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Idling jumping around with DCOE

 
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After_Thought  



Joined: 08 Oct 2019
Posts: 24
Location: Hudson ohio

PostPosted: Tue Mar 17, 2020 12:42 pm    Post subject: Idling jumping around with DCOE Reply with quote

Installed Side-drafts (Weber 45 DCOE) onto my 924 and having idle problems. when idling the car jumps between 1000-2000 rpm and sometimes even randomly jumps to near 3000 rpm. I don't know what's causing it and could use some guidance.

Some things to note ::

--Car will immediately die if speed screw is only turned 1/2 turn in, no matter what the idle screws are set to.
--The butterfly valves are relativity balanced (looked through the progression holes)
--Car has good compression, 150 - 160 across all cylinders
--Getting 4.5 psi to carb using Holley bypass regulator
--Carbs were cleaned before installation (maybe not well enough?)

I don't know much about carbs (new to cars in general) and dont really know where to start. anyone with knowledge I greatly appreciate your help.




Jetting table(jets that are installed): https://www.carbparts.eu/jetting_table

Video of my car idling: https://youtu.be/3n1Ho7IkE1Q
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Juho  



Joined: 03 Oct 2018
Posts: 125
Location: Finland

PostPosted: Tue Mar 17, 2020 6:19 pm    Post subject: Reply with quote

when i had webers i couldnt get the engine idle because of the aggresive camshaft i had on it. The rpms jumped between 1000-2000rpm and sometimes it almost died if not given gas.
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 904
Location: Maysville, Colorado

PostPosted: Tue Mar 17, 2020 10:06 pm    Post subject: Reply with quote

Get fuel pressure down to 3 max, 2.5 better. Close all the air bypass screws(the ones under the white caps)if the 152 series. Then balance the carbs. It can be difficult even with a air flow meter available from any Weber dealer, some can do it by sound listening to the front throat on each carb with a about 1" hose. Then adjust the idle on the back carb. Then play with the fuel mixture on each carb. If the newer 152 series the idle screw set up should be a 2.5 turns out. It is still no guarantee it won't jump around a bit. Use some carburator cleaner spray to make sure you don't have and vacuum leaks around the vibration mounts. It is not an easy procedure to get right.
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Mike
Poco a Poco, #033 '78 Vintage racer, SCCA Dp-81
'77 924
cricketdesigns.com
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After_Thought  



Joined: 08 Oct 2019
Posts: 24
Location: Hudson ohio

PostPosted: Wed Mar 18, 2020 2:58 am    Post subject: Reply with quote

I don't have the newer 152 (i'm pretty sure). is it normal to not be able to idle unless speed screw is like 1.5 turn - 2 turn in? all of my air bypass screws are in
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 904
Location: Maysville, Colorado

PostPosted: Wed Mar 18, 2020 8:48 am    Post subject: Reply with quote

Look at the stamped label on top of the float bowl cover. It will say 45DCOE152 or 45DCOE 19 or 34 or 78 many numbers. There should also be a cast W on the top that says it is a real Weber(There are Chinese and I think some Chezch copies). It will also say made in Spain(after 1992+-, or Italy(older). Typically if it is a 152 start adjusting the idle at 2-1/2 turns out, if it is the earlier one I believe it is 1-1/2 turn. Apparently the Chinese copies are junk.

Google how to tune the weber carbs there is lots of information. Much of the published stuff is for early carbs and refer to the 1-1/2 turn. This includes Redline who is the major supplier. They generally do give a good progressive proceedure
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Mike
Poco a Poco, #033 '78 Vintage racer, SCCA Dp-81
'77 924
cricketdesigns.com
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After_Thought  



Joined: 08 Oct 2019
Posts: 24
Location: Hudson ohio

PostPosted: Wed Mar 18, 2020 9:42 am    Post subject: Reply with quote

Ill go check the numbers tomorrow when i get home
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safe  



Joined: 18 Mar 2017
Posts: 166
Location: Sweden

PostPosted: Wed Mar 18, 2020 6:06 pm    Post subject: Reply with quote

Are the throttle shaft bushings ok? If they are worn and leak you will never get a good idle. As said balance the butterflys, that is step one, by flow or vacuum behind them, not by eye.

If they are the Chinese knockoffs, you can probably just throw them in the bin right away and save a lot of time... (from research I've done about them and other Chinese carbs I tried using...) or maybe you'll get lucky.
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After_Thought  



Joined: 08 Oct 2019
Posts: 24
Location: Hudson ohio

PostPosted: Thu Mar 19, 2020 1:14 pm    Post subject: Reply with quote

Got them working today!! You were right about them being the newer ones that start with the idle mixture at 2.5 turns out. Car is running much much better thank you so much.

next is my tail lights and brake lights don't work :/. what fuse should i be checking for the tail lights? I've read online that it is the same as the headlights (mine headlights work)

and my brake switch wiring seems completely disconnected. not sure what to wire it up too
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After_Thought  



Joined: 08 Oct 2019
Posts: 24
Location: Hudson ohio

PostPosted: Thu Mar 19, 2020 1:17 pm    Post subject: Reply with quote

[img]https://imgur.com/smMPuWy[/img]
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