Vapor lock...Mk III

[arm@telus.net]

Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. Ross

[Stephen D Stierman]

I was out in TC this morning, drove to Cars and Coffee, stopped at the ATM on the way home for a few minutes that allowed things to heat soak a bit... .it was probably high 80's low 90's at that time. Car ran fine, started up, just a bit "fluffy" for a minute and all was well. Stock needles, heat shield, carb spacers, ceramic coated exhaust manifold and mixture and timing pretty well on, all with 10% ethanol. The point is that it can be made to run reasonably well under these conditions. Steve TC2911 On Saturday, July 20, 2019, 3:31:32 PM EDT, 'arm@telus.net' arm@telus.net [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:   Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. 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[Clive Sherriff]

Ross, If you want ethanol free petrol, just buy the regular stuff. Throw in a load of water. Shake it around a bit and the ethanol will disolve in the water, then just drain the water off. Bingo! Ethanol free petrol ! Clive, Oxford, UK m mmmmmmmmmmmmmmmmmmmmmm [img]https://ec.yimg.com/ec?url=https%3A%2F%2Fipmcdn.avast.com%2Fimages%2Ficons%2Ficon-envelope-tick-round-orange-animated-no-repeat-v1.gif&t=1565903544&sig=ovjV70lHFioDIh9tNUucHw--~E[/img] Virus-free. www.avast.com

On Sat, 20 Jul 2019 at 20:31, 'arm@telus.net' arm@telus.net [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote: [u][/u] Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. Ross

[img]https://ec.yimg.com/ec?url=https%3A%2F%2Fipmcdn.avast.com%2Fimages%2Ficons%2Ficon-envelope-tick-round-orange-animated-no-repeat-v1.gif&t=1565903544&sig=ovjV70lHFioDIh9tNUucHw--~E[/img] Virus-free. www.avast.com

[arm@telus.net]

Uhhhh.....thanks Clive.....but I've found most 'Premium'  grades in Canada are ethanol free. But thanks anyway...I'll keep that in mind [b]From: [/b]"CLIVE SHERRIFF" csherriff99@gmail.com> [b]To: [/b]arm@telus.net [b]Cc: [/b]"mg-tabc" mg-tabc@yahoogroups.com> [b]Sent: [/b]Saturday, 20 July, 2019 12:55:10 [b]Subject: [/b]Re: [mg-tabc] Vapor lock...Mk III Ross, If you want ethanol free petrol, just buy the regular stuff.  Throw in a load of water.  Shake it around a bit and the ethanol will disolve in the water, then just drain the water off.   Bingo!  Ethanol free petrol ! Clive, Oxford, UK m mmmmmmmmmmmmmmmmmmmmmm [img]https://ec.yimg.com/ec?url=https%3A%2F%2Fipmcdn.avast.com%2Fimages%2Ficons%2Ficon-envelope-tick-round-orange-animated-no-repeat-v1.gif&t=1565903544&sig=ovjV70lHFioDIh9tNUucHw--~E[/img] Virus-free. www.avast.com

On Sat, 20 Jul 2019 at 20:31, 'arm@telus.net' arm@telus.net [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:   Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. Ross

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[Steve S]

I've been following this thread to see if there is any pattern to those who have vapor lock issues and those who don't. Unfortunately I haven't seen any pattern whatsoever. Myself and several other locals have taken our cars out many times in triple digit temperatures without issue. The cars do not overheat even in traffic, nor suffer vapor lock. After stopping in these temperatures they do sputter for about 30 seconds as Steve Stierman notes, but a bit of choke clears it up quickly. This is with stock carbs, stock metal fan, stock radiator, no heat shield, no ceramic coated manifolds, etc. And it's on California's 10% ethanol gasoline. I do have a 6-blade impeller on my water pump and it seems to keep temps slightly lower, but I never had vapor lock problems with the stock impeller either. But then I know a few people also in our region who suffer overheating and vapor lock in those conditions. It's a curiosity. - Steve Simmons, TC8975 On 7/20/2019 12:39 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote:

