eddy 500 running rich

sidecar · Post by **sidecar** » Sun Mar 04, 2012 4:07 pm

mgbloke wrote:More feedback.
Today I fitted 83jets with 65/52 rods with silver springs and 92 secondaries.
Briefly drove the car and it was immediateley apparent that there was a big flat spot coming onto part throttle. Once the engine picked up again it felt good. AFR was around 16 on cruise and flicked to 18 momentaerily as the engine stumbled before going back to around 15.
Didnt try WOT for obvious reasons.
Going to try same setup with 62/52 rods when the rain stops.

Mark

Hi Mark,

Your AFR figures are certainly showing that its too lean on cruise, I guess this just goes to show that not all engines are going to run the same carb setup in order to get the same AFR readings. My tests have shown that these lumps really don't run well once the cruise goes past 15:1 (when running a carb), It will stumble badly on 16:1 and 18:1 is just fresh air as far as the engine is concerned, it won't even manage to light the mixture!

Your 83 jet with a 65 cruise is 16% leaner than base, if you stick in a 62 rod it will be 4% leaner than base. I would have thought that something in-between would be required in order to give you 14.5-15:1 on cruise.

Maybe the 86 jet with a 67 cruise rod is what is needed? Of course once you have the cruise setup you then have to find a rod that keeps the cruise percentage right whilst giving you around 12.5:1 on acceleration, this can be tricky! (Just noticed that the 86 67-55 rod is what you started with!...Oh well you might be able to go a bit leaner on cruise than this!)

I think that to 'a degree' the different carb setups are required because of the different amounts of vacuum that different engines might pull even under the same cruise conditions. Its worth using a vac gauge on the non-timed port so that you can judge when the rods are up or down. It helps to have someone else reading the AFR and the vac gauge so that you can just drive! With the silver springs get them to tell you to keep opening the throttle until the gauge reads around 5-8 inches, that way you will know the rods are up, they then need to read the AFR for the acceleration reading. Keep posting what you find!

Did I email you the spread sheet or was it someone else?

sidecar · Post by **sidecar** » Sun Mar 04, 2012 4:31 pm

I'm bored so I've worked out a load of cruise settings, I've not worked out any acceleration settings:-

JET------CRUISE ROD------% LEANER

77---------- 57---------------15.4%
80-----------58---------------4%
80-----------60---------------11.7%
83-----------62---------------7.9%
83-----------65---------------15.9% (The setting that you have just tried)
86-----------67----------------8.3% (Your old setting)
86-----------68----------------12.5% (This might be OK!)
89-----------70----------------4.7%
89-----------71----------------9.1%
92-----------75----------------10.4%

In fact there is a 68-52 rod, this will give 12.% leaner on cruise and 0% leaner than base on acceleration. (when used with an 86 jet)

mgbloke · Post by **mgbloke** » Sun Mar 04, 2012 6:12 pm

Pete
Dont forget Im not that bothered about economy. I am aiming to lean things off at higher RPM without affecting power. Just reducing the size of the secondaries is not the answer. Im hoping that the 83 jets with 62/52 rods will do the trick.
Maybe I should accept the inevitable and start thinking about FI. Those four barrel throttle bodies look nice! Bung a few injectors in my Huffaker with a few other choice bits. spend spend spend thats my motto.

sidecar · Post by **sidecar** » Sun Mar 04, 2012 6:27 pm

mgbloke wrote:Pete
Dont forget Im not that bothered about economy. I am aiming to lean things off at higher RPM without affecting power. Just reducing the size of the secondaries is not the answer. Im hoping that the 83 jets with 62/52 rods will do the trick.
Maybe I should accept the inevitable and start thinking about FI. Those four barrel throttle bodies look nice! Bung a few injectors in my Huffaker with a few other choice bits. spend spend spend thats my motto.

Mark, If you re not bothered by economy you may as well bung in the 86 jet and 67 rod if that ran OK, I think the setup that you are going to try is pretty rich on cruise. I know MPG is not important but it would be best not to go massively rich just to avoid bore wash. Your 83 62-52 setup will of course lean off the acceleration phase of the carb compared to base.

If you want the spreadsheet PM me an email address and I'll send you it.
It makes working out effect of a jet or rod change in terms of percentage compared to the base setup very easy to do.

mgbloke · Post by **mgbloke** » Mon Mar 05, 2012 6:20 pm

Just tried the 62/52 rods.
Cruise AFR is 13.8 average and part throttle is about 14.2 average.
Throttle response is amazingly good.
I think a trip to the rolling road is in order, firstly to have the timing properly set then a power run with my old settings then a comparison with the new.

Im glad I spotted this thread thanks.

Mark

sidecar · Post by **sidecar** » Mon Mar 05, 2012 6:46 pm

mgbloke wrote:Just tried the 62/52 rods.
Cruise AFR is 13.8 average and part throttle is about 14.2 average.
Throttle response is amazingly good.
I think a trip to the rolling road is in order, firstly to have the timing properly set then a power run with my old settings then a comparison with the new.

Im glad I spotted this thread thanks.

Mark

Hi Mark,

I guess 13.8:1 on cruise is OK for your needs but you could go a bit leaner if you were bothered about MPG (which you ain't!)

Before you bung the car on the rollers you could try setting up the acceleration and WOT. (WOT can be a bit tricky on public roads!).

According to Vizards good book and carbs and manifolds you certainly don't want either mode to be leaner than 13:1, Really acceleration wants to be around 12.5:1 It's best to use a vac gauge, try to use the least amount of throttle whilst getting around 5-8 inches of vac showing on the gauge, basically you don't want too much or any of the secondary circuits supply fuel if possible. That way you know that the AFR that you are reading is due to the thin part of the rod and the primary jets. (Use the non-timed port for the vac gauge)

Once that lots sorted you can aim for 12.8-13:1 for the WOT, use the secondaries to adjust this circuit.

