Naughty Monkey
100cc
Maiden on Saturday or Sunday? 
New ZDZ112 B2RV / Installation into PAU Edge 540
- Thread starter Terryscustom
- Start date
Terryscustom
640cc Uber Pimp
We'll see, lots of non airplane stuff cooking right now. Typically you have it about right though.
pawnshopmike
Staff member
Terryscustom
640cc Uber Pimp
I did not get a lot done today, work took longer and had some business to take care off till late evening. Tomorrow though the weekend is looking much more productive.
So, since this is an engine thread with an airplane build as well, I'm going to dive right into the business end of things. I made a few jigs that I am going to fine tune and when happy will send to Joe to post on his website or wherever in .pdf format to print and use. Anyone that can use .dxf can also PM me and I'll send you files to print or cut for yourself.
So I lasered out a little jig to verify center on firewall in relation to the cowl. This is the circle thing with the long 1/8" drill bit going through this. (I do this with ALL airplanes so this is nothing new, just an updated design I'm testing).
Next I drew up a bolt pattern jig for the firewall based on that previously verified center point. It looks like the 112 is set up for 10-24 mounting bolts which should be more than adequate. Using the bolt pattern as a reference point I drew up a firewall hole pattern template based on the ZDZ drawings on their website.
So, since this is an engine thread with an airplane build as well, I'm going to dive right into the business end of things. I made a few jigs that I am going to fine tune and when happy will send to Joe to post on his website or wherever in .pdf format to print and use. Anyone that can use .dxf can also PM me and I'll send you files to print or cut for yourself.
So I lasered out a little jig to verify center on firewall in relation to the cowl. This is the circle thing with the long 1/8" drill bit going through this. (I do this with ALL airplanes so this is nothing new, just an updated design I'm testing).
Next I drew up a bolt pattern jig for the firewall based on that previously verified center point. It looks like the 112 is set up for 10-24 mounting bolts which should be more than adequate. Using the bolt pattern as a reference point I drew up a firewall hole pattern template based on the ZDZ drawings on their website.
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Terryscustom
640cc Uber Pimp
for pre drilled I'll usually check with the engine but most are not perfect. Safe bet nothing will be pre drilled for a ZDZ though.
Terryscustom
640cc Uber Pimp
Well, I had planned for a day off and business dictated otherwise
. THAT is the sucky part of taking a day off and still being at work.
So lets take a look at the carb end of things first. I just want to show this in steps because a lot of people dream up all kinds of ways to mess up a carb. So, I'll just post in steps with the pics in order. The carb is an out-of-the-box carb straight from Walbro so it needs a couple of mods to make it friendly for our use.
1 - KEEP IT CLEAN! Small dirt makes big problems with carbs. Don't do this in a dirty area, on a dusty bench or anything like that. Use clean tools as well!
2 - You will notice a plastic arm that locks onto the throttle and pushes the throttle open slightly. This needs to be removed because your throttle servo will bind when you choke it, also you need to have more flexability for throttle setting while choking.
3 - There is a second portion of that plastic arm that is connected to a spring, clip that to disconnect the spring, and you can leave the spring, I chose to pull it off just pinching and pulling with a pliers.
4 - Next we need to remove the factory idle screw for the throttle and deposit it where it belongs. These get a lot of new guy's in trouble and they complain about how fast their airplane lands!! Don't need it. You do need to hold the throttle open to remove this type.
5 - This is not mandatory but I chose to use a velocity stack on mine. I know they don't really add any RPM's but all rear carbs spit at least a little crap out of the carb. I have used stacks on every single I installed down to 20cc and had good results.
6 - This stack came with screws. The holes at the base need to be angled and the screws do not have clearance for the fillet / weld at the base of the cone. I beveled the inside so that it would not rub, it should slide through the carb holes easily.
7 - There is the spacer that we talked about earlier that you need to make sure the hole lines up with the hole on the bottom of the carb.
8 - VERY IMPORTANT: The holes the carb bolts into can only be "so" deep because of the rotary valve assembly. What I did was screw in a prop bolt until it just started to snug. I wrapped tape around it and backed it out. This gives me a depth that you are too deep! The bolts sticking out beyond the carb that were supplied with the stack are right there in the "too long" zone. I ground off about 1.5mm off of each and put a slight bevel on the threads. This should be perfect.
9 - Snug the bolts and check that the choke operates freely. Then tighten the bolts, not muffler tight, but nicely snug. After a couple of runs we will snug these again when the engine is warm because of that plastic spacer.
