Go Back   DIY Go Kart Forum > Building Plans And Advice > Engines & Clutches

Notices

Reply
 
Thread Tools Display Modes
  #1  
Old 10-30-2018, 04:26 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default GX140 Hemi build

I'm starting this so I don't get tempted to clog-up another thread with my own stuff.

I've had this GX140 for about 25 years and it was always used for experimenting. It was disassembled 10+ years ago and I thought it got thrown out, but low and behold I found the parts! The original head was ported, cut, and modified beyond use, so what now?

Enter the hemi Predator head. Stock 140 valves are 24/22mm; the hemi's are 27/25 and the ports are larger to boot. By my estimation, with valve springs it could move the 140's power peak to over 7000rpm without porting. So I got one. It will be styled after the second-gen Chrysler Hemi in orange with a black valve cover.

Anyone else thinking about this should know that the compression ratio will only be about 6.8-7.0:1 and there will be no quench because the piston is so small. Currently I'm stalled waiting for some parts.
Attached Images
File Type: jpg DSC01777-web.jpg (29.5 KB, 11 views)
File Type: jpg DSC01778-web.jpg (16.1 KB, 7 views)
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
  #2  
Old 10-30-2018, 06:01 PM
pearl111 pearl111 is offline
Senior Member
 
Join Date: May 2016
Location: Maryland
Posts: 226
Thanks: 246
Thanked 32 Times in 23 Posts
Default

I am interested in what you are doing with the GX 140. As a member here on DIY I have learned how to do my own builds ( still learning ). What do you mean by THERE WILL BE NO QUENCH BECAUSE THE PISTON IS SO SMALL. Thanks.
Reply With Quote
  #3  
Old 10-30-2018, 08:20 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

Quote:
Originally Posted by pearl111 View Post
I am interested in what you are doing with the GX 140. As a member here on DIY I have learned how to do my own builds ( still learning ). What do you mean by THERE WILL BE NO QUENCH BECAUSE THE PISTON IS SO SMALL. Thanks.
I'm going to answer that in my other thread about the hemi head here:

http://www.diygokarts.com/vb/showthr...in this thread.

Quote:
Originally Posted by tgus3 View Post
wow cool i love the color..ill be following this
Thanks. It's actually "Chrysler Hemi Orange" is a slight pearl. I don't know if all brands of this color are the same, but Dupli-Color DE1652 has the worst coverage ever. There are two cans of paint on that tiny engine. Not two coats, two cans.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
The Following User Says Thank You to 65ShelbyClone For This Useful Post:
pearl111 (10-31-2018)
  #4  
Old 10-30-2018, 08:28 PM
Tpdingo Tpdingo is offline
Senior Member
 
Join Date: Nov 2017
Location: Bellmore, NY
Posts: 834
Thanks: 13
Thanked 234 Times in 198 Posts
Default

Put hydrazine in the motor and I'll follow it.

Just kidding, I'm looking forward to this thread regardless
__________________
Give a wrench long enough and WD-40, and I can remove the world's rusty bolts.
Reply With Quote
The Following User Says Thank You to Tpdingo For This Useful Post:
Jim turner (01-13-2019)
  #5  
Old 10-30-2018, 09:17 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

If I do that there won't be any motor left. Maybe not any of me left either, just a crater in the garage floor.

Nitromethane might get involved at a later date, but only at a point when I'm done with testing and the engine becomes expendable.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
  #6  
Old 10-30-2018, 08:03 PM
tgus3's Avatar
tgus3 tgus3 is offline
a member
 
Join Date: Aug 2017
Location: a long ways from the end of the rainbow
Posts: 241
Thanks: 121
Thanked 26 Times in 24 Posts
Default

Quote:
Originally Posted by 65ShelbyClone View Post
I'm starting this so I don't get tempted to clog-up another thread with my own stuff.

I've had this GX140 for about 25 years and it was always used for experimenting. It was disassembled 10+ years ago and I thought it got thrown out, but low and behold I found the parts! The original head was ported, cut, and modified beyond use, so what now?

Enter the hemi Predator head. Stock 140 valves are 24/22mm; the hemi's are 27/25 and the ports are larger to boot. By my estimation, with valve springs it could move the 140's power peak to over 7000rpm without porting. So I got one. It will be styled after the second-gen Chrysler Hemi in orange with a black valve cover.

Anyone else thinking about this should know that the compression ratio will only be about 6.8-7.0:1 and there will be no quench because the piston is so small. Currently I'm stalled waiting for some parts.
wow cool i love the color..ill be following this
__________________
Only know you love it when you let it go..
Reply With Quote
  #7  
Old 10-30-2018, 10:35 PM
bob58o's Avatar
bob58o bob58o is offline
Sick, Tired, and in Debt
 
Join Date: Jan 2016
Location: Under the Rothschild Whip
Posts: 7,475
Thanks: 3,214
Thanked 2,195 Times in 1,713 Posts
Default

Do we get a sneak peak? What parts are we waiting for?

