Model Engine Maker

Engines => Your Own Design => Topic started by: Longboy on December 26, 2014, 04:43:07 AM

Title: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 26, 2014, 04:43:07 AM
About 3 yrs. since I built my first I/C twin engine. My "GEMINI" is a good start but I want another crack at an inline twin to address a couple of shortcomings in its build. Can I make improvements in servicing, durability and a new feature using basic machine shop know how and NO PLANS :o in the same scale? :thinking: ....The story of "OVERTIME" starts this weekend! :popcorn:

(https://i.imgur.com/fWYoxNg.jpg)

Title: Frame,bearings & flywheel.
Post by: Longboy on December 28, 2014, 01:13:20 AM
(https://i.imgur.com/BmfLird.jpg)

  With this engine being an open crank style, a 4 piece frame is the backbone of Overtime. Two end plates, a deck plate and base plate. The deck is overlapped to the endplates and the endplates are overlapped to the base. Eight, 6-32 socketheads holds it together. For servicing you can remove the deck with all top side components as a unit and either end plate for access and removal of the crankshaft.  A couple of brass bearing holders for each end plate will be the crankshaft support. I'll be using Oilite bushings here, 3/4 inch long ( 1/2 in. shown). More bearing area than a set of roller bearings that also will work fine, just builders choice here!
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: stevehuckss396 on December 28, 2014, 02:49:24 AM
Interesting!  Wondering, how is the rotating assembly lubricated? Do you just put a few drops of oil in places before a run?
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 28, 2014, 04:23:56 AM
Hasn't been necessary....yet! Oilite bushings are self lubed, impregnated with 30W. Initial first runs a couple drops of WD40. I'll see how it goes after more run time.   http://en.wikipedia.org/wiki/Oilite
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 28, 2014, 06:09:51 PM
(https://i.imgur.com/JriqltN.jpg)

A brass flywheel is secured to the crankshaft with a taper collet made from Delrin. A 3 screw retainer makes the press fit or actually draws the flywheel back into the collet. This 1st collet was too short, didn't get the grip and a longer one was made without the split and tried out...the right length worked out better! The Delrin seems to compress enough without having the split down the side. 

(https://i.imgur.com/raZKAUA.jpg)

Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: crueby on December 28, 2014, 08:46:49 PM
Is the hole in the flywheel tapered same as delrin as well? Neat way to do it.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 28, 2014, 10:33:02 PM
Yes crueby....it has to be a matching taper inside the flywheel hub.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 29, 2014, 06:19:09 PM





(https://i.imgur.com/2mDqgbz.jpg)



A fabricated 5 piece crank starts with 12L14 steel web material. A generous length of each web 5/8in. long for heft and support of a 5/16in main shaft and 1/4in throw pin of stainless round stock. Drilled and reamed as one piece then parted to length.

(https://i.imgur.com/SnvPhG7.jpg)

(https://i.imgur.com/rWFm9vW.jpg)

(https://i.imgur.com/OvhzXkq.jpg)

Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Roger B on December 29, 2014, 06:26:54 PM
Good start on the "Overtime"   :ThumbsUp:  :ThumbsUp: I will be following along  :popcorn:  :DrinkPint:
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 30, 2014, 05:47:57 PM
(https://i.imgur.com/ECu3ZFV.jpg)

The webs are internally balanced to the piston/rod assembly. Two half inch through holes at 5/8 inch yields a hair under 1 oz. of removed material.

(https://i.imgur.com/1DzmTrH.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: tvoght on December 30, 2014, 06:06:31 PM
I'm watching and enjoying your build. Your Delrin tapered collet gave me an idea at the precise moment I needed one!

--Tim
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 30, 2014, 06:14:25 PM
Good Tim, something I presented here helped you. :ThumbsUp:    Dave.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on December 31, 2014, 07:24:38 PM
The shaft is joined to the web by press fit. A straight knurl gets the bite into the web. Some cold bonding agent, either thread locker or Epoxy, supplements the primary grip of the knurl when driven in. After pressing, the assembly is chucked in the lathe. The shaft is paralleled to the web with some light taps and the assembly is then set aside and repeated for the other end.

