Pressure tapping a Zenoah 26PUM

[nighthawk355]

I have a clutch and water pump, but I have not yet bought my engine yet. I’m going to next week. Anyways, the water pump is a WIP-10 and it says I have to pressure tap the crankcase on my engine... I have looked all over for how the heck you do that and I have been unsuccessful at finding out how to do that. Can anyone help me out here? Also, I’m ordering my engine from BH Hanson, should I maybe ask him if he could pressure tap it for me for an extra cost???

Thanks,

-Garrett

[scorpien boats]

Hi and welcome,
pressure tapping is very easy (I once had trouble finding out how).
see where the aero is in the pic, that is where the hole is,

What I did was- I put a piece of brass/aluminum (dosn't matter what type of metel) tubing inside the hole and then drilled it out, so it dosn't mess up the threads.

* you should magnatize the drill bid so you don't have to go hunting inside your engine for the shavings* ( I learned my lesson the hard way)

GETTING THOSE RINGS BACK IN THERE IS NOT FUN.


well I hope this helps.

[scorpien boats]

oh and DON'T pay extra for that, it takes like 3min.....

[nighthawk355]

Hey, thanks! Ya but in my case, i have to go through the back of the crank case i guess, so i can just take the case off the engine and drill through it, then tap it... right? And that also should solve the issue with the shavings. I'm confused though about when you said you inserted the tubing into the whole then drilled out ... didn’t you have to drill the hole anyways? How do u get the tubing in the whole to be drilled out w/ out drilling the whole first? Confused... sorry lol I’m a nooby to this stuff. Heres an image of what the setup looks like. its a pretty big tap....

-Garrett

Thanks for your help !! its well appreciated =o)

[Doubledog]

You can also hit the plastic spacer between the carby. Of course then it'll need tapping. :O

[scorpien boats]

do you have the engine yet?

ok
all the tubing does is keep the drill bit from messing up the threds inside the hole. (the brass colored peice in your pic should just screw in there like a normal screw) you just take the brass tubing out when your done drilling.

That is the exact pump that I have.
just wondering why you have to go through the back?
and yes you could take the whole case off like I did but putting the ring back in is a pain, a big pain.

And yes like dd said you could put it in the space between the carb.

Hope this clears it up a little, If you are still confused let us know.

[nighthawk355]

lol thanks,

I was told to put it through the crankshaft for the best pressure... that’s y. But I was reading up on Zenoah engines online, and actually... there might be a pressure tap already in them underneath the needle valve area??? I don’t know if I’m up for the task either, I could screw up and loose out 800$ on the engine if I do one thing wrong. Today I had enouph pressure n worries installing the drive shaft, outdrive, trim tabs and prop. I wont know if I installed them right till I run it tho I guess.

[Doubledog]

$800 for an engine or just a little exaggeration? :eek:

If you can get your hands on the latest issue of RCBM (August) theres a fine article by Tony Castronovo.

I'll quote some from the article: [begin quote]
"You must have a clean tap. Since you are taking pressure (air) from the crankcase to use in the pump, you are also taking any of the lubricating oil that may be combined with it. When you tap the case, its best to do so in the centerand just under the caarburetor because this tends to be the area with the least amount of contamination in the air/fuel mixture. if you understand the mechanics and routing of the pulse that operates the carberator pump, you can see why the best area to to get the cleanest pulse is to tap into that region of the intake manifold and use the air from there." [end quote]

Thats exactly whats happened to me a few times. My pump would not work because it was filled up with sludge from tapping in the exact hole you've mentioned. Never again will I do that when its too easy to do the intake. Sounds like a little complaining, yes. Reason is after having waisted an 1.5 hours for a round trip drive only to find out your pipes are clogged isn't fun.:D

Another thing mentioned in the article was to use as short of line as possible for the feed from the engine to the pump (5-6" max) as pressure will drop the longer it is.

[nighthawk355]

lol 800$!! thats not that much for a zenoah now days!!! I origonally was ganna get the 35CC for $1200, but then after buying my boat and equipment, it got up to that price, so ran outta money lol.

But, thanks for the quote, thats then exactly where i will tap it if i do tap it. Thanks!!! =o)

[Burkey1000]

Just to pick up on a point here. If you tape the carb spacer, thats what i would do rather than the engine, make sure when you put the pulse nipple in it doesnt block the little hole thats there. The carb needs this hole to be clear,a fiber washer on the nipple should be enough to stop the thred of the nipple poping through into the hole above. If it blocks the hole or fouls it to much the engine will never run right.

[nighthawk355]

hehe. the person who i bought the engine from is tapping it for me. i dont tihnk at any aditional cost.

-Garrett