Strip down the AAZ pump and gov mod tuning

[regcheeseman]

(large post removed and loads of pictures)

Despite having several good results - I'll concur that the original procedure needs to be changed so I'll remove it. The governor mod procedure is pretty confused.

[Rabbit on Roids]

woah, im never going to use a AAZ pump for anything. those things are way more complex than a 1.6 pump.

[burnt_servo]

i hate to say this but the way you modded that govenor is wrong.

the engine will have a tendancy to hang and be difficult to drive .  worst case senario it causes a accident .

instead you should have shimmed each spring 1/8 to 1/4 inch ( any more than 1/4 inch and you should start to cut the springs back ) .

i've done and helped guys to alot of these , and i've never seen a engine not hand when either of the springs is replaced with something solid .

but other than that , good thread .

[zukgod1]

Burnt_servo is correct...

**I'm referring to the larger main spring below**

Mine was replaced with a piece of steel brake line. Worked great.

53_willys was replaced with a piece of steel line as well, ran fine...

The main spring is fine to replace with a solid piece from my experience but not the smaller intermediate spring, I've found it best to just leave it alone.

I've have done several of these pumps, not just gov springs but full out bad ass pumps. Done the same gov mod every time, all work great but as stated above, the main spring only.

[Rabbit on Roids]

my main spring is nuts, literally, just some tiny little stainless nuts that were exactly the right size for what i needed. the intermediate and idle springs are left alone. still gets good mileage and no throttle hangs. excellent driveablilty.

[burnt_servo]

that is something i haven't tried yet , replacing the main spring .....

at what rpm  does it start to defuel the engine ?

anyone else have this one swapped out for something solid

after having the engine hang after replacing the smaller of the 2 springs i assumed the same thing would happen with the larger spring too   .

[regcheeseman]

i hate to say this but the way you modded that govenor is wrong.

the engine will have a tendancy to hang and be difficult to drive .  worst case senario it causes a accident .

instead you should have shimmed each spring 1/8 to 1/4 inch ( any more than 1/4 inch and you should start to cut the springs back ) .

So you shim each spring 3mm - 6mm! You sure? a 3mm shim would coil bind the intermediate spring and render it solid anyway. At most I preload the main spring 1mm

I've done a fair few of these and not had hanging problems but I'd be interested in your theory about why the pump would hang up.

Surely removing the heavy main spring would push the rev limit up whilst leaving the progressive restriction on fuelling imposed by the intermediate spring.

Looking at the assembly from a physics aspect, the linkage remains solid, giving 100% of throttle input until the pump reaches enough velocity to compress the heavier main spring and therefore impose the rev limit.

Have I got my thinking all wrong?

I have a collection of gov mod photos taken from this forum before I started messing with pumps and all show a variety of methods but main spring replacement I've not seen...


edit....

Just had a dig through my personal store of forum info and great posts that taught me a lot in my early days and I believe this particular one is still used as a point of reference by a LOT of people and to quote...

5. Modify the governor to eliminate the intermediate spring as follows. Measure the travel of the intermediate spring by pulling on the ends of the governor capsule. (The intermediate spring is the first one of the two inside the capsule that compresses.) You can see the intermediate spring seats are wide things that only allow a small amount of spring travel:
Find a shim that will take up this movement when inserted between the intermediate spring seats at the area where they are closest to each other. 3/16" aluminium pop rivet backing washers are of suitable ID and OD, but you'll need to arrive at the right overall shim thickness (possibly re-using the original shims between the intermediate spring seats if present and if needed.) The idea behind the shims is to fix the intermediate spring solidly in the extended position, so it can be removed.

and another.....

Now once you are in there you will see a spring assembly that has three parts a very soft idle spring **leave this one as is** an intermediate spring and a long main spring. These springs are set so that once the idle spring has been compressed it starts to work on the intermediate spring and once that has been taken care of it starts on the main spring, now this main spring is long enough that you never actually get to the end of it in the real world. Here is the options for this mod, you can:

1. replace the intermediate and main spring with a solid piece of tube or strong wire etc... Something that doesn’t compress (I have even heard of fuel line)

2. You can place shims (read washers or what have you) in the intermediate spring placing it in coil bind and preloading the main spring by about a 1/4"

3. Or you can just replace the intermediate spring with something solid, and preload the main again by about 1/4"

then re-assemble and double check the spring assembly on the outside cover

[regcheeseman]

definitely got my cage rattled guys!.....

thinking more about the pump, I'm making a whole load of assumptions, please guide me if wrong.


the throttle plate seems to control the amount of fuel injected by way of stroke length on the pump.