(https://i.imgur.com/8EZoVTz.jpg)

(https://i.imgur.com/tXsUKOG.jpg)

(https://i.imgur.com/4UnbmRt.jpg)

(https://i.imgur.com/MXxSIQy.jpg)



Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Graham G on December 31, 2014, 07:34:59 PM
 :popcorn: Yup i'm in for the ride, I like what I see so far
cheers
Graham
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 02, 2015, 06:40:16 PM
(https://i.imgur.com/zFHu6mJ.jpg)

The weak link in a 360 Deg. crankshaft for a two bearing inline twin is the throw pin. Its long and narrow and joins the heaviest parts of the crank. I used 1/4in. stainless round here, upsized from my GEMINI engine.

(https://i.imgur.com/0KzDLK7.jpg)

The pin is locked to the web with a 10-32 set screw instead of being pined or silver soldered to the web. The pin has to be removable as I am using roller bearings on the rods.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 04, 2015, 06:54:31 PM
(https://i.imgur.com/9HgKGqw.jpg)

 In the big end here I'm using FR168ZZ bearings. The rods are beefier than need to be for scale to accommodate the 1/4in. throw pin and hold the bearing. The flange makes the bearing support slightly broader around the pin and also shows more rigidness in the 90deg. relation of rod to crank. You want some lateral float for the rod on the pin between the webs.

(https://i.imgur.com/q567ppg.jpg)

In the lathe the throw pin is reduced in diameter a couple thousands by file between the lines here where the rod runs on the pin. Area is cleaned up with 400grit carbide paper and now the rod will "walk" between these lines.

(https://i.imgur.com/Ep8FclW.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 05, 2015, 10:39:46 PM
(https://i.imgur.com/RHr45zi.jpg)

The con rod starts out as a piece of 3/8in x 3/4in aluminum bar for the big end and 3/8in same hex stock for the piston end. The beam is hollowed by a tap drill for 6-32 threads and a stud joins the hex to beam. With two pieces, the final beam length of the assembly will be determined later. R144ZZ bearings in the hex join the piston with a 1/8in pin locked in position with 4-40 set screws.
 
(https://i.imgur.com/OEhG7BR.jpg)

 In this mock up I have a "too" long rod that would make a Diesel cry out. The beam is unscrewed from the hex end and shortened to where the piston rises to the top of the cylinder at this time.

(https://i.imgur.com/gu2EoFs.jpg)

 Components are then scaled in to aid in the counter weighting.

(https://i.imgur.com/RY0lFMT.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 06, 2015, 08:23:36 PM
(https://i.imgur.com/BfHLEuw.jpg)

Doing the static balancing here, you can see a 3rd crank web member between the con rods. Saw this on an Italian modelers twin engine. Don't know why its there but I had to have it and esthetically keeps the continuity of the crank webs the whole length of the crankshaft now. Internally lightened about 50% and is locked to the throw pin with 2 set screws. For balance note the neo magnets on top of the outboard webs.

(https://i.imgur.com/xQSDFHG.jpg)

The weight of a couple of nuts completes the balance. I weigh the nuts (do not weigh neo magnets) and take the weight reduction externally at the nose damper.

   (https://i.imgur.com/YGB55C9.jpg)

Looks like I need a near half OZ.                                                                                                 

(https://i.imgur.com/kJ8obtc.jpg)

And ready to roll.

(https://i.imgur.com/AqUzHqb.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Roger B on January 06, 2015, 08:31:42 PM
Coming along nicely  :ThumbsUp:  :ThumbsUp: I'm not sure about the need for the centre web on a four stroke twin  :headscratch: On a two stroke it would be essential for crankcase compression. However as you say it seems to complete the crankshaft.
Title: Re: Longboy's "OVERTIME" I/C Twin! Cams & valvetrain
Post by: Longboy on January 07, 2015, 07:33:39 PM
(https://i.imgur.com/oUwpLi1.jpg)

I make camshafts by pieces. :???: Starting out with 5/8in CR round in the lathe with one jaw shimmed (or a jaw offset in chuck) and drill for a 3/16in. shaft. Your amount of offset will determine the baseline lobe lift.                   

(https://i.imgur.com/VduJTZd.jpg)

I'll be using a prototype lobe with the engine and will need to make 3 new lobes. Dye the end of shaft and I put my lobe on a short length of shaft, insert into new stock and trace the profile to new stock.

(https://i.imgur.com/02OuNEg.jpg)

With the stock overhanging in the machinists vise, in 5 steps ( each side of lobe nose) mill to the scribe line your rough profile.

(https://i.imgur.com/15fyubY.jpg)

This what it looks like. The shaft is cut back between the lobes for part lines and to drill & tap for a 6-32 set screw to lock the lobes to its shaft.                                                   
Title: Re: Longboy's "OVERTIME" I/C Twin! Cams & valvetrain
Post by: Longboy on January 08, 2015, 08:48:40 PM
(https://i.imgur.com/busdvFo.jpg)

In the bench vice file over the milled facets to blend into a traditional shape finished lobe.  You can get them perpendicular flat to their shaft by filing without being machine cut perfect and they will work fine.

(https://i.imgur.com/dnk6ESW.jpg)


Without a degree wheel the only thing I can check is the lobe lift running the profile on the lathe. Shows .180in lift here but for its duration, do I have a race profile.....or a RV profile? :shrug: Looking for a smooth idler I will have to wait till assembly of Overtime and see the relations of valve open duration to the crank degree position.                                                               
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: smfr on January 08, 2015, 09:27:58 PM
Longboy: just a tip for the forums. Putting an empty line before and after your pics would make your posts more nicely formatted.

Interesting to see this build progress!

Simon
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 09, 2015, 04:11:17 AM
Thanks Simon...I struggle to format and margin the text with the photos. I'll try the empty line segregation.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Jo on January 09, 2015, 07:02:58 AM
There you go Dave: I have added a few empty lines to space out your pictures on your previous posts  ;)

Jo
Title: Re: Longboy's "OVERTIME" I/C Twin! Running changes
Post by: Longboy on January 09, 2015, 08:08:12 PM
(https://i.imgur.com/lZzSkTL.jpg)
                                                                                                                                                                           
I had two pairs of timing gears available for Overtime. Using the larger dia. of the two I set the meshing using a transfer punch into the bore of the cam drive and finger spin. Then make the mark and drill both end plates for the camshaft bearings......it was later I saw reasons that my cam to crank centerline would be too close together.  :ShakeHead:  My "added feature" :stir:  would be too close to the nose damper.     
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           (https://i.imgur.com/ZKXT73G.jpg)                                                                                                                                                                       

To set the cam farther from the crank I ordered some Delrin idlers and then used my smaller diameter pair of gears. The deck plate had to be shifted over toward the cam side so the lifters would be over the camshaft then . Since I didn't have the deck bored for the cylinders yet it was a minor operation . :ThumbsUp:

(https://i.imgur.com/kvKDQYY.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin! Cams & valvetrain
Post by: Longboy on January 11, 2015, 06:05:33 PM
(https://i.imgur.com/eXhOpvz.jpg)

On top of the cyl. heads go a pair of rocker pedestals. 3/8 x 3/4in brass bar is free style cut to something that looks like it will work :) with a roughing mill and a clean finished mounting tab that screws into the side of the heads. Its pattern is traced onto the bar stock and the duplicate is cut and drilled.

