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UK Luke 72
Samba Member
Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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 Posted: Tue Jan 31, 2017 12:37 pm Post subject: Removing guides |
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When the boss has been cut down for duals... Doesn't leave enough meat for me to have confidence that it isn't going to crack around the bottom of the spring seat...
What are my options? |
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raul arrese
Samba Member
Joined: July 23, 2006
Posts: 1330
Location: miami florida
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| Posted: Tue Jan 31, 2017 1:34 pm Post subject: Re: Removing guides |
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You need to core them , so it will relieve the pressure against the bore and try to prevent cracking ...
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UK Luke 72
Samba Member
Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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| Posted: Tue Jan 31, 2017 1:48 pm Post subject: Re: Removing guides |
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| You think that'll save them? What if one does crack? how is best to repair that? |
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mcmscott
Samba Member
Joined: March 12, 2010
Posts: 4856
Location: sanger ca
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| Posted: Tue Jan 31, 2017 2:39 pm Post subject: Re: Removing guides |
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Core them almost to the end(chamber side) then, or before, spot face the top even with the boss and then push into the chamber side. Easy
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Brian_e
Samba Member
Joined: July 28, 2009
Posts: 3291
Location: Rapid City, SD
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| Posted: Tue Jan 31, 2017 2:47 pm Post subject: Re: Removing guides |
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Getting them out without cracking the boss is easy. Pressing the new ones in without cracking is a whole nother issue....
Maybe Scott or Modok have a suggestion, but I have tried all different preheat temps, press/hammer methods, and I still usually have one break on a pair of heads. Usually the last one. My measurements are all good, but there always seems to be one that will crack.
Brian |
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UK Luke 72
Samba Member
Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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| Posted: Tue Jan 31, 2017 3:09 pm Post subject: Re: Removing guides |
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| And what is the fix if/when it does? |
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Brian_e
Samba Member
Joined: July 28, 2009
Posts: 3291
Location: Rapid City, SD
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| Posted: Tue Jan 31, 2017 3:30 pm Post subject: Re: Removing guides |
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| UK Luke 72 wrote: |
| And what is the fix if/when it does? |
Depending on the application, I have faced the remaining boss flat in the mill, and turned a new sleeve the dimensions of the old guide boss. Then I press the new machined piece onto the guide before I drive the guide in. This really only acts as a spacer to keep the guide at the correct height, and to keep the spring centered. The guide will of course have less press fit holding it in now. I have done this on lower HP applications with good results.
Brian |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Tue Jan 31, 2017 5:36 pm Post subject: Re: Removing guides |
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If it breaks make a "prostetic boss" to go on the valve guide.
Getting them out will be no problem but getting them back in will be when you may have a problem. There are at least three reasons it is better to drill off the guide even with the boss, and core at least partway though and pull them out of the port side. There is probably a fourth reason if i can think of it, at any rate, do that.
If they are all a consistent size may be able to make a steel sleeve to go around the boss to prevent it from ballooning out when you drive them in.
Will you be turning the port side of the intake guide a little smaller? it's not JUST for flow.
as always the secret is:
.001-.0015 press fit
-generous chamfer
-lube with anti-sieze
if the new guide is too tight polish it smaller with 320 grit. One time I had one halfway in and decided it was too tight, decided to abort!
Drove it back out and I went over it maybe two swipes with the abrasive paper, not enough to really do anything, then CHANGED MY MIND. yeah I waffled. so I re-lubed it and tried it again and it went in EASY.
WTF just happened
What do you think? I think I know why but you would not believe me if I just said it. |
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UK Luke 72
Samba Member
Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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| Posted: Wed Feb 22, 2017 1:03 pm Post subject: Re: Removing guides |
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Cool story Modok  So I've left the heads with a guy I trust to do the job... Remove the guides, port them and refit new guides... He said he'd just make a prosthetic boss up if he had too.
Lets see if he breaks something  |
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9467
Location: NOVA
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| Posted: Sun Feb 26, 2017 9:31 am Post subject: Re: Removing guides |
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This is how I remove guides..
Here I line up the hole center at proper angle and drilling down 3/4 way. This relieves the pressure on the OD and guides come out easy. Just tap them out.