The throttle plate position is essentially dependant on three forces,

1- the governor weights doing there best to shut the throttle closed
2- the applied throttle input pulling the throttle plate open - via drivers foot - accel pedal - cable - throttle actuator arm and governor spring assembly. i.e. these parts have NO positive effect in closing the throttle
3- return spring closing the throttle plate

An engine hanging is when the drivers input is at odds with the fuel delivered to engine - typically evident at zero throttle input

The governor spring assembly is not really a governor at all and merely a method for varying the linkage between driver and throttle plate - allowing the weighted governor assembly to do it's job

Therefore the only way I can see the governor spring assembly causing revs to hang up would be if it's effective length was shorter than the length required to hold the throttle plate in the desired position.

The only realistic way the linkage could be too short would be way too much preload (this could be corrected to a considerable degree by changing the throttle stop screw position)

-------------------------------------------------

I can see that removal of the the intermediate spring would remove it's damping effect and make the pump more sensitive to throttle position. I'd liken this situation to CV carbs versus Pumper carbs (and then I'd apologise for using a bike related petrol based analogy!)

[Rabbit on Roids]

that is something i haven't tried yet , replacing the main spring .....

at what rpm  does it start to defuel the engine ?

anyone else have this one swapped out for something solid

after having the engine hang after replacing the smaller of the 2 springs i assumed the same thing would happen with the larger spring too   .

you only shim the big main spring. i dont know where it starts to de fuel the engine, i havent had enough balls to turn it that high. the intermediate (small spring inside the cage) controls the engine from anything over idle, to about 2500 rpms, if im remembering right. thats why if you shim that one, it will hang.

[burnt_servo]

but I'd be interested in your theory about why the pump would hang up.

not theory , my experience with doing my my car for the first time and f*cking it up  and helping others when they can't figure out why their engines rpm won't now drop down after modding the govenor .

and i thought i mentioned this ...... a person may have to cut some of the coils off if they are adding alot of shims to keep the coils from binding

[regcheeseman]

Thanks for the reply, from a logical point of view I cannot see why it would hang and from my experience I've not had the problem either - although I've had one pump that had a very small flat spot at 1700 - 1800 rpm but I don't believe that was anything to do with gov.

My method uses a single 1mm shim at max on the main spring (1/25") which is way smaller than your two shims of 1/8" minimum.
I believe this may be the reason for differing experiences?

and i thought i mentioned this ...... a person may have to cut some of the coils off if they are adding alot of shims to keep the coils from binding

you did indeed, you also suggested that it would be required if anything greater than a 6mm shim which to my mind is absolutely huge.

Do you have any idea of the fuelling reduction characteristic of the mod you describe? I'd have thought it would lift the revs where the intermediate spring comes in and also limit it's action, also the top end rev limit must be much higher too.

Studying the open pump vid on you tube would suggest that the main spring compresses a considerable amount to impose the rev limit - probably 65% of the governors total movement is controlled by the main spring. Replacing it with something solid would compromise the gov movement to a large degree - you must have serious theoretical rev limits.

Apologies if I come across as annoying with my refusal to accept the facts, but I really like to understand these things properly and question, question, question! - My teachers always told me to ask questions, think they may have regretted this. 

[Andy@React]

anyone else got any thoughts on this - i have a pump modded in this way (by regcheeseman) and on the short 1st gear test runs i have done (my car is not road legal yet!) it revs up like crazy and does not "hang" at all... 

[carrizog60]

also interested in this, as i am going to do this and want to know the best way...
i just want to have fuel every time,even knowing that this would leave me with no rpm cut...

[carrizog60]

up

[Rabbit on Roids]

i had to advance my throttle arm a spline to get my government to work right after i modded it.