Taking shape nicely! REALLY looking forward to the lower end construction portion, that’ll explain everything!
LONGBOY'S "SUPER TEE" MODEL GAS ENGINE.
- Thread starter Longboy
- Start date
Help Support Home Model Engine Machinist Forum:
- Joined
- Sep 2, 2011
- Messages
- 1,381
- Reaction score
- 370
me to. the crank connection is really puzzeling me as well.
GreggA
Active Member
- Joined
- Nov 2, 2015
- Messages
- 34
- Reaction score
- 13
So...if the pistons are all mounted on that gear arrangement they must be then, driving the cam... but the clue was given "can a distributor drive a crankshaft"
It would seem unlikely....given the camshaft would normally be smaller with a larger timing gear......wait I lost my point. something seems backwards here...the gears on the pistons are 62 tooth, so to get 2-1 ratio, that's a 124 tooth gear on the cam? How/....What? no, no, no....your doing something else right?
I hope your having fun making me wait.....
It would seem unlikely....given the camshaft would normally be smaller with a larger timing gear......wait I lost my point. something seems backwards here...the gears on the pistons are 62 tooth, so to get 2-1 ratio, that's a 124 tooth gear on the cam? How/....What? no, no, no....your doing something else right?
I hope your having fun making me wait.....
OK GreggA....going to let you and others off some and lead you to......
......"Modeling Revelation Glory"!
Actually the question was: Can a distributor drive a camshaft? You bet!
On the lead edge of the cylinder deck a couple bearing posts mount the camshaft. The distributor shaft on the lower deck passes under the heads and between the radiators on #1 and #2 cyl. and connect the two via these brass 24T- .5 Mod 90 degree bevel gears on 3/16 in. shafts.
The distributor body mounted to some scrap angle, bolted to the lower deck. A brass bushing in the distributor and a roller in the bearing post for support.
The cam lobes are fashioned from 3/8 in. round CR. Bored/ reamed, machined cut ramps and hand filed finished profile. 4-40 set screws tie them to the shaft then.
......"Modeling Revelation Glory"!Actually the question was: Can a distributor drive a camshaft? You bet!
On the lead edge of the cylinder deck a couple bearing posts mount the camshaft. The distributor shaft on the lower deck passes under the heads and between the radiators on #1 and #2 cyl. and connect the two via these brass 24T- .5 Mod 90 degree bevel gears on 3/16 in. shafts.
The distributor body mounted to some scrap angle, bolted to the lower deck. A brass bushing in the distributor and a roller in the bearing post for support.
The cam lobes are fashioned from 3/8 in. round CR. Bored/ reamed, machined cut ramps and hand filed finished profile. 4-40 set screws tie them to the shaft then.
Last edited:
I’m really enjoying this! Can’t wait to see you prove your design.
"You hear that Longboy? The boys back in the forum are waiting. This piece of junk better run at the end of your presentation..........or else"! 
The drive from the crankshaft is furnished by 20/40 MXL belt cogs. Deck slot milled in for a straight to distributor shaft connection with the drive belt. Dist. cap is 3/4 in. internal diameter PVC end cap.
From 3/8 brass hex stock, a post and idler wheel keep the top of belt from dragging against the end of the slot.
And from the underside. On the right in the photo is the cam trigger for the Tecumseh points set. Back on the top side, I see now that I will have room for an accessory between the cog and the back of vertical leg of the tall frame piece.....very pleased! Off to Ace Hardware to get the accessory!
From 3/8 brass hex stock, a post and idler wheel keep the top of belt from dragging against the end of the slot.
And from the underside. On the right in the photo is the cam trigger for the Tecumseh points set. Back on the top side, I see now that I will have room for an accessory between the cog and the back of vertical leg of the tall frame piece.....very pleased! Off to Ace Hardware to get the accessory!
SUPER TEE will now be a fan cooled motor. A pair of 2 in. dia. fan blades from Ace breezes air between the cylinders at twice crank speed. Hubs are made from Delrin and are epoxyed to the fan hub recessed area. The right side fan is pressed fit onto a shaft riding in a bearing post.
The left fan hub is over bored with a # 11 or #12 drill bit to the 3/16 in. distributor shaft to free spin upon in counter rotation to the distributor drive. The fans turn counter clockwise. O-rings bring the power up driven by the stub shaft for #3 cylinder.
The left fan hub is over bored with a # 11 or #12 drill bit to the 3/16 in. distributor shaft to free spin upon in counter rotation to the distributor drive. The fans turn counter clockwise. O-rings bring the power up driven by the stub shaft for #3 cylinder.
I'm waiting to see more .... I still do not understand how you set up the crankshaft and combine them together.
