valve guide bore size in block

[Earl Baker]

I need to redrill the hole in the block for the valve guide since when I bent a valve I also broke the guide but left half in the block which will not come out. I need to drill it out but leave the right size to press in the new valve guide. Does anyone know the right diameter drill to use. This has been a learning experience about replacing the valve guides.  Even my local machine shop found this amazing and very difficult. I measured the new guide itself and it is about 5/8 or .625 but it should be a press or inference fit.

[Rus Curtis]

Earl,
I leave these jobs for others to do.  But I've read about it.  The Service Manual describes the process in para, E-63. Valve Guide Replacement.  Of course they have a Valve Guide Tool....

What I've read is some have created a press using a bolt and washers.  Your's is broken, so I don't know if it will press out easily.  While a drill might work, I'd worry that it could be pushed into the block while drilling and damage the valve guide bore.  If I were to try a repair, I think I'd try pressing it out.  My thinking is that's easier to control vs. a drill.

Stubborn parts that won't come out usually need to be soaked in penetrate for a few days. 

[PercyUK]

Hi Earl, I have recently done some of my guides and sadly none came out by pressing using a threaded bar. I have seen it done but for me it just never worked. I think drilling is a very risky strategy and agree with the others that if it goes wrong you could trash the block.
If it was mine I would make a drift with a narrow section that fits inside the remaining sleeve and a thicker diameter just smaller than the bore.
Then drive it downwards using big hammer 4 or 5lbs.
They are tough but it will drive out and exit down into the tappet void.
Make sure you stop before you hit the tappet and break it off with a blow from a chisel. It is brittle and will break easily.
Then continue to drive the remainder out.
I did this successfully on four of my guides

Good luck.

[Earl Baker]

well, I finally got the valve guide out without damaging the bore except for one small nick. I bored it out to 1/2 inch to fit in a hacksaw blade then over much time cut the guide in two places by hand. I then use the threaded rod , metal block and nut method to pull it out which still took some effort. I have heard Briggs and Stratton makes a special antiseize for this that they use on airplanes. I have seen it on ebay and will try it even though most videos say to install them dry. Hope to never do this again .