tecumseh 5 hp air gap adjustment


Old 10-11-06, 08:48 AM
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tecumseh 5 hp air gap adjustment

I have been rebuilding a 5 hp tecumseh snowblower engine. I have fuel to the engine but only intermittent spark. I've rebuilt the carb and put in new points and cond. I've tried different plugs with same results. If I crank the engine with the plug out and grounded I see a spark. However, after a few pulls trying to start it, I loose the spark. I'm guessing either the magneto is bad or one of it's wires are shorting out. My problem is I hate to pull the magneto because it's under the flywheel and I have no idea how to reset the air gap after. Is there a trick to adjusting an under flywheel magneto? Could really use your help. This site is Awesome!
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Old 10-11-06, 10:30 AM
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Well firstly get all the rust off of the maget of the flywheel and laminations of the coil.You can set the airgap with a business card.Just put the card between the coil and flywheel,turn the wheel until the magnet lines up and draws the coil to it.Have you got the points set at 0.20?Did you clean them after you installed them?And it doesn't do any good to put new points in without a new condensor,or vice-versa.
I run a dolar between the closed points to clean (money has just enough cloth in it as to not leave any debres behind).

Has your ground wire got a short in it and viberating?
Old 10-11-06, 11:05 AM
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Thanks for the response. The points and condenser are new, the gap is .02. My magneto is under the flywheel so how do I tighten it after the magnets draw it up to the bus. card?
Old 10-11-06, 11:17 AM
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on the older Tecumseh engines with the magneto assy under the flywheel, you don't have to worry about the air gap. The mounting bolts are slotted so that the ignition timing can be set, this allows the entire mag assy to rotate back and forth to advance or retard the ignition timing.

Make sure that the condenser is mounted with the wire coming out of it down towards the engine block, also make sure that none of the wires where they connect to the points are touching any metal portion of the mag. Look at the spring arm that keeps tension on the points, make sure that it is not touching the mag housing anywhere.

Trace the kill switch wire from the mag assy. to the kill switch and make sure it is not grounding out anywhere.

One last thing, just because the points are new does not mean they are making a good electrical contact. Points are from another era and the ones you purchase may have been sitting in stock a long time. You can test them with an ohm meter, but be sure to disconnect the coil and condenser before you test them.

Hope this helps some
Old 10-11-06, 11:23 AM
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I must have mis read your first post,didnt get the part where you said the magneto was under the flywheel.SBT.They do make a special tool to do this.But if you've just got to do the one,it wouldn't pay.Tell ya what you do if the ears to the magneto hasent got any marks on it as to where the bolts was.Take the spark plug out....turn the crankshaft until the piston is just before TDC (top-dead center) on the compresson stroke,turn the magneto till the points are fully open.Then tighten the two 7/16 bolts.that should put it back into time again.
Old 10-11-06, 11:25 AM
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Much appreciated!!
Old 10-11-06, 04:12 PM
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I'm going to add my 2 cents. First off from your other post, you said the points were gapped at .02, I'm hoping that you meant .020. Another thing to look at is that the contacts on the points have to be clean and free from oil and dirt. I hope you bought genuine Tecumseh ignition parts of course that's just my preference from experience. You say that you have intermittent spark, I would double check and maybe try a different condensor. Enough of my rambling about this and let's get to the timing issue. Depending on the engine model the timing which is BTDC is quite different on the two models that I checked out. For the HS50 model the timing is .035 BTDC and for the H50 and HH50 the timing is .080 BTDC that's a little bit of a differential. The tool you need to easily do this is a dial gauge and an ohm meter for the continuity to see when BTDC your points open. Usually these can be bought for around $20.00 each or less.
I hope this is helpful to you.

Old 03-18-09, 06:36 PM
Join Date: Mar 2009
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BTW: .02 and .020 are the same thing. Unusual to see it written that way, true. But technically, both mean the exact same measurment. I could write it as: .02000 and it's still the same thing. Add as many zeros as you like, so long as they ARE zeros, it doesn't matter. Same if you remove a zero, or three... Does not matter. Mechanics tend to be traditionalists, and see things a certian way, and only that way, but the math says it's all the same thing. After the decimal, it's: Tenth's, Hundredth's and thousandth's, and so on. Leaving out an irrelevant zero just confounds someone used to seeing it there. (Myself included)
Just my .02(0000) cents worth! (All a cent IS worth these days, no?)
Old 03-18-09, 07:20 PM
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Correct, although I think all involved parties already knew that...

Hopefully after 2 1/2 years, this has already been resolved.

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