HS40 HS50 worn valve guides

#1
For my rupp continental project I am thinking of building a tecumseh hs50 painted white to make it resemble the original engines used in the 67 continental electra. My problem now is the motor I am about to rebuild was ridden hard and put away wet. I am currently trying to decide what to do if anything to the valve guides. The guides are on the loose side and I would prefer to either reline them or completely replace the guides. I do not want to use the oversize stem valves as this will be a performance motor. I purchased a briggs valve guide repair kit 19269 and it comes with the 7mm tap and puller bolt to remove the guides as well as a piloted reamer to ream the cast Iron guide to .281. Now my dilemma. Tecumseh never made inserts or replacement guides so I am on my own if I don't use the oversize stem valves. In addition to this I have run into a issue that the new replacement exhaust valves have a thinner stem than the original tecumseh valves did. So I have found that a new guide that would fit the tecumseh used to be sold by goodson (250 ID x 376OD) but is no longer carried and I can't find anyone else that sells them. Briggs sells a replacement guide that Is in the mail to me but I have no idea of what the OD is till I get it. So my options are as follows:
1) use the briggs piloted reamer and ream the current guides out to .281 and use the manganese bronze guides from goodson which are 250ID by 283OD and drive them into the cast iron. The drawback to this is if the fit between the briggs reamer which measures .281 and the guide which measures .283 is too loose (I don't
know what the reamed hole will measure) then I have a stock guide that the puller will not work on. I would have to use a larger tap and bolt I guess.

2) I have some universal goodson guides that are .222 inside and 680 outside and machine them to a 250ID and .378OD cut them to size and press them in the motor. I would have to set a interference fit of.0015 and Try to get the inside concentric with the outside, which I am not sure I can do.

3) Pray the briggs inserts have the same OD as the old tecumseh guide.

I am also trying to make a briggs exhaust fit as it has the same OD as the old tec valves .246 just have to try to cut a retainer groove in the correct place. The new valve I got has a 243 stem which If I go with option 2 is OK as I can just make the ID smaller than .250.

Has anyone here tried to replace the tec guides? Anyone know of a guide that is available to buy that would fit?

One other thing, in the briggs valve guide repair kit comes a plug gauge that checks if the guide is worn. The end of the guage should not fit in the guide, if it does the guide needs to be replaced. The gauge is around .265 which to me would mean the guide is way way worn out. Am I missing something here??



 

125ccCrazy

Well-Known Member
#2
I ran into the same issue with a small tec engine, the guide was worn bad, so I used a Briggs guide, only issue was it was just enough to small o.d it didn't press in tight so I carefully laid down a series of small dimples (basically knurled it) using a sharp punch, slathered it with red loctite and pressed it in the block and then honed it to fit the valve...it pressed in tight, actually a bit tighter than it would into a Briggs.. It may not be the preferred or professional approach but for a minibike engine it worked out good.
 
#3
Thanks for the info I found the briggs guides but after getting all the tools reamers drills for reaming manganese bronze I wound up not changing the guides the new intake was OK and I used a briggs ex valve which is a couple of thousandths
larger than the new tec replacement ex valves and it is OK guide measures .251 at the top and bottom and 250 in the middle.
 
#4
dang! How big can they get? till the valves almost kiss the edge of the bore? my HS40 already looks pretty close as it is and i assume it's stock. how muhc bigger can the valves get?
 
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