I recently refreshed all the seals/gaskets/o rings in my OE Stromberg 175 CD carbs. I don't like changing settings on things that seem to be OK as is, car starts fine, runs fine, no hiccups, etc. just wanted to do the seals and check status of interior. Did not take out the butterflies. Idle was set at 750 as indicated by the tag on my air cleaner, before doing any of this work.

Idle has gone up to 1050 1250. Popping the acc. pedal doesn't change it. I also don't like changing things with the idea that there may be collateral effects. After examining the linkages. I noticed that the idle adjustment/stop on the carb closest to firewall hits the little screw with the choke fully off/closed. As a result, that cam does not come down as far as the cam on the front carb. I did find some documentation that seemed to indicate that there should be a gap when the choke is in this position, a gap of about 1mm. Thought I would check with those of you who know these carbs better than I do for your thoughts.

 

Hi Valerie,
I Don't know the Strombergs very well, I have SU on my series 1 but my brother has a Lotus with Strombergs. From your description I would guess that you have a vacuum leak since you didn't touch/adjust any of the linkage. I would start with checking the tightness of the carb mounting nuts and/or the intake to engine nuts. Then the vacuum lines, pull them off one by one and plug the port on the carb and note if there is a change in the idle. A vacuum line may have come off at the other end, cracked or split. Then spray carb cleaner around the carb shaft seals, carb to manifold gaskets and finally the intake to engine gaskets to see if the idle changes.

I hope this helps!

P.S. How is it going with your friend dad's 3.8S?

 

Valerie,
I am showing a gap of.067 in or 1.6 mmm..
Rgds
David

 

The two carbs closest to the firewall have a fast idle setting. the first notch on the choke is the fast idle. It engages the cams you pictured. The screw should not touch the cam. 1 mm seems right.

 

Bob, thank you for you suggestions. These are pretty simple Stroms, no vacuum. Will try the carb spray to check for air leaks.. Drove the car Saturday, put him in the garage, idle still high, and didn't look at the linkage. Today I looked at it and now there IS a gap between that screw and the cam!! Maybe I need to look at that carb's cable and see if it is holding that cam up too high. (moral so far, no good deed goes unpunished).
Friend has legal paper giving her ownership, but can't find title. I sent link to her State's lost title process, so now the ball in in her court.

 

Valerie, the Haynes manual specifies 0.8 mm but I find a slightly larger gap is not an issue. With the engine warm, the usual procedure is to back the screws out, balance the carbs and set the idle mixture. Then set the idle speed and gap. Visually check that the choke cable lengths are proper and matched by noting that the cams move together and cover the entire travel range. Incidentally, I think the Haynes Zenith Stromberg manual would be quite useful although it is hard to find copies.

You did not mention the state of the smog controls if they are still installed. That can be a real complication.

 

HI Bill and thank you for your time and help. I think it IS the cable and synching those cams. The front cam (towards radiator) rotates lower than the rear (firewall). It appears that I have sufficient cable and sheathing to loosen it from the clip, undo the little screw and push a bit more cable in the little clamp hole. No work today, but will get on it Tuesday. I know I had that STromberg manual, but among my gazillion Jaguar books, do you think I can find it?? at least, not yet.

 

Spent some more time checking the choke cable operation. I removed the clip holding the cable to the bracket to see if the cam would go any lower and it does not. When I pull the choke out, both cams operate the same, the 'flat' at the top of the cam is in the same position on both. I consulted section QY in my Bentley manual for additional enlightenment, but didn't get much. Perhaps a choke cable replacement is in my future (oh the horror of it all!). Also looked at the S2 parts book, no light there either. However, there is now consistantly a gap between the stop screw and the cam when the choke is fully closed. Oh, this is a black hole....

 

Valerie, just a warning, I converted to triple SU's awhile back and am relying on memory (somewhat ravaged by the years). If I understand correctly, the cams are aligned when the choke is on but one cam does not rotate enough with the choke off. Back both fast idle screws out so there is no contact. Remove the air cleaner and look at the throttle plates. If both are closed completely and the cams still are not synced, disconnect the choke cables. Something should be make sense at this point.

A major source of confusion might be caused by the smog system. If they have not been removed, you may have secondary butterflies in the intake manifold that are operated by the throttle linkage. This shouldn't effect the choke cams but who knows? Good luck, Bill

 

Worked a bit on the carb linkage yesterday along with working the choke (ignition off). I spritzed a bit of penetrating oil in along side the choke lever inside the car and that seems to have helped. The cam on the carb closest to the firewall/bulkhead now consistently rotates to a position where there is the gap between that and the fast idle screwhead. When I work the choke, both cams are consistent in their position and with each other. I removed the choke cable from that carb closest to firewall and there is no further rotation possible for that cam. I will take the air cleaner off and check the throttle plates. I looked through my notes again from the seal refresh job and on one of the carbs, when I checked the float height (without gasket), found it a bit off. I believe 16-17 mm is correct setting? I checked the float height on the second carb and it was within range. Went out looking online for the Haynes Stromberg manual and have one coming. Thank you so much for all your help!