# Formula 1 RC 1/3 with V8 engine



## bernimodels (Jul 14, 2014)

Hello Gents, I haven´t posted much on the forum before, but I decided it is time to show some of my projects.
I have successfully made some RC F1 cars in the past and some working 4 stroke engines, ( see here www.bernimodels.com). At the moment I am working on a F1 RC 1/3 scale car. It is a massive project as I have the determination to make all the systems that the real car has. The biggest challenge is the V8 engine, no doubt, but I also intend to make the gearbox, clutch and drive line, etc. This is why I think it might be interesting to show this project on the HMEM forum as I expect to learn a lot from your comments, and hopefully inspire others.
The complete car will also feature suspensions, tyres, steering, and control system, so you can actually have a real driving experience. I expect to complete it in a few years time.


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## DickInOhio (Jul 14, 2014)

Welcome. thats some pretty serious modeling. Wonderful work.
Dick


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## Swifty (Jul 15, 2014)

Great looking work, what sort of CNC mill do you have?

Paul.


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## bernimodels (Jul 15, 2014)

I have got an Optimus BF20 L vario with CNC kit and rotary table. I am still a long way behind with CNC machining, but I have been learning a lot with the recent engines. Also a manual lathe.


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## mu38&Bg# (Jul 15, 2014)

I stumbled upon your site a couple months ago. Your work is impressive. My question is have you looked at what's been done in model engines? OS produced the FS-40S-C (6.5cc) with bore 21.2 and stroke 18.4. This engine was rated for peak power at 17kRPM and redlined at 21kRPM with normal construction (no different than the first aircraft version one they produced in 1982). Your bore stroke ratio will of course lead to a shorter engine overall, but I wonder how such a short piston will work at model scale. The RC engines I've seen with short pistons I would not buy, but they aren't popular so I don't know if what I saw was really a problem. Detailed information about F1 engines is not easy to find, so this is a unique project for sure. Gas or wire springs?

Welcome!

Greg


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## bernimodels (Jul 15, 2014)

Hi Dieselpilot, I am glad you saw my website already. 

There are many RC engines at this range of stroke, but as you say not with this level of bore/stroke ratio. I went for this construction as a) it is aimed to high revs (above 10000 rpm) b) I want to create the 1/3 scale of the real engine. The real engines have around bore = 100mm and stroke = 40mm ( so a ratio of 2-2,5). On my engine I went a bit conservative with a bore 35 and stroke 20mm.

With regards to piston skirt area and height it is quite aggressive for a scaled engine piston, but again I wanted to scale the real piston and it is not an engine aimed at lasting very long anyway. With this sort of construction there are less friction loses so therefore there should be a performance advantage.

And this is just a single cylinder test engine before getting on the V8. Any problems with cylinder design should pop up now and hopefully make my life a little bit more easier on the V8.


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## mu38&Bg# (Jul 15, 2014)

Sure, that makes sense. I look forward to hearing about how the short piston runs. That head looks great by the way.


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## johnny1320 (Jul 15, 2014)

This is a very nice project, with the large piston and short stroke and rod it will generate fast piston speeds at tdc, which will lend it's self to very good scavenging, I will be watching for sure.


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## bernimodels (Jul 20, 2014)

Hi there! I have virtually completed the lower assembly of the engine. The crankshaft is finished and finally assembled with con rod inside the crankcase. 

You can see that the crankshaft has 6 holes on the counterweight area. These will be filled with tungsten bars. This is to adjust the amount of weight on the counterweight as well as keeping the inertia low. On the V8 one I might not do it as it is a lot of hassle as the tungsten is really hard to work with. I have to use a right angle grinder and because the pieces are so tiny it is quite a dangerous job.

The bolts to on the con rod are M2. I will replace the current stainless steel by 12.9 steel ones.

The cylinder liner is from a Lapped internal H7 steel off the self tube, that I turned to fit the aluminium engine block. It is not hardened but I hope it will be just fine for this test engine.

I am going to use gasket sealant, like Loctite 5800 as I do not plan to use any joints on between the crankcase and engine block. Any suggestions?


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## hedgehog (Jul 20, 2014)

Nice work on the engine.  Very unique looking

As for sealant. I would recommend a product called threebond.  If you cant find it where your from go to a honda dealership and ask for Hondabond.  Same thing but more money.

These sealants are designed for sealing flanges on engines, and would be ideal on your engine


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## johnny1320 (Jul 20, 2014)

I would use ultra grey silicone to seal the cases, this is what I use for my engine cases on my drag bike, you need only a light skim to seal them


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## bernimodels (Jul 21, 2014)

Thanks guys, I think any of them will do. I will check what is easier to get.