(https://i.imgur.com/9WU9S7Q.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Roger B on January 11, 2015, 07:13:08 PM
If I understand correctly, the pedestals will be fixed to the head by the hole in the thinner section and the rockers will pivot on a pin through the hole in the thicker section?
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 11, 2015, 09:30:49 PM
That is correct Roger! :ThumbsUp:
Title: Re: Longboy's "OVERTIME" I/C Twin! Cams & valvetrain
Post by: Longboy on January 12, 2015, 05:31:52 PM
(https://i.imgur.com/OX4od6v.jpg)

This is called "rocker arms on a stick"....... not to be confused with a county fair treat! ^-^ CR steel here a pair at a time, their counterparts are a mirror image by a staggered cut. Brass bushings for the pivot and stainless 4-40 socket caps for the pushrod with homegrown lock nuts.

(https://i.imgur.com/xLJvhDS.jpg)

A 3/8in brass rod is threaded down about 3/4in and a straight knurl is run across the threads for a superior finger grip in setting the pushrod length. Drilled and threaded for the stainless screws.

(https://i.imgur.com/SVaiUqw.jpg)

Finally the rockers are flame colored to a plum/ violet hue for contrast. I like the effect and here a matched pair are done!

(https://i.imgur.com/QM5mrqJ.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin! Cylinders & heads
Post by: Longboy on January 13, 2015, 06:49:42 PM
(https://i.imgur.com/70FgEWW.jpg)

The radiator is bored for a DOM tube that takes 7/8in. dia. pistons. Separate block style heads will sit on top.

(https://i.imgur.com/CqUqMsl.jpg)

To reduce the bore centerline distance, the radiators are milled & fly cut flat.....and butted together on the deck.

(https://i.imgur.com/eOjPVIv.jpg)

(https://i.imgur.com/Uh1HKxI.jpg)

The shinny arc inside of the radiator is a slight overbore to a 1/4in. depth from the bottom. A film of Epoxy here bonds the cylinder to the radiator as a unit then.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: 90LX_Notch on January 14, 2015, 02:52:08 AM
Longboy-

This is an interesting build.

-Bob
Title: Re: Longboy's "OVERTIME" I/C Twin! Cylinders & heads
Post by: Longboy on January 14, 2015, 05:57:55 PM
(https://i.imgur.com/tIN8rls.jpg)

Thanks Bob and others who follow!...... The deck is bored oversize to the O.D of the cylinders, squared up to the crank centerline and a trio of 4-40 screws tie them together. Though it ended up not necessary, the deck overbore when the crank is close to the underside and a longer stroke displacement or just short rods can aid in clearance with rod angles. I had enough clearance with a 1 inch stroke without shaving the deck underside or narrowing the rod beam.

(https://i.imgur.com/lA7gdv2.jpg)

(https://i.imgur.com/9RRv7Tz.jpg)

Clamped together, scribing a perimeter line around radiators to help locate the screws in deck.
Title: Re: Longboy's "OVERTIME" I/C Twin! Cylinders & heads
Post by: Longboy on January 15, 2015, 07:57:31 PM
(https://i.imgur.com/dPhowSF.jpg)

With the cylinders now located on the frame work begins on the cyl. heads. A 3/16in. deep combustion chamber bored to the O.D. of the cylinder here.

(https://i.imgur.com/W6pElcf.jpg)

The cylinder rises above the radiator 1/8in and a 1/16in O-ring is laid over. No need to make gaskets, the head sits on the O-ring to make the seal.

(https://i.imgur.com/YCBQRta.jpg)

The sides of each head is fly cut to match the radiator butt when sitting on top of the cylinders. Heads now ready for drilling of ports, sparkplug, valves guides, rocker pedestals and head bolts. :)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Graham G on January 16, 2015, 09:10:54 AM
 :popcornsmall: Hi there Longboy, now I'm really getting settled in, I do like your methods and I have a question, The cam gear assembly with the plastic idler gear, should it not be the same size as one or the other gears as you would loose the 2-1 ratio or is it maybe an optical delusion on my part ha ha.
As you may be able to tell, I am not that great with working out gears/ratios
Cheers
Graham
 :NotWorthy:
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: 90LX_Notch on January 16, 2015, 11:01:08 AM
Graham-

 An idler has no effect on the final ratio.

