Author Topic: Weber 28/36 running too rich  (Read 81 times)

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Offline johnn1493

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Weber 28/36 running too rich
« on: Tuesday,May 07, 2024, 04:01:32 AM »
Hi everyone
First post from me. I’ve a Series 2 with a stock 1470cc engine which is taking its first few runs after years off road. Over the last two years I have swapped the chassis and renewed most of the suspension etc. The engine received new liners from the previous owner and so I haven’t really touched that side other than changing fluids. All new fuel tank and lines and an electric fuel pump with regulator.
Starts reasonably well but black sooty exhaust. Plugs fouling up very quickly.
The 28/36 Weber looks relatively new. I’ve stripped and cleaned reset float height. Checked ignition timing, replaced plugs and coil.

All jet sizes are as per ford cortina 1500 settings in book.

Put all back but still running rich with sooty black smoke exhaust. Turning the idle adjustment screw seems not to make any difference.

Haven’t checked valve clearances yet or given it a compression test.

Any ideas would be gratefully received.
Thanks
John

Online 4129R

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Re: Weber 28/36 running too rich
« Reply #1 on: Tuesday,May 07, 2024, 04:08:21 AM »
Does the Weber have an air filter?

Dirty air filter will restrict oxygen and make the engine run richer.

If the mixture is rich, they start easier, but run too rich when hot.

Offline BDA

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Re: Weber 28/36 running too rich
« Reply #2 on: Tuesday,May 07, 2024, 07:54:19 AM »
 :Welcome: johnn1493!!

Wish I could help you with your carb.

I know we’d all love to see pictures of your baby!

Offline jbcollier

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Re: Weber 28/36 running too rich
« Reply #3 on: Tuesday,May 07, 2024, 08:08:23 AM »
“Electric fuel pump with a regulator”

High fuel pressures cause the fuel to “squirt” and create turbulence in the float bowl.  This messes with the jetting.  Fit a proper low-pressure fuel pump that does not require a regulator.

While waiting for the pump, check your valve clearances.

If you search the forum there are posts with recommended 28/36 jet settings.

Offline Clifton

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Re: Weber 28/36 running too rich
« Reply #4 on: Tuesday,May 07, 2024, 11:30:28 AM »
Without a wideband you won't know where it is rich.
https://www.youtube.com/watch?v=MMTC6u0Nmk4

Offline johnn1493

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Re: Weber 28/36 running too rich
« Reply #5 on: Today at 12:02:30 AM »
Thanks for the responses guys.
 To answer the various issues. 4129R -Sadly the air filter is new, so no lack of breathing. BDA - I bet you say that to all the guys but I've not got the hang of uploading yet! JBC - Good point, not sure that it is a low pressure pump. I put regulator on to 'ensure' low pressure. The pump is a Facet Posiflow. Any suggestion as to a good replacement or should I go back to a mechanical pump?  Will try temporary gravity feeding fuel from a can to see if any difference. The valves will need checking though. Clifton - Wide band video link interesting.

BDA  in lieu of photos members may be familiar with the car as I rather foolishly bought it at auction, unseen, for far too much £££(after one too many glasses of wine). Bought from Mathewsons (see Youtube Mathewsons Lotus Europa April 2022). Mathewsons are a well known classic car auctioneer in UK (Bangers & Cash TV programme) and having auctions on a Friday night on-line, as they did then, was a masterstroke in marketing!! As stated, I discovered the car needed a new chassis so lesson well learned - Don't drink and bid!! :-)
John   

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Re: Weber 28/36 running too rich
« Reply #6 on: Today at 12:53:05 AM »

Offline johnn1493

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Re: Weber 28/36 running too rich
« Reply #7 on: Today at 03:01:12 AM »
Yes that’s the one.