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## johnny1320 (Jul 21, 2014)

three bond is the same product as ultra grey, the ultra grey is made by permatex either one works great


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## dman (Jul 21, 2014)

one thing that happens with small scale is th rev range increases. Galileo was the first to notice the cube square law as it applied to animals but it applies to mechanical engineering. with 1/3 scale you may be increasing the rev range 3 times. your port area to cylinder volume ratios should allow for this if the ports have the same efficiency as full scale. 

bore to stroke ratio isn't as important as you think. the same displacement with the same BMEP makes the same power and torque regardless of ratio. a longer stroke makes for more mechanical advantage but a small piston makes for less force. it balances mathematically. one doesn't have an advantage over the other. the reasons long stroke engines make good torques have to do with other factors. a small bore will shroud valves of the same size, so valves are either smaller or flow less effectively. the results are more air velocity to create charge motion. the other thing is the rod/stroke ratio is often decreased with a long stroke giving more velocity at the top of the bore and less at the bottom, this may give the intake charge more energy as well but also gives the piston more mechanical advantage at the top of the bore, this may be beneficial when the burn rate is very fast or the engine is running slower.. 


formula 1 engines have a short rod so they have a low rod/stroke ratio despite the short stroke. the biggest reason this scale engine might have trouble is the valve area may be just too large to generate velocity. it may have difficulty idling. the idle speed can be several thousand rpm. you can bring the rpm range down with a really short intake came lobe timing that is retarded to give a late intake valve opening. simply retarding the cam could increase the rpm range by giving a late closing which works at high rpm because the port motion will lag behind the piston, but if you only have a late opening the piston can generate some suction before the valve opens helping to ram the air into the cylinder. shorter timing will increase he average velocity.


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## johnny1320 (Jul 22, 2014)

Dman, I have to disagree with you about bore to stroke ratios not mattering, it all depends on the engine application, a nitro engine likes a long stroke to take advantage of the slow long burn rates, not so much a gas engine. I also believe the reason for short rod lengths in F1 is to shorten the dwell time at TDC and BDC to increase VE in an NA engine, I do think that the idle speed will have to be high depending on the port and valve size, the larger the port the higher the air speed is needed. prostock motorcycles found that when they went to the large port Vortex heads, the engines had to leave at 10000 to make any power on the launch.


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## dman (Jul 22, 2014)

johnny1320 said:


> Dman, I have to disagree with you about bore to stroke ratios not mattering, it all depends on the engine application, a nitro engine likes a long stroke to take advantage of the slow long burn rates, not so much a gas engine. I also believe the reason for short rod lengths in F1 is to shorten the dwell time at TDC and BDC to increase VE in an NA engine, I do think that the idle speed will have to be high depending on the port and valve size, the larger the port the higher the air speed is needed. prostock motorcycles found that when they went to the large port Vortex heads, the engines had to leave at 10000 to make any power on the launch.



if you map volume over time or volume to crank angle the only difference is rod:stroke. bore:stroke has zero effect on expansion volume vs crank angle. it's also note worthy that the difference rod:stroke makes is surprisingly small. 1.5:1 is very similar to 1.75:1 but when you push the extremes you can see a difference between 1.45:1 and 2:1. 

long stroke engines may have more charge motion (tumble/swirl) for a combination of reasons and they have a lower cross section to displacement ratio giving them more port velocity. but the traditional explanations about "why" they have more torque do not apply. a scaled down engine has more cross section compared to volume, bassically a scale engine has less volume to take advantage of the port so the rpms will have to be higher. on a 1/3rd scale engine the ports will need to be shrunk down to .577 of the scale diameter to run in the same rpm range as the full size engine. i would expect this model engine to rev to 40,000+rpm.


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## johnny1320 (Jul 22, 2014)

The proof is in the pudding, this is a scaled down 4 stroke, not a two stroke it's not likely that the engine can flow enough air to reach 40000 rpms, and rod length makes a huge difference in charging formulas not included, for formulas are not the real world. I have built enough race engines to know. &#128513;


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## mu38&Bg# (Jul 22, 2014)

Are you certain about rod stroke ratios of F1 engines?  http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm

Besides, the goal here is recreating existing engine design not developing something new.