I was out in TC this morning, drove to Cars and Coffee, stopped at the ATM on the way home for a few minutes that allowed things to heat soak a bit... .it was probably high 80's low 90's at that time. Car ran fine, started up, just a bit "fluffy" for a minute and all was well. Stock needles, heat shield, carb spacers, ceramic coated exhaust manifold and mixture and timing pretty well on, all with 10% ethanol. The point is that it can be made to run reasonably well under these conditions. Steve TC2911 On Saturday, July 20, 2019, 3:31:32 PM EDT, 'arm@telus.net' arm@telus.net [mg-tabc] mg-tabc-noreply@yahoogroups.com wrote: Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. Ross

[phil smith]

Steve et al;, What I've not been convinced about yet from all this discussion is the role of the thermostat....the "aftermarket" housing is an aluminum thing that uses a modern-type thermostat, and that's what's been in exu7617 since I built the engine.  After a good run, I have always heard gurgling in the head, and I've managed vapor lock by opening the right bonnet when stopped for some reason.  An IR temp gage always showed sub-boiling temps on the block and the coolant in the radiator.   I've just changed over to an original-style thermostat (machined cast iron?), based on studying the coolant flow diagrams.  I think the "aftermarket" setup might not allow good coolant circulation from head to radiator etc.... and so a hot head.  I've wondered if some of that excess heat gets dissipated to the atmosphere via the manifolding and thus the carbs, contributing to the vapor lock story.  It looks to me like the XPAG design guys thought of head cooling when designing the original-style thermostat.   I've not yet had the time to go test the "original set up" but your question makes wonder - among those who do (or don't) have vapor lock on stock manifolding/carbs setups, who has a stock vs. "aftermarket" thermostat housing?   ----pps

On Saturday, July 20, 2019, 04:22:10 PM EDT, Steve S mail@mgnuts.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:

  I've been following this thread to see if there is any pattern to those who have vapor lock issues and those who don't.  Unfortunately I haven't seen any pattern whatsoever. Myself and several other locals have taken our cars out many times in triple digit temperatures without issue.  The cars do not overheat even in traffic, nor suffer vapor lock.  After stopping in these temperatures they do sputter for about 30 seconds as Steve Stierman notes, but a bit of choke clears it up quickly.  This is with stock carbs, stock metal fan, stock radiator, no heat shield, no ceramic coated manifolds, etc.  And it's on California's 10% ethanol gasoline.  I do have a 6-blade impeller on my water pump and it seems to keep temps slightly lower, but I never had vapor lock problems with the stock impeller either.  But then I know a few people also in our region who suffer overheating and vapor lock in those conditions.  It's a curiosity. - Steve Simmons, TC8975 On 7/20/2019 12:39 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote:   I was out in TC this morning, drove to Cars and Coffee, stopped at the ATM on the way home for a few minutes that allowed things to heat soak a bit... .it was probably high 80's low 90's at that time. Car ran fine, started up, just a bit "fluffy" for a minute and all was well. Stock needles, heat shield, carb spacers, ceramic coated exhaust manifold and mixture and timing pretty well on, all with 10% ethanol. The point is that it can be made to run reasonably well under these conditions. Steve TC2911 On Saturday, July 20, 2019, 3:31:32 PM EDT, 'arm@telus.net' arm@telus.net [mg-tabc] mg-tabc-noreply@yahoogroups.com wrote:   Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. Ross

[Steve S]

