Thread: RPM's 2.25 petrol

IMO 850 is too high
Mine idles easily at 600, and will go as low as 450 when warm

Originally Posted by Phil B

IMO 850 is too high
Mine idles easily at 600, and will go as low as 450 when warm

Mines the same, 450-500 rpm warmed up. So smooth and sweet.....

Cheers Rod

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Specified idling speed for the 2.25 petrol was 500rpm, but I believe this had to be increased to meet emissions levels in late Series 3 vehicles. And these had sealed idle speed and mixture adjustment screws.

John

Specified idle speed for the 78 Series 3 I have is 800. However there are a number of different carbies that were around at the time as far as what pollution control gear they had on them. They are all Zenith 36IV but lots of differences none the less. If the pollution control has all been blocked or removed then you can probably drop below the 800 but it will not idle as low as the earlier ones. Check the timing as well as that can have a major effect on the idle that the carburettor will get to.

Cheers,

TimJ.

Interesting and thanks as usual for all the responses.
I need to do a bit more research by the sounds of it.
Having re-checked the 34ICH literature which was sold as suitable for the 2.25 petrol it definitely says you should aim for 800-850.
I've put off taking a look at the timing as I find the thought of it rather daunting. I should get to it. I'll let you know how I get on.
cheers,
D

Assuming your not setting up for the emission controlled version idle of 750-800.

spark timing is most likely out. you need to set the static timing for emission or non emission idle speeds depending on if you have emission control or not.

you could also have a rich setting and a vac leak after the butterfly.

low compression 2.25s without emission control should get down to 400rpm
hi compression without emission should get down to 500
with the emission control you should be able to sneak down to 600 rpm but most likely you'll struggle to get down below 650 without hunting.

I generally aim for 650 as the start point and then work it up or down to the point where it just starts to hunt and then raise the idle 25 RPM or so.

Originally Posted by Blknight.aus

Assuming your not setting up for the emission controlled version idle of 750-800.

spark timing is most likely out. you need to set the static timing for emission or non emission idle speeds depending on if you have emission control or not.

you could also have a rich setting and a vac leak after the butterfly.

low compression 2.25s without emission control should get down to 400rpm
hi compression without emission should get down to 500
with the emission control you should be able to sneak down to 600 rpm but most likely you'll struggle to get down below 650 without hunting.

I generally aim for 650 as the start point and then work it up or down to the point where it just starts to hunt and then raise the idle 25 RPM or so.

I've just checked mine. Engaged the capstan winch at idle. The bollard did 5.3 revs/m. The worm drive is 75:1 Idle speed 75x5.3 =397.5 revs/m

So if I have the engine with emission control , 800-850 is ok?
What tells me whether I have emission control or not then.
cheers,
D