Triple Oer Carburetor Troubleshooting - Help

[adam.]

Being the first set of triples I have ever played with, I'm not 100% sure, but I would say I think they're right! Linkages themselves are the same length and are adjusted so that the open at the same time.

 

I only have an old school unisyn flow measuring tool. At idle, it is quite hard to measure because there's so little vacuum but I can gauge the level of flow enough with it.

 

I will have another little play around and try to remove that accelerator pump factor and report back soon!

[Reverend]

All this is good info! Looking forward to use this with my SK/OER carbs as well. Thanks!

[240260280z]

We are all in the same boat. I'll have mine on a motor later this iceage I mean spring.

[Reverend]

Btw, what would be the best fuel level "check" tool for OER/SK carbs? I remember there was some discussion about DIY ones somewhere.

[Travel'n Man]

Dump the unisyn and get one of these - you'll be glad you did

 

http://www.aptfast.com/ShowItem/101420%20Carburetor%20Synchrometer%20Universal.aspx

[adam.]

http://lupinusflower.ocnk.net/product/58

 

This is the fuel level gauge I use, Reverend. It's a fairly basic tool which I believe you could make one up yourself..

[240260280z]

The unisync fits in tighter spots and fits on more carbs. It can measure a larger range of airflows. It is also very tough (metal) and can live in a tool box.

The STE (Modles SK and BK) is designed for airflows where 1 barrel feeds 1 cylinder. It has a more precise gauge and is easier to read. It is big and made of plastic so it is difficult to fit on some carbs. Adapters are made that can help.

I like using the Unisync on twin SU's and STE's on triple webers.

Edited March 23, 2015 by Blue

[adam.]

So I had a chance to tinker a little yesterday evening and following Blue's diagram of how the idle screw adjustments affect cruise and idle AFRs, I simply just dialed in a little more fuel (turning another half turn on the idle mixtures) and the lean hesitation on cruise and acceleration has disappeared (for the most part)! 

 

Here's a graph of me taking off in first gear, shifting until forth and then cruising and then slowing down to idle.

 

 

As you can see, the rich dip after the gear changes are still there, but the pump adjustment is at the point where there is no longer lean pops after aggressive WOT at low RPMs. So as long as that works, I am not too fussed about the rich dip on gear changes.

 

Second gear acceleration goes a tad lean as you can see but there's no hesitation and with the light load, I am not too fussed once again. Third gear onwards is fine. Cruise is at about 13.5:1 which I am happy with and idle is around 12-13 which is on the rich side but if everything else drives fine, I am happy with that!

 

I believe under WOT, the mid range is in the 12.5-13 AFR range but top end is a little rich meaning I need larger air correctors which I don't have. Other than that, I am quite happy with how the car drives now. Feels amazing.

 

Thought I'd update you all! And thanks again for the tips and help.

[madkaw]

You would be corrected harshly by Todd at Wolf Creek for calling the pilot screws idle mixture screws.

Idle mixture is incorrect and misleading because it adjusts way beyond idle.

I also think the Mikuni manual recommendation for a single turn out is more for a stock engine application. I never could get a proper mixture using just one turn to cover all the areas the pilot jet covers. I think I was about 2 turns. It sounds like you got it close- congratulations

[adam.]

Thanks As pointed out by Blue earlier on in the thread, OER carbs recommend 2 turns out, plus or minus half a turn. Mines currently at 2.25 out which is within spec. And I'm glad.

Time to get it on a dyno and see if the triples can crack a higher than 83rwkw it has with the SUs.

[adam.]

Okay, so I tried to get the car dynod yesterday and the car just broke down. The air temps were a tad cooler than the other day when I got the carbs to run spot on, but I think it's now running lean again...

 

Idle is still around 13:1, cruise is not far off that, but slow/medium acceleration between 2-3krpms, it just loves to go up to and over 14:1 and stutter/miss/carry on. I can only get around it by accelerating and then while keeping an eye on the AFRs, jab the throttle to activate the pump jets to richen it back to 12-13:1 AFRs every few seconds which is quite annoying and isn't the way a car should be driven.

 

I am really puzzled as to why it is doing this. I tried dialing out the idle/pilot mixture screws again like the other day but it had no effect whatsoever.

[240260280z]

It is difficult to see this in your plots above. Most of the data is below 14 apart from when you shift.

If you are really going lean on the dyno then consider:

Raising the fuel level or closing the holes on the higher end of your emulsion tubes above the fuel level to bring main fuel in earlier.