Opening the right bonnet while stopped definitely prevents the hot start up issue because you're letting manifold heat out of the engine bay before it soaks into the carburetor bowls. I was in a caravan through the Mojave desert in the middle of summer one time and every time we stopped in a town for a break, every car in the line had the right side of the bonnet raised. I don't feel that coolant temperature is the primary factor in the vapor lock issue. But just for the data, I don't run a thermostat in my TC. I did block off the bypass with a solid gasket and put an 1/8" hole in it to let air escape from the bypass line. This is one reason why I don't like the aftermarket thermostat housings that use modern thermostats. You have to leave the bypass open for when the thermostat is closed, but then it doesn't close itself like the original did when the thermostat opens. - Steve Simmons, TC8975

On July 20, 2019 1:36:34 PM phil smith mgpsmith@att.net> wrote:

Steve et al;, What I've not been convinced about yet from all this discussion is the role of the thermostat....the "aftermarket" housing is an aluminum thing that uses a modern-type thermostat, and that's what's been in exu7617 since I built the engine.  After a good run, I have always heard gurgling in the head, and I've managed vapor lock by opening the right bonnet when stopped for some reason.  An IR temp gage always showed sub-boiling temps on the block and the coolant in the radiator.   I've just changed over to an original-style thermostat (machined cast iron?), based on studying the coolant flow diagrams.  I think the "aftermarket" setup might not allow good coolant circulation from head to radiator etc.... and so a hot head.  I've wondered if some of that excess heat gets dissipated to the atmosphere via the manifolding and thus the carbs, contributing to the vapor lock story.  It looks to me like the XPAG design guys thought of head cooling when designing the original-style thermostat.   I've not yet had the time to go test the "original set up" but your question makes wonder - among those who do (or don't) have vapor lock on stock manifolding/carbs setups, who has a stock vs. "aftermarket" thermostat housing?   ----pps On Saturday, July 20, 2019, 04:22:10 PM EDT, Steve S mail@mgnuts.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:   I've been following this thread to see if there is any pattern to those who have vapor lock issues and those who don't.  Unfortunately I haven't seen any pattern whatsoever. Myself and several other locals have taken our cars out many times in triple digit temperatures without issue.  The cars do not overheat even in traffic, nor suffer vapor lock.  After stopping in these temperatures they do sputter for about 30 seconds as Steve Stierman notes, but a bit of choke clears it up quickly.  This is with stock carbs, stock metal fan, stock radiator, no heat shield, no ceramic coated manifolds, etc.  And it's on California's 10% ethanol gasoline.  I do have a 6-blade impeller on my water pump and it seems to keep temps slightly lower, but I never had vapor lock problems with the stock impeller either.  But then I know a few people also in our region who suffer overheating and vapor lock in those conditions.  It's a curiosity. - Steve Simmons, TC8975 On 7/20/2019 12:39 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote:   I was out in TC this morning, drove to Cars and Coffee, stopped at the ATM on the way home for a few minutes that allowed things to heat soak a bit... .it was probably high 80's low 90's at that time. Car ran fine, started up, just a bit "fluffy" for a minute and all was well. Stock needles, heat shield, carb spacers, ceramic coated exhaust manifold and mixture and timing pretty well on, all with 10% ethanol. The point is that it can be made to run reasonably well under these conditions. Steve TC2911 On Saturday, July 20, 2019, 3:31:32 PM EDT, 'arm@telus.net' arm@telus.net [mg-tabc] mg-tabc-noreply@yahoogroups.com wrote:   Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. Ross

[phil smith]

And that's exactly what I noticed when studying the diagram, and why just replaced the "modern" unit with an old but functioning unit.  p  ---

On Saturday, July 20, 2019, 05:08:03 PM EDT, Steve S mail@mgnuts.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:

  Opening the right bonnet while stopped definitely prevents the hot start up issue because you're letting manifold heat out of the engine bay before it soaks into the carburetor bowls. I was in a caravan through the Mojave desert in the middle of summer one time and every time we stopped in a town for a break, every car in the line had the right side of the bonnet raised. I don't feel that coolant temperature is the primary factor in the vapor lock issue. But just for the data, I don't run a thermostat in my TC. I did block off the bypass with a solid gasket and put an 1/8" hole in it to let air escape from the bypass line. This is one reason why I don't like the aftermarket thermostat housings that use modern thermostats. You have to leave the bypass open for when the thermostat is closed, but then it doesn't close itself like the original did when the thermostat opens. - Steve Simmons, TC8975 On July 20, 2019 1:36:34 PM phil smith mgpsmith@att.net> wrote:

