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  #51  
Old 09-04-2018, 07:25 PM
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Vlad Vlad is offline
 
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Andy give it a second thought on removing the gascolator. Initially I planned to get rid of it but a smart man gave me a good reason not to. It does help to keep the wrong stuff from getting into the combustion chamber or clog an orifice.

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  #52  
Old 09-04-2018, 08:29 PM
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BillL BillL is offline
 
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OK , back to the problem. Andy, do you have a thermocouple reader? (sorry if I missed it in the thread) I have some fuel issues on my IO360 hot as well. I am not sure mine is temperature, but have been measuring some points to understand it. I made some K type bead thermocouples by stripping and sticking the twist into a TIG flame to create the beads. They will slide into a slit in the fire-sleeve to get a bit closer to actual fuel temps in the teflon hose. I found what I think are elevated temps at the firewall bulkhead fitting. There are too many points that need to be measured at once, so I have not progressed in this project, but will measure the temp rise from the entry from the wing root to the bulkhead fitting to see how much the rise is coming from inside the "tunnel". I don't remember all the temps involved, but was really surprised that the bulkhead fitting inside the cabin was so hot relative to what I though the tank was and ambient temps. +15F is my recollection.

Anyway -I would suggest temperature measurement of the fuel might be very helpful to this process.
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  #53  
Old 09-04-2018, 08:33 PM
crabandy crabandy is offline
 
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Quote:
Originally Posted by DanH View Post
Conventional wisdom says carbs do need a gascolator.

That said, have you ever seen any water in yours?
Nope. It?s not a regular preflight item either, right or wrong because the cowling must be removed for access. Whenever I remove the cowling I turn on the boost pump and sump the gascolator checking for debris and water. At condition inspection time the bowl of the gascolator is also inspected. I could add an extension to make it more feasible to check on preflight.

Water in the fuel has been almost non-existent in 4 years and 300+ hours. With partial tanks and large temp/humidity swings I may see a few drops up to a teaspoon from the tank sumps. I do park outside more than I would like on XC flights through rain and snow. First condition inspection I was suprised to find numerous red shop rag fibers in the filter prior to the gascolator, following condition inspections usually reveal small bits of various debris in the fuel filter. I have not found anything in the gascolator or carb screen.

My understanding is that the higher fuel pressures required for fuel injection systems would negate the gravity effect the gascolator has for trapping water and debris at the lower pressures and hopefully deliver a burnable mixture of fuel and water at the higher pressures.

Although the gascolator is providing my carb?d 360 a conceivable benefit in the cooler months, it is pre-heating the fuel 3 months out of the year. I have never experienced rough running due to water (that I know of) but I have and can reproduce the effects of fuel boiling in the carb during warmer months. Do a search on engine outs due to ?vapor lock? vs water in fuel.

I do not believe a blast tube/shroud around the gascolator will provide a solution because my lower cowling temps start increasing below 90 knots and slower, especially on the ground. A mile out on downwind I?m at idle and slowing down below 90 knots where the hot fuel sitting and not moving in the increasing lower cowling temps gets the final boil in the carb. It takes several minutes at idle and taxi to burn a carb bowl of fuel.


I do appreciate everyone comments, knowledge and advice furthering my education and recreation.
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  #54  
Old 09-04-2018, 08:54 PM
crabandy crabandy is offline
 
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Quote:
Originally Posted by BillL View Post
OK , back to the problem. Andy, do you have a thermocouple reader? (sorry if I missed it in the thread) I have some fuel issues on my IO360 hot as well. I am not sure mine is temperature, but have been measuring some points to understand it. I made some K type bead thermocouples by stripping and sticking the twist into a TIG flame to create the beads. They will slide into a slit in the fire-sleeve to get a bit closer to actual fuel temps in the teflon hose. I found what I think are elevated temps at the firewall bulkhead fitting. There are too many points that need to be measured at once, so I have not progressed in this project, but will measure the temp rise from the entry from the wing root to the bulkhead fitting to see how much the rise is coming from inside the "tunnel". I don't remember all the temps involved, but was really surprised that the bulkhead fitting inside the cabin was so hot relative to what I though the tank was and ambient temps. +15F is my recollection.

Anyway -I would suggest temperature measurement of the fuel might be very helpful to this process.
Bill,

I have a ?roving probe? made from this little guy DanH recommended:

https://www.digikey.com/product-deta...NOPB-ND/182346

As far as specific fuel line temp gathering I?m all ears.
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  #55  
Old 09-09-2018, 08:03 PM
crabandy crabandy is offline
 
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I've decided to keep the gascolator for now.

I've also decided to add a 1/16" inch Phenolic spacer between the carb and sump, the 1/16" inch should work with the existing studs and airbox to cowl angle.

Prior to making the spacer I wanted to get a fresh look at the carb/cable bracket/oil sump assembly. I found the center hole of the cable bracket was too small, it stuck out into the sump hole creating a sharp lip.



The carb gasket is the size of the sump throat, the carb throat is the same size as the center hole in the cable bracket.





The sump throat is cone shaped and wider on the bottom and tapers up to a smaller diameter.



I never questioned this when I assembled it, but the lip sticking out cant be good for effective area and mixture distribution. Online search seems the problem is prevalent on O-320 engines with O-360 sumps reference SB-258 which I haven't found.

Although I could've mated the cable bracket to the carb with a custom gasket of the same diatmeter and then taper my phenolic spacer I decided to open up the cable bracket center hole to the same size as the sump/gasket and then make the phenolic spacer tapered.



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  #56  
Old 09-10-2018, 07:14 AM
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airguy airguy is offline
 
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Quote:
Originally Posted by crabandy View Post
Bill,

I have a ?roving probe? made from this little guy DanH recommended:

https://www.digikey.com/product-deta...NOPB-ND/182346

As far as specific fuel line temp gathering I?m all ears.
I'm very much wanting to add a fuel temp probe, preferably at the fuel divider, and failing that at least at the servo inlet. That little device looks like it might work but I would prefer a smaller profile flat-form-factor that could be easily slipped into the firesleeve.
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  #57  
Old 09-10-2018, 07:40 AM
jacoby jacoby is offline
 
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Quote:
Originally Posted by crabandy View Post
I never questioned this when I assembled it, but the lip sticking out cant be good for effective area and mixture distribution. Online search seems the problem is prevalent on O-320 engines with O-360 sumps reference SB-258 which I haven't found.
SB-258 can be downloaded from here: http://www.shortwingpipers.org/forum...ll=1#post95175

(Be sure to get the more clear version at the bottom in post 5)

I'd attach it here but it doesn't seem like this forum supports attachments.
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  #58  
Old 09-12-2018, 03:20 PM
crabandy crabandy is offline
 
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The circle cutter was definitely a no-go on the steel bracket, I bought a 2 3/8 bi-metal hole saw to finish the hole.

I started making the phenolic spacer, I screwed the phenolic to a scrap piece of lumber. I used another hole saw 2 1/8" to make the center cut to match the carb throat diameter.



I used the gasket to scribe the bolt holes and center 2 3/8" hole. I filed a taper from the 2 3/8" mark to the 2 1/8" hole trying to eliminate some of the sharp lip.

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