FM150 cowl clearance issue

[Steve N.]

I have a Superior IO-360 parallel valve engine with a cold air sump and a FM 150 fuel servo. The bolt that holds the mixture arm to the servo and the arm itself is contacting the bottom of my RV-8 cowl. Anyone else have to deal with this problem?

 

[fl-mike]

yes. Wait until you get to the snorkel!
Titan IOX-370 in my case. I tried alternate orientations, but all seemed to create other,worse issues. I ended up adding a blister to the cowl.
Probably a more elegant solution would be to shift the cowl forward a bit and add a prop spacer.

 

[rsr3]

Bush this item from 5/16” to 1/4” - problem solved, no blister.

Throttle Lever (Reverse Offset) - AIRFLOW PERFORMANCE

Shaft Hole to outside hole – 2″ Shaft Hole to inside hole – 1.5″ Offset – minus 1/4″ Cable Mount Hole – 3/16″ Shaft Hole Fits- 5/16″

airflowperformance.com

 

[Carl Froehlich]

Wrong fuel servo. You want the FM-150C. The photos are the 150C mounting on my RV-8 IO-360-M1B.
Carl

 

[Steve N.]

yes. Wait until you get to the snorkel!
Titan IOX-370 in my case. I tried alternate orientations, but all seemed to create other,worse issues. I ended up adding a blister to the cowl.
Probably a more elegant solution would be to shift the cowl forward a bit and add a prop spacer.

It’s beginning to look like a blister is going to be the solution.

 

[Steve N.]

Bush this item from 5/16” to 1/4” - problem solved, no blister.

Throttle Lever (Reverse Offset) - AIRFLOW PERFORMANCE

Shaft Hole to outside hole – 2″ Shaft Hole to inside hole – 1.5″ Offset – minus 1/4″ Cable Mount Hole – 3/16″ Shaft Hole Fits- 5/16″

airflowperformance.com

Sorry, I don’t see how changing the lever is going to change the length of the bolt extending below the shaft hole unless you file it off.

 

[Steve N.]

Wrong fuel servo. You want the FM-150C. The photos are the 150C mounting on my RV-8 IO-360-M1B.
Carl

Carl, your sump is different than mine. The bosses for the cable brackets are in different locations.

Thanks all for replies.

 

[Carl Froehlich]

Carl, your sump is different than mine. The bosses for the cable brackets are in different locations.

Thanks all for replies.

Correct, the cable brackets are different, as are the mixuture and thottle controls. I recommend a call to Don at Air Flow Performance.

I know for fact that the standard FM150 will result in the problem you have as that happened to me on the engine I ordered from Thunderbolt with the FM-150 (2019 time frame) (see photo of this original fuel servo). Lycoming replaced it with the Precision unit when I (and other customers) pointed out it did not work with the RV-8 cowl. I was the beta tester for the FM-150C and associated new control brackets to make sure the fit up worked for the RV-8 cowl.

I’m very happy with the FM-150C.

Carl

 

[Webb]

I had the same issue. Cut a hole in the cowl and glassed a blister. Not wanting to see a belly button on the cowl, added foam on the cowl and then glassed a large patch. It turned out well and you can’t tell a mod was done.

 

[DanH]

I was the beta tester for the FM-150C and associated new control brackets to make sure the fit up worked for the RV-8 cowl.

Carl

Cool mixture control system. Your idea or Don's? My compliments to somebody either way

 

[Carl Froehlich]

Cool mixture control system. Your idea or Don's? My compliments to somebody either way

That was all Don. One minor tweak to make Van’s happy and it was good to go.

Carl

 

[8MikeXray]

Superior Cold Air sump and FM-200 on my 390, shortened the mixture shaft and made a low profile cnc mixture arm. Had to install a small blister to clear.

 

[Steve N.]

Correct, the cable brackets are different, as are the mixuture and thottle controls. I recommend a call to Don at Air Flow Performance.

I know for fact that the standard FM150 will result in the problem you have as that happened to me on the engine I ordered from Thunderbolt with the FM-150 (2019 time frame) (see photo of this original fuel servo). Lycoming replaced it with the Precision unit when I (and other customers) pointed out it did not work with the RV-8 cowl. I was the beta tester for the FM-150C and associated new control brackets to make sure the fit up worked for the RV-8 cowl.

I’m very happy with the FM-150C.

Carl

I will give Don a call tomorrow. I must admit that this problem didn’t manifest itself until after I’ve done numerous engine runs without the cowl on. I was ready to schedule the AW inspection with my DAR and now this. Oh the trials and tribulations of home building.

