Shaving some Tecumseh heads

[cattailhaas]

So a few weeks ago Markus asked if anyone could cut a sprocket and some tec. heads which led to talk on the thread about kustom kart kid cutting some heads using a spud screwed into the spark plug hole, which sounded like a good idea. When I received the heads I lightly sanded the heads on a surface plate to see if they were some what flat and then I made a spud to turn them. At this point my first thoughts when I heard this trick were confirmed. When I checked the surface around the head with the indicator, it was out .015 . You would think the plug hole would be square to the surface, but not in this case. With no way to adjust it I decided to build a adjustable fixture to fly cut them on the mill. Interesting to see that the later

model heads are smaller chambered as when you take .010 off you get into the squish area. and on a older head you don't.

 

[delray]

thats interesting that you found the plug threads where not square with the head surface. where all of them like that or just the one you check?
i plan on milling a flathead in the future. i will double check my head too....:thumbsup:
great job on making that jeg and all. that takes some time to do that and set it up.
i wondering if you where going to surface grind them? you had mentioned in the other thread you where going to that.
i see you decided to mill them. can the aluminum also sometimes gum up little when surface grinding.

i like to see a thread started on the open chamber head and the close style head.
advantages and disadvantages.
are the two open heads for 4hp and the other a 5hp? sorry for asking. just little rusty on my flathead tecumseh's

 

[cattailhaas]

After finding the first two heads were out I didn't bother with the third. As for the surface grinding, it was just a suggestion I mentioned. I was thinking of using a precision grinder that's capable of removing a half a thousands in a pass and not an automotive type surfacer. And I'm not sure on the heads. Markus said they were 4 hp and 5 hp heads. The one that got into the squish has the tapered fin were the coil wire runs through which I believe is a later style head, but I might be wrong....

 

[Havasu Dave]

After finding the first two heads were out I didn't bother with the third.

The premise was that as long as the surface was blemish-free and flat, the resultant slight plug angle would be of no effect. Still, I applaud your attention to detail in developing an adjustable fixture to keep everything square. It's taking care of the little things that add up to the most performance in the end.

There have been several times when I could have used your expertise and equipment to square up some old Cat wheels and sprockets for me.

 

[markus]

Cat, you Da man!! thank you :bowdown: regarding the squish band area, Those early heads simply showed the most lip around them compared others I have loose in the bin, the late one was middle of the road in depth. There does not seem to be any rhyme or reason with part numbers, they were always the same except for the change for the plug wire cutout in the later 70's. I dont know if it was due to maybe coming out of different casting molds or they simply just cut those suckers till the got past any imperfections...I am guessing the latter :laugh: some of them, even the early ones are milled into the squish band area...Including an NOS in the box early one I have.

I did run around the perimeter of them around the valve cut outs and got some different depths, but I was not being uber precise. It did appear that maybe the ones with more lip were not as deep. I need to make up a plexi plate so I can Measure/CC them out and compare them.

There's still hope to save the original 5" wheel set on my caper cycle with the sprocket cut unk: Thank you!

 

[Street Smart]

Very impressive idea in the set up!
I remember going to the local machine shop/auto parts place asking about milling the head on my HS50. I was maybe 14 years old, all the workers came over and laughed at me. One of them invited me into the back to show me what it would take to have it done. So at least I understood why they didn`t want to do the job or at a price a 14yo could afford. He handed me a couple sheets of emery paper ( no charge) and explained how to knock down a couple of thousands with the paper on a flat surface. Was a very nice and memorable jester.

 

[delray]

ok markus keep me in the loop if you find any good info on head design. by the way i have one of them hard to find small block full bearing crankshaft flathead motors. maybe future performance build...:smile: i got a super bronc needs to be done..:doah: and another ohh-motor build...:doah: