplate. Did anyone else have the problem? Or does anyone have suggestions? I still have the engine (I don't get rid of anything).

Ken Cook Fri Nov 03, 2023 3:49 pm

The Hornet is quite a desirable engine. One major thing that could certainly impact your success is the size of the intake. That could cause issues with properly drawing fuel. Even a engine with a leaking backplate, it would still run on prime. A leaking backplate and a overly large intake results in a no go situation. Currently, there's no source for plugs for the Hornet. Doug Galbreath who passed away was making head adapters for the Nelson style glow plugs. These plugs are unlike a standard plug in which they have a tapered seat and seal on the bottom vs a standard sealing at the top of the head on a copper washer. You don't lose the performance due to volume loss of the plug cavity and around the threads.

You can remove the backplate and lap the rear of the case on a flat piece of glass with some 400 sandpaper and oil. Once clean, I apply the 400 to the case with 3M spray adhesive on the paper and stick it to the case grit obviously facing out. Cut out the paper in the area of the crankshaft and insert the backplate. You can now lap the backplate to the flattened surface of the case. Hopefully you can save the old gasket. Mecoa owned by Randy Linsalato owns the Holland Hornet rights. He has some of the original tooling used to make the engines. Unfortunately, he makes claims that he will make parts and engines and never does. He currently lists the gasket out of stock. The Hornet backplate is a simple gasket to make.

I think it would be pretty cool if you made a attempt again to run it. You don't see many of them around and in my opinion, they're the prettiest engines ever made.

balogh Fri Nov 03, 2023 4:19 pm

If the Galbreath head with Nelson plug was a fit for the Hornet, then maybe the Kamtechnik head with turbo plug is also compatible?

Ken Cook Fri Nov 03, 2023 4:46 pm

Andras, Doug made a Galbreath head exclusively for the Hornet. I'm not certain as to what thread size the Hornet is, it's not the same as the Cox.

Chemman Fri Nov 03, 2023 6:19 pm

Guys, maybe this is why I wasn't successful with the Hornet. I didn't keep up with third party equipment. All I've ever had was the original Hornet glow head. No heads and separate plugs. But even if these third party parts improve the running, I would have to question any manufacturer who would release their product knowing it would never run. They wouldn't sell many that way. Apparently the Hornet did run directly from the manufacturer. I just couldn't do it. Without digging through my stuff upstairs I don't remember details about the head, like whether it had a head gasket or not. But I bought a replacement head. I would have noticed if anything were different. I still think the crankcase back makes a difference. Cox crankcase is sealed with a separate set of screws than those that hold it to the plane bulkhead. Metal on metal can be tightened really well. With one set (only two at that) of screws for both crankcase and mounting, the back is tightened metal on wood. Can't tighten as tight. If I were really serious about trying the Hornet again, I would certainly try the third party heads. But you know the old saying "Fool me once, shame on you,..."

Ken Cook Sat Nov 04, 2023 5:10 am

The stock Hornet plugs work and they do work well. I've seen many run perfectly. The Hornet was THE engine prior to the release of the TD. Bob Holland was also responsible for input in the design of the Cox TD. Your battery could've been more responsible than the head itself. Currently, there's no replacement for your Holland head. You mentioned the two bolt attachment of the backplate. Several manufacturers utilized this and it works just fine. As I mentioned above, insuring it's flat is the key. It doesn't require it to be Superman grip tight. As in the Cox, with a metal backplate and 4 screws. I can say first hand, this is a terrible design. You have the potential for all 4 screw heads to leak which can and will. The tank to tank back with the v-groove leaks, the needle valve spraybar which is pressed into the tank back leaks, and the case to tank connection leaks. Not only that, you have the venturi to tank back which can also leak. Regardless of how tight it is. This is why those integral tanked bees can be most problematic.

getback Sat Nov 04, 2023 7:04 am

For one when you mount the engine the screws are long enough to tighten the back plate nuts and go through the firewall and put nuts on the back side , that will eliminate the leak there Very Happy

getback Sat Nov 04, 2023 7:04 am

For one when you mount the engine the screws are long enough to tighten the back plate nuts and go through the firewall and put nuts on the back side , that will eliminate the leak there Very Happy

1/2A Nut Sun Nov 05, 2023 1:33 am

Spotted some info on CEF regarding the plugs.

Nelson adapter and standard plug adapter pics.
It is possible to spot replacement plugs on ebay if willing to monitor routinely.

Turkey