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Old 10-24-2018, 10:54 AM
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Quote:
Originally Posted by G Heiman View Post
Don't give up on the ignitions yet. I used another DA engine and plugged its' sensor into the ignition in question. That allowed me to rock the prop hub magnet back and forth at a high rate to see if the ignition was any good. Also, I used a A123 two cell pack for power. A standard 4 cell NiCad wouldn't work.
I went and took a 7.4 v Fromeco battery and plugged it into a 6v regulator and I was able to get a spark. Got to check that 4 cell NiCad

Thanks
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Old 10-25-2018, 04:40 PM
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Update -Woodruf key vs. Dowel

FYI

Recently received the prop hub and found out I did not specify which type. Evidently there are two different models.

The Woodruf design has a half semicircular key way and key. The other uses a dowel.
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Old 11-04-2018, 07:21 AM
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DA150 Manual and DA Information (all models)

Hi all!!!


Will be back in the saddle with this project next week. Meantime, please review for your information the DA150 manual and a PDF file placed on this site by Super08 back in 2013 with information on all DA engines. If you are working on an engine you should always get updated information from DA. The information on the PDF file from Super08 has some torque settings for steel bolts. This information can be used as a guide.
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Old 11-04-2018, 08:55 AM
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My experience is the M5x16mm aluminum head bolts get really stretchy at 70 in. lbs. It's never been clear to me if you torque to 70 in lbs initially and stop, or if you allow them to relax and keep re-torquing until they settle in at 70 in Ibs. Is there an industry standard procedure for torquing alum bolts? Last time I did those I got to thinking I'd rather have a small weight penalty using steel bolts rather than risk snapping an alum off in the crankcase.
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Old 11-04-2018, 10:29 AM
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Originally Posted by Kevin K View Post
My experience is the M5x16mm aluminum head bolts get really stretchy at 70 in. lbs. It's never been clear to me if you torque to 70 in lbs initially and stop, or if you allow them to relax and keep re-torquing until they settle in at 70 in Ibs. Is there an industry standard procedure for torquing alum bolts? Last time I did those I got to thinking I'd rather have a small weight penalty using steel bolts rather than risk snapping an alum off in the crankcase.

Bolts should not be re-torqued if the bolt relaxes. Bolts are torqued wet (lubricant) or dry. When torqueing a bolt with lubricant, the number is always less than the dry setting. For example, last year I torqued bolts on a job to 1800ft-lbs dry. To achieve the same force with lubricant, a number of 1600 ft-lbs was used. If I torqued at 1800 ft-lbs with lubricant, the bolts would have been over-stretched.


In our case, we will use a small amount of loctite(242) which in effect will act as a lubricant. Further tightening should not be necessary. I am sure that DA has taken this into account when listing their settings .


The aluminum bolt is good in that it expands equally to the case and head during operation. The Loctite will ensure that the bolts will not come out even if there is relaxation. Bolt relaxation could occur if assembling components warm


The most important part of this process is an accurate torque wrench as the values are very small.
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Old 11-05-2018, 02:50 AM
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Bolts should not be re-torqued if the bolt relaxes.
Well this is what confuses me, because they recommend in the manual to occasionally check them for tightness. So wouldn't you use the toque wrench when checking them? Also I've never noticed any blue loctite on the aluminum bolts as assembled by DA.
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Old 11-05-2018, 06:58 AM
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Originally Posted by Kevin K View Post
Well this is what confuses me, because they recommend in the manual to occasionally check them for tightness. So wouldn't you use the toque wrench when checking them? Also I've never noticed any blue loctite on the aluminum bolts as assembled by DA.
I was told by DA to use 242 Loctite on the aluminum bolts.

Part of this build is to run the engine on a test stand. We will check for bolt tightness during this process. These are all good questions, some of which we are learning the answers together.

My issue with loose bolts is that there are three reasons for a bolt coming loose. One is the bolt is turning due to vibration. The second is compression of the gasket between the head and crank case. The last is permanent deformation or stretching due to cyclical heating and cooling. If the latter happens, your initial assumption is correct that any more tightening will continuously stretch the bolt. One way of determining this is by measuring the length of the bolts prior to use. After running the engine several times, a bolt can be removed and re-measured for stretch. Like you, I do not know the answer to this question.
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Old 11-05-2018, 01:54 PM
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Quote:
Originally Posted by ChemE View Post
>>>> If the latter happens, your initial assumption is correct that any more tightening will continuously stretch the bolt. One way of determining this is by measuring the length of the bolts prior to use. After running the engine several times, a bolt can be removed and re-measured for stretch. Like you, I do not know the answer to this question.
DA states these are single use bolts.

Why not just replace with steel and eliminate the questions? Even DA is using steel on several of their engines now. 90% + of engine companies use steel bolts for fasteners. What advantage is there to using aluminum bolts other than a tiny weight savings.
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Old 11-05-2018, 02:09 PM
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Originally Posted by Truckracer View Post
DA states these are single use bolts.

Why not just replace with steel and eliminate the questions? Even DA is using steel on several of their engines now. 90% + of engine companies use steel bolts for fasteners. What advantage is there to using aluminum bolts other than a tiny weight savings.
You know, we have 2 engines to work on. We can do one of each if that is what you all want and we can compare.

When I took the heads off, all of the bolts were tight and they were all aluminum.

The red aluminum bolts look nicer in my opinion.
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Old 11-05-2018, 02:55 PM
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Yes the red bolts do look nice but I can’t see them inside the cowl or in the air.
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Old 11-05-2018, 03:46 PM
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Yes the red bolts do look nice but I canít see them inside the cowl or in the air.
LOL
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Old 11-08-2018, 08:24 PM
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Crank shaft QC update-Engine #2

I brought the crank shaft to a friend of mine to do a better QC check on the shaft. The run-out on the journals were .0012. I then placed the shaft on centers ( the shaft does have centers contrary to my previous statement) and found the run-out was not reproducible. The threaded portion of the crank which accepts the prop shaft is also bent .005 like the prop hub.

Evidently when the engine struck ground and bent the prop shaft, it also bent the end of the crank.

The play in the shaft needle bearings were .0005. This was difficult to measure due to the side movement of the crank on the needle bearing and am not sure of its accuracy. Suffice it to say, I am not worried about bad needle bearings.

So far we have the following:

Bent prop shaft ( received a new one)
Bad hub ( received a new one)
Bad bearings ( received a new set, front middle and back)
Bent shaft tip-will attempt to straighten

I will attempt to straighten the end of the shaft this weekend in the shop and will also contact DA to discuss this and ask their opinion.
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Old 11-08-2018, 08:34 PM
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Tools and supplies

Kevin K said that he did not notice any loctite on the threads of the ones he removed from his engines. Attached is a picture of a removed head bolt with what seems to be a coating. I do not know if the blue loctite turns white subject to heat.

Also attached is a picture of my torque wrench that i use, and 3/8" socket hex key extension for head bolt tightening. The torque wrench goes to 150 inch-lb. This wrench is very accurate for this type of work.

Last, I got a 400 F temperature stick for the disassembly of the next engine.

Verifying gel time of 24 hours for loctite 620 green. Some users said that the loctite was moist when they dissembled their engines,. Will verify Friday night that the small sample gelled.
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Old 11-09-2018, 12:43 AM
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That does look like Loctite on the head bolt. It turns white when removed due to the shearing action between the threads and also helps stops the bolts galling when you want to take them out. If its still wet when removing the bolts, then it didn't set properly.
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Old 11-09-2018, 10:16 AM
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Your the man if you can straighten just the tip of that crank.
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