Jim
New Member
In my professional working life I was never successful using any adhesive on Delrin. I’m curious what you used and how well it holds up.
Thanks Jim. 5 minute epoxy. The fan side of its hub is bored to just before the hub set screw the diameter of the pulley stem and pressed in. The length of the bore in is shallow, under 3/16 in. and a dab of super glue or epoxy might help the grip. Not an issue on the right side fan as the pulley is a press fit and fan is set screwed to a shaft but the fan on dist. shaft runs free. More ways than one, I could of over bored thru the fan hub and pressed set the pulley in a half inch, a better mate of items. With no twisting or bending, pulley on dist. shaft fan, unlikely to separate anyway. Dave.
Last edited:
A bar of Delrin for the intake manifold.
Ported for some brass 3/16 in. tubing to the valve blocks.
Trimming excess material away after port holes drilled.
The Traxxas carburetor is mounted horizontal from the bottom on a barrel plenum chamber. #4-40 screws draw it up to the manifold body.
Fitment to engine before trim.
Ported for some brass 3/16 in. tubing to the valve blocks.
Trimming excess material away after port holes drilled.
The Traxxas carburetor is mounted horizontal from the bottom on a barrel plenum chamber. #4-40 screws draw it up to the manifold body.
Fitment to engine before trim.
A straight shot in from the distributor for the wiring to the spark plugs.
I didn't find the proper stainless plug clips on Ebay this time. These mini 'gator clips do the job and look fine.
Finalizing SUPER TEE! A free standing engine, vertical fuel tank strapped to the side. Just no room on the deck for it!
Some paint work now and re-assembly. Tighten up the loose items, loosen up the tight items and then readied for run trials. You will get your first look/see at the business side of this engine......this weekend! Dave.
I didn't find the proper stainless plug clips on Ebay this time. These mini 'gator clips do the job and look fine.
Finalizing SUPER TEE! A free standing engine, vertical fuel tank strapped to the side. Just no room on the deck for it!
Some paint work now and re-assembly. Tighten up the loose items, loosen up the tight items and then readied for run trials. You will get your first look/see at the business side of this engine......this weekend!
Dave.
Although it looks a little disconcerting, the crank pin phasing is correct for SUPER TEE.
And now...."A Little Engineering Explanation" by Longboy!
Crank pins for 3 cylinder engines are at 120 degrees. Looks like the figure on left at 12, 4 and 8 o'clock position looking end wise down crankshaft. For a geared crankshaft, it is 12, 8 and 8 looking across, right to left next figure. Firing order 1-2-3.
Yep.....I did......do a 12,4,8 set-up initially and it looked outta wack, the pistons coming up to TDC then. Apparently, I did get it right figuring in the counter rotation.
Come back tomorrow and see SUPER TEE at work! Dave
And now...."A Little Engineering Explanation" by Longboy!
Crank pins for 3 cylinder engines are at 120 degrees. Looks like the figure on left at 12, 4 and 8 o'clock position looking end wise down crankshaft. For a geared crankshaft, it is 12, 8 and 8 looking across, right to left next figure. Firing order 1-2-3.
Yep.....I did
......do a 12,4,8 set-up initially and it looked outta wack, the pistons coming up to TDC then. Apparently, I did get it right figuring in the counter rotation.
Come back tomorrow and see SUPER TEE at work!
Dave
Welcome to todays introduction of the Longboy "SUPER TEE" model gas engine!
3 cylinders. 43CC's. Bore & Stroke: 1.0 x 1.125 inch.
Build of SUPER TEE started Sept 5th and completed Nov 9th. (10 weeks).
Something new! Featuring geared cylinders to crankshaft.
SUPER TEE is a fine runner!
See it now!
Thanks for coming by to follow the progression of SUPER TEE. Share your thoughts and questions. Sometimes....I have answers! Dave
3 cylinders. 43CC's. Bore & Stroke: 1.0 x 1.125 inch.
Build of SUPER TEE started Sept 5th and completed Nov 9th. (10 weeks).
Something new! Featuring geared cylinders to crankshaft.
SUPER TEE is a fine runner!
See it now!
Thanks for coming by to follow the progression of SUPER TEE. Share your thoughts and questions. Sometimes....I have answers! Dave
Attachments
Them with doubts just got their come uppance! I love it!!!
What kind of fuel are your running, and what is your oil mix? I assume you’re lubing the upper with something in the mixture.
Beautiful (and damn fast!) build!!! Thanks for sharing the progress front to back.
P.S. love the atmospheric intake valves!!!
What kind of fuel are your running, and what is your oil mix? I assume you’re lubing the upper with something in the mixture.
Beautiful (and damn fast!) build!!! Thanks for sharing the progress front to back.
P.S. love the atmospheric intake valves!!!
