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7 hp thermoil


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  #1  
Old 10-28-2014, 05:03:22 PM
Dale Freidline Dale Freidline is offline
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Default 7 hp thermoil

going to trade for a 7 hp thermoil and am not familiar with thermoils at all . looked on you tube at a few and they are kind of a neat engine , and understand they fire from compression only . my main question is what do they run best on , kerosene ? or what . any other tips on these are appreciated . dale
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Old 10-28-2014, 06:26:19 PM
NGeorgia NGeorgia is offline
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Default Re: 7 hp thermoil

I know very little about them. I had an friend who had one. I know from what I have seen and heard they can be very difficult to get running properly. But again only my experience.
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Old 10-28-2014, 07:34:10 PM
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Default Re: 7 hp thermoil

Dale:

My favorite engine is a home-made HVID. That is what the Thermoil is.

These engines are otherwise known as "explosion cup" engines. The way they operate is, during the intake stroke, a tiny amount of fuel is allowed to enter a small cup that connects to the combustion chamber.

This cup has one or more small holes that allow air compressed by the piston to enter.

As the piston rises toward TDC, pressure and air temperature increase until, at about TDC, it has gotten hot enough to fire the fuel in the cup. This small explosion blows the rest of the charge into the combustion chamber where it burns.

The compression needs to be changed to suit differing fuels. Diesel or kerosene (I run Jet-A) can be used. Timing is affected by the amount of compression and fuel type. Diesel takes a bit more compression (heat) to fire than kerosene.

Compression is changed by adding or removing shims from the joint between the big end bearing and the rod. If the engine refuses to fire when cranking (and everything else is correct), the compression needs to be raised a little at a time until the engine will start.

What I do if it's cold outside or I'm trying a new fuel type is to dampen a rag with naphtha (Coleman fuel) or gasoline and hold the rag close to the air intake when starting. The vapor of the naphtha or gasoline will lower the combustion point to where the engine will fire. Once it has started to warm up, it can be "weaned-off" of the naphtha. DO NOT USE STARTING FLUID!

If the compression is set too high, the engine will hammer more loudly than normal and may not start, acting like a gasoline engine with the spark advanced too much.

As long as the rings and valves are in good condition and the compression is correct for the type of fuel used, HVID engines are relatively easy to start as long as it's not too cold.

Have fun! They are addictive and the smell of burned kero or Diesel will be like fine cologne to you.
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Old 10-28-2014, 07:55:22 PM
Dale Freidline Dale Freidline is offline
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Default Re: 7 hp thermoil

thanks eldon , man needs a new toy to play with and i think this thermoil will be the thing to have . thanks , dale
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Old 10-28-2014, 07:58:12 PM
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Default Re: 7 hp thermoil

Once you figger it out, Dale, you'll like it......... If it doesn't drive you bonkers first.
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Old 10-28-2014, 08:45:51 PM
larry bee larry bee is offline
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Default Re: 7 hp thermoil

I have a couple thermoils that I cannot keep grease in the rod bearing grease cup. When you run them for a while, shut them Down and check the rod bearing cup almost all the grease is gone. Sometimes the rod bearing gets pretty warm to the touch. I have tried different types of grease but no luck. I think maybe the rod bearing needs to be tighten up. It doesn't seem to be excessively loose.Any thoughts would be helpful. Thanks in advance.
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Old 10-28-2014, 09:32:11 PM
Dale Freidline Dale Freidline is offline
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Default Re: 7 hp thermoil

thanks for the headsup on bearing grease . i will look at that first and go from there . dale
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Old 10-28-2014, 09:44:06 PM
thermoilbob thermoilbob is offline
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Default Re: 7 hp thermoil

Dale; congrats on the Thermoil i have a 6Hp model U that i took around the show circuit this past summer . it was a rough one and had to have freeze cracks repaired , cyl sleeved etc... i run mine on K1 Kerosene and that burns quite clean with very little carbon buildup on the fuel valve cup . i know that K1 is expensive but it will run an 8 Hr day on a little over one gallon . I use royal purple synthetic grease in my bearings and shut it down to grease the rod every two hours and have not had to remove any shims from any of the bearings even though i ran it over 120 hours this season . you may find you will want to put a pony starting engine on it to save yourself a lot of orthopedic issues as they are very difficult to get rolling fast enough to get over top dead center when cold . once warmed up they will start fairly easily by hand crank . getting the Hvid fuel valve to fit tightly in the seat ( and keeping it that way is critical to getting them to start and run correctly , that is assuming the compression is already at its peak to start with . have fun
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Old 10-28-2014, 10:40:33 PM
Dale Freidline Dale Freidline is offline
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Default Re: 7 hp thermoil

