Stromberg question

[Bainford]

Do Twin Cams fitted with Stromberg carbs have a Cold Start Device and a Throttle By-Pass Valve device fitted to both carburetors?

The Lotus manual says 'Yes' for the Cold Start Device, but doesn't specify for the Throttle By-Pass Valve. However, the 'original' carbs fitted to my car (I can't be absolutely sure they are original) have these devices fitted to the Front carb only. Several years ago I purchased a pair of rebuilt carbs from Paltech, and that pair also had these devices fitted to the Front carb only. Regarding the Cold Start Device, this doesn't make sense, and I'm not sure it makes sense for the Throttle By-Pass, either.

[Grumblebuns]

Like your TC, both of my TCs and a Plus 2 have the cold start device/choke on the front carb only. If you read the manual, it states that pulling out the choke cable operates the cold start device for both carbs, a bit confusing.

[Bainford]

Yeah, that mention in the manual was the confusing bit for me too. That, and the notion that having cold mixture enrichment on only one carb seems odd.

[EuropaTC]

If it's any consolation years ago I had a Marcos 1800 which had the 1800 Volvo engine and it had been fitted with Strombergs at some point. That also had the choke only on the front carb which I thought was an installation bodge by a DPO at the time but based on your comments, probably not !
Brian

[Bainford]

Strangely, Brian, that does make me feel a little better.

Thank you Joji and Brian. Clearly this is a normal arrangement. I remain puzzled by it, but I shall summon the courage to move on.

[jbcollier]

Normal as in stock?  Yes.  Normal as in ideal?  No.

TCs are susceptible to cold start plug fouling.  Obviously two enrichment devices was too much so, rather than pay Stromberg for a custom enrichment device, Lotus just deleted one.  Sounds about par for Lotus at the time.  Works though, just warm it up properly, and don't drive with the cold start engaged.

[Bainford]

Cheers John. Thanks for confirming my concerns that it isn't 'technically' right, and my suspicions that it may be a corner-cutting exercise by Lotus. I can stop dwelling on it now and get some sleep. Not that it mattered too much, as I have had my cold start device disconnected since shortly after buying the car, but it has long puzzled me.

[Grumblebuns]

Trevor, with your cold start device disconnected, you don't have issues starting a cold engine in cool weather?

[Bainford]

No, none at all. In fact, one thing that has always impressed me is the way it fires up instantly, regardless of weather. In the fall of the year, I drive it up until they salt the roads, so it gets driven in temperatures approaching freezing. This may have a little to do with the fact the Strombergs are old & worn, and running a bit rich in low speed operation. That may change when I fit a fresh set of carbs next summer. A (different) fresh set I had temporarily fitted last year showed no starting issues, though were only used in warm weather.

[BDA]

The original TC motor that came in my car started almost instantly without using the choke. That engine started the second quickest of any I have ever seen. It must be said that living in New Orleans and most of it's mileage was during the summer so maybe that isn't such a big deal. But the Europa I had prior to this one did start INSTANTLY, and by instantly I mean that as soon as the key touched the third position of the ignition switch, it fired up. If I had ever needed to "bump" the starter to position the engine for some reason, I wouldn't be able to. I have never seen any engine in any car start that quickly and easily! It was amazing! Again, that was always without a choke but cold weather is not a problem in New Orleans where I owned that car.

Rightly or wrongly, I always credited the carbs. I think maybe I was right.

[Grumblebuns]

In starting my TCS, it's always been a habit to pull the choke cable out before starting it, even in tropical Hawaii and So Cal. After I  install my newly rebuilt TC motor, I'll have to keep your comments in mind and try starting the car without the choke..

[Bryan Boyle]

In starting my TCS, it's always been a habit to pull the choke cable out before starting it, even in tropical Hawaii and So Cal. After I  install my newly rebuilt TC motor, I'll have to keep your comments in mind and try starting the car without the choke..

I went down to take my buggy for a ride yesterday; 50-ish here on the SE coast of Massachusetts...haven't started her for a few days, pulled the cold start knob out, nudged the starter, and she fired right off.  No foot on the loud pedal...let it run for 30 seconds or so, dropped the cold start back in, and no stumble or hesitation.

Still have to replace the butterfly shaft seals and the o-rings on the bottom of the vacuum chamber dashpots...but, after 3.5 years of fiddling with the motor and such in 3291R...those strombergs are working ok.

[jbcollier]

Strombergs are a fine carb and work very well indeed when set-up properly.  Emission adaptations were less well done and a bit problematic but all "emissions" carbs had similar issues as the requirements for ultra-fine adjustments means they are very sensitive.  The emission adaptations are easily disabled on a Stromberg, another plus in their favour.  Stombergs also flow very well as there is nothing cluttering up the carb throat, such as auxiliary venturi, accel pump nozzles, etc.

[Bryan Boyle]

Strombergs are a fine carb and work very well indeed when set-up properly.  Emission adaptations were less well done and a bit problematic but all "emissions" carbs had similar issues as the requirements for ultra-fine adjustments means they are very sensitive.  The emission adaptations are easily disabled on a Stromberg, another plus in their favour.  Stombergs also flow very well as there is nothing cluttering up the carb throat, such as auxiliary venturi, accel pump nozzles, etc.

IIRC, in the Road and Track review of the TC when it came out, the test of the Fed car was done in the UK...and the tester complained/mentioned the hesitation with the R suffix carbs.  The US editor inline commented "now you see what we're dealing with over here" or something to that effect.  IIRC, even the domestic cars (FI wasn't that widespread at that point...73-74ish) had issues with the add-on emission stuff in terms of driveability when cold (and even when hot...).

I'm OK with my strombergs; no secondary throttle interference, even with the need to replace a couple seals, I'm still averaging (if I don't suddenly develop lead soles on my shoes) 28-32 MPG, responsiveness is just fine.  Figure when I go through them again...and get the seals I missed done...will be even incrementally better.