# T-Head Engine Plans



## vederstein (Feb 14, 2021)

Ok,

For me, this engine was a failure.  I just couldn't get the valves to seal worth a damn.  I don't necessarily think it's in the design, I think it's because I suck.,

So in the following few posts, I present the design for this four stroke engine.  If anybody tackles this thing and is successful, please contact me and let me know your secrets.

...Ved.


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## vederstein (Feb 14, 2021)

First up we have assembly drawings...


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## vederstein (Feb 14, 2021)

And now individual part prints...


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## vederstein (Feb 14, 2021)

...more part prints....


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## vederstein (Feb 14, 2021)

The solid model of the engine in Step format...

Note that the step file is zipped.


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## vederstein (Feb 14, 2021)

...and finally the casting patterns in .stl format...


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## Leo (Feb 15, 2021)

Thanks much for posting these plans.  It looks like an interesting project. Who knows I might actually build it.  If I live long enough.


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## Willyb (Feb 16, 2021)

Thank you for taking the time to put your design up for others to look at and possibly build.  Looks like a neat engine.
May take a run at it when I get my other projects finished.  

Cheers
Willy


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## lathe nut (Feb 16, 2021)

great looking engine and thanks for the plans, will there be a video to see it running, really like the design, thanks for sharing with us, Joe


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## Makin chips (Feb 16, 2021)

I'm wondering if the valve stem and the accompanying adjusting rod tappet assembly need a definitive separation. That's a lot of weight and leverage flopping around as they motion and try to seat... Maybe a guide for the lower assembly and the valve stem just butts against a rod end. Just my $.02  Nice work in the CAD system too. Very easy to understand!! 

If you learned something on the build it is never a failure.

Best of luck, Chuck


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## James Barker (Feb 16, 2021)

Ved, thank you so very much for posting up these drawings for us here. I especially like the files for making the patterns required to cast the base. I am going to see if I can bribe the high school shop instructor into allowing me access to the foundry section some weekend. It has been a long time since I cast anything but think I still remember how to do it. I have also been looking at the drawings and may change a bit here and there but am enjoying seeing something different as the subject of discussion. Many thanks again and stay safe.

BC1
Jim


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## jkimberln (Feb 16, 2021)

Ved, echo....thanks from me also on posting the drawings.  Doesn't look too hard to make and I'll attempt it.  Wondering if by chance there is an stl file of the flywheel?  Those of us with casting facilities and a 3d printer would find that very useful.


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## vederstein (Feb 16, 2021)

Thank you all for the encouragement.  As I wrote earlier, I built the engine and failed.  I was never able to get my valves to seal.  I don't think it's the design, I think I just suck.  For those that question the long valve lifters, I did have a problem with alignment.  That's why I added the guide plate at the bottom cylinder.


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## xj35s (Feb 19, 2021)

jkimberln said:


> Ved, echo....thanks from me also on posting the drawings.  Doesn't look too hard to make and I'll attempt it.  Wondering if by chance there is an stl file of the flywheel?  Those of us with casting facilities and a 3d printer would find that very useful.




I will attempt this today. Are the angled and threaded holes needed in the pla part? Also should the center hole be a smaller diameter for light machining later or actual size?


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## vederstein (Feb 24, 2021)

When it comes to the castings, just assume any mating surface is a machined surface.  Therefore a mating surface in the casting is undersized.

For this engine, I didn't use any cores in the castings.

...Ved.


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## Brian Rupnow (Jul 5, 2021)

Vederstein---I just downloaded your solid model, and I see something immediately. You have it shown with the gas tank higher than the carburetor. Since the Traxxas carburetor you show has no float, needle, or seat, the gas tank must set below the carburetor, or it will be constantly flooding itself.---Brian


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## ultralight1 (Jul 6, 2021)

This is just my observation from working on Studebaker and Chevy flat head engine's when I was younger. Looking at the valve pdf, from what I see the adjustment you are showing looks like it adjusts the valve spring tension on the valve which in itself is fine. But you do not show a way to adjust the tappet clearance or clearance value. On a full sized flat head, which your Tee head basically is, the tappets are adjustable to give a running clearance. This allow;s the valves to completely seat (close) properly. Clearance runs from .006 to .024 on intakes to .009 to .026 on exhaust depending on the particular engine. This allows for expansion of the valve stem due to heat and lets the valve always close properly. Without being able to adjust for this clearance the valve may not seat as it should. This is just my opinion so take it with a grain of salt.         Dave


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## vederstein (Jul 17, 2021)

The design does allow for the valve clearance adjustment.  The interpretation of the nut adjusting the spring compression is correct.  Below the thread, the valve tappet is adjusted.  The intent was that the tappet would either be constrained with a second nut or held in place with a light loctite or other thread locking method.

Other than Brian's remark about the position of the gas tank, I don't think the design itself had too many (or any) critical design flaws.

I completely admit my skills just weren't up to the task of getting the valves lapped in.

(believe me, I tried and tried and tried...)

It's surprising to me that this thread is coming alive again.  I abandoned this thing many months ago and have long since progressed to my next boondoggle.

Ved.


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## Brian Rupnow (Jul 17, 2021)

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