air valve flow ratings hand printed

Propane, Butane, LPG, GPL, C3H8, C4H10
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Location: New South Wales, Oz

air valve flow ratings hand printed

Post by jono » Mon Sep 03, 2018 5:40 am

Is there a good reference to understand the mixer air valve hand printed flow ratings?

On my collection of 200 series I have what looks like 90 to 94 on feedback FB ( not facebook !!) air valves, yet to see or be able to read values on clean air diaphragms to be able to recall a figure.

Today I opened up a new but hoarded 200M-2 to find no 16 or 45 on the cone (expected this) and a AV1-12-6-2 with a flippin' 105 on it
some of us know the last -2 is silicone material and the -6 is simply RICH
I figure RICH is RICH
Richer than a feedback AV1- 1234? with 94 or 95 on it

Is the only thing that makes a FB or CA mixer its own the diaphragm in its basic design ? I sort of thought so, but willing to be corrected

A mate once pointed to CA in the casting and said look clean air ...but never seen one with FB for feedback in the casting - the labels yes, by decoding part numbers only - I think

This 105 was causing all sorts of rich grief on O2 readers and propane computer and end results

The AV1-12-2 I had hoarded has made one big difference, so long as the balance tube is not connected

this is all on a NA 1800cc (110 ci) boxer (flat4) L converter in prep for the turbo variant and emissions compliance

Gosh a sealed balance tube can create lean dramas. Currently playing with 1.5mm bleed on balance tube. Going to either add another or enlarge the 1.5

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Re: air valve flow ratings hand printed

Post by franz » Mon Feb 18, 2019 11:23 am

Jono, look in the Diagnostic Guide, somewhere around page 53 for some info on the Impco air-valves. From what I've been told, in recent production runs from around 2017 on, the valves were computer coded and may not have the hand printed values.


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Re: air valve flow ratings hand printed

Post by jono » Sat Feb 23, 2019 7:24 pm

Aha, OK Franz. Thankyou.
It is good to see you are still fronting to this quiet little forum from time to time

I took a break on this little project when the main supplier near me had a staff member state he was not going to go through all his stock to find my desired number - can you believe it? His attitude defeated the whole purpose of hand flow recording !!

Ahem, lucky for me that was too as my memory was broken and I was sourcing mid 90 numbers which I now recall as being dirty old feedback rich. I know I need mid 80's and have one at 85 and my goodness it was perfect!

I defied all Impco sizing, all I had learnt over near 30 years and went L converter, 200 fresh air on my flat four 1800 cc with about 6500 rpm max on it, 3000 rpm for 70 mph

It hauls erm.. backside! It snorts, it pulls and delivers the best fuel economy to boot!

So, typically with that sorted, engine out, turbo variant in and back to tuning - this time as a fresh air non FB system but with Peel Instruments Lean Bias Logic vapour enrichment via the secondary port of the converter and a on off valve controlled by a box of electronic smarts

I have to get fresh air to run lean, then size up a jet in the enrichment circuit to get a duty cycle of 40% at idle then ensure the O2 controlled box can handle boost enrichment to keep it stoichiometry

So a call to management to ask for hand flow selection will be my next move

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Re: air valve flow ratings hand printed

Post by storm » Sat Feb 23, 2019 9:44 pm

I remember when I setup my 5.7 stroker with the GRA throttle body I had an enrichment injector for stoichiometric. It wasn't a fiddly system but it wasn't all that great either. I stear clear of those types of things now.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

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