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 Acc pump pistone stuck in its bore 
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
Hello every one, finally people are coming out of theirs Igloos after the Winter her in Sweden, and starts thinking of how fun it can bee to start
there engin ups again. Well that means som carby problems to.
I was asked to do a tune up on a 260 z -70 something, imported from US with triple Weber 40DCOE carbs ( sitting for years ) that only
runs on idle (actually just runs on choke) and after cleaning clogged low speed fuel jets " Weber language" ( the ones that i could get up from the carbs not being seized up in there treads) it manage to run pretty ok on idle with out choke.So decided to take the carbys of and give them a total cleaning with new gaskets .

Now the problems begun. some of the low and high speed jet emulsion holders where so seized i had to molest them with a nut plier after heating the main body
with a heater gun and only manage to turn them 1/8 of a turn at each time, heating turning back and fort heating more turning and so on fore hours and finally
gat them out without damaging the treads in the main body " phuuu"

Hade them soaking fore days in different solution's with out any positive results.

Anyone out there that might dealt with this problem before ore have a good idea how to tackle it successfully.

Mon Apr 17, 2017 8:13 am
Site Admin

Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
Wear rubber gloves.

Have you tried boiling water?

Do you have access to an ultrasonic cleaner?

Wear rubber gloves.

The method to use depends on the form of deposit causing the problem. Is it fuel gum or oxide growth of the dissimilar metals, or both?

Gum is removed with solvents, carb cleaners, etc, with gasoline related hydrocarbon ingredients like toluene and MEK (methyl ethyl ketone), or paint and lacquer thinners.

Wear rubber gloves and eye protection.

Oxides can be reduced (un-oxidized) by acids, in this case, mild and diluted acids, so as to not attack the actual carb metal itself and minimize the effect on the carb metal.

Because not all oxides are formed of the same elements, some acids work OK on some oxides and some are better on others. Sometimes trial and error is the necessary method.

Wear rubber gloves and eye protection.

You need a shop sink with hot and cold running water. Water will dilute the acid to control the strength and rate of attack on oxide and metal parts, however heat will increase the rate or strength of action of acids, even though water dilutes it. Rinse with cold water to stop it. Rinse and wash with an alkaline soap after using acids. Sodium metasilicate is good, be careful with sodium hydroxide because it will attack aluminum and zinc.

Wear rubber gloves.

Depending on the deposit causing the problem, you may have success with vinegar (acetic acid) or lemon juice (citric acid). It requires days or weeks of patience, but aluminum and iron pistons frozen in iron engine cylinders have been released by soaking with Coca Cola, which contains a very small amount of Phosphoric Acid.

In Sweden, do you have household bathroom fixture stain removers that contain Sulfamic Acid, Lactic Acid, Oxalic Acid, Phosphoric Acid, or Citric Acid? In the US a brand which usually (but not always) contains Sulfamic is "Lime Away". You need to read the labels on the particular bottles, because, here in the US anyway, it appears different production runs of the same brand name products are made with different acids. For cleaning hard water stain off porcelain toilets, sinks and bathtubs it doesn't matter, the different acids are OK for that because they don't attack the porcelain but they all remove the mineral stains.

Unfortunately, in carb cleaning the carb isn't made of porcelain and the acids react with the metals the carb is made of. Be aware the different acids each behave quite different (than each other). Some acids, particularly Hydrochloric (sometimes called Muriatic) and Sulfuric (different than Sulfamic) are very aggressive and are aggressive even when dilute. Most are aggressive to aluminum and zinc, brass and steel not as much.

For cleaning carbs we just want to remove the oxidation and fuel gum deposits while not disturbing or attacking the metal of the carb at all if possible, so the acids must be dilute and used with care because they are reactive with carb metals, some more than others.

The trick is to remove the deposits without affecting the carb itself. This isn't easily accomplished because the deposits do not always contain the same elements, so sometimes one acid will have more favorable effect than another.

Heat, even a few degrees slightly higher temperature, will increase the speed and aggressiveness of acid activity toward both the deposits and the metals, so to avoid damage to the metal heat must be used with care in conjunction with any acid.

You need a sink with running hot and cold water to do this effectively and safely.

Wear rubber gloves and eye protection.

Before you get out the heavy artillery, boil the carb in straight water, no chemicals, just clean water, so there is no reaction on the metal. Water is the universal solvent.

An ultrasonic cleaner with 65-70 deg. C water, perhaps with a very small amount of (web search this) “pH neutral rust remover” … The ultrasonic cleaner amplifies the effect of additives in the water, so a very small amount, perhaps .5 cc per Liter, is effective on the oxide deposits and results in less effect on the carb metal itself.

Acid brushes like this are useful.


Mon Apr 17, 2017 3:34 pm
Site Admin

Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
Any luck, or is the piston still stuck in the igloo?

Another suggestion is to back fill the pump circuit with motor oil and use a punch and light hammer to apply hydraulic force from below the piston. This very obviously depends on the location and removal of the check valve and requires making a suitable hydraulic pump cylinder arrangement. You may be able to make something to screw into the pump discharge location, using a suitable threaded rod or long screw, drill it in a lathe to fit a 'piston' made of a nail or suitable size rod.

Sat Apr 22, 2017 11:01 am

Joined: Fri May 20, 2016 5:18 am
Posts: 117
Got the Acc pump pistons out of the IGLO . :=D Thanks Tuner. Never vent fore the heavy artillery .
Went home to my HEMI cuda pall Saturday knight "his wife was att work that knight" .
He has a real good ultra sonic bath he uses to clean hes sons lightly oiled and dusted Go cart parts with, and he has a special detergent solvent for aluminum
material and is environment friendly . It took a couple of hours fore each carb to loosen up thr pump pistons that much so we could jerk it out with a plier
safely with out damaging the pump bore . The heat range of ultr son bath was max 70*C
I think boiling them in apple cider vinneager would also do the trick.

We was ready 1.30 Sunday morning after watching some you tube vids :=D of a-68 427" side-oiler Holman Moody historic race mustang lecturing a bunch of Corvetts on a Corvette anniversary race at Portland historic .
I have a wide range of music taste every thing from "Jussi, Franky, Shirley Bassey, Elvis ,Burt Bacharach Deep Purple and on, but if anything is "sweet music to my ear" Man just take your time and listen to that 427 pushing past 7000. What can you say?
And thanks again Tuner fore taking your time with all of us.

Mon Apr 24, 2017 6:00 am
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