P

prkaye

Well Known Member
I just bolted my carb to the sump. The bottom of hte carb is open (see pic). Does it stay this way? There are four threaded holes around the big opening, suggesting something eventually gets bolted up to the bottom of the carb...

Also, is there a torque setting for the nuts that hold the carb to the bottom of the sump? Or just hand tighten to compress the gaskets?

 
Phil,

This is where the FAB comes into play. Check out this picture:


As for the torque, yes, there is a set value for them but my book is at the hangar and I can't look it up. You also want to safety wire the bolts that hold the FAB plate to the bottom of the carb.
 
Airbox

prkaye said:
I just bolted my carb to the sump. The bottom of hte carb is open (see pic). Does it stay this way? There are four threaded holes around the big opening, suggesting something eventually gets bolted up to the bottom of the carb...
Click to expand...

Phil,

Gasket and carb air box top-plate go there. Take a look at your FWFWD kit, you should find those items there, as well as instructions and a diagram.

You will need to modify the air filter to clear the bottom of the fuel enricher plunger (accelerator pump), as per the instructions.
 
that's where your airbox will go

You'll bolt the airbox to the bottom, allowing filtered air to be provided to the carb:

RV-6AN731CK150.JPG



I used standard torque for that size bolt but don't have the book with me and don't remember what it is.
 
prkaye said:
Also, is there a torque setting for the nuts that hold the carb to the bottom of the sump? Or just hand tighten to compress the gaskets?
Click to expand...
These are coarse thread studs on that hold the carb/engine control bracket on (at least mine from Aerosport are coarse), so make sure you used the proper torque for coarse thread bolts. It is way less than what is called for with the fine thread bolts we usually use.
 
prkaye said:
Also, is there a torque setting for the nuts that hold the carb to the bottom of the sump? Or just hand tighten to compress the gaskets?
Click to expand...

The torque spec is in the Lycoming Overhaul Manual 60294-7.

I do not remember the size. The manual has the following in Table 1.

From Table 1.
Bolts, Screws, and Nuts
Note: Lubricate Threads Unless Otherwise Specified.
Thread - In. Lb.
10 ------ 49
1/4 ------ 96
5/16 ----- 204
3/8 ------ 360
7/16 ----- 600
1/2 ------ 900

Remember that the above size is the diameter and not the size wrench that goes on the fastener. I do not remember if the carb is held to the engine with 1/4 or 5/16. I do remember that the FAB mounts to the screw holes in the bottom of the carb with 1/4" bolts. Van gives your locking tabs with the FAB. I did not use the locking tabs but used drilled head bolts instead. My guess is that the carb mounts to the studs on the engine with 5/16 nuts that use a 1/2" wrench. Remember to calculate the torque value for the use of a crowsfoot IAW AC 43.13.
 
..and note that Lycoming...

RV6_flyer said:
The torque spec is in the Lycoming Overhaul Manual 60294-7.
.....
From Table 1.
Bolts, Screws, and Nuts
Note: Lubricate Threads Unless Otherwise Specified.
Thread - In. Lb.
10 ------ 49
1/4 ------ 96
5/16 ----- 204
3/8 ------ 360
7/16 ----- 600
1/2 ------ 900
.......
Click to expand...

...specifies the torque values with lubricated threads, unlike the airfame specifications which assume dry threads.....

Gary's guess is also correct - they are 5/16 - 18 size nuts.
 
Last edited:
RV6_flyer said:
The torque spec is in the Lycoming Overhaul Manual 60294-7.

From Table 1.
Bolts, Screws, and Nuts
Note: Lubricate Threads Unless Otherwise Specified.
Thread - In. Lb.
10 ------ 49
1/4 ------ 96
5/16 ----- 204
3/8 ------ 360
7/16 ----- 600
1/2 ------ 900
Click to expand...

Gary-
Thanks for the numbers from the Overhaul Manual. I'm always learning!

Can you confirm that there are no typos in the numbers above? I don't doubt them, except that they are WAY higher (almost double) than the numbers shown in all the charts I've used to date, all of which use the same basic numbers (Van's Section 5, Standard Aircraft Handbook, Cleaveland Tool catalog insert, etc.)

For example, my Cleaveland Tools chart shows the following for coarse threads (all in.#):
10 ---- 20-25
1/4 ---- 40-50
5/16 ---- 80-90 (This is the size, 5/16-18, that holds my carb on.)
3/8 ---- 160-185
7/16 ---- 235-255
1/2 ---- 400-480

Even the fine-thread table is showing numbers well below the numbers you're providing:
10 --- 20-25
1/4 --- 50-70
5/16 --- 100-140
3/8 --- 160-190
7/16 --- 450-500
1/2 --- 480-690

If your numbers are correct (which I assume they are), does this mean we should all have a copy of the Lycoming Overhaul Manual just to follow Van's FWF instructions? (I'm guessing that answer must be yes!)

Thanks Gary.
 
Last edited:
alpinelakespilot2000 said:
Gary-

--- snip ---

Can you confirm that there are no typos in the numbers above? I don't doubt them, except that they are WAY higher (almost double) than the numbers shown in all the charts I've used to date, all of which use the same basic numbers (Van's Section 5, Standard Aircraft Handbook, Cleaveland Tool catalog insert, etc.)
-snip

If your numbers are correct (which I assume they are), does this mean we should all have a copy of the Lycoming Overhaul Manual just to follow Van's FWF instructions? (I'm guessing that answer must be yes!)

Thanks Gary.
Click to expand...

Copied right out of the manual.
 
Lycoming publishes the torque values as part of SSP1776.

I found a copy of SSP1776 on the web. Go to page 5 for Table 1 in the PDF document.

I have a copy of the Overhaul manual that says SSP1776 in the lower left hand corner of the page. I then went to Google and did a search for SSP1776. The second result returned took me to the above link.

Lycoming Letter L114AQ lists the documents that Lycoming publishes and how to obtain them.

This web site has some reference documents about Lycoming engines that may be of value.
 
You must log in or register to reply here.