30FFIA carb

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RobHomewood
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30FFIA carb

Post by RobHomewood » Fri Nov 01, 2019 4:20 pm

I have been trying for some time to reduce the rich running of my 16 P2 engine. I replaced the carb a while ago but failed to get it tuned right I think whilst concentrating on other issues so it remains running rich - and I mean rich - it leaves a large soot stain on the ground when I start it up, doesnt pull well up hills and returns max 19mpg. I have now reset the mixture screws, at high tickover revs, to what feels like the optimum setting but I am concerned that this setting has the mixture screws virtually fully home (ie closed) - actually only about 1/4 turn and 1/2 turn out respectively. Is it normal for this to be the correct setting or is there something else not right in the carb? Any views please

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luli
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Re: 30FFIA carb

Post by luli » Sun Nov 03, 2019 7:58 am

The first step I think is to check the spindle. If it has some freedom it would suck air and force you to close the idle adjustment screws. The other is to make sure that the fuel level in the float chamber is correct. If it is too high it will result in a rich mixture. Reasons for that may be a bad needle valve, a needle valve which is too high (not enough fiber washers), or a high pressure fuel pump. See more here: [url] ]https://lulis.org/2014/07/16/%d7%a8%d7% ... 5%d7%a8-1/ [/url
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RobHomewood
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Re: 30FFIA carb

Post by RobHomewood » Sun Nov 03, 2019 7:40 pm

Thanks Luli
I dont think the shaft should be leaking as the carb has been refurbished,
The fuel pump pressure is throttled down with a valve and I checked this with a pressure gauge recently and it is set at 1.5 psi so that shouldnt be the problem. I think maybe I shall fit an extra fibre washer or two under the float valve and just see if that makes any difference.

RobHomewood
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Joined: Tue Oct 22, 2013 8:04 pm

Re: 30FFIA carb

Post by RobHomewood » Tue Nov 05, 2019 7:08 pm

Well it doesnt look like the mixture problem is the float level. I added 2 fibre washers to the float valve but the car wouldn't start until I removed both of them - leaving the 3 shims already there.
Trying the mixture screw adjustment again I found the optimum setting still seemed to be with the screws almost fully home.
I did try changing the octane selector adjustment on the distributor and this did possibly seem to improve the engine output as I advanced it. The timing is set to the handbook FA position ie 3 teeth before TDC but maybe that is not correct for its present state?

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luli
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Re: 30FFIA carb

Post by luli » Tue Nov 05, 2019 7:59 pm

How good is the gasket between the carburetor and the manifold? Do you feel any air sucking down there?
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RobHomewood
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Re: 30FFIA carb

Post by RobHomewood » Wed Nov 06, 2019 11:27 am

Surely if there was a leak on the manifold the engine would run weaker not richer? Or have I got my head on the wrong way this morning?

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luli
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Re: 30FFIA carb

Post by luli » Thu Nov 07, 2019 1:19 pm

Do you have a vacuum indicator? what is the reading on idle?
The idle circuit is quite complicated and running not-as-designed can result unexpected results. May its time to check the pilot jet air bleed u and the pilot jet g. They are small and very sensitive to dirt. See more here https://wp.me/pXLKy-29A
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RobHomewood
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Re: 30FFIA carb

Post by RobHomewood » Mon Nov 11, 2019 11:18 am

Hi Luli
I can certainly try and take a vacuum reading on the inlet manifold. I seem to remember there is a fitting there somewhere. What would be a reasonable figure to expect?
I have taken the air bleed jets and pilot jets out and they look clear but they are difficult to blow through with the orifice being so small. I will look for some very fine wire
Rob

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luli
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Re: 30FFIA carb

Post by luli » Mon Nov 11, 2019 4:55 pm

Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

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