Greg


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## dman (Jul 22, 2014)

johnny1320 said:


> The proof is in the pudding, this is a scaled down 4 stroke, not a two stroke it's not likely that the engine can flow enough air to reach 40000 rpms, and rod length makes a huge difference in charging formulas not included, for formulas are not the real world. I have built enough race engines to know. &#128513;



it's a scaled down engine that revs to 20,000 rpm in full size. the ports are gigantic. the biggest thing holdings it back will be valve stability and and timing events. put some ducati style desmodramics on that thing as and see how fast it turns...

about the rod:stroke ratio, when it comes to this sort of thing sometimes a small difference makes all the difference. but reher morrison published a book and their opinion was that it's not worth worrying about. you build the engine to have a stable piston and good ring seal you you put the longest rod in it that doesn't interfere with the rings too much to keep the skirt short and that's all you worry about. i had a formula to map the curves on a graphing calculator and i showed it to a friend, he showed me the page in the reher morison book and that did the same as my formula and in print you couldn't see a difference between 3 overlapped curves. on my iphone screen with zoom you could see that there was a difference but the differences weren't visable to the full curve unless you put some very low numbers in there or numbers above 2:1. the difference to a pure sine wave was obvious but in the normal range of numbers used in performance engines they were similar.... i asked a long time racer about it and he said a stock chevy 350 was "about right" when he put long rods in they were heavy and didn't run worth a damn, and when he tried extra short rods he pushed pistons through cylinder walls. this sis something that is always going to be debated. all i can do is say what i've demonstrated mathematically and who has said what. other than that the discussion may never end...


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## dman (Jul 22, 2014)

dieselpilot said:


> Are you certain about rod stroke ratios of F1 engines?  http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm
> 
> Besides, the goal here is recreating existing engine design not developing something new.
> 
> Greg



gues i was mistaken. i didn't realize the stroke would be that short... seems whenever i see a cutaway of these things the rod look short and leaned over pretty hard but perhaps what i've seen hasn't been accurate or i've seen engines from another open wheel series and assumed it was f1.. 2.5:1 certainly is not a "short" rod.. and what i am saying is that if you recreate an engine dimensionally you will end up with something that revs much higher both due to structure and airflow. galileo understood the idea that makes this true in 1638 when he notices big animals have thicker leg compared to their body size and that strength goes up with te square and weight goes up with the cube..


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## bernimodels (Jul 22, 2014)

Gents, interesting discussion here! I am not a professional engine designer myself so this is good for learning.
The process I followed to dimension the engine was:

- V8 F1 Engine (roughly) based on existing literature: Bore 97 mm, stroke 41 mm, con rod about 102 mm. This scaled equals to 32.3, 13.7, 34 mm. The dimensions chosen for my engine are 35 mm, 20.8 mm (bore / stroke). The reasons for the difference are that I wanted to achieve more displacement to get more power. Bore is mainly based on the actual scaled value (so engine length on the V8 is true scale). There are hardly any model engines with such a short stroke and so I did not want to risk it. Still, with 20.8 mm stroke I am sure I can achieve above 14000 rpm to max 20000 rpm. The closer I can get to the 18000 rpm the better, as the whole transmission will be easier to scale down from the real thing (all gear box / final drive ratios) and frequency of noise will be on the same range of real engine. F1 engines were limited to 18000 rpm.

- With a longer stroke than the scaled value, I had to reduce con rod length so the overall height of the engine was the real scaled value. The engine cover on the car is so tight to the engine, that otherwise I would have to modify the external shape . Therefore the con rod length is under scaled. This produces a more aggressive maximum angle of the con rod during, so more compression load and wear on the bearings and piston. The acceleration profile on my engine due to a smaller con rod / stroke is flat around for about 40 deg b/a TDC, more similar to the Cup engine on the article. The only advantage I can think is less weight/inertia, but mainly this will have a negative effect on power.

- Valve design: I chose a 0,85 inlet / outlet valve diameter ratio. Based on that, and recommended flow speeds from literature I determined valve lift for IN / EX. Basically, I could use all the available cylinder area.

F1 engines have such a short stroke to rev higher and achieve more power. This is the main reason. Rod lengths are optimized to reduce friction losses, mass, and maximize flow efficiency.

Let me know what you guys think.


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## dman (Jul 22, 2014)

ahh, so you have made some alterations.. with the stroke and displacement up that much and by making the ports to match recommended flow speed then you avoided the things i was talking about. if it was 100% to scale you'd rev too high. this will be fun to see come together.