great information from all , much appreciated . im printing all this post off for reference reading because my memory aint what it used to be . i also have a 6 hp hercules that i havent tried to start yet , and some sort of starting motor is going to be needed for both . again , thanks dale
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Old 10-29-2014, 11:14:18 AM
Andrew Mackey Andrew Mackey is offline
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Exclamation Re: 7 hp thermoil

look carefully at the flange and mount bolts that mount the cylinder to the block. The Thermoils are prone to cracking there. some have been known to blow the cylinder clean off the block, if the bolts or flange fail! Look for worn fuel system componants. Links should be tight, not floppy loose. Good luck with the engine. You do not see too many Thermoils to begin with, especially the large ones.
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Old 10-29-2014, 11:22:44 AM
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Default Re: 7 hp thermoil

Welded and repaired crankshafts are another place to pay close attention...
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Old 10-29-2014, 03:19:39 PM
larry bee larry bee is offline
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Default Re: 7 hp thermoil

I will pass along what I was told when I bought my first thermoil. You will be bit by the bug and the smell. They were right. I started with one and now I own six. They are an interesting engine. Have fun
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Old 10-29-2014, 04:43:55 PM
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Default Re: 7 hp thermoil

Here are a couple of photos of a friend's original paint 7 hp.
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Old 10-29-2014, 07:44:33 PM
thermoilbob thermoilbob is offline
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Default Re: 7 hp thermoil

Dale ; all the problems the guys are referring to on the thermoils such as the blocks ,cranks heads etc... was mostly confined to the model T which was the first model . it was basically a converted gas engine ( like the Oldsmobile Diesel fiasco ) the model U and UA were pretty well built and unless someone used starting fluid on them or abused them badly they rarely had those issues but yes it is good advice to look them over good anyway , especially look closely under the block inside the base at the water jacket for freeze cracks as that is where mine was cracked and they are very hard to see under there . and also they are correct when they refer to issues with the fuel valve as it can have corrosion issues due to water having gotten in there . and i can tell you from experience that Hvid valve is a very costly part to rebuild . good luck
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Old 10-29-2014, 08:08:21 PM
Dale Freidline Dale Freidline is offline
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Default Re: 7 hp thermoil

thanks all , i havent seen it yet but he said the fuel tank is on top , so must be a u or ua . a real good look over is planned as it has a high compression but the hvid valve is something to really consider taking a close look at . i my be calling on you guys if i get in a jam with it . i had to laugh when i went to hit the thanks button and it said grunt . great . thanks all , dale
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Old 10-29-2014, 11:21:31 PM
thermoilbob thermoilbob is offline
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Default Re: 7 hp thermoil

Dale ; if the fuel tank is on top it is a T model . that is the one you have to watch out for problems with . they are the ones prone to the major casting and component failures . it is possible someone rigged up a fuel tank on top of a model U or UA also i suppose but the one with the factory top mounted tank is a T model . i do not have hands on experience with that model but do have with the U and UA model .
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Old 10-30-2014, 06:07:49 AM
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Default Re: 7 hp thermoil

Dale:

You might want to visit my web page and go to The Homebrew Hvid article. In it, I go through the design and debugging of the fuel valve/explosion cup assembly.

The way you lap the fuel valve has a lot to do with how well it works. If you can do it without messing anything up, you may want to put a piece of clear plastic tubing in the fuel line. If the fuel valve is leaking, you will see bubbles in the fuel.

Without some way to see if it's leaking (one of the major reasons for non-starting), you'll spend a lot of time chasing the problem.

Since my experience is only with my design, it may not be a characteristic
problem with commercially built Hvids.
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Old 10-30-2014, 12:01:14 PM
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Default Re: 7 hp thermoil

Help me Eldon. How do I get to your web page. I like to keep informed. Thanks

---------- Post added at 12:01 PM ---------- Previous post was at 11:17 AM ----------

Never mind eldon it was right in front of me
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Old 10-30-2014, 05:33:10 PM
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Default Re: 7 hp thermoil

http://www.eldensengines.com/

Bruce in Saint Ignace

Because it was right in front of me...........

Last edited by midpw; 10-30-2014 at 05:34:42 PM. Reason: Just because...........
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Old 10-31-2014, 06:24:00 PM
Dale Freidline Dale Freidline is offline
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Default Re: 7 hp thermoil

thanks for the headsup on the model t style . i should get a look at it this weekend and go from there . dale
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