Origin7

A quick update on my DCOE adventures: @SENC is correct. Thanks again for chiming in. Apparently, the useful range of the long taper screws is about 5 turns out from seated. With this in mind, I purchased another set of 45F9 idle jets. I tested these with my F11 emulsion tubes and left everything else factory. I found 12.5:1 at idle with the screws out 2.5 turns...perfect. From idle to cruise, it held ~12.5 very well. This resolved the rich cruising condition I've been working on. However, at WOT things started to go lean, as it did previously. Also, I was getting some spitting back through the carbs when I reved the engine. So, it appears I have a bit of leaness somewhere as the RPMs transition. Regardless, I am happy with how the 45F9 idle jets performed. So, I left them in and put the factory F16 emulsion tubes back in. The spitting went away, and the transition from cruise to WOT appeared steadier in terms of AFR. My observation is that the 45F9 idle jets seem to work better with F16 tubes than F11 tubes. It's a bit subjective, but Caterham seemed to have the same idea when they originally supplied these tubes. Long story short, I am back to the factory setup, and things are looking closer to optimized. This setup is probably just fine for people that aren't overly obsessive about this kind of thing. For the rest of us, hopefully this thread saves some headaches. I've tormented my neighbors enough for one evening, so tomorrow I am going to try 125 main jets in an attempt to richen WOT. If that doesn't work, I have 00 pump discharge valves to install. Making progress...

FOUND!

@IamScotticus I put the 55F8s in. Idle was lean (~16:1). I would have had to come out probably 1 turn or so on the idle mixture screws to get it down to 12.5:1. So, that would put me at about 3.25 turns out. My understanding is that any more than 2 turns out is an indicator that you need a larger idle jet. @SENC I am glad you mentioned this. I recall reading about this somewhere. I replaced all my idle screws and springs before I began this endeavor. I got these from Pegasus. It looks like they are the "long taper". I don't recall doing it, but I would typically check to make sure the new matched the old. It's probably worth confirming. I just read that 3 turns out is more of the limit with DCOE 40 151. The older versions 2, 19, 18 run the shorter screws max out at around 1.5. So, it looks like I do have some room to adjust. Thanks for mentioning this! I'll try the EZ turn lube as well.

Looking for a set of indicator pods if anyone has them. I guess these come in imperial and metric. Either should do. Used is fine as long as they are in decent shape.

Work continues on tuning my Webers. Here is an update: The mixture at idle is perfect. The idle screws are 2.25 turns out from the seated position. With this setup, I was running rich (10:1) at cruise and light tip-in. At WOT and over 2700 rpm, I am going lean (15:1). At the advice of Keith Franck, I switched to F11 emulsion tubes and left everything else the same for the first test. The results were excellent. My idle AFR stayed the same (great). When I crack the throttle 50% or greater, and the RPMs increased, the AFR was more stable and didn't lean out. Overall, it appears that the F11 emulsion tubes are an improvement over the F16 at least in my case. However, my rich cruising condition remains. Next, I pulled the idle jets. I expected them to be 45F9, which I installed a short while ago. Apparently, the shop that did some head work for me installed 60F8 and never mentioned it to me. So, I may have identified the root cause. If you compare the air-to-fuel orifice areas, here is what we see: Jet Fuel Ø Fuel area Air Ø Air area Air/fuel area ratio 45F6 0.45 0.1590 0.70 0.3848 2.42 45F9 — factory 0.45 0.1590 1.00 0.7854 4.94 40F9 0.40 0.1257 1.00 0.7854 6.25 45F8 0.45 0.1590 1.20 1.1310 7.11 50F8 0.50 0.1963 1.20 1.1310 5.76 55F8 0.55 0.2376 1.20 1.1310 4.76 60F8 0.60 0.2827 1.20 1.1310 4.00 The 45F9 jet is slightly leaner than the 60F8 jet, so this is probably the logical change to make. The only thing that has me scratching my head is that with 60F8s I am already 2.25 turns out on the mixture screws to achieve 12.5:1 at idle. This is the maximum your supposed to have these backed out. In theory, if I went to 45F9s, I would need to back them out even more. I can't recall how far out there they were before.... I happened to have 55F8s, so I put those in. I would have had to back out the idle screws another turn or so to get the AFR correct at idle. This would put me way too far out on the idle screw, so I bagged this idea. Long story short, I think my comparison above oversimplifies the differences between idle jets. It seems like there are other factors at play than just the opening sizes. TLDR: F11 emulsion tubes are great. I am leaving these in. More work needs to be done to figure out the ideal idle jet size.

Excellent color choice!

Thanks for the info.

I can't figure out who makes these. They are readily available in the UK through car builder solutions, Caterham, etc. Just not sold in the USA as a generic (not Caterham) part.

That would be excellent!

Still on the hunt for OEM black 5-3/4" headlight bowls w/ or w/o lamps. Specifically these: Willing to trade my 7" lights. Please PM me if you have something.

@JB455 Looks good. Well done!

FYI - I contacted Fristom to see if they have a distributor in the USA. They do not, so we'd need to import. If I can find something nice that is available here in the US, I'll design a housing and make it open source.

This is interesting and reinforces something I found recently. As I started tuning my carbs, I pulled and inspected the idle mixture screws (not the jets shown here). They were noticeably pitted at the ends or perhaps someone overtightened them at some point. New screws and springs are cheap, and probably a good idea to replace if you are fine-tuning your carbs. I am not sure how much replacing them helped me, but it certainly didn't hurt. Now that I see this, it makes me wonder what the inside surface looks like.

https://optronicsinc.com/products/brands/optronicsled/products.aspx?seriesid=787

I've been casually looking into this as well. This is the best value I've seen so far: https://uberniche.co.uk/big-col-flashy-lights The LED manufacturer, Fistom, does not have a distributor in the US, so unfortunately, you'll need to import/pay tariffs.

They are around $710 USD before tariffs and shipping. So, I'd budget for $1K

Go for it! I wouldn't bother with the threads, though. Printing threads doesn't go well typically. For stuff like this, I normally epoxy in a bolt. Another alternative is to design a void in the part, pause the print, insert a magnet into the void, then resume printing. The magnet should hold this part in place quite well.

@hahuang65 unbernich has some nice stuff. Thanks for mentioning him. I'm digging the rear LED cluster. At 170 quid, for everything (housing, light, connector, that's pretty hard to beat. Just wishing the tarriffs go away... https://uberniche.co.uk/big-col-flashy-lights

Speaking of 3D-printed components, here is an interesting idea from DPR: https://parts.dpr-motorsport.com/contents/en-uk/p119

Well done, @hahuang65

123 Ignition.

@Croc something like this?

That sounds exactly like the lean bog I was getting from having my floats sitting too low. I'd recommend measuring the fuel level to see how close you are to 25mm. WDB did a good job outlining the technique using the dial calipers. A couple of additional comments: make sure the car is level and run it right before checking. Per Keith, measure within 60 sec. Be prepared to take the covers ON/OFF a couple of times before you get it right. I should also note that like WDB, my floats were set correctly according to the weber spec, but my bowl level was low. Correcting this completely resolved the issue you describe.

@hahuang65 Nice work! This area is ripe with possibilities. I just did a gauge holder for my AFR gauge. I am not sure about the newer 7s, but on the older ones, you can hook underneath the tunnel cover to hold things securely without fasteners.

@Vovchandr That's a great idea. Another reason for me to get Tillet seats. I'd do this, but without the seat, it would be tough to match the geometry. I'll ask Tillet if they can send me a 3D model of this seat. It's probably a long shot.