Hemi GX140 build

#42
Yeah, lol... You have to be really careful with nitro when the temps drop. I'll never forget one year at Rockingham on the morning of eliminations... the temps were down and the air a bit damp. I bet I heard 6 fuel engines blow up, one right at the line when he wicked it for the burnout... BOOOOM! It was a deadly morning for the nitro motors!
 

65ShelbyClone

Well-Known Member
#43
Something else they talked about was how much more durable and reliable the engine became as they improved fuel control and vaporization. The vapor burns while liquid tends to detonate and break things when the burn and/or piston is trying to compress it. A lot of those engines were running low compression (The Surfers in particular) and no quench to speak of.

Yesterday I got the starter cup finished, today the magneto bracket done and mounted. The only thing really left is to set the timing, check fluids, and see if it'll pop on gas....and I think it will.

Decades ago this is what racers used in their fuelers. Mine came in today for the more serious fuel:
 
#44
Something else they talked about was how much more durable and reliable the engine became as they improved fuel control and vaporization. The vapor burns while liquid tends to detonate and break things when the burn and/or piston is trying to compress it. A lot of those engines were running low compression (The Surfers in particular) and no quench to speak of.

Yesterday I got the starter cup finished, today the magneto bracket done and mounted. The only thing really left is to set the timing, check fluids, and see if it'll pop on gas....and I think it will.

Decades ago this is what racers used in their fuelers. Mine came in today for the more serious fuel:
This is some great info that you'd hear nowhere else. Keep it comin'!
 
#45
Something else they talked about was how much more durable and reliable the engine became as they improved fuel control and vaporization. The vapor burns while liquid tends to detonate and break things when the burn and/or piston is trying to compress it. A lot of those engines were running low compression (The Surfers in particular) and no quench to speak of.

Yesterday I got the starter cup finished, today the magneto bracket done and mounted. The only thing really left is to set the timing, check fluids, and see if it'll pop on gas....and I think it will.

Decades ago this is what racers used in their fuelers. Mine came in today for the more serious fuel:
Cool, never seen those. Kinda reminds me of the old "Fire Injectors" JC Whitney sold back in the 70's. We always used Autolites in the drag bikes. You speak of vaporization... It was Really strange, the Pro Drag bikes (carb'd) smelled way different than the Pro Fuel and Top Fuel bikes (injected) running the same fuel. All due to atomization.
 

65ShelbyClone

Well-Known Member
#46
The only thing really left is to set the timing, check fluids, and see if it'll pop on gas....and I think it will.
I used a piston stop and degree wheel to set timing at about 34°, cranked it over with a drill motor and timing light to verify, and then put the recoil on and gave it a few tugs. Despite the tiny flywheel, it's not that hard to turn over with such low compression and a stock cam. It gave me two little pops on ether and then the rope gave up. Not much to see, so here's finding TDC:

 

65ShelbyClone

Well-Known Member
#47
After beating the tar out of my arm last week, I'm thinking that the magneto is suspect. Spark strength has become erratic and the engine doesn't want to stay lit. No change in air gap and you'll notice no kill switch, so it wasn't that either. I've had problems with these weed wacker ignitions on weed wackers. The eBay Tillotson clone is also junk, so this part of the experiment was fun, but over.

There's one thing I have have had excellent results with, and that's the combination of an inductive coil, 12v power, and a microcontroller. Different engine;
 

delray

Well-Known Member
#49
I see on your application trying to go with a lite flywheel setup. being that it's a honda crank and the engine not going to spin super high rev's. have you thought maybe trying a kohler aluminum flywheel. they are lite and cheap to find too. might be easier setup with that, then trying to reinvent the wheel or in your case the ignition. just a thought?
 
#50
After beating the tar out of my arm last week, I'm thinking that the magneto is suspect. Spark strength has become erratic and the engine doesn't want to stay lit. No change in air gap and you'll notice no kill switch, so it wasn't that either. I've had problems with these weed wacker ignitions on weed wackers. The eBay Tillotson clone is also junk, so this part of the experiment was fun, but over.

There's one thing I have have had excellent results with, and that's the combination of an inductive coil, 12v power, and a microcontroller. Different engine;
What uC do you use?
 

65ShelbyClone

Well-Known Member
#51
Thanks for posting some feed back on that carb. The frustration level with a bad carb, and a bad spark on a recoil started engine can be high.
I always make the joke that most persistent carb problems are caused by ignition. ;)

I see on your application trying to go with a lite flywheel setup. being that it's a honda crank and the engine not going to spin super high rev's. have you thought maybe trying a kohler aluminum flywheel. they are lite and cheap to find too. might be easier setup with that, then trying to reinvent the wheel or in your case the ignition. just a thought?
Will it fit a GX140 crank? There's also the complication that I don't have the 140 magneto any more whereas I do have all the parts to run digital. I wanted to in the long run ayway; it's just happening sooner now.

