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Exhaust valve guide reaming

J

Jbon

Active Member
I've been reading posts about valve guide reaming. It was interesting to note that some advocate not reaming the guide, but rather to just hone it using a 1/2" ball hone.

It makes sense to me that this would be a safer alternative, if indeed it does the job, and certainly a lot cheaper than the $150 McFarlane wants for their wiz-bang reamer.

My question is, which one to get? I see the Flex-Hone 1/2" ball reamer comes in 120, 180, 240, 320, and 800 grit. Any recommendations?
 
How will you know how long to hone? I personally follow Lycomings service instruction and use a ream. If you have not performed this procedure before, I recommend that you find someone that has to walk you through the process. There a several tools that can be purchased to simplify the task of valve spring removal. This is the one I use. https://valvewizard.com/lycoming.html
There are also a couple of techniques to speed up the process. For example Dental floss, rope trick, and magnets. Also, you might find someone who has the reamer you could borrow. I always use a ream and have done this task numerous times. The advantage of the ream, is you are quickly able to identify tight guides.
 
Thanks for your reply. My intention is to perform the wobble test first to see where I am regarding clearance. If the clearance is within spec, I figured running a ball hone would just spruce things up a bit. I've read folks just running it in and out for about five seconds. Seems unlikely you'd remove enough metal to harm things. . . but no one mentioned what grit they were using. I'm sure you don't want to be too aggressive. Just curious which one people are using.

If you read McFarlane's description, their reamer is sized and designed to not muck things up if you get started a bit crooked. I just don't want to pay their price.
 
Thanks for the link. I had read this, but didn’t pick up on the advice to go with 240 grit. Looks like a happy medium.
 
Just did the exhaust valves on my C-90, after 800 hours it was time to clean them out. McFarland sells "cleaning reamers" which are ordered by your exhaust valve guide size. These reamers have a channel machined into them to catch the crud as it is removed. You can drop the exhaust valve into the cylinder, ream the guide and polish up the valve stem through the spark plug hole. Noticeable increase in power after the ream job on my Cub.
The reamers are pricey, but these reamers do an excellent job, and do not remove any metal from the guide.I would not take a chance with a reamer that may damaage or oversize the guides. You think a $125 reamer is pricey, how about replacing damaged valve guides!
 
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I recently reamed then honed all of mine. Just go slow and you will be fine. The ball hones come in different grits and abrasive type. One is made for the bronze valve guides (I THINK it is the aluminum oxide one..??) If you contact Flex Hone they will confirm which abrasive and which grit is correct for your job.
 
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Exhaust valve guide cleaning/reaming

Jbon said:
I've been reading posts about valve guide reaming.
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I've heard of either 28 gauge shotgun barrel cleaning brush or a .50 caliber black powder rifle brush being used successfully. They are phosphor bronze and might be able to do the job for $4.00 and not mess up the guide. Not advocating; just reporting what I've heard....
 
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Blasting a guide.....

isosceles said:
Did anybody try to clean the guide with blasting, like using walnut shells media or something like that?
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Um.....no. I'm thinking that wouldn't work. A little difficult to get into a 1/2 inch hole/guide and blast it out.....not to mention where all the media would end up.....:eek::eek::eek:
 
Roadjunkie1 said:
Um.....no. I'm thinking that wouldn't work. A little difficult to get into a 1/2 inch hole/guide and blast it out.....not to mention where all the media would end up.....:eek::eek::eek:
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There is a lycoming SB to clean pistons in-situ using walnut shell blasting though spark plug holes, so it is not totally crazy. I was thinking of blasting walnut shells media though the guides but but not sure if the pass-through air can catch anything on the walls.
 
I used a reamer and was told to be very careful with a ball hone as it removes guide materiel very quickly and it is easy to over hone. YMMV
 
Better life through chemistry

Hoppe’s #9 gun bore solvent and cleaner, few q-tips cleans the stem and guide just as clean as a new penny. Now that they have a foaming version the hardest part of the job is taking the exhaust apart and back together and dealing with those little contrary valve keepers .
 
Not a crazy idea . . . .but proven

isosceles said:
There is a lycoming SB to clean pistons in-situ using walnut shell blasting though spark plug holes, so it is not totally crazy. I was thinking of blasting walnut shells media though the guides but but not sure if the pass-through air can catch anything on the walls.
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I have, and would inject some water in the primer ports before trying to clean pistons with walnut shells. A little water has no drawbacks and will leave the piston and head clean as new. A head gasket leak on auto engines will leave the chamber clean as a whistle.

This is done on large landfill gas engines as there are components in the gas that leave deposits.
 
I read someplace that the carbon layer on the piston increases thermal efficicency - leaving the "heat" in the cylinder to perform work rather than passing the energy to the oil.

Wondering if running some water through the engine would remove the carbon just as well with less effort.
 
VA Maule said:
Hoppe’s #9 gun bore solvent and cleaner, few q-tips cleans the stem and guide just as clean as a new penny. Now that they have a foaming version the hardest part of the job is taking the exhaust apart and back together and dealing with those little contrary valve keepers .
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In less time than it takes to type this reply I can have a guide cleaned out with a 320 grit ball hone. Done correctly the amount of material removed is of no consequence.
 
rocketbob said:
In less time than it takes to type this reply I can have a guide cleaned out with a 320 grit ball hone. Done correctly the amount of material removed is of no consequence.
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I'll second this statement. The ball hone is very fast and very easy to accomplish. I had followed Bob's original advice on this topic and had purchased two ball hones, one at 320 grit and one coarser grit. The 320 grit was more than adequate for the task and the coarser grit hone remains in its unopened package. A 50/50 mix of acetone and ATF, used sparingly, works very well as a flushing agent while honing.
 
I used the ball hone that Bob recommended (320 grit?) when I did the field overhaul of my engine. About 5 seconds with a slow speed drill removed 90+% of the deposit inside the guide. The ball hone is more of a surface finish tool than cutting tool as long as you don't go crazy with it.
 
I don't have a straight access to the exhaust guides of the back cylinders in my airplane (not an RV) and have to look for alternatives.
 
Mconner7 said:
was told to be very careful with a ball hone as it removes guide materiel very quickly and it is easy to over hone. YMMV
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clearly that guy never bored a cylinder out 10 over. I am here to tell you that it takes WAYYY more grit, pressure and effort than you think it does. You would have to go high speed for quite a long time to get a 320 grit ball hone to actually remove metal. It is designed to make light scratches, NOT remove material. Find a piece of silicone bronze and mic it. Attack it with a power sander with 320 grit for 15 minutes (don't replace the paper) and mic it again. Tell us how much material you removed. Pretty sure you'll be surprised. The silica grit dulls and stops working LONGGG before it removes any significant material.

I am shocked that people would prefer a reamer, as it is VERY quick and efficient at removing metal.
 
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