But word of caution: If you don't have a way to perfectly center and angle the head, do NOT do it. Or you will destroy and otherwise pristine guide bore. I made my jig just for this occassion. |
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mark tucker
Samba Member
Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sun Feb 26, 2017 9:34 am Post subject: Re: Removing guides |
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| most proper core drills are self centering...but I suppose any moron could eff it up. I just use my seat&guide machine.....but have done it by hand with a core drill. |
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UK Luke 72
Samba Member
Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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| Posted: Sun Feb 26, 2017 10:12 am Post subject: Re: Removing guides |
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| Great setup NS |
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ALB
Samba Member
Joined: August 05, 2008
Posts: 3483
Location: beautiful suburban Wet Coast of Canada
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| Posted: Sun Feb 26, 2017 10:56 am Post subject: Re: Removing guides |
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| modok wrote: |
If it breaks make a "prostetic boss" to go on the valve guide.
Getting them out will be no problem but getting them back in will be when you may have a problem. There are at least three reasons it is better to drill off the guide even with the boss, and core at least partway though and pull them out of the port side. There is probably a fourth reason if i can think of it, at any rate, do that.
If they are all a consistent size may be able to make a steel sleeve to go around the boss to prevent it from ballooning out when you drive them in.
Will you be turning the port side of the intake guide a little smaller? it's not JUST for flow.
as always the secret is:
.001-.0015 press fit
-generous chamfer
-lube with anti-sieze
if the new guide is too tight polish it smaller with 320 grit. One time I had one halfway in and decided it was too tight, decided to abort!
Drove it back out and I went over it maybe two swipes with the abrasive paper, not enough to really do anything, then CHANGED MY MIND. yeah I waffled. so I re-lubed it and tried it again and it went in EASY.
WTF just happened
What do you think? I think I know why but you would not believe me if I just said it. |
I'm all ears....
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9467
Location: NOVA
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| Posted: Sun Feb 26, 2017 11:02 am Post subject: Re: Removing guides |
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I machined that jig back in the day -miss that jig and mill. Both sold few years ago to someone in Kentucky. I gave up on rebuilding heads for the moment - too laborious and not much profit in it for the work you have to do.
I did heavy-duty topend rebuilds back in the day... big valve conversions and things. I will pick it up again someday when time permits it maybe in my near retirement.
I will be converting to cranks and whole engines/trans shortly. Once I get my Go-Power dyno running. Cannot wait to fire up my Gleason crankwelder.
This hobby is dying a slow death. We all have to make sure we can support this love of aircooled VWs till our end.  |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Sun Feb 26, 2017 4:23 pm Post subject: Re: Removing guides |
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OK Nick, you do cranks I'll tale up heads. But you have to do doweling, match doweling.
I thought it was all slowing down but there is a SURGE this year. CNC heads are great but they have not yet begun to eliminate the needs to do a lot of hand work.
| ALB wrote: |
I'm all ears.... |
Well, there is a few possibilities. One is, sanding the guide just briefly with 320? grit created a nice crosshatched surface finish that made the lubricant work far better.
Another possibility is removing the oxide from the surface reduced friction. These things sit on a shelf a long time after being machined.
Or both, or something else.
In any case it's a true story. I am seeing more and more every year, this same property in all I do.
Cam/lifters, cylinders, rings, press-fits, bearings, valve seats, even combustion chambers, paint, coatings, installing cam bearings in a ford, valve stems, rockers, bushings. Had a great lightbulb moment with Ray Greenwood about "Dyne testing", yes that's a big clue.
The secret is in the sauce, and the ideal surface finish is the one that makes the sauce work best. It's everywhere.
I think nobody will really believe it, because, well, I don't know why. It's crazy.
It's just like all those "speed secrets" They are secrets because nobody asks, and nobody will believe it if you told them.
So I'm not upset at all the other guys in the thread are not following my simple instructions, because if somebody had told me, I'd not have believed it either.
Yesterday I helped my brother modify a fancy motorcycle piston to run pump gas. Had to CC the piston in the cylinder because of the 5 valve reliefs. As machined.....it sucked to do the CC test as the water would resist sticking to the aluminum. After I did "something" to the piston it was easy to CC because the water crawled and spread out on the piston on it's own. You will never guess what I did. It's a speed secret.  |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Sun Feb 26, 2017 4:50 pm Post subject: Re: Removing guides |
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| I have not found a piloted core drill the right size. Not a normal catalog item these days. if I find one for sale I'll let everybody know but right now it would have to be custom ground, by one of those tool re-sharpeing places that have all shut down. |
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mark tucker
Samba Member
Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sun Feb 26, 2