Are you estimating that the stock cam will give you peak power around 7k RPM? If you have the tools, is there any way you could find out and report back with the Intake Center Line of the stock cam?
__________________
History doesn't repeat but it rhymes Name a successful fiat currency in the last 5k years
Reply With Quote
  #8  
Old 10-30-2018, 11:40 PM
landuse's Avatar
landuse landuse is online now
Moderator
 
Join Date: Nov 2010
Location: Pietermaritzburg, South Africa
Posts: 17,105
Thanks: 2,015
Thanked 3,374 Times in 2,747 Posts
Default

Quote:
Originally Posted by bob58o View Post
Do we get a sneak peak? What parts are we waiting for?
Flux capacitor??
Reply With Quote
  #9  
Old 10-30-2018, 11:58 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

Quote:
Originally Posted by bob58o View Post
Do we get a sneak peak? What parts are we waiting for?
Just a few basic items the engine can't run without.

Quote:
Originally Posted by bob58o View Post
Are you estimating that the stock cam will give you peak power around 7k RPM?
I think it's hypothetically possible, but not sure. More that the head *should* flow enough to not choke the engine below 7k. It might take rockers or more cam to get there.

Quote:
If you have the tools, is there any way you could find out and report back with the Intake Center Line of the stock cam?
I can, but first have to build a fixture for holding an indicator in line with the valve. It's straightforward with a Honda's inline valves, not so much with a hemi.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
The Following User Says Thank You to 65ShelbyClone For This Useful Post:
bob58o (10-31-2018)
  #10  
Old 10-31-2018, 08:10 PM
bob58o's Avatar
bob58o bob58o is offline
Sick, Tired, and in Debt
 
Join Date: Jan 2016
Location: Under the Rothschild Whip
Posts: 7,475
Thanks: 3,214
Thanked 2,195 Times in 1,713 Posts
Default

Quote:
Originally Posted by 65ShelbyClone View Post
I think it's hypothetically possible, but not sure. More that the head *should* flow enough to not choke the engine below 7k. It might take rockers or more cam to get there.
I ran some numbers in my Engine Analyzer Program to see what I got.

I used 2.50" Bore, 1.77" Stroke, 3.303" Rod Length, and 6.8 :1 Compression Ratio (but I'm not sure how you got there unless you have a flat top piston or a milled hemi head - I got 6.8:1 with a 22cc chamber, a flat-top piston, 0.010" head gasket and the piston sitting at 0.020" in the hole).

I used 27/25mm valves and average port diameter of 0.85" with flow efficiency percentage of 34%. I used 38 cfm for the intake flow (carb).

For exhaust I used 0.85" diameter and 16" long with flow efficiency at 85%.

I used the specs for a CL1 cam (for gx200) with 1.05:1 rocker ratio.

Here's what the program spat out....
Pk TQ around 4300 RPM and Pk HP around 7300 RPM.
Attached Images
File Type: jpg Hemi gx140.jpg (143.2 KB, 24 views)
__________________
History doesn't repeat but it rhymes Name a successful fiat currency in the last 5k years
Reply With Quote
  #11  
Old 10-31-2018, 11:04 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

That's cool, thanks.

All I did was divide the 212's displacement by the 140's displacement(144cc ) to get a multiplier(1.472), then multiply the (212's) peak power RPM(~4800) by it. It comes out to about 7100rpm that way. Should I see if the stock rod can do it?

Quote:
Originally Posted by bob58o View Post
I used 2.50" Bore, 1.77" Stroke, 3.303" Rod Length, and 6.8 :1 Compression Ratio (but I'm not sure how you got there unless you have a flat top piston or a milled hemi head - I got 6.8:1 with a 22cc chamber, a flat-top piston, 0.010" head gasket and the piston sitting at 0.020" in the hole).
I went with what other people report on the hemi chamber volume (22-23cc) until I measure mine. Gasket will probably be 0.010" and the piston is a flat top, but I don't think it's any more than 0.010" below deck. There again, still need to measure. It could be anywhere from 6.2 to 7.1:1 depending on the combination.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.