Steve et al;, What I've not been convinced about yet from all this discussion is the role of the thermostat....the "aftermarket" housing is an aluminum thing that uses a modern-type thermostat, and that's what's been in exu7617 since I built the engine.  After a good run, I have always heard gurgling in the head, and I've managed vapor lock by opening the right bonnet when stopped for some reason.  An IR temp gage always showed sub-boiling temps on the block and the coolant in the radiator.   I've just changed over to an original-style thermostat (machined cast iron?), based on studying the coolant flow diagrams.  I think the "aftermarket" setup might not allow good coolant circulation from head to radiator etc.... and so a hot head.  I've wondered if some of that excess heat gets dissipated to the atmosphere via the manifolding and thus the carbs, contributing to the vapor lock story.  It looks to me like the XPAG design guys thought of head cooling when designing the original-style thermostat.   I've not yet had the time to go test the "original set up" but your question makes wonder - among those who do (or don't) have vapor lock on stock manifolding/carbs setups, who has a stock vs. "aftermarket" thermostat housing?   ----pps On Saturday, July 20, 2019, 04:22:10 PM EDT, Steve S mail@mgnuts.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:   I've been following this thread to see if there is any pattern to those who have vapor lock issues and those who don't.  Unfortunately I haven't seen any pattern whatsoever. Myself and several other locals have taken our cars out many times in triple digit temperatures without issue.  The cars do not overheat even in traffic, nor suffer vapor lock.  After stopping in these temperatures they do sputter for about 30 seconds as Steve Stierman notes, but a bit of choke clears it up quickly.  This is with stock carbs, stock metal fan, stock radiator, no heat shield, no ceramic coated manifolds, etc.  And it's on California's 10% ethanol gasoline.  I do have a 6-blade impeller on my water pump and it seems to keep temps slightly lower, but I never had vapor lock problems with the stock impeller either.  But then I know a few people also in our region who suffer overheating and vapor lock in those conditions.  It's a curiosity. - Steve Simmons, TC8975 On 7/20/2019 12:39 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote:   I was out in TC this morning, drove to Cars and Coffee, stopped at the ATM on the way home for a few minutes that allowed things to heat soak a bit... .it was probably high 80's low 90's at that time. Car ran fine, started up, just a bit "fluffy" for a minute and all was well. Stock needles, heat shield, carb spacers, ceramic coated exhaust manifold and mixture and timing pretty well on, all with 10% ethanol. The point is that it can be made to run reasonably well under these conditions. Steve TC2911 On Saturday, July 20, 2019, 3:31:32 PM EDT, 'arm@telus.net' arm@telus.net [mg-tabc] mg-tabc-noreply@yahoogroups.com wrote:   Many thanks to all who replied to my query, both on and offline.. After reading and rereading the thread I have decided to go with a few mods. Firstly though I should note that I don't agree that the fuel pump is in the hottest part of the engine compartment. I think the exhaust manifold is the hottest part and note that the float bowls are mere cm's away. I have always understood that vapor lock is the boiling of the fuel in the bowls that drives the liquid level below the jets and starves the engine of fuel. I have a brand new fuel pump btw... I have decided to install Doug's insulating spacers and a 7 blade MGB fan. As well I plan to check and adjust the mixture and timing. I also found the discussion on needles very informative. Hopefully all this help and advice and some elbow grease on my part will give my TC a bit more power and a reliability that seems to have diminished. And next tank I'm going to look for ethanol free fuel, though I suspect the octane will be much higher than desired. Cheers and thanks again. This list is truely a fabulous resource. Ross