MG Sports Cars

engine swaps and other performance upgrades, plus "factory" and Costello V8s

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mstemp
Mike Stemp
Calgary, Canada
(223 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Carb Heat & Vapour Lock
Posted by: mstemp
Date: August 21, 2012 05:32PM

Posted on MG Experience wo much luck so thought I would try here.

Having some trouble with my Rover 4.6 when hot. Been hotter than usual here, 30C. Engine temp is kept in check with my fans at 190 F. In slow traffic or ideling, car loads up and starts to run rough and stall. Will start most times right away or after a minute or two. Buick 215 manifold and Edelbrock 500, Delco disy with pertronix.

Tried adding a edelbrock 0.320" insulator but still having the issue. It's made of some black sort of insulating material. Would a phenolic one make any difference? Don't have much more room, maybe could use a 0.5" spacer total.
Is the Mr gasket #98 (alternating layers of metal & insulator) any better at keep heat out of the fuel bowls?
Gas Tank is vented. Carter pump, filter is before pump just after the tank. Checked float levels, in spec.

Injection is going on this winter but want to enjoy driving for the rest of summer without fear of causing traffic jams!
Thanks for any help.



Edited 1 time(s). Last edit at 08/21/2012 05:33PM by mstemp.


mgb260
Jim Nichols
Sequim,WA
(2465 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Carb Heat & Vapour Lock
Posted by: mgb260
Date: August 21, 2012 07:54PM

Mike, Sometimes the problem is the fuel line,not the carb. I have had good luck with a thin aluminum plate with a gasket on each side under the carb instead of insulator.


mstemp
Mike Stemp
Calgary, Canada
(223 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Carb Heat & Vapour Lock
Posted by: mstemp
Date: August 22, 2012 08:30AM

Jim,

Thanks. Was at a car show last night and a Rover SD1 had something similar to what you mentioned. Will try that.


pspeaks
Paul Speaks
Dallas, Texas
(698 posts)

Registered:
07/20/2009 06:40PM

Main British Car:
1972 MGB-GT 1979 Ford 302

authors avatar
Re: Carb Heat & Vapour Lock
Posted by: pspeaks
Date: August 22, 2012 09:01AM

I donít suggest doing this because it looks hideous, but when I went to high school in Texas, I drove a 1953 Ford with a flathead and during the summer it vapor locked almost every day. As I said, I donít suggest this method nor do I suggest wood, but itís what we could afford at the time. We would put wooden clothes pins on the metal fuel line to work as a rather poor heat sink. Would it help to wrap the fuel line up to the carb with something a little more modern and attractive? Just an idea!



Paul


mstemp
Mike Stemp
Calgary, Canada
(223 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Carb Heat & Vapour Lock
Posted by: mstemp
Date: August 22, 2012 01:33PM

Going to try this from Mr Gasket as it looks to cover the fule bowls etc.

[www.jegs.com]

If it still persists I will cover the fule line with a thermal sleeve insulation.


pspeaks
Paul Speaks
Dallas, Texas
(698 posts)

Registered:
07/20/2009 06:40PM

Main British Car:
1972 MGB-GT 1979 Ford 302

authors avatar
Re: Carb Heat & Vapour Lock
Posted by: pspeaks
Date: August 22, 2012 02:23PM

Let us know how it works Mike. Sadly I no longer have the flat head, but I do still live in Texas.


Paul


mstemp
Mike Stemp
Calgary, Canada
(223 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Carb Heat & Vapour Lock
Posted by: mstemp
Date: August 25, 2012 01:55PM

Up date,

Installed the heat shield/spacer from Mr Gasket (3710) as well as cover the fuel line in a DEI insulator for the engine bay section. Now the ambient temp is cooler so can't tell if it solved the problem or not! Oh well it's great for driving (23 C).



mgb260
Jim Nichols
Sequim,WA
(2465 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Carb Heat & Vapour Lock
Posted by: mgb260
Date: August 25, 2012 02:21PM

Mike,you can put louvered panels in inner fenders to help get the heat out. also shroud around radiator and fan to help cooling.


mstemp
Mike Stemp
Calgary, Canada
(223 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Carb Heat & Vapour Lock
Posted by: mstemp
Date: August 25, 2012 05:32PM

Thanks Jim.
Already have RV8 headers with the holes. Temp of motor can be kept in check just fine, just the carb seemed to have issues after lots of hot idling in traffic.
Hope it's solved now.


mstemp
Mike Stemp
Calgary, Canada
(223 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Carb Heat & Vapour Lock
Posted by: mstemp
Date: August 26, 2012 10:47AM

Ok no luck!
Drove car for a good run but the ambient temps are lower so I had no issues. Came home and let it idle with hood closed and left fan off till it hit 210.
As fan brought temp back down car seemed like it was out of gas once temp got below 195 and stalled. Car restarted fine.
I have checked the floats already and found the down position much lower then the 1" max spec, re set to spec . I am beginning to think my issue is a sticking needle valve preventing fuel from entering carb? Any tests for this? Other ideas? Fuel filter is see through and looks clear, will replace and also pull fuel pick up tube for inspection.


302GT
Larry Shimp

(241 posts)

Registered:
11/17/2007 01:13PM

Main British Car:
1968 MGB GT Ford 302 crate engine

authors avatar
Re: Carb Heat & Vapour Lock
Posted by: 302GT
Date: August 26, 2012 03:27PM

You could have a bad ignition coil. Weak coils often show first symptoms when they get hot.


deltron63
tony barnett
suffolk, uk
(8 posts)

Registered:
06/23/2009 04:55PM

Main British Car:
76 factory mgb gt v8 3528cc

Re: Carb Heat & Vapour Lock
Posted by: deltron63
Date: August 27, 2012 02:33PM

I had the same problem, I spoke to RPI Engineering who told me to remove the fuel filter and regulator from the engine bay. Problem solved. They also said not to bother with an isolator plate, but they would sell me one if i wanted to waste my money.
Really helpful chaps


mstemp
Mike Stemp
Calgary, Canada
(223 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: Carb Heat & Vapour Lock
Posted by: mstemp
Date: August 27, 2012 05:07PM

Tony,

If only my filter was in the engine bay!
But I am begining to think the isolator plate was a waste of $$$.
Might just be my Pertronix Coil. Just seems strange that most times it fires immediatly back up.


bestdog
Romney Palma

(11 posts)

Registered:
11/08/2011 01:48PM

Main British Car:


Re: Carb Heat & Vapour Lock
Posted by: bestdog
Date: August 28, 2012 01:37PM

Mike,
i am having same issues, car starts fine ,go for a spin acts like is starving for fuel and dies. i have cleaned the gas tank, new fuel filter, clean carb needles and jets, problem persists, i am begining to think is an electrical issue. Edelbrok carb, pertronix ignition. I am swithing to fuel injection as we speak, lets see what happens.
Romney.


donfaber
Don Faber
Terra Alta WV
(111 posts)

Registered:
10/31/2007 10:53PM

Main British Car:
1979 MGB 3.9L Rover V8

authors avatar
Re: Carb Heat & Vapour Lock
Posted by: donfaber
Date: April 27, 2023 08:52AM

A different twist - I have a 3.9L V8 with 1404 Edelbrock carb. Car has a rough time starting when hot, EXCEPT when i don't press the throttle at all. WHat causes this? Thanks - Don



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