Finally getting around to CMA on my MFI

[declang]

Update:
Fixed the breather cover leak, but found 3 drips from the lower cam covers

Ho Hum.

[declang]

ok, finally all the oil leaks are sorted.

Now, I'm intent on getting the afr sorted at part load, so does it make a difference with & without the air intake shroud ? (Thats the big piece with the air filter in it).

I'm guessing it would affect the amount of air intake, but mabye not.

It would be easier to get at the adjustment screw with it off, but if it affects the afr setting, then I have to leave it on.

Thanks. I'm determined to get there before 12 months have passed !!

[orange911]

It has been nearly a month and I am awaiting an update. I hope that the news is good and the only reason you have not posted is because you are flying through the paths of Europe.

[declang]

Well, ahem, I'm emabrassed to say I've done nothing since.

I *will* get back to it soon.

I still have to check fuel pressure & flow, and then do the afr adjustments.

[declang]

ahem, Looks like I missed my 12 month target

Still havent finished CMA

[Grady Clay]

Sir G. - Ahem, some of the components are going to die of old age and dis-use first.

Best,
Your American namesake ,
Grady

[declang]

yeah, go on. rub it in.

[declang]

and today .... I got the insurance forms in the post.

Next week ... next week....

[declang]

next week.

[declang]

OK. Taxed & Insured again
Now, have to blow off all the dust & get back to it. Has it really been 15 months since I started this thread ?

Anyway ... I have a few CMA steps left to do.

Check Pump timing
Measure Fuel Pressure
Measure Fuel Flow
Measure & Adjust AFR part load & idle


One thing that has been bugging me is that the hand throttle is loose. It does operate the throttle correctly but will not stay in position. When I let go of it, it simply falls down again to the off position. Is there a quick & easy fix ? Any pointers to other threads on this. (I did search !)

I presume it is assembled with the heater hand controls somehow so I'll go off and lookup the PET to see if it shows any decent diagrams.

Cheers,
Declan

edit: found this thread Missing Hand Throttle- '68 coupe with some good info on it. I guess I need some of the cork friction washers.

[declang]

OK, here we go.
I need to measure fuel pressure & fuel flow.

I've been reading up on the plumbing at the fuel filter & found Grady's photo of the corrected plumbing:


OK. So I plumb my fuel pressure gauge into the return from the MFI pump: Good.

Next, for fuel flow, where should I measure this magic figure ?
Is it the flow from the filter to the MFI pump ?

I plan on doing the suggested return line into the fuel tank filler, letting the pump run for a while, then measure flow, then let it flow back into tank again for a while, measure flow rate again ... etc etc.
How long is "a while" - How long should I let it run back into the tank between measurements of flow ? 10 minutes ? 20 minutes ?

Thanks,
Declan

[declang]

Right, new fuel filter in, and measurement done.

Fuel pressure without engine running is a little over 0.8bar, mabye 0.81 or 0.82. Thats 11.75psi.
Is the 11.8psi spec without engine running ?

Fuel flow. 1150ml in 30 seconds, or 2300ml in 1 minute.
I believe that is within spec.
I measured, let it flow for 5 minutes, measured again, then 10 minutes, and up to 20 minutes.
Same figure each time, so thats good.


Little CMA progress, but more than I've made in the past few months

[declang]

I guess you folks have given up on me

Anyway, I checked fuel pressure again, and got around 0.65bar without engine running.

This confused me, as I originally got just over 0.80 bar.
I started the engine to see what effect, and it increased to around 0.75bar.
Revving engine made very slight fluctuation.
If I rev to around 3K, (at a guess) fuel pressure drops to around 0.65, but only for an instant, then climbs back to a steady 0.75bar and stays there.
if I drop the revs to idle, it stays at 0.75bar until I rev again, then a momentary drop & back up to 0.75bar

I preume this is good, as 0.75bar = 10.8psi and even the low 0.65bar = 9.4psi
All within spec of 11.8+/-3psi

Any advice / Suggestions ?

Is there any problem in using 8mm fuel hose instead of specified 7mm between the fuel filter & the mfi pump ?
I wouldn't think so, but thought I should check.

[declang]

Ahem, cough cough.

I've been waiting since May for an answer.








well, thats my excuse for not having done any miles in the car since.
Next year. Next year. Really.

[Grady Clay]

More to come later today or in the morning.
Have to run earands now.

Best,
Grady

[declang]

In the meantime, I've been reading the CMA bible again.

If I understand correctly, for part load, I need to set a 9 degree angle on the
throttle plates (butterflies).

Am I understanding correctly, that I can use either

A. the special tool that clamps onto the mfi pump, (pics below from cma)
or
B. the hand throttle


But, how do I measure the 9 degrees ?

I presume I can make a tool of some sort with the 9 degree angle, but I just cant see how I can measure 9 degrees without the protractor.

Please tell me I'm just being silly, and its simple.

Thanks,
Declan

[declang]

Long time no update ...

Finally got some miles on it, still tweaking mixtures, but am a bit confused at something.

I can adjust part load AFR & adjust idle AFR to nice levels.

However, when driving along at low revs, sub 3k, (maybe sub 2.5k ?) if i completely release the throttle and use engine braking, AFR goes very very lean eventually up to 19:1 / 20:1 - as if its just not getting any fuel at all. If I change down a gear and do the same thing at higher revs it seems fine - Does go a little lean, but nothing major.

Any ideas ?

Should I suspect the link from throttle "bar" to mfi pump ? I did measure it previously and it was exactly right length.

Apart from that annoyance it seems to be running very very nicely and really comes alive at about 5k revs and up. I had forgotten how good it was on the road.

[tobluforu]

Do you have the microswith connected which basically shuts fuel off on throttle lift?

[declang]

Nope. Microswitch is removed, but cables arent insulated.

However, that should not matter, as the fuel cutoff relay/control circuit is also removed for repair. (the famous "rattle from loose transistors")

[dicklague]

if you have the microswitch hooked up this might be normal. Is the switch and solenoid and speed sensor box all working?