Last edited by 65ShelbyClone; 11-01-2018 at 03:19 PM. Reason: clarification
Reply With Quote
The Following User Says Thank You to 65ShelbyClone For This Useful Post:
bob58o (11-01-2018)
  #12  
Old 11-01-2018, 10:39 AM
KartFab's Avatar
KartFab KartFab is offline
Senior Member
 
Join Date: Jan 2013
Location: Dallas, TX
Posts: 3,258
Thanks: 488
Thanked 1,431 Times in 1,013 Posts
Default

man you are getting into briggs flathead compression ratio range here
__________________
Free Go Kart Plans https://kartfab.com Go Kart Videos https://www.youtube.com/c/KartFab
Reply With Quote
  #13  
Old 11-01-2018, 05:34 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

It shouldn't be too picky about gas. I'm hoping to put an ultralight flywheel on it and keep the recoil start, so maybe it won't kick too bad. Stock cam with compression release for now ought to help too.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
  #14  
Old 11-03-2018, 04:14 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

Parts were due today, but the U.S. Postal Service dropped the ball so they won't be here (and I can't button-up the engine until) at least Tuesday now.

In the meantime, here's why a 212 head gasket would be less than ideal.


And I don't know why I took this.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
The Following User Says Thank You to 65ShelbyClone For This Useful Post:
bob58o (11-05-2018)
  #15  
Old 11-05-2018, 03:53 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

Quote:
Originally Posted by 65ShelbyClone View Post
Parts were due today, but the U.S. Postal Service dropped the ball so they won't be here (and I can't button-up the engine until) at least Tuesday now.
Update: the PO played football with my box, but it was only three days late and they nicely taped-up the gaping hole. Come to find out the seller sent the wrong stuff anyway.

Is it Monday? I think it's a Monday.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
  #16  
Old 11-05-2018, 04:08 PM
bob58o's Avatar
bob58o bob58o is offline
Sick, Tired, and in Debt
 
Join Date: Jan 2016
Location: Under the Rothschild Whip
Posts: 7,475
Thanks: 3,214
Thanked 2,195 Times in 1,713 Posts
Default

Amr 300? Looks perfect on there. Let's see ... 300cc per revolution on the blower. 70cc per revolution on the 4 stroke 140... Should be good for like 50 psi of boost with a 1:1 ratio. LOL

__________________
History doesn't repeat but it rhymes Name a successful fiat currency in the last 5k years
Reply With Quote
The Following User Says Thank You to bob58o For This Useful Post:
65ShelbyClone (11-05-2018)
  #17  
Old 11-05-2018, 04:26 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

It's actually the larger 500. Believe me, I still think about it using it. It would be kind of like this:
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
The Following User Says Thank You to 65ShelbyClone For This Useful Post:
bob58o (11-05-2018)
  #18  
Old 11-10-2018, 10:10 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

Alright, back in the saddle.

Hemi 212 valve covers look taller in the photos. The stocker simply won't do given the theme of this engine, but it will at least keep the oil in for now. I know, lets make it shorter!




Brass shim stock because the thing was uneven by 0.008" from end-to-end. Shims reduced that to 0.001" before cutting.



The letters are still visible shadows, but that's just due to the grain of the metal when it was die cast.

None of my torque wrenches would fit in the 140 crankcase and I have no 10mm crow's foot, so I had to make this hokey tool for tightening the rod bolts:



It is exactly two inches from center-to-center, so 0.857 is the correction factor. 12 (12+2) = 0.857. The welding is ugly because I'm not practiced.

Going by calibrated eyeball, it looks like 140 lifters coupled with 212 pushrods will net some usable valvetrain geometry.

I also blueprinted the intake flange. The yellow paper is a proof and it matches the intake port exactly.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
The Following User Says Thank You to 65ShelbyClone For This Useful Post:
ezcome-ezgo (11-12-2018)
  #19  
Old 11-12-2018, 08:16 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

Quote:
Originally Posted by 65ShelbyClone View Post
Going by calibrated eyeball, it looks like 140 lifters coupled with 212 pushrods will net some usable valvetrain geometry.
Update 1: usable, not great. 212 lifters and 140 pushrods made a better contact patch, but they are still a bit short. Mock-up was done with a thick fiber gasket, so some of that length will be
recovered with a 0.010 gasket. It's going to require custom pushrods to get it correct either way and now there are enough spares for cutting up to make some. Titanium with steel tips maybe?

Update 2: VHT wrinkle paint is awesome. This the first time I've had wrinkle paint come out correctly on the first try. The picture doesn't do it justice.


Inspiration:
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
  #20  
Old 12-06-2018, 09:38 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 437
Thanks: 40
Thanked 174 Times in 145 Posts
Default

It's only money and you can't take it with you, right?

26lb springs, two Tillotson 324 clones, and a cog belt. The underdrive ratio looks really low, but it's geared for about 15psi with that large blower. Rotor leakage will probably be a bit high at lower speeds.



I doubt that this little flywheel has enough material for machining the GX140 taper into it. If it does, I'll try it with the matching mag.



If not, I have a few other ideas.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
The Following User Says Thank You to 65ShelbyClone For This Useful Post:
bob58o (12-07-2018)
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 07:47 AM.