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## johnny1320 (Jul 23, 2014)

I just want to see it built, it's something new and it will be used in a model. I am designing a parallel twin based on  Per Bengtsson's supertwin fuel bike, I am hoping to start machining soon. I will be building the bike as well


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## SixSixSevenSeven (Jul 23, 2014)

Interesting discussion, hopefully I can take some info away from that for my "eventual" engine build.


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## e.picler (Jul 23, 2014)

bernimodels said:


> I have got an Optimus BF20 L vario with CNC kit and rotary table. I am still a long way behind with CNC machining, but I have been learning a lot with the recent engines. Also a manual lathe.



HI Bernimodels!
I also have the same milling machine you have with original cnc kit. Are you using the NCDrive software controler (supplied with the cnc kit) from Optimum?
As I observed you are using the 4th axis to machine the engine block.
Are you using a sort of cam software to generate the G codes?
I`m trying to machine the crankshaft on this machine using the all the 4 axis. Fisrt test showed to be promising. 
I also recently got a SIEG Slant mini CNC lathe with 8 tools turret. I`m still getting used to it. For now I`m manually programming but plan to do it on the Master Cam software, I alread use it for the milling machine.

Congratulations for your project. It will be very interesting to follow this project.
Where are you located? I`m in Brazil.


Good luck on you construction.

Edi


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## bernimodels (Jul 24, 2014)

> I also have the same milling machine you have with original cnc kit. Are you using the NCDrive software controler (supplied with the cnc kit) from Optimum?
> As I observed you are using the 4th axis to machine the engine block.
> Are you using a sort of cam software to generate the G codes?
> I`m trying to machine the crankshaft on this machine using the all the 4 axis. Fisrt test showed to be promising.
> I also recently got a SIEG Slant mini CNC lathe with 8 tools turret. I`m still getting used to it. For now I`m manually programming but plan to do it on the Master Cam software, I alread use it for the milling machine.



Thanks for your comments e.picler.  I am using Visual Mill for CAM and Mach3 as the controller software. I only use the CAM software, although for really simple operations I type the code at the machine as it is quicker. 

I have a Belflex BF 520c TME manual lathe. To be honest I have not missed that much the CNC capability on the lathe, but on the milling machine it is great.

I am based in Surrey, UK. Good luck with your project too and to johnny1320 as well.


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## johnny1320 (Jul 24, 2014)

Thanks, I look forward to seeing your finished project


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## bernimodels (Jul 27, 2014)

This weekend I have made some progress with the engine head. The inlet and exhaust ports have been polished and valve seals have been pressed in. It all went quite nice together. I used some Dremel tools and polishing compound to polish the ports in the inside, with extreme care to not damage the mating surfaces for the inlet and exhaust and valve seats. On the pictures you can see the dedicated fixtures to press the valve seats and guides into the head.

The upper assembly with the camshaft carriers and little brackets has also been put together. As the top of the engine will be open, it will be possible to see any leaks or other issues inside the head. The brackets are only for the test engine as the V8 holds the cam shafts with the head covers. 

The valves were almost finished, I just had to grind the top and bottom surfaces to final dimension. So they are ready to install. The material for valves is SS AISI 316.

During the week I expect to finish the bores for the cam shafts, including the bronze split bearings installation. Also the countersunk on the valve seats.


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## barnesrickw (Jul 27, 2014)

Nice detail and excellent work. 


Sent from my iPad using Model Engines


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## johnny1320 (Jul 28, 2014)

Bernimodels nice prgress, my question is why not make the head the same way as the V8 to see how it works and if the cam cover holds the cams in how will you be able to check the valve clearance?


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## bernimodels (Jul 28, 2014)

> Bernimodels nice prgress, my question is why not make the head the same way as the V8 to see how it works and if the cam cover holds the cams in how will you be able to check the valve clearance?


 
the reason for not using the same design is that the cam cover is quite a complex part to design and machine, as it is very thin and full 3D machining on both sides. Using the brackets is a simpler way to do the same job. The function of the brackets is to hold the cam shafts as the covers will do. I will probably get a lot of oil spillage once the cams spin at full speed but this is easy to put a transparent plastic cover.

Valve clearance is set with the brackets on. After that, the brackets are replaced with the cam cover. It does not affect the valve clearance adjustment.


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## bernimodels (Sep 4, 2014)

Hi there, it´s been a while after last post, but batteries fully charged after the summer break. Hope you all had a good time too.
The engine head has been assembled and is almost completed. All four valves, rockers, cam shafts are working together. All is left is the valve lapping and cups to be ground. I pretend to adjust cam clearance by grinding the cups, so each cup will have to be numbered according to its position and valve.
The valve seats were already cut with an HSS custom made tool. This tool is basically a countersinking tool with a pilot steam to achieve good concentricity with the valve guide. I am sure most of you use the same system.
I hope I can grind the cups and lap the valves this weekend, so I will be posting more pictures soon.

