engine warm up and acceleration

Hi I own a 1987 automatic volvo 240 gl on a solex cisac carburetor. The Pulse Air System was cut and sealed off (the steel pipe running at the exhaust side near the fire wall and the one directly under the intake manifold). My concern is, it takes about 5 minutes and sometimes more of engine idling to be able to make the brick run smoothly, otherwise if idling is done less than the 5 minute limit, upon acceleration, the engine conks out. My other concern is, acceleration is turtle slow but upon reaching a certain speed/rpm or high speed, engine response is ok. Upon deceleration, engine response to accelerate or to pick-up speed is again painstakingly slow. I suspect that I have not completely sealed off all the vacuum lines/tubings of the Pulse Air System. Did I leave out something? I also would like to know where the flame trap tube that runs into the middle of the intake manifold and runs under the carburetor is connected?

There is a cold running heater element in the carburrettor, contacts very prone to corroding or gumming up. There would originally have been a thermostatic vacuum valve in the block, under the inlet manifold, looking a bit like the alternative electrical sensor but with two pipes attached. I can't off hand remember what it connects to, but if still connected it has to work otherwise the engine won't run properly until warmed up.

engine warm-up and acceleration 

Thanks Clifford! Nice to hear from you again! Can you describe where this cold running heating element is located in the carburetor and how can I check if it is still working or not? A photo may be of great help. With regards to the thermostatic vacuum valve located in the block under the intake manifold, I assume that this can be only checked when the vehicle is raised in a lifter. Would you also know how to check if this part is defective or not? By the way, where does the flame trap connect to and what is if for? In my vehicle, the flame trap was also removed, do I have to seal of anything in particular?

When I say "under" the manifold I just mean screwed into the block on the inlet manifold side, about by no. 3 cylinder. It's a bit tricky to get at, but quite easy with the right spanner. The valve should be closed when cold, but open when hot. So you can test by blowing. A test in practice without removing anything is just to clamp one of the pipes at the nearest rubber joiner and see how the engine runs when first started. You can in fact use the car like that, just getting out and releasing the clamp after warm-up. But it may be this part too has been blanked off, in which case ignore all the above. Probably on reflection the cold start heater is not relevant. I think it might be more to cope with carb icing than normal cold running. But anyway, it is mounted just above the mounting flange on the engine side of the carb, popped into a hole and secured with a bolt, as I recall. There is a spade terminal on the end, with a wire. It may just need jiggling and repositioning. Maybe it is live all the time, or may be through a thermostat, I can't remember.

engine warm-up and acceleration 

Thanks again Clifford! I will check the thermostatic vacuum valve and get back to you. The same goes with the cold start heater. Would have any insights or suggestions what to check regarding my poor acceleration/engine response problem?

Not specifically. There are the usual things like distributor tracking, ignition leads, plugs, inlet air leaks. From memory, the carburettor has some extra devices like a thermostaic valve and possibly an accelerator pump, to give a shot of fuel when accelerating. You really need to study the green Haynes to gen up on that sort of thing. Best of luck

1. If the system you have disconnected has metal tubes on the inlet side of the head as well as the outlet side, it would be the EGR system, not the Pulse Air system. This has been a subject of previous threads involving you, Clifford, and me. 2. My B21A with SU carby did much the same thing when cold and new. Dealers in Australia had never seen a 21A before and could not rectify the problem, but it was easily solved. SU carb was a manual "choke" system with the usual cam and adjustment screw to increase the idle speed when the choke is activated, and this system was way out of kilter. Consequently, the engine had to be over choked to lift the idle speed to a viable idle point, and the engine ended up way too rich when launching and stuttered and stalled about 1/2 a car length into an intersection. Happened regularly and predictably until the engine was warm enough to operate without the choke applied. I adjusted the fast idle screw to give about 1000 RPM on 1/4 choke (cold) and found that the engine was happy to start at that point and would launch happily from start at that setting. Choke was then decreased in a couple of steps over a couple of minutes as the engine warmed up. According to my green Haynes, your carb has a similar fast idle screw above the throttle and kickdown quadrant, but I don't know enough about the choke system setup to reduce the choke effect.

b230 engine warm-up and acceleration