Ye olden MegaSquirt-I. It's not highly regarded anymore, but still does a fine job and has tons of fun features. Table switching, launch control, flat shift, flex fuel, yadda yadda.
 

delray

Well-Known Member
#52
Will it fit a GX140 crank? There's also the complication that I don't have the 140 magneto any more whereas I do have all the parts to run digital. I wanted to in the long run ayway; it's just happening sooner now.
I do remember the kohler aluminum flywheel fitting the greyhound crank for sure and if I am correct that crank is the same has the gx200. i'm assuming your gx140 also has the same tapper shaft as the gx200? either way here is the part number for the Kohler 1402502-S ,cheap on ebay $25 or offer.
little off the subject,but have you seen the new small block clone motor that now comes with a larger head bolt pattern and thicker cylinder casting for bigger bores. when that motor hits the market it will kill everything else .
 

65ShelbyClone

Well-Known Member
#53
I do remember the kohler aluminum flywheel fitting the greyhound crank for sure and if I am correct that crank is the same has the gx200. i'm assuming your gx140 also has the same tapper shaft as the gx200?
What little I've been able to find over the years suggests that the 140 has a smaller flywheel taper, perhaps similar to a GX110 or 120.

little off the subject,but have you seen the new small block clone motor that now comes with a larger head bolt pattern and thicker cylinder casting for bigger bores. when that motor hits the market it will kill everything else .
No, hadn't even heard about it.
 
#54
I do remember the kohler aluminum flywheel fitting the greyhound crank for sure and if I am correct that crank is the same has the gx200. i'm assuming your gx140 also has the same tapper shaft as the gx200? either way here is the part number for the Kohler 1402502-S ,cheap on ebay $25 or offer.
little off the subject,but have you seen the new small block clone motor that now comes with a larger head bolt pattern and thicker cylinder casting for bigger bores. when that motor hits the market it will kill everything else .
A Greyhound crank and GX200 crank are identical.
 

65ShelbyClone

Well-Known Member
#55
I can't for the life of me find a wiring harness I made for the engine in that last picture. Also missing is the ignition coil I used on that GX340. Oh well, took inventory and this is only part of what's the shelf:


That bare board on the far left has been patched back together into a fully functional EFI controller again.

I put the stock GX140 flywheel assembly back on and need to get a crank trigger rigged-up.
 

65ShelbyClone

Well-Known Member
#56
I can't for the life of me find a wiring harness I made for the engine in that last picture. Also missing is the ignition coil I used on that GX340.


I found 'em!


*squints*.....What's that say?


I put the stock GX140 flywheel assembly back on and need to get a crank trigger rigged-up.
I expect that to be on the the menu for this weekend. :cool: Once a hot ignition is up and running, getting the engine to fire will be much, much easier. I may use a regular round initially since the ECU is already set up for it, but for later I have a D585 Chevy LS2 coil with integral logic-level(5v) igniter and it's an arc welder! It has the fattest sparks I've seen and it blew the fuse in my power supply. Picked up a variety of spark plug wires for it today and am waiting for some Hall effect sensors in the snail mail, but those won't cause a delay.

And here, photo of an old failed experiment. Because reasons.
 

65ShelbyClone

Well-Known Member
#57
I was waiting for some Hall sensors in the mail and it turns out they are in fact three-wire VR sensors with the third wire being a shield ground, not a signal output. That's okay because I just outfitted the spare MegaSquirt with toggle switches for all the tach settings. Instead of soldering, unsoldering, and resoldering jumpers everywhere(and risk damaging the board each time), a flip of the switch will do. Still have to do it for the ignition output, but that's more complicated.



I had found out that the industrial inductive proximity sensors I planned on using actually can't trigger fast enough to use anything more than a four-tooth trigger wheel. That's a pretty low count, so I opted to wait and do it right which is why there's no video of it running yet.
 

65ShelbyClone

Well-Known Member
#58
Put in some time crankin' handles this afternoon.




The trigger wheel is really chunky because the sensor above was intended to read reluctor teeth on a car's flywheel. Generally the teeth need to be as wide and long as the sensor tip, so a 3.25" diameter 12-1 (twelve minus one) configuration ended up like this. It's low carbon steel so the sensor's magnet will be less prone to magnetizing the wheel. over time. I'm not afraid to say it; it was a PITA making this without a rotary table.
 
#59
Put in some time crankin' handles this afternoon.




The trigger wheel is really chunky because the sensor above was intended to read reluctor teeth on a car's flywheel. Generally the teeth need to be as wide and long as the sensor tip, so a 3.25" diameter 12-1 (twelve minus one) configuration ended up like this. It's low carbon steel so the sensor's magnet will be less prone to magnetizing the wheel. over time. I'm not afraid to say it; it was a PITA making this without a rotary table.
Beautiful! Nuthin' better than spending a day with giant precision hunks of cast iron!
 

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