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Home Model Engine Machinist > Showing Them > A Work In Progress > Rockerblock I.C.--Something a little different-

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Old 07-01-2017, 04:49 AM   #211
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Converted my standby generator to propane a couple of years ago, the propane
regulator required a vacuum line to the back of the diaphragm to control the flow of propane, the propane was introduced into the top of the carb. above the butterfly.
The regulator had the same button on the rear of the diaphragm, to Prime at start.
I am running a 25 hp twin on 8 psi propane


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Old 07-01-2017, 02:41 PM   #212
Brian Rupnow
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So here we are, ready for round two of the propane game. This set up is as per the video I watched, with a separate venturi tube extending out in front of the carburetor air intake. The small metal pipe which the clear flexible tube is attached to, protrudes approximately half way into the "venturi tube. This will create a restriction in the inrushing air so it will create a low pressure area where the end of the tube is. The carburetor has not been changed in any way. The liquid fuel line which runs up to the bottom of the carburetor has been plugged with a piece of 1/8" steel dowel inserted into the original fuel feed line. The new brass "venturi tube" is a very light press fit over the carburetor air horn with a bit of green Loctite to help it stay in place. The original carburetor throttle should work to control engine speed, same as it always did. I will give the Loctite a few hours to set up, then try the engine again to see what happens.


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Old 07-01-2017, 08:46 PM   #213
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Hello Brian,
Due to computer problems I am unable to send attachments, but I feel you have the basis of a working unit. In principle, similar to a vehicle gas conversion. Will be very interested to see how you fare with this unit. Norm
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Old 07-02-2017, 12:25 PM   #214
Brian Rupnow
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Sadly, I must report that I had no luck at all with Propane. I have tried all of my bag of tricks, and the engine simply won't fire and run on Propane. This is not a really big deal, and like many other things, you don't know until you have tried. I do have a spare gas tank setting around, and by making a simple bracket I can add it to the existing Rockerblock assembly. With the coming of summer, I don't want to spend a lot of time in my machine shop, so I will end this thread now and say a big Thank You to all the people who have followed my build.---Brian
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Old 07-02-2017, 11:42 PM   #215
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Brian, don't think of your demand valve so much as a regulator for pressure of your gas, think in terms of scuba diving. The air from your tank only flows when you draw on it. It's known as a demand regulator also. It will only flow gas when it's asked. Propane forklift is the same way. More people have problems with too rich a mixture of propane than they do with too lean. It takes a surprisingly little amount to make an engine run. If I recall correctly the explosive concentration of propane is somewhere in the neighborhood of 2-10 %. Any more or any less= no joy. With enough patience and persistence I'm certain your motor will run on propane, not throwing in the towel is key. Your ability to create these little gems is amazing. Keep at it and if I can be of assistance don't hesitate to message me, I'm not the sharpest knife in the drawer but I do have a little experience that I will gladly share.
To
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Old 07-06-2017, 12:18 AM   #216
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After my failed attempt to even have the engine fire on Propane fuel, I was beginning to wonder if perhaps the ignition timing or valve timing had "slipped" from the original settings where it ran so well on naptha gas. I had a spare gas tank setting around, so I installed it on the engine, and without readjusting anything the engine fired right up and ran well. I decided to have a 40 minute "endurance run", and about half way thru the run I picked up my camera and shot a short video. That explains the nasty oil on everything.---I had given all of the bearing surfaces a good squirt of lubricating oil and filled the water reservoir before starting the run. The water stays in the reservoir with no problem, but the oil quickly turns black and splashes all over the place.---Brian
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Old 07-06-2017, 12:35 PM   #217
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Brian,

Thank you for posting the latest video. I would say the great sound and hit-and-miss kind of makes up for the oil splashes.

Anyway, I know you build your engines to work, not look good on the shelf (which they do, anyway).

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Old 09-03-2017, 01:40 AM   #218
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I have a few people around the world building this engine now, and I am being asked about setting the valve timing. The set screws in the cams are difficult to access. I covered how I did this back on post #158, but here is a repeat of the way I did it. I was very lucky and the very first setting I used seems to work fine.
--There is a bit of trickery involved in setting the valve timing. You must have the cylinder head and lifters and rockers all in place, and have the valve lash set at about 0.010" when the lifters are not "up" on the cams. I sawcut a 0.030" slot in the end of the camshaft that is on the same side as the cam gear, so that I could turn the camshaft with a screwdriver. I removed the flywheel on the side where the timing gears are and turned the other flywheel in the direction I intended the engine to run (clockwise when viewed from the side with the gears on.) The set screws in the exhaust cam were tightened at any random spot by reaching up through the bottom of the engine. The intake cam was left loose on the shaft. The setscrews in the cam gear were left loose. The crankshaft gear was tightened on the crankshaft at any random position. I turned the flywheel until the piston was about 40 degrees or so before bottom dead center, then used a screwdriver to turn the camshaft in the opposite direction to the crankshaft until the cam lobe was just beginning to influence the exhaust valve. At that point, I tightened the camshaft gear setscrews. That "locked in" the exhaust valve timing. I then kept turning the flywheel until the piston was about 30 degrees before top dead center. At that point I reached up through the bottom of the engine (with great difficulty) and rotated the intake cam until it was just beginning to influence the intake valve, then I locked it in place. The cam set screws are "accessible" either through the underside of the engine or through the vertical slots in the "bolster" which stiffens the cylinder head plate. If you simply can not get at the screws for the intake side cam, you can remove the other flywheel, the ignition cam, and the entire sideplate to get to the intake cam set-screws to tighten them. I think I covered this in post #158 in the original build thread.---Brian
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Old 09-12-2017, 09:10 PM   #219
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Gee Whiz--I'm going international in a big way. The second Rockerblock engine ever built was just finished by DavidLloyd2 in New Zealand. Cogsy in Australia has a set of the plans, and a fellow in the U.K. also has a set. I just sold a set of plans to a fellow in Spain. I'm pretty sure I sold a set to someone in USA but I'm not certain---can't remember. David Lloyd2 in New Zealand has posted a video of his Rockerblock running on HMEM, and I think his actually runs better than mine.---Brian
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Old 09-13-2017, 11:51 AM   #220
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Thank You Brian. for the Grate set of plans
I enjoyed making it,

DavidLloyd


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