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Carb lube cd 150s

Acollin

Platinum Level Sponsor
Series V. 1966

I am a bit confused about what oil to use in my carbs and was wonder what the effect would be on rich/lean depending on the lubrication.

*****My owners manual says to use 20w in the dampers. Owners manual also says 5w/20 can be used in engine in extreme cold and straight w20 can be used between temps 80 f to 20 f.Page 24

******The wsm says to use engine oil ----NOT " 5w/20 must not be used"section C page 58. I am running 10w/40 or 10w/30 in my engine.

What grade should one use and what are the effects on lean/ rich when a improper weight is used?

Thanks
 

RootesRacer

Donation Time
The more viscous the oil, the longer the engine runs rich after you open the throttles.
This because it forces the piston to resist its opening during throttle increase.
When the piston resists opening, the vacuum on the throttle side of the piston creates more fuel lift and causes a richer than steady state mixture.
Once the piston hits its diaphragm/spring-gravity equilibrium, it will stop at that position and the fuel mixture goes steady state.

Consider it a tuning adjustment for the acceleration enrichment (accelerator pump).
 

hartmandm

Moderator
Diamond Level Sponsor
Andrew,

My notes for Stromberg damper oil are:

Use Automatic Transmission Fluid "Type F" (equiv to SAE 15 oil), or
original Zenith-Stromberg Damper Oil (equiv to SAE 20 oil).

I don't remember where the 'equiv to SAE xx oil' came from, so not 100% on that.

The original Stromberg carb damper oil is relatively expensive. I am using Automatic Transmission Fluid "Type F".

As a side note, I swapped in richer metering needles in my Strombergs to counter today's ethanol blended gas. I don't have ethanol-free sources near me. See this thread for more info: http://www.sunbeamalpine.org/forum/showthread.php?p=174191

Mike
 

65beam

Donation Time
lube

A 4oz bottle of damper oil is available from either Moss or VB. Usual cost is around 4.25. I usually buy from Moss.
 

bernd_st

Bronze Level Sponsor
I always use standard 20w50 . Works well and follows the manual instruction. Any thinner oil will reduce the accelerator pump function plus will be sucked out from the damper lot more faster...
 

Tim R

Silver Level Sponsor
I always use mono grade. My understanding is that it should be between SAE 5 and SAE 20 depending on where the car is (Climate and temperature) and specifically NOT a multigrade because they change consistence with temperature.


The cheapest way to get mono grade like this is to buy Motorcycle Fork oil. There is a wide choice of mono grades between SAE 5 and 20. You will get a large bottle in the UK for about £9.00, probably cheaper in US.

Tim R
 
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