Model Engine Company of America
Be sure to scroll all the way to the bottom of the page to see all our nuts.
7-30-2025
HEX and PROP NUTS

These are from our engines and products but are very common across all brands.

SAE - American Threads - All nuts are made from steel (unless noted)
Part Number
Thread
Hex
Thickness
Finish
Used on our engines but fit many others too
4-40
        
5-40
        
8-32
    
None
Atwood amd Holland Hornet
 
10-32
        
10-32
1/4"
3/32"
Zinc
Used on draw bars
 
12-32
        
1/4"x28
5/32"
Black Oxide
McCoy Series 21
1/4"x28
10mm
Black Oxide
HB .40-.61 HP.61 VT.49
Black Oxide
Taipan .40
1/4"x28
Black Oxide
1/4"x28
Cad Plated
Remco .29
5/16"x24
7/16"
Black Oxide
RJL K.61 & Kraft .61
5/16"x24
None
Forster 99 - Cunningham .647
Black Oxide
HB 20-21-25, HP 20, VT 21-25
3/8"X24
      
K&B 100 AERO DF
Metric Threads
Part Number
Thread
mm
Hex
mm
Thickness
mm
Finish
Used on our engines but fit many others too
3x.5
5.5
2.25
Bright Zinc
TOKI, SHUWA 12 15 18 20 21
5x.8
8
5
Black Oxide
K&B, TOKI, SHUWA 12 15 18 20 21
6x1
Black Oxide
HP 40
7x1
11
5.5
Class 8
8x1
13
6.35
Black Oxide
HP 1.2 Twin
8x1.25
Black Oxide
Webra 1037-20
924-10x125
10x1.25
14
8
Bright Zinc
Flange and Lock Nuts Metric Threads
Part Number
Thread
mm
Hex
mm
Thickness
mm
Finish
Type
3x.5
5.5
3.7
Zinc
Serrated Flange Nut
3x.5
5.5
3.7
Zinc
Smooth Flange Nut
4x.7
7
5.5
Zinc
Hex with Nylon Lock
4x.7
7
5.5
Black Oxide
Hex with Nylon Lock
5x.8
8
5.5
Zinc
Serrated Flange Nut
         
PROP Washers
These are from our engines but are very common across all brands.
Most are machined from bar but some are stamped steel. Click part number for more information.
Only some of the FOX prop washers have the knurle shown above.
Part Number
Hole Dia
OD
Thickness
Finish
Material
Used On Our
1/4"
3/4"
.080"
Black Oxide
Steel
McCoy Series 21
1/4"
None
Aluminum
Taipan .40 must be used with 24-0401 nut
1/4"
Cad Plated
Steel
Remco .29 - Forster 29
1/4"
25mm
3mm
Black Oxide
Steel
HB 40 50 61
1/4"
22mm
2.5mm
Black Anodize
Aluminum
HP 20, VT 21-25
1/4"
Black Anodize
Aluminum
HP .61 VT.49 .61
1/4"
3/4"
3/32"
Black Oxide
Steel
Most K&B with 1/4" Shaft
1/4"
Cad Plated
Steel
FOX 35 and many other FOX engines
1/4" None Aluminum
MECOA .40 - .46
5/16"
None
Steel
Forster 99 "D" shaped hole
5/16"
None
Steel
Cunningham .647
5/16"
15/16"
Black Oxide
Steel
RJL K.61 & Kraft .61
Black Oxide
Steel
HB 20 21 25
5mm
17mm
1mm
Black Oxide
Steel
K&B, TOKI, SHUWA 12 15 18 20 21
6mm
22mm
2.5mm
Black Anodize
Aluminum
HP .40
7mm
8mm
25mm
3mm
Black Anodize
Aluminum
HP 1.2 Twin
FOX PROP SHAFT EXTENSIONS
Use these to put the prop forward 1/2" to 3/4"
6520 10-32 Thread x 1/2" Long  
6521 5x.8mm Thread x 1/2" Long  
6525 10-32 Thread x 3/4" Long  
6526 5x.8mm Thread x 3/4" Long  
6530 1/4-28 Thread x 1/2" Long  
6535 1/4-28 Thread x 3/4" Long  
6540 5/16x24 Thread x 1/2" Long  
6541 8x1mm Thread x 1/2" Long  
6545 5/16x24 Thread x 3/4" Long  
6546 8x1mm Thread x 3/4" Long  
SHOULDER NUT AND WASHER SETS
Use these when you don't have enough threads due to thick spinner plates and props.
924-001

Steel Shoulder Nut, 1/4X28 - Standard Length

  
924-002 Steel Shoulder Nut, 5/16X24 - Standard Length  
924-003 Steel Shoulder Nut, 1/4X28 - Extra Long  
924-004 Steel Shoulder Nut, 5/16X24 - Extra Long