10 - CHECK THE NEEDLE SETTINGS!!!! These engines are run at the factory, it actually smells like gas in the cylinders too. However even from companies like DA, having an engine run and having it tuned are two things. On this carb on any 100-120cc engine the base settings are 1.5L and 1.5H. I usually go just about 1/8 turn more for first starts. This one was a mile off to the rich so I know it was not "tuned". Check them, otherwise you have no idea where you are starting and you will be chasing your tail during tuning!
. THAT is the sucky part of taking a day off and still being at work.So lets take a look at the carb end of things first. I just want to show this in steps because a lot of people dream up all kinds of ways to mess up a carb. So, I'll just post in steps with the pics in order. The carb is an out-of-the-box carb straight from Walbro so it needs a couple of mods to make it friendly for our use.
1 - KEEP IT CLEAN! Small dirt makes big problems with carbs. Don't do this in a dirty area, on a dusty bench or anything like that. Use clean tools as well!
2 - You will notice a plastic arm that locks onto the throttle and pushes the throttle open slightly. This needs to be removed because your throttle servo will bind when you choke it, also you need to have more flexability for throttle setting while choking.
3 - There is a second portion of that plastic arm that is connected to a spring, clip that to disconnect the spring, and you can leave the spring, I chose to pull it off just pinching and pulling with a pliers.
4 - Next we need to remove the factory idle screw for the throttle and deposit it where it belongs. These get a lot of new guy's in trouble and they complain about how fast their airplane lands!! Don't need it. You do need to hold the throttle open to remove this type.
5 - This is not mandatory but I chose to use a velocity stack on mine. I know they don't really add any RPM's but all rear carbs spit at least a little crap out of the carb. I have used stacks on every single I installed down to 20cc and had good results.
6 - This stack came with screws. The holes at the base need to be angled and the screws do not have clearance for the fillet / weld at the base of the cone. I beveled the inside so that it would not rub, it should slide through the carb holes easily.
7 - There is the spacer that we talked about earlier that you need to make sure the hole lines up with the hole on the bottom of the carb.
8 - VERY IMPORTANT: The holes the carb bolts into can only be "so" deep because of the rotary valve assembly. What I did was screw in a prop bolt until it just started to snug. I wrapped tape around it and backed it out. This gives me a depth that you are too deep! The bolts sticking out beyond the carb that were supplied with the stack are right there in the "too long" zone. I ground off about 1.5mm off of each and put a slight bevel on the threads. This should be perfect.
9 - Snug the bolts and check that the choke operates freely. Then tighten the bolts, not muffler tight, but nicely snug. After a couple of runs we will snug these again when the engine is warm because of that plastic spacer.
10 - CHECK THE NEEDLE SETTINGS!!!! These engines are run at the factory, it actually smells like gas in the cylinders too. However even from companies like DA, having an engine run and having it tuned are two things. On this carb on any 100-120cc engine the base settings are 1.5L and 1.5H. I usually go just about 1/8 turn more for first starts. This one was a mile off to the rich so I know it was not "tuned". Check them, otherwise you have no idea where you are starting and you will be chasing your tail during tuning!
Attachments
Last edited:
Terryscustom
640cc Uber Pimp
So with all the hubub on the engine out of the way, lets mount this baby.
I drilled a hole at the center point of the engine on the firewall and used my jig to drill the mounting holes. No matter what plane, the top bolts are going to be close to the top of the firewall, so it is handy that I picked this plane as the top of the engine box actually tapers down towards the fuse. That is not a problem, the engine box top can be slightly "adjusted" for bolt access without causing structural issues. After installation we will also be adding a few things to the engine box, stay tuned....
I designed a G-10 push rod for the throttle that is set up for linear throttle movement when the throttle servo is mounted against the inside of the engine box. I do not believe in clipping the spring on the throttle arm so I used a file to recess the bottom of the G-10 arm to not pinch the spring clip. @thelaw was cutting parts so I had her machine it out for me.
I drilled a hole at the center point of the engine on the firewall and used my jig to drill the mounting holes. No matter what plane, the top bolts are going to be close to the top of the firewall, so it is handy that I picked this plane as the top of the engine box actually tapers down towards the fuse. That is not a problem, the engine box top can be slightly "adjusted" for bolt access without causing structural issues. After installation we will also be adding a few things to the engine box, stay tuned....
I designed a G-10 push rod for the throttle that is set up for linear throttle movement when the throttle servo is mounted against the inside of the engine box. I do not believe in clipping the spring on the throttle arm so I used a file to recess the bottom of the G-10 arm to not pinch the spring clip. @thelaw was cutting parts so I had her machine it out for me.
Attachments
dhal22
GSN Sponsor Tier 1
Agree. Good thread.