 

[TroyW]

I will give Don a call tomorrow. I must admit that this problem didn’t manifest itself until after I’ve done numerous engine runs without the cowl on. I was ready to schedule the AW inspection with my DAR and now this. Oh the trials and tribulations of home building.

Steve,

Please let me know what solution you find. I recently purchased an RV-7 that has chafing in two spots on the lower cowl:

The cold air plenum (forward chafing spot) and the mixture control arm on the FM-150. Pictures attached, I found this thread while searching for possible solutions to address the problem during my upcoming condition inspection.

 

[Carl Froehlich]

Steve,

Please let me know what solution you find. I recently purchased an RV-7 that has chafing in two spots on the lower cowl:

The cold air plenum (forward chafing spot) and the mixture control arm on the FM-150. Pictures attached, I found this thread while searching for possible solutions to address the problem during my upcoming condition inspection.

Troy,

It looks like your engine mounts have sag a bit (nothing unusual). A simple fix could be to add a washer (AN970) between the lower engine mounts and the engine. That 1/16” thick washer should raise the spinner to be better flush with the upper cowl.

You may or may not need to get a longer engine mount bolt.

Carl

 

[TroyW]

Troy,

It looks like your engine mounts have sag a bit (nothing unusual). A simple fix could be to add a washer (AN970) between the lower engine mounts and the engine. That 1/16” thick washer should raise the spinner to be better flush with the upper cowl.

You may or may not need to get a longer engine mount bolt.

Carl

Thanks, Carl! I saw that suggestion in this thread, too! Certainly, an option to explore. The airplane/engine only has 350 hours on it--so one would expect it to continue to sag more, worsening the chafing situation.

 

[TroyW]

Don at Airflow Performance looked at my pictures and had these suggestions:

It looks like from your pictures you can re-clock the mixture lever one or two teeth to limit forward movement. Yes, make sure the control cannot go over center at ICO.

Also, if the bolt is hitting the cowl, you can replace the bolt with a flat head (countersink) cap screw, countersink the lever, which would eliminate the bolt head hanging down thus giving you more clearance. Or grind the cowl out on the inside, and re-glass to give more clearance.

 

[Steve N.]

Steve,

Please let me know what solution you find. I recently purchased an RV-7 that has chafing in two spots on the lower cowl:

The cold air plenum (forward chafing spot) and the mixture control arm on the FM-150. Pictures attached, I found this thread while searching for possible solutions to address the problem during my upcoming condition inspection.

Troy,

I also spoke with Don and he gave me the same advice. Webb in Post #9 also had the same problem and described his fix which I did. I reclocked the mixture lever and will eventually replace the bolt with a flat head screw. I also cut a hole in the cowl then added high density foam on the outside of the cowl, sanded it to shape and covered it with a fiberglass and microballoon slurry and more sanding. On the inside of the cowl if you have the honey comb, be sure to fill honey comb holes with slurry and cover it with fiberglass. Once the cowl is painted, the repair will hardly be noticeable .

 

[Steve N.]

Wrong fuel servo. You want the FM-150C. The photos are the 150C mounting on my RV-8 IO-360-M1B.
Carl

In my discussion with Don, he told me that it would be extremely difficult to replace the fuel servo at this point. He designed the FM150C specifically for the Lycoming engine. My engine is a Superior with cold air sump. Van's control cable brackets do not work with my engine. Reworking the cowl was a simple task.

 

[TroyW]

Troy,

I also spoke with Don and he gave me the same advice. Webb in Post #9 also had the same problem and described his fix which I did. I reclocked the mixture lever and will eventually replace the bolt with a flat head screw. I also cut a hole in the cowl then added high density foam on the outside of the cowl, sanded it to shape and covered it with a fiberglass and microballoon slurry and more sanding. On the inside of the cowl if you have the honey comb, be sure to fill honey comb holes with slurry and cover it with fiberglass. Once the cowl is painted, the repair will hardly be noticeable . View attachment 80788View attachment 80789View attachment 80790View attachment 80791View attachment 80792View attachment 80793

Nice job, Steve! Thank you for the follow up.

 

[Carlosanlley]

Superior Cold Air sump and FM-200 on my 390, shortened the mixture shaft and made a low profile cnc mixture arm. Had to install a small blister to clear.
View attachment 79195

Hi Mike! can you share which exhaust system brand and model are you using in your 390 setup? tnks.