With regards to the timing as your motor is quite large I reckon that you will want an all in of only 28 degrees @ 2700-3000 RPM. The idle timing will need to be up around 14-16 degrees and the vac system should not be used if you even have one. (The Lucas vac system does not suit the Eddy carb at all)

Oh one other thing you could try as your motor is quite large is that you can drill two holes in the secondary air valve counter weights in order to lighten it, this allows the valve to open quicker. I have details of the holes that I drilled if you want them. I would not do this mod when using the carb on a 3.5 lump!

All just my humble (And what I have found out my messing about with stuff!)

mgbloke · Post by **mgbloke** » Sat Mar 10, 2012 4:16 pm

Thanks Pete for the spreadsheet.

Have now altered the 65/52 rods making them now 63/52 as near as I can
This has raised the cruise AFR to 14.8 with the power mode now in the 15s, Cant see why the power mode has changed as this part of the rod is the same. Anyway although the hesitation has gone this combination doesnt feel as good as the 62/52 rods.
One other combination that I would like to try is 86 primaries with 68/57 rods. Anyone done this or have these rods that I can buy?

Cheers

Mark

sidecar · Post by **sidecar** » Sat Mar 10, 2012 4:52 pm

mgbloke wrote:Thanks Pete for the spreadsheet.

Have now altered the 65/52 rods making them now 63/52 as near as I can
This has raised the cruise AFR to 14.8 with the power mode now in the 15s, Cant see why the power mode has changed as this part of the rod is the same. Anyway although the hesitation has gone this combination doesnt feel as good as the 62/52 rods.
One other combination that I would like to try is 86 primaries with 68/57 rods. Anyone done this or have these rods that I can buy?

Cheers

Mark

Er am I getting this right...you have thinned the 65 part of the rod down to
63 thou, this will richen up the cruise AFR if you left the same jet in the primary side that you had in when you were using 65 rods. My understanding is that the AFR on cruise is actually now leaner, it was 13:1 and now its 14.8:1, the only way that can happen is with a smaller jet. If you have fitted a smaller jet then that's why the acceleration mode has gone too lean.

Give us a bit more info on what you have been up to!

Do you use the car on drag strips or do you use the car for circuit racing? The reason that I ask is that I've noticed that my car used to go very rich when braking hard, I can explain how I fixed the problem if your form of racing requires you to brake hard.

mgbloke · Post by **mgbloke** » Sat Mar 10, 2012 5:04 pm

Pete
Sorry, to explain better the 62/52 rod was 13.8 on cruise which is not quite as lean as it could be so I have thinned down a 65/52 rod to 63/52 hence the cruise has now gone to leaner to 14.8 but the power mode has also gone leaner too.

does that make sense?

My car is used mainly for trackdays and so yes I do extreme braking. I havent noticed much difference in the AFR but then I probably havent been looking. Did have a problem with lean spots when cornering but high flow float needles and double fuel entry has totally cured that.
Just going for a drive to do more back to back tests with my 63/52 and the 62/52 rods.
Cheers

Mark

sidecar · Post by **sidecar** » Sat Mar 10, 2012 5:21 pm

mgbloke wrote:Pete
Sorry, to explain better the 62/52 rod was 13.8 on cruise which is not quite as lean as it could be so I have thinned down a 65/52 rod to 63/52 hence the cruise has now gone to leaner to 14.8 but the power mode has also gone leaner too.

does that make sense?

My car is used mainly for trackdays and so yes I do extreme braking. I havent noticed much difference in the AFR but then I probably havent been looking. Did have a problem with lean spots when cornering but high flow float needles and double fuel entry has totally cured that.
Just going for a drive to do more back to back tests with my 63/52 and the 62/52 rods.
Cheers

Mark

Hi Mark,

OK I understand what you have done, Like you I can not understand why the acceleration mode has gone lean as the rods that you have used have all been 52 thou thick. My first thoughts are that the carb was still running in cruise mode even though you were accelerating hard. This is where the vac gauge can help, if you know what the vacuum is under the carb you can deduce whether the rods are up or down. The orange springs are weak, the vacuum can be quite low (i.e. the throttle open a long way) but the rods will still be in lean mode. The stiffer the springs the sooner the carb goes into acceleration mode.

I guess one way of deciding what springs to fit would be to see how much vacuum is under the carb say at 1/2 throttle (Before the secondaries start to open). You could then fit suitable springs that would make sure that the rods are up at this vacuum level. Not sure but do you have the silver springs fitted?

Just in case you have not managed to use the spreadsheet yet your 83 jet 62 rod is 4% leaner than base. Your 83 jet 63 rod is 8% leaner than base. It just shows what 1 thou can do to the percentage changes!

Cheers,

Pete

mgbloke · Post by **mgbloke** » Sat Mar 10, 2012 8:34 pm

Pete
Im using the Silver springs.

Just discovered a big problem, One of my Merlins is leaking water again in the same place as before.

Not a Happy Chappy

Mark

mgbloke · Post by **mgbloke** » Tue Mar 20, 2012 9:01 pm

More feedback.

been doing some more testing. trying to simulate track driving without getting a speeding ticket.
3rd gear, straight road accelerating to 4000rpm, throttle off down to about 3500rpm then hard on the gas. This results in a stumble/flat spot. tried moving the accelerator pump to inside hole without success.
Replaced the 86 jets and 67/55 rods, middle hole on accelerator pump.
Same test and no hesitation at all.
So I guess we can conclude that the best road setup is not good when driven on the limit.