740 Throttle body

From a point at sea, to the circles of your mind, this is Bill:

It's under the inlet manifold - that big aluminium thing with legs on top of the engine. There's a black rubber boot that connects the air flow meter to the throttle body. If you operate the accellerator cam (the accellerator cable attaches to it) you will see a linkage moving

- follow this linkage to the throttle body.

Thanks Stewart, I will have another look later. I got the Haynes manual you recommended (the black covered one). I see why it is preferred over the new one, certainly more comprehensive, except for the throttle body!

Bill

I have just been out and had another look. As you say there is the rubber boot. The throttle body is the bit between the boot and the inlet manifold, correct? To remove it is it just a simple operation of undoing the worm drive clip that holds the boot to the TB, removing everything connected to it, then undoing the nuts. There is a microswitch attached which is operated by the linkage, but looking at my picture again I don't think it is attached to the TB, just blocks easy access to the nut. Is the throttle position switch inside the TB, or does it remain in the inlet tract when the TB is removed.

Apologies for so many questions, but I would rather ask before I start than get stuck halfway through the job!

Thanks again

Bill

From a point at sea, to the circles of your mind, this is Bill:

Yep.

Never needed to get that far myself, but it sounds about right. I would anticipate that there would be a gasket or O-ring between it and the manifold.

My car is a bit earlier than yours ('87) and doesn't have a TPS, so I don't know the answer to that. AIUI, unless you have a catalyst, K-Jet doesn't need one. Thinking about it, mine too has a microswitch that I've puzzled over. It's not connected to anything, so my guess is that it is there for models that have some sort of constant idle control - it seems it would only sense when the throttle is fully closed - and is redundent on mine.

TBH, unless you have a problem specifically related to the throttle valve I wouldn't be going to the trouble of removing it. Clean and lubricate the outside linkage mechanism, make sure this is working smoothly, and opening and closing properly. There is much less inside the TB than outside it (only the butterfly valve of the throttle). It's not nearly as complicated as a carburetter.

Weird, that's the first time I've seen that setup, looks almost like an '81 or earlier 240 except for the distributor on the back of the head. Was KJet cheaper than LH Jet or something?

When I did this on a '79 240 I found it was easier to remove the intake manifold, though you should replace the gasket if you do that. There's also a gasket between the TB and the manifold that should probably be replaced but if you're careful you can reuse it if you have to.

On your Fuel system there is no throttle body as in a LH car what would have to be done is either remove the rubber boot that goes in between the Intake Manifold & the throttle unit or as others have suggested remove the intake manifold

Sure there is, in fact it's the exact same throttle body LH Jet uses, it's just mounted on a different manifold.

K-Jet is cheaper, and simpler, so there's less to go wrong. However it's not as precise, so emissions are higher. It was always used on the normally aspirated 8 valve "E" engines.

Perhaps less to go wrong, but what can go wrong seems to do so more often. I know some have had great luck with KJet but for me it's been nothing but hassle, LH Jet always seems to run perfectly and when it doesn't the problem is generally pretty obvious and easily diagnosed.

Sitting for a long time without use is hard on K-Jet, because of the accurately machined steel parts in the fuel distributor. Other than that the only part that really fails is the warmup regulator, and sometimes injectors. It's biggest flaw is how it reacts to vacuum leaks though.