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Norvel .074 diesel head availability

Old 12-23-2015, 06:42 PM
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DeviousDave
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Default Norvel .074 diesel head availability

Hey guys,

I logged into the forum for the first time in many eons because I noticed last week that Norvel had listed a "limited" quantity of diesel conversion heads for the .074. I ordered one and it arrived a few days ago, looks better than my 1cc heads and has a tommy bar.

Just thought you guys might want to know they are available at the moment because the Norvel .074 is a fantastic diesel conversion.
Old 12-25-2015, 12:40 PM
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Bill Adair
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Originally Posted by DeviousDave View Post
The Norvel .074 is a fantastic diesel conversion.
Hi Dave,

Don't make the mistake I made with the .061 conversion! Be sure your .074 is broke in on glow fuel before you run it on diesel.

I bought the .061 on eBay, and was told it was used, but it turns out it was probably new. It had a healthy pinch at TDC, so I just assumed it was tight from too little running time.

When I ran it on the NV head first, it never got up to proper break-in temperature, and apparently wore rapidly on only a few tanks of diesel fuel. All pinch was gone by then, and it ran poorly on diesel.

Put the glow head back on, and then noticed compression was very low. Finally had to install a new piston/cylinder, but have not had a chance to run it since.

Bill
Old 12-28-2015, 03:36 PM
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Originally Posted by Bill Adair View Post
Hi Dave,

Don't make the mistake I made with the .061 conversion! Be sure your .074 is broke in on glow fuel before you run it on diesel.

I bought the .061 on eBay, and was told it was used, but it turns out it was probably new. It had a healthy pinch at TDC, so I just assumed it was tight from too little running time.

When I ran it on the NV head first, it never got up to proper break-in temperature, and apparently wore rapidly on only a few tanks of diesel fuel. All pinch was gone by then, and it ran poorly on diesel.

Put the glow head back on, and then noticed compression was very low. Finally had to install a new piston/cylinder, but have not had a chance to run it since.

Bill
The engine I plan to put it on first is one that was new when it had the conversion head made by Gkamysz installed and test ran. That was a brand new engine when I handed it off to him and he did the initial break in with it. I wasn't there so I don't know how he went about it as far as heat cycles, but I do know that Norvels are very tight sometimes, there are stories of bent rods from people trying to run them in. My guess is that QC was poor towards the end with engines assembled quickly out of parts... Unlike a plated and ground cylinder, the size of the bore on these is dictated by the anodizing process.

I think the official direction from NV is to hit the head with a heat gun prior to starting it the first time. I know that the glow version I have been flying forever has a huge number of hours on it and still gets stuck at TDC with fresh fuel on the cylinder walls. when the engine is cold, she's tighter than Prom Night, but it is perfect when running hot. After Four hours, I still can't pull it thru TDC without the piston getting stuck. With the jug and slug both being made from aluminum, the expansion rate should be very fast, and like the VA .049 the alloys are selected to manage that fit as the engine heats up,

I'd make that first run easy on yourself by putting a drop of motor oil in the cylinder and heating it with a heat gun, followed by a couple of long bursts with the starter. Once you get it running, I'd proceed to lean her out until you are at a very fast 2-stroke, let it run like that for 30sec to a minute and then run it as lean as you can without sagging. I think getting these to operating temperature early in life is key to their health. The Anodized cylinders have a lot of advantages (biggest being cost for Norvel) and I'm happy to have them this way, but the plated cylinders were better in most respects.
Old 12-28-2015, 07:56 PM
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My glow one is pretty tight, but runs good, until it is cold outside. At about 10 deg. C or 50 F, it seizes right up. If you can get it to fire up then it is loose for a bit. I tried lapping it a little, but it seized quite easily and I twisted the rod. I got it straightened out, but the rod is quite soft. It must have a big difference in expansion rates with the piston and cylinder. It is quite a good running motor on a normal warmer day.
Old 12-29-2015, 03:04 PM
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Bill Adair
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Originally Posted by DeviousDave View Post
I think the official direction from NV is to hit the head with a heat gun prior to starting it the first time.
Sometimes I wish I had an electrical outlet at the field to do that, but warm weather also helps. I use a 5X3 prop for the first starts, and often resort to the electric starter to get it going. After a few runs it usually starts by hand, but your correct about a cooling prime causing it to bind.

I hand started my first Norvel .049, and beat my poor finger almost bloody before I got it going! Now I keep the electric starter at hand, and don't hesitate to use it. I always check to be sure the engine is not hydraulic locked, or flooded before using the starter.

Bill

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