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General Discussion => Tech Tips => Topic started by: mrunderhill1975a on October 14, 2013, 11:07:15 pm

Title: Valve grinding tool
Post by: mrunderhill1975a on October 14, 2013, 11:07:15 pm
Has anyone used a mechanical hand tool valve grinder such as the one shown in the link below?

http://www.ombwarehouse.com/Valve-Grinder.html

Do these things work or is it better to use the stick/suction cup type grinder?
Title: Re: Valve grinding tool
Post by: ERC on October 14, 2013, 11:43:42 pm
They're equally effective.  ERC
Title: Re: Valve grinding tool
Post by: ace.cafe on October 14, 2013, 11:54:53 pm
Use the cheapest method that gives you decent control.
You want minimum material removed. Just enough to remove any pits or burn grooves.
The wider you grind the working seat angle, the worse the flow will get.
On a real performance valve job like we do, I specify to never touch the seats with a stone or grinding paste. We use a cutter on a Serdi machine. No stones or paste on any seats we do.
Title: Re: Valve grinding tool
Post by: D the D on October 15, 2013, 12:33:59 am
I had one of those cranky things back in the '70s.  Way overkill for the job and a little clumsy.  It's really just a hand crank drill like your great grandpa used before Black and Decker made electric cheap.
The hand ones, the piece of dowel with cups on the end, are more than adequate if you're going to do grinding compound.  As Ace says, there should be no need to compound if you had a machine shop cut new seats.
Title: Re: Valve grinding tool
Post by: High On Octane on October 15, 2013, 03:42:23 am
Why would anyone want to use something that big and bulky for a precision job that only take 10 seconds to do by hand?   ???  Just get a regular old valve lapping tool with a suction cup for $5 from any auto parts store.  That crank job is WAY overkill.  I find it hard to believe it even exists.

Scottie
Title: Re: Valve grinding tool
Post by: D the D on October 15, 2013, 03:52:44 am
It's a gadget Scottie!  We gots to have gadgets!  Like most gadgets, it is a solution to a problem that doesn't exist.
Title: Re: Valve grinding tool
Post by: AussieDave on October 15, 2013, 07:52:19 am
 I feel like a bunney for asking this question, but should one re seat the valves when de- coking  the head?
Title: Re: Valve grinding tool
Post by: ace.cafe on October 15, 2013, 01:05:09 pm
I feel like a bunney for asking this question, but should one re seat the valves when de- coking  the head?

Not if it doesn't need it.
You remove the valves, and inspect the seats and valves for evidence of burnt or pitted areas on the contact surfaces, which may cause compression leaks. If you are unsure about it, when you re-assemble the valves and springs into the head, put the head on the bench with the combustion chamber facing up, and pour enough ATF into the chamber to completely cover the valves and maybe even fill it up all the way if you haven't de-coked the chamber. Leave it overnight. If there is any leakage at the valves, you will see ATF has leaked down into the ports. And leaving the the ATF in the chamber overnight will also dissolve the stubborn carbon in the chamber that was difficult to get off with your soft bristle brush.
If the ATF leaked into the ports, you can do the valve lapping. Also, even if it doesn't leak, if  your visual inspection shows that there are places which are burnt or pitted to the degree that it appears they will begin to leak soon after you put it back together, then do a valve lap.

IMO, unless there  is some extreme budgetary limitation, it would be better to have an actual valve job done if it needs it. The stock valve job is pathetic, and the flow performance could really benefit from getting some decent multi-angle valve and seat work. The valve seats are the place which could give the biggest bang for the buck in porting work, and you don't even have to touch the ports. Just the seats and the back of the valve. Of course, I realize that you'd have to go to bigger valves to do any corrections of the flow angle in the bowls, which is what we do, but you can get a reasonable improvement with the stock valves and a better valve job, in a budget scenario. Heck, we have a budget head mod done to your head casting for $500 called the "Clubman head", and we can do our Mondello multi-angle valve job on any Bullet head, even with stock valves for less than half of that price.

The valve lapping is a cheap effective way to restore burnt stock valve seats and valves to working condition, but it doesn't do anything for improving the flow. If anything, it usually will hurt the flow some. A proper valve job with performance angles is not really expensive, and it's a lot better than just lapping the stock seat angles with compound, unless there is a serious budget issue or there is no desire for better running involved.
Title: Re: Valve grinding tool
Post by: mrunderhill1975a on October 15, 2013, 08:50:03 pm
Why would anyone want to use something that big and bulky for a precision job that only take 10 seconds to do by hand?   ???  Just get a regular old valve lapping tool with a suction cup for $5 from any auto parts store.  That crank job is WAY overkill.  I find it hard to believe it even exists.

Scottie

Ten seconds to do by hand....if that is the case the device is not needed, however, after viewing the video below of a nice English gentleman lapping his valves on a RE 350, I noticed that about half way through he mentions that it is necessary to lap for several hours and many blisters.  Is the gentleman pulling my leg or yanking my crank when he says several hours of lapping is necessary?

http://www.youtube.com/watch?v=kbY_L19fmeA
Title: Re: Valve grinding tool
Post by: ace.cafe on October 15, 2013, 09:05:48 pm
He's joking about doing it that long.
It's a few minutes at most. If it needs more than that, then it needs to have a real valve job with the seats cut.
Title: Re: Valve grinding tool
Post by: barenekd on October 15, 2013, 09:23:57 pm
If he hand ground the valves for several hours, he wouldn't have any valves left! The seats would be screwed, and the valves would have a deep groove in them.
It doesn't take long with the stick and suction cup to do all you should have to do manually anyway. But, then I used a lot of hand cutters for seats, too. Back in the day, the whole job was done by hand
The "Machine" they're trying to sell was originally sold as hand drill known as a "hurdy gurdy". They're are a turn of the century tool, or maybe before that. They were pretty much around up into the 50s or so until electric drills became affordable. I had one in my tool box for until fairly recently, but it seems to have disappeared in the last few years. I would use it occasionally when I had a quick job to do in some soft material, wood, aluminum, etc. But  then I used a lot of hand cutters, too! But I never used one to seat valves!
Bare
Title: Re: Valve grinding tool
Post by: AussieDave on October 16, 2013, 02:00:30 pm
Yeah, I have one of these I got from my dad . It's just a drill. I also have a brace and bits which are great for putting holes in seasoned Aussie hardwood. Redgum is a beautiful timber and gets magnificent compression ripples in the grain as it ages but burns out an electric drill bit in no time if you're not careful.
Title: Re: Valve grinding tool
Post by: AussieDave on October 16, 2013, 02:20:45 pm
And thanks ace once again, you sir are ahold mine that just keeps on giving. Your advice is much Appreciated. I would have no hesitation in sending my head to you for a valve and flow job, but I am gonna wait intill you finish prototyping the hi lift rockers and piston. Also , my bike is my only wheels so I think I need to find a new head to send . Not sure where to look as I haven't seen them listed anywhere. I did see  on the Indian royal Enfield zone site complete iron barrel motors- along with some crazy brass bling ! No prices listed unfortunatly . Cheers