Stromberg carb temperature compensators

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baganz.sven@web.de
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Stromberg carb temperature compensators

#1

Postby baganz.sven@web.de » Thu Aug 03, 2017 7:56 pm

Dear forum members,

my carb specialist has told me that I should screw the temperature compensators to completely closed position because they never work properly and are not really necessary.
It is better to have them all closed than having different bypass volumes.

What do you think, what are your experiences?

I have planned to syncronize them fully open a 65°C.
Close them is easy.

Thank's for advice for my Strombergs

Sven
Sven
'71 S3 coupe LHD manual

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MarekH
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Re: Stromberg carb temperature compensators

#2

Postby MarekH » Thu Aug 03, 2017 8:49 pm

They are nothing more than a steel spring with a plug on the end. Put them in the oven and look to see how they perform against each other.
You should be able to make them open and close mostly in sync with each other.

Presumably they will have most effect at idle by admitting extra air past the throttle plates.

kind regards
Marek

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abowie
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Re: Stromberg carb temperature compensators

#3

Postby abowie » Fri Aug 04, 2017 1:55 am

baganz.sven@web.de wrote:Dear forum members,

my carb specialist has told me that I should screw the temperature compensators to completely closed position because they never work properly and are not really necessary.
Sven


That has been my belief as well. I have found temperature compensated carbs to add an additional level of complexity that doesn't seem to help get the car running well.
Andrew.
881824, 1E21538. 889457..oops
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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baganz.sven@web.de
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Re: Stromberg carb temperature compensators

#4

Postby baganz.sven@web.de » Fri Aug 04, 2017 7:03 am

Hello Marek,

Mine were completely stuck in different opening positions.
I think they might work after cleaning and adjustment for some time, but are they really necesssary?

Perhaps someone un the forum has already tested the differences between blocked and not blocked.

Best regards

Sven
Sven
'71 S3 coupe LHD manual

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42south
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Re: Stromberg carb temperature compensators

#5

Postby 42south » Fri Aug 04, 2017 9:06 pm

Hi,
I agree disable them.
While you are at it also disable the bypass valve on the side of each carb. To do this just remove the vacuum source from the little pipe on the top of the valve and plug it. These units were only there for emission control purposes.
Also I would remove the vacuum from the retard unit on the distributor and block this as well. This was another attempt by jaguar to meet emission controls. This unit causedthe car to run hotter, and spoils fuel consumption.

Regards
Mark Brown
1971 S3 Etype
When my ship comes in it will probably be at the airport.

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jagwit
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Re: Stromberg carb temperature compensators

#6

Postby jagwit » Thu Aug 10, 2017 9:59 am

I have recently fiddled with these temp compensators and found it very easy to clean and tune.

I had a bowl of cold water (20degC) and a bowl of luke warm water (40degC). In the cold water they had to be closed and in the warm water they had to be open (or at least open to the same extent). After having cleaned them, I found it quite easy to "tune" them to be closed in the cold water and equally open in the hot water by adjusting the blade nut.

The only gotcha worth mentioning is that its important to have the blade perfectly dead centre of the needle, otherwise the needle may stick and will not open/close freely.

I suppose disabling them is also an option, but then they should be disabled in the open position surely? (after all they are supposed to be open once the engine is warm)
Best Regards
Philip
71 E-type V12 Coupe,
83 DD6, 80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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Tbob
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Re: Stromberg carb temperature compensators

#7

Postby Tbob » Thu Aug 10, 2017 3:11 pm

baganz.sven@web.de wrote:Dear forum members,

my carb specialist has told me that I should screw the temperature compensators to completely closed position

Sven


That is Joe Curto's recommendation when running adjustable jets. He also recommends closing the idle trim screw. His assertion is that they contribute to a "lean when hot" condition. Placed there to help manage emissions in the 70s, today's ethanol-enhanced fuels run leaner and our old carbs need to be adjusted to compensate.
Bob t

LHD '69 OTS. (Former) basket case

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Adamski
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Re: Stromberg carb temperature compensators

#8

Postby Adamski » Thu Aug 24, 2017 7:55 am

There's a mix up here between the compensators and the anti pop valves, that have a vacuum source attached. There's a lot of info here on Stromberg's if you search. I've wrestled with this issue for a long time. The compensators were a fudge to weaken the mixture when hot and this raise the tickover to make the engine run at higher revs and thus make the water pump run faster to provide better cooling. It also gave better pollution readings. How useless is that. They didn't get the fuel injection designed in time.
I nearly seized an engine when a so called carburettor specialist in the 'Southern' part of England rebuilt my carburettors and left the temperature compensators open. I was running so weak that the knock on effect was nearly a disaster and took me absolutely ages to diagnose. After doing all the tests in accordance with Paul Clarksons post I came to the conclusion that YES they are best tightened up and dispensed with.
The pop off valves open on overrun detecting strong vacuum. I also found that the gaskets between the blocks were leaking and had never been addressed in the rebuild. I dismantled them and sealed the joints correctly. They have a little screw to calibrate the pop off point that can be done with a vacuum source.
After much calibrating I came to the conclusion that they were not worth the trouble and dispensed with them and the vacuum pipes.
Adam
S3 V12 E Type FHC Manual 1972-owned since 1978

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