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Tecumseh Degrees of Timing


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  #1  
Old 12-30-2017, 04:53:09 PM
delray delray is offline
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Photo Tecumseh Degrees of Timing

hey guys, do any of you have a 70's or early 80's tecumseh handbook that shows how much much timing advance a factory points hs-40 has. i know i have seen it before in a book and i believe it was some where around 30+ degrees they run at.

not looking to set the timing or anything. just would like have some verification on this. picture maybe too would be great.

thanks .....
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Old 12-30-2017, 07:47:08 PM
Frank in PA Frank in PA is offline
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Default Re: Tecumseh Degrees of Timing

Tecumseh uses a dimension checked with a dial indicator rather than degrees. The indicator mounts in the spark plug hole and calibrated for top dead center. For an HS 40 the dimension that the points open is .035 inches before top dead center. I hope this makes sense and helps.
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Old 12-30-2017, 08:22:27 PM
delray delray is offline
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Default Re: Tecumseh Degrees of Timing

sorry thats not what i was looking for.
looking for the information that tecumseh has in there manual book that shows the degrees of timng the hs-40 runs at. i believe it was around 30+ degrees.
just would like some verification .
still thanks for your reply.
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Old 12-31-2017, 09:42:50 PM
Bruce Dorsi Bruce Dorsi is offline
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Default Re: Tecumseh Degrees of Timing

I was a Tecumseh dealer in the 60's, 70's, and into the mid '80's, and worked on many Tecumseh engines!

I have never seen or heard timing specified in degrees B.T.D.C. for a Tecumseh engine.

I have a Tecumseh Mechanic's Handbook dated 1/1977 in front of me. ...I have just paged through the entire manual and do not see any reference to degrees of advance.

As others have told you, the .035" below BTDC is where the timing is set. ...This is set once the point gap is set at .020".

If you really need to know degrees, use a continuity tester, degree wheel, and TDC indicator.
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Old 01-01-2018, 12:55:55 PM
delray delray is offline
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Default Re: Tecumseh Degrees of Timing

yes bruce, i have been thinking about just degreeing the flywheel and hooking up a timing light. this will take little time to do ,because it is the only points motor i have. all my other motors are electronic ignition. being you where a tecumseh dealer and all i am really surprise you didn't know any more about this. for example the newer electronic ignitions coils run about 20+ degress factory. if a guy wanted to advance the timing you could buy a tecumseh performance coil part# 36605K
i pretty confident the older points systems will allow to advance the motor to 30 degrees. i was just looking for some verification on this so i didn't have to double check and setup motor for this process. reason i am asking about this , the motor i am working on is a built up hs-40,.080 over.billet rod, animal springs/retainer,dellorto carb...etc... going back on a original black widow. at the end of the day i will still have to double check the timing so i am getting best of what i can get out of it.
i do appreciate your help.
thanks again all......
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Old 01-01-2018, 09:29:34 PM
Ogrebeast64 Ogrebeast64 is offline
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Default Re: Tecumseh Degrees of Timing

As Bruce stated, I've also never seen a BTDC timing for a Tecumseh. It was always set with either a dial indicator or a straightedge and the proper feeler gauge. I always used the feeler gauge method as I couldn't afford a dial indicator back then.
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Old 01-20-2018, 05:45:00 PM
Andrew Mackey Andrew Mackey is offline
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Thumbs up Re: Tecumseh Degrees of Timing

At a shop I worked at, one of the mechanics used to race minibikes. On his HS 40, he would set the points in the following manner: Set the engine at TDC compression. Mark the flywheel along with a corresponding mark on the block. Turn the flywheel backwards about 1" at the rim. Make a second mark on the flywheel, alignned with the mark on the block, and put a paint dot on it. This identified it as the advanced timing mark. Using a 9 volt radio battery and a test light. note points opening time and adjust the mag assembly to set timing. This set spark timing at about 25 degrees BTC. He would fiddle from there. Much more advance and you would run into kickback on starting. That engine sure would wind up fast though! He also had specialty items in it - cam, rod, springs, titanium valves, milled head and porting. That engine would spin the tire on his Rupp minibike. It was something to watch him go around a dirt track - he would actually drift the corners! Last I heard, he was fiddling with tuned exhaust pipes for it!
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Old 01-22-2018, 11:21:20 AM
DTurner DTurner is offline
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Default Re: Tecumseh Degrees of Timing

I just did this on my ariens hm-80 snowthro . I found this video on you tube very helpful , have cup a coffe and enjoy a danesh , it was very help to me anyway. Let the factory tech take you thru the procees , I learned a lot of what needs to happen . Good luck , a picture helps me.
There is an arrow on the point cam to help you also when points open I might have missed that in video , or saw it mentioned on another video ,hope this helps ! https://m.youtube.com/watch?v=axCzcFI4kek
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Old 01-22-2018, 06:32:58 PM
RustySteele RustySteele is offline
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Default Re: Tecumseh Degrees of Timing

I was a small engine mechanic for over 30 years, I never saw a Tecumseh that had the timing set by degrees. I`ve done that with the older Kohlers, possibly that is what you are thinking of?
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Old 01-26-2018, 01:51:30 PM
delray delray is offline
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Default Re: Tecumseh Degrees of Timing

ok guys i have played around with the timing and it looks like i can get about 26 degrees without modifying the mag adjustment. i did clean up the slots little. that allowed it to move little. i may try it at 26 degrees and if i don't like it there i will modify the mag little. i have played with the elcetronic ignition and use the factory performance coil they have and that runs about 30 degrees. i will be using a newer style ohh-cam that has just little larger lift then the original cam did and has compression relief arm. that will help big on the kick back. the old cams use a bump built in the back side of the cam lobe. not the best design,but then again they weren't looking for big hp gains. (just 4hp) i have had really good results with this cam in the newer electronic ignition engine. it will pull real strong up to 4500+ . it should be a ideal cam for this project and what i mean by that is i will be still using the factory 19mm dellorto carb with adjustable main jet and factory header pipe. also this engine i am working on is not my engine. it's a friends of mine and still wants that factory look with more power. any bigger cam and i don't think the carb would run right? not a real big fan with some of the guys i have seen on other forums where they install a racing cam that turns over 6000+ or even 7000 and even a 8500 cam they make. funny thing is all the people i have seen a thread on them building motor with a big cam have never got there engines to run right or even run? two big problems i see with this is the factory points are set with about 15 degrees. you need alot more timing with these cams and they only come option with a bearing on the pto side and the flywheel side is a bushing......not good if your trying to spin a motor at a very high rpm's. make it three big problems. racing cams don't have a compression relief on them.
here's a picture of the valve spring setup.
running a set of animal 16 pound springs and retainers/keepers. i believe am the first to do this in flathead. animal engine wasn't not around back in the day when people started to hot rod there engines. it was shim the springs tight and hope the factory tecumseh retainers didn't pop out.


clean up the bowls little. had to be careful here. casting can be thin in some spots.

before


after

.080 over wiseco piston ,billet rod and the cylinder wall has been nickel silicon plating done.
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