-Bob
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Stuart on January 16, 2015, 11:48:41 AM
Graham

To get your head round what Bob has said think about teeth not size one tooth one the driven will move one tooth in the gear train

The ratio is the number of teeth on the driven and driver all the idler does is to transmit one tooth and change direction

Stuart
Title: Re: Longboy's "OVERTIME" I/C Twin! Head work
Post by: Longboy on January 16, 2015, 06:58:46 PM
(https://i.imgur.com/x8GEnyD.jpg)

Valve guides from 3/8in brass rod test fitted here.

(https://i.imgur.com/0eOaf8y.jpg)

The horizontal V-groove in the machinist vise provides an arbitrary head angle for the spark plugs. Shown is a flat being cut in the chamber with a 3/16 end mill for a 90 deg. approach by the center drill, then tap drill for CM6 sparkies.

(https://i.imgur.com/6E9v9TG.jpg)

The head is milled & flycut across parallel to the plug angle to a point to expose the plug hex to get a socket around it.
From the top side of heads the CM6 hex will not clear the opening to engage the head threading. Since they don't make a reduced shank 13/16in end mill to fit my machine, the China special boring bar will broaden the space. 

(https://i.imgur.com/k2nsqRR.jpg)

The heads are cross milled & fly cut parallel to plug angle to a point exposing the hex to get a socket around them.  :ThumbsUp:
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Graham G on January 16, 2015, 09:20:45 PM
Thanx Bob and Stuart, it's dammed easy when explained simply :slap:
Cheers
Graham
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 17, 2015, 11:37:26 PM
(https://i.imgur.com/U3ilboz.jpg)

The valves are made form 1/4-20 long stem hardware bolts. :o  ....yep, they cut and work fine!

(https://i.imgur.com/JUVKfKN.jpg)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: 90LX_Notch on January 18, 2015, 03:08:31 AM
LB-

I assume the bolts are stainless.

-Bob
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 18, 2015, 03:30:31 AM
They are Zinc plated grade fives Bob.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: 90LX_Notch on January 18, 2015, 03:47:12 AM
I know them well.  I use 5/16 to make shear pins for my snowblower. 

Why not use stainless for the valves?
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 18, 2015, 04:06:47 AM
You know, I tried these out for valves previously. Thought they would chunk & gall up under the tool bit but getting close to the final diameter and taking light cuts under oil they clean up fine, even the valve face which they must. So I continue you use them!
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 19, 2015, 06:07:20 PM
(https://i.imgur.com/lDtvQRE.jpg)

Five head bolts are used due to the porting, one intersecting the butt of the heads. Between the plugs, the exit ports for the intakes.

(https://i.imgur.com/3Dxq7UR.jpg)

Outboard valves are the exhaust, inboard are intakes. A two step port drilling is needed to get between the plug boss, valve guide and head bolt. 1st step starting at the butt into the valve guide seat and then the 2nd.step drilling an exit straight outside along the butt seam. From this 1st. access point a transfer punch is used to mark the valve guide when placed. Removed and drilled separately, then epoxied into the head. Access point is then sealed off with short 10-32 set screws.

(https://i.imgur.com/IC0Cy3e.jpg)

(https://i.imgur.com/tUdPEHo.jpg)

A diagonal is milled at the head corners and then arc filed for styling. 8)

Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Roger B on January 19, 2015, 06:58:23 PM
Looking good  :praise2:  :praise2: I have used stainless steel bolts/screws to make my valves so far.
Title: Re: Longboy's "OVERTIME" I/C Twin! Electrics
Post by: Longboy on January 20, 2015, 06:02:09 PM
(https://i.imgur.com/znzjhPv.jpg)

Tecumseh ignition points are located on the end plate and are camshaft driven. I like their compact size that wraps around the cam trigger. The coil stud attached to the tension spring is low and inside on the plate here. I want to bring that to the outside edge of frame for easy connect.

