H35 Excessive Valve Clearance Issue

M

Mailman

New Member
#1
#1
Hello all,
I have a HT35 aspera motor which is pretty much the same as a H35 Tecumseh. I am rebuilding it and with new valves installed, the valve clearances are .014 and .028 for intake and exhaust, repectively.
I know the clearances should be .004 and .008 as per spec and I know to grind the valve stems when the valve clearances are too tight but how do you remove excessive clearance?

Can I get longer lifters? Do I need to weld a little bit on to lengthen a valve or lifter?

Any help would be appreciated.

Mailman
 
ATKRIDER

ATKRIDER

New Member
#2
#2
I personally have run into this more times than not. I think the engineers figured that over time the seat would get hammered down ie:shortening the required length of the valve.Either that or they just saved a half a penny by making them shorter. You can either get some more valves and try them or cut the seat moving it down basically making the valve longer. Make sense?
 
M

Mailman

New Member
#3
#3
Yes, that makes sense. Thank you.
What is the best way to cut the seats? What special tools are needed?
One person on another site suggested to lap the valves back into spec. but that seems like it would take forever.
I have never cut seats before so any advise is greatly appreciated.

Mailman
 
ATKRIDER

ATKRIDER

New Member
#4
#4
I personally use a Neway cutter but thay are kinda $$$ and do take some getting use to. If you were to lap it as much as you need the seat would get pretty wide-probably tooo wide. I do 3 angles and the actual seat is usually only .050 wide. I would think about any automotive machine shop can fix you up.
 
M

Mailman

New Member
#5
#5
I did not have the cover on the motor when I checked it so that really threw off the measurement on the exhaust. Foolish me.

My original numbers posted were actually backwards. My intake was .028 and my exhaust was .014. With the cover on, I checked again and I now have neg. clearance on the exhaust which I can just grind the stem to fit. Yeah!
My intake clearance is now .026 so I will have to go the "cut seat" route.

Thank you.
 
M

Mailman

New Member
#8
#8
I tried to swap the lifters but there was only .001" difference so no big gain there but it was worth a try.
Since the valve was good and the seat was good, I thought it was a little odd to grind on it so I had a little metal welded on to the lifter to lengthen it. I then ground that down to fit.
Everything is in spec now.:smile:

Thank you,

Mailman
 
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