What grit do you apply for polishing valves cups and cams?
What clearance do you use on valve/cams?


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## canadianhorsepower (Sep 4, 2014)

Nice work, 
 hope not to many "my opinion  says you are wrong " will ruined your great project:hDe:Thm:Thm:


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## Swifty (Sep 5, 2014)

I don't have a lot of experience on IC models, however on the Lynx that I recently finished, I allowed 0.10mm (.004") clearance between the cams and the valve caps. I suppose that the amount of clearance would depend on how long the valve stems are and the expansion rate when hot.

Paul.


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## bernimodels (Sep 5, 2014)

Thanks Swifty, what you say makes a lot of sense. I just wanted to make sure that there was no other reasons.


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## bernimodels (Sep 15, 2014)

The spark plug is almost ready to assembly. Last weekend I almost finished the individual components, including the ceramic bits machining. The ceramic machined quite easily, but it was very challenging because of the wall thickness required (<0.5mm in some cases). The only bit missing is the electrode which will be from a HSS drill bit (Ø1mm). I will use epoxy adhesive to seal the bits together, and then swage it to ensure the electrode is not ejected when the engine is running. The thread will be M5, still to make.
The head and block are now together with he timing belt on. On the V8 engine, the distribution will be made with gears only, but I though I could save a bit of work and money on this one by just making the upper stage with gears and the rest with a chain. The rubber belt is only as a temporary replacement before the actual spring is assembled. 
Also see a comparison with a RC plug and the my own spark plug.
Only left: finishing of spark plug, mounting of carb and exhaust. Can´t wait!


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## artist334 (Sep 22, 2014)

Unbelievable work! Can I ask how you machined the valve stems and to what kind of tolerances did you bind yourself in to? 
I tried to do similar valves on lathe but I had taper of perhaps 0.04mm over the length of 40mm stem.


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## bernimodels (Sep 22, 2014)

Hi artist334, thanks for your comment. Valves are within 0,01 mm tolerance, measured with a digital Vernier Calliper, so cannot guarantee this is absolutely correct. I usually turn up to 0,02-0,01 oversize, and then use SiC paper to achieve better surface finish and the desired final size, up to grit 1200.

To reduce the taper you might have, I used the tailstock, but I cannot guarantee more than 0,01 as I cannot measure beyond that. To be honest there should not make a big difference, maybe more oil consumption.


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## petertha (Sep 22, 2014)

bernimodels, I wanted to inquire about your neat chain drive. 
 - what reference size is it & where did you acquire it?
 - did you make the sprockets or adapted from commercial stock?
 - is there some sort of calculation that specifies max velocity, particularly as a function of sprocket diameter?


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## bernimodels (Sep 23, 2014)

Hi peterha! 
The chain is a 6mm pitch, from Chiaravalli (Ref. CAT. RCX P.6 SEMPLICE ISO9001). I bought the sprockets from Technobots, 04B, z=8 and 16 (Ref. 4804-008, 4804-016).
Spur gears are from HPC Gears, m=1mm, z=24 (Ref.  G1-24).
Both sprockets and gears are then machined to suit my design.

This is a good design guide for chain transmissions http://www.crossmorse.com/pdf/DriveDesign-Cross-Morse.pdf

The chain/sprockets I am using are outside recommended design allowables, but since engine life is going to be relatively short it can be tolerated. On the V8 I will use gears only. Also minimum recommended Z is 17 and I am using 8!


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## bernimodels (Nov 29, 2014)

Finally the engine is alive! the recent weeks have been really busy at work, leaving not so much time for hobbing and delaying the fire up. But at last the final bits were assembled and after a few mods to the fly wheel, the engine run for first time.

The progress from the previous post have only been a new flywheel and the preliminary exhaust manifold. As you can see the engine is fixed in a very crudely manner, which will be changed to make it safer to operate and extra stuff around it (gas tank, etc) properly secured. Obviously the white cable will go away too.

Watch the video on youtube http://youtu.be/jF7d9OiEKGg

I will make a better and longer video and post it after everything is adjusted. It is mainly tuning the carburettor settings to achieve the full performance that hopefully is in it.


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## stevehuckss396 (Nov 29, 2014)

Bravo sir!  Now is the time I grab a cold one and bask in the glow!


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