(https://i.imgur.com/ZGXVFzR.jpg)

An eyelet over the stud with a brass rod encased in a Delrin tube threaded to a bracket mounted to the side of plate solves the location issue. Condenser to be mounted to opposite side plate edge.

(https://i.imgur.com/IEByUpE.jpg)

When the bottom plate is joined to the end plate the stud sits on its top for a ground out. A relief area is milled out for the stud here for isolation.



Now ready to work on the "special feature"!   ....anybody see it yet?  :thinking:
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Perry on January 20, 2015, 07:05:47 PM
hmm would that be a fuel tank?
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 21, 2015, 12:05:38 AM
Nope....sorry Perry. :facepalm: Fuel tank is the wrong answer...... but you do have this on your 2 cyl. engine!  Anyone else!
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Roger B on January 21, 2015, 07:35:16 AM
As you are working on the ignition system I would guess that it is the distributor.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 21, 2015, 04:57:49 PM
You got it Roger B. :cheers:
Title: Re: Longboy's "OVERTIME" I/C Twin! Electrics
Post by: Longboy on January 21, 2015, 06:55:51 PM
On my "Gemini" twin, I have a dedicated dual fire coil and 6 volt battery ignition mounted with the engine on a oak board. For "Overtime",  I wanted a free standing engine and be able to use my traveling 3 volt battery pack & coil. To do so requires a distributor.

(https://i.imgur.com/dTiF3VX.jpg)

From Home Depot, I picked up both a 1-3/8in and 1 inch PVC end cap and bag of #8 brass machine screws & nuts. Used the 1 inch cap on the engine. Three drilled and taped holes located for coil and plug leads.

(https://i.imgur.com/Fsw4D1Z.jpg)

The rotor is Delrin with brass strap, stainless #4 screw. The coil screw is dished out to a ball & socket mate with the rotor screw head with a round nose tool bit on lathe. Threaded into cap from the inside, when placed over the distributor base it is threaded down till contact with the rotor screw and locked nutted in place.

(https://i.imgur.com/D60yEYL.jpg)

Rotor brass is located on the camshaft for line up with the plug leads. Distributor base is machined with a wrap around to the side of the end plate and a matching piece serves as a timing gear guard at other end.

(https://i.imgur.com/gCh2qT7.jpg)

(https://i.imgur.com/JtJVZYw.jpg)

Plug lead screws are threaded in till contact and locked. Being a sweep contact, fine tune by finger rotating camshaft and feeling for it then. The screws where replaced with longer studs to fasten the wiring. Though a press fit to the base, a finger screw was added to hold cap in its base.......cuzz I like doo dadz on the engine! :Lol:
Title: Re: Longboy's "OVERTIME" I/C Twin! Shoes
Post by: Longboy on January 22, 2015, 06:13:08 PM
(https://i.imgur.com/V5h1SEA.jpg)

Overtime went to the cobbler last month. Some steel tabs, hood bumpers and custom nuts mounted to the bottom plate should make it as stable ....as a turtle!  :Lol:

(https://i.imgur.com/ScyWKjb.jpg)

(https://i.imgur.com/MGqd15J.jpg)

Title: Re: Longboy's "OVERTIME" I/C Twin! Finish up
Post by: Longboy on January 23, 2015, 07:29:37 PM
(https://i.imgur.com/8weoPiG.jpg)

Delrin intake is used with .10 to.15 size carburetor. Press fit brass tubes join intake to engine........I didn't like the looks with the carb jutting out from the engine too far and a duplicate was made at a right angle shown on engine here.

(https://i.imgur.com/uMnCYjJ.jpg)

A gathering of parts for the fuel tank. I used the decorative steel tube with a nickel finish for both the tank & muffler.

