Author Topic: Longboy's "BRATZ" Model Gas Engine.  (Read 2323 times)

Offline Longboy

  • Full Member
  • ****
  • Posts: 143
Re: Longboy's "BRATZ" Model Gas Engine. Rod/ Piston.
« Reply #15 on: September 14, 2017, 01:05:56 AM »
   The piston and rod assembly lightened on the con rod, they weigh 1.34 oz.  Roller bearings in small end, no bearing inserts in big end.




The O rings on the pistons are Metric riding on an inch sized bore. Close but slightly smaller outside diameter....I hope they don't give me grief losing compression in running. :facepalm:



Wadda you mean, "It don't run"???

Offline Longboy

  • Full Member
  • ****
  • Posts: 143
Re: Longboy's "BRATZ" Model Gas Engine. Valvetrain.
« Reply #16 on: September 14, 2017, 09:17:56 PM »
   The rocker arms and their pedestals are all brass with SS hardware. Easier to cut and shape than steel arms in this scale.



With half of the valve spring below the head surface the rocker assembles show a low profile compact fit as do the spark plugs to the cylinder head. There are no lock nuts for the push rods. :o  Drilled for a 6-32 threaded hole, the 3/32 in. dia. piano wire push rods slip up in the arms and a set screw within then maintains the valve clearance. Some blue Loctite on set screw holds its position.

Wadda you mean, "It don't run"???

Offline Longboy

  • Full Member
  • ****
  • Posts: 143
Re: Longboy's "BRATZ" Model Gas Engine. Cooling.
« Reply #17 on: September 15, 2017, 10:51:51 PM »
   Using heat sink material on the BEST FRIEND engine worked so well I bought some more with greater fining area and bolted to the perimeter of the cyl head.



Also a couple bars on the upper engine block, BRATZ has little chance of becoming a hot head in the Arizona summer. :ThumbsUp:

Wadda you mean, "It don't run"???

Offline Longboy

  • Full Member
  • ****
  • Posts: 143
Re: Longboy's "BRATZ" Model Gas Engine. Assembly.
« Reply #18 on: September 17, 2017, 06:34:51 PM »
   Almost finished here, the top side of engine.



Block and head with all external components except wiring. Tecumseh points supply the coil spark.



The legs on the crank cradle. The three slots allow pass through of rod caps to separate rods from crank shaft while in the cradle.



Loading of the bores joining crank to block.

Wadda you mean, "It don't run"???

Offline Longboy

  • Full Member
  • ****
  • Posts: 143
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #19 on: September 18, 2017, 06:17:01 PM »
    The "BRATZ" engine is now completed! :whoohoo:



Work was started first week of April.



Finished early July and up and running well about 10 days later.



The largest flywheel I have used, spacers under the feet were added later to clear my hand for hand starting.



Troubleshooting the fuel and timing to get the right sound, more displacement and same size exhaust porting as the BEST FRIEND engine gives a sharp Ba-Brat cadence to the exhaust pipes, hense its namesake.



My first summer build of an engine.   :o   I suffered greatly :ROFL: .....in the 90deg garage  :LittleDevil:.....I just couldn't help myself! :shrug:



But the job gets done! :ThumbsUp:

Come back now for the video and more photos! :popcorn:
Wadda you mean, "It don't run"???

Offline Longboy

  • Full Member
  • ****
  • Posts: 143
Re: Longboy's "BRATZ" Model Gas Engine. Proof of Life.
« Reply #20 on: September 19, 2017, 10:14:29 PM »
   Welcome to the "proof of life" video of the BRATZ engine. Enjoy! :cheers:

















 :popcorn:

Thanks for following along on this presentation!     Dave.
Wadda you mean, "It don't run"???

Offline yogi

  • Full Member
  • ****
  • Posts: 299
  • Duncannon, PA USA
    • Yogi's Workshop
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #21 on: September 19, 2017, 11:15:48 PM »
Well done Dave!!!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
Runs fantastic.

Offline Gas_mantle

  • Full Member
  • ****
  • Posts: 552
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #22 on: September 19, 2017, 11:33:34 PM »
Great engine Dave, one to be proud of  :)


Offline Nick_G

  • Full Member
  • ****
  • Posts: 274
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #23 on: September 19, 2017, 11:38:09 PM »
.
That is totally ace.  :)

Nick

Online b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 10352
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #24 on: September 20, 2017, 12:39:42 AM »
Very nice runner Dave. The slow speed is fantastic to listen to as well !!

Bill

Online Dave Otto

  • Full Member
  • *****
  • Posts: 2927
  • Boise, Idaho USA
    • Photo Bucket
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #25 on: September 20, 2017, 01:18:30 AM »
Nice work Dave!
She runs real nice!


Dave

Offline ShopShoe

  • Full Member
  • ****
  • Posts: 209
  • Central Iowa, Central USA
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #26 on: September 20, 2017, 01:26:05 PM »
Nice Work and a good runner.

I enjoyed your posts, too.

--ShopShoe

Offline Longboy

  • Full Member
  • ****
  • Posts: 143
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #27 on: September 20, 2017, 08:59:46 PM »
Thanks fellow modelers! :Love:     Dave.
Wadda you mean, "It don't run"???

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 3414
  • Barrie, Ontario Canada
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #28 on: September 20, 2017, 11:47:01 PM »
Very nice build. It looks good and runs good.---Brian

Offline Plani

  • Full Member
  • ****
  • Posts: 42
Re: Longboy's "BRATZ" Model Gas Engine.
« Reply #29 on: September 21, 2017, 07:49:01 AM »
Congratulations to this really nice running engine!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
And the O rings on the pistons seem to work well too. Did you check them yet?

Plani