(https://i.imgur.com/QKWQnVD.jpg)

Cutting off the neck of mini liquor or energy drink bottles make great fuel filler necks for fuel tanks. :ThumbsUp:

(https://i.imgur.com/mD9AENb.jpg)

Some fillister head bolts turned into studs by cutting heads off.

(https://i.imgur.com/7ndhJMW.jpg)

(https://i.imgur.com/q4GYmDY.jpg)

The exhaust port is threaded for them that is thru drilled and tapped for 4-40 socket heads to secure muffler. Stud is cross drilled to exit into muffler after spacing out with brass collars.

 :popcorn:.....Hey come back this weekend to the conclusion to Overtime's build with some tips, troubleshooting, the beauty shots and maybe a video! :)

Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Roger B on January 23, 2015, 07:51:42 PM
We're waiting for the happy dance  ;) Tutus are available from various longstanding (or longsitting) members of the forum  :ThumbsUp:  :ThumbsUp:
Title: Re: Longboy's "OVERTIME" I/C Twin! Build tips
Post by: Longboy on January 24, 2015, 07:38:04 PM
(https://i.imgur.com/lJXuWwO.jpg)

Instead of a press fit for the lifter guides, set screws are used to secure them to the deck. The lifter heads are small enough to pass thru removing them with the guides otherwise, depending on how long the lifter stems are, you may have to pull the cam to drop them out the bottom.

(https://i.imgur.com/StKsdpH.jpg)

The brass collar in front of the timing gear is the collet knockout. Pushing and twisting the flywheel, as it will ride over this collar pops the collet for removal then.

(https://i.imgur.com/0tNAnqh.jpg)

Flywheel retainer is drilled & tapped for a stud and brass acorn nut. Socket on the cordless drill for a starter drive!

(https://i.imgur.com/09EIOzm.jpg)

One of Overtimes cylinders had no compression. To reveal the leak, some dish soap suds over combustion chamber, a blow off nozzle from your compressor set to 10PSI into port shows where. In this case some epoxy dried on the valve guide seat preventing the seal.



Title: Re: Longboy's "OVERTIME" I/C Twin! Troubleshoot
Post by: Longboy on January 25, 2015, 03:59:17 AM
(https://i.imgur.com/g4EETh5.jpg)

With the valve train set up now, I see that my lift and duration on the lobes is too great. The valve keeper bottoms on valve guide stem. Re-profile the lobes and cut lobe lift back by .035 and I have a nice idle cam profile.

(https://i.imgur.com/VG5R8ng.jpg)

Checking the spark here. The distributor cap rocked some as the rotor made contact. Some filing of rotor tip and a spin of the camshaft with electric drill for wear in left some brass dust  under cap and proper clearances.

(https://i.imgur.com/Whuyu1T.jpg)
Some paint work in black and polishing the bright work...... and it looks like I'm ready to go!  :whoohoo:
__________________

Title: Re: Longboy's "OVERTIME" I/C Twin! Showcase
Post by: Longboy on January 25, 2015, 06:59:04 PM
     Welcome to the reveal of my new engine! :cheers: Work on "OVERTIME" was started Sept. 25th and its first signs of life happened Dec. 15th.

(https://i.imgur.com/QGJbFji.jpg)

I meet my goals & benefits of a distributor ignition, a stronger crankshaft and boxed open frame.

(https://i.imgur.com/TvSC7hc.jpg)

Pleasant solitude hours in the garage. A few trips to metal supply and hardware store.

(https://i.imgur.com/NZKkv4r.jpg)

And then its time! :whoohoo:

(https://i.imgur.com/C6lMJjo.jpg)

(https://i.imgur.com/DuoFEIl.jpg)

(https://i.imgur.com/9qK94yJ.jpg)

(https://i.imgur.com/wjtjFpz.jpg)

....Well that about does it for Overtime........(not so fast LONGBOY.... :thinking:.....WHERE'S THE VIDEO?  :popcorn:) ...Geez you guys are a tough crowd! :Lol:




https://www.youtube.com/watch?v=qh09Fsku3ZU

Hey thanks for following along on this project. "OVERTIME" is alive and well...........see my other model engine projects on YouTube, Longboy4.      Dave.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Roger B on January 25, 2015, 07:05:30 PM
Great runner and great video  :praise2:   :praise2:  I'm proud if I can get the video up without Jo having to fix the link  ::)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: fumopuc on January 25, 2015, 07:09:43 PM
Hi Dave, congratulations for this runner. I like the "open" design of this engine.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Jo on January 25, 2015, 07:10:20 PM
 8) Very nice, I wish mine did that  :(

I'm proud if I can get the video up without Jo having to fix the link  ::)
I have my uses  ;)

Jo

Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: tvoght on January 25, 2015, 07:15:04 PM
Congratulations! Overtime idles beautifully.

--Tim
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Kim on January 25, 2015, 07:28:13 PM
Hi Dave,
Congratulations!  It runs beautifully. You should feel quite proud!
Thanks for sharing the build and the video!
Kim
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Graham G on January 25, 2015, 08:20:31 PM
 :jumpingsmileys: very nice and it runs well too.  :ThumbsUp:
Cheers
Graham
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: 90LX_Notch on January 25, 2015, 08:41:59 PM
Awesome Dave.  What an inspiring build.  It runs very well.

-Bob
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Perry on January 25, 2015, 09:56:17 PM
Runs like a dream  :ThumbsUp: congratulations !
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Admiral_dk on January 25, 2015, 10:51:20 PM
Looks good and runs nicely  :cartwheel: ..... which makes me miss the sound much more .....  :old: .... sorry .... senior moment (muted speakers)  :slap:

Enjoy your well deserved beverage  :cheers:
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: ths on January 26, 2015, 01:29:22 AM
Great build, runs beautifully. No wonder you're pleased. Cheers, Hugh.
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 26, 2015, 05:57:47 PM
Thanks fellow hobbiests! :praise2: I'm probably going to go with a larger fuel tank for Overtime.....that extra cylinder is using all the gas up! :lolb:
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: vcutajar on January 26, 2015, 08:06:47 PM
Great job Dave.

Thanks for the build log.

Vince
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Perry on January 26, 2015, 09:18:07 PM
Watched it again , love the mechanical sound it makes - perhaps the tappets? Have you considered to enclose the bottom to allow splash lubrication? One wall could be from plexi or similar to allow view on rotating components. Just my thoughts

I also like intake being made from delrin.. No heat transfer..
Peter
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Brian Rupnow on January 27, 2015, 12:24:35 AM
Lovely job, well done. A very nice running engine. Congratulations.---Brian
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 27, 2015, 05:44:26 AM
Watched it again , love the mechanical sound it makes - perhaps the tappets? Have you considered to enclose the bottom to allow splash lubrication? One wall could be from plexi or similar to allow view on rotating components. Just my thoughts

I also like intake being made from delrin.. No heat transfer..
Peter

Thanks Peter. I have just enough WD40 in the Coleman fuel to sling a few droplets onto the cams for lubrication but not sling oil all over the table. Since there are oilite bushings and roller bearings for crank and rods there is no lub maintenance of the bottom end.  Delrin a good material for intakes! When I start Overtime my index finger is over carb with thumb on back of manifold so when I refuel and choke start again, I never get burned. :ThumbsUp:
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: Longboy on January 28, 2015, 05:13:31 PM
(https://i.imgur.com/PUTUOOY.jpg)

Overtime gets a new underslung fuel tank to extend run times to 14 minutes. :)
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: metalmad on January 28, 2015, 06:34:22 PM
Hi Dave
 Top Runner, Congratulations on a great Build  :praise2:
Pete
Title: Re: Longboy's "OVERTIME" I/C Twin!
Post by: ShopShoe on January 29, 2015, 01:55:37 PM
Didn't catch the video until today. Congratulations on a smooth runner. The final clean-up makes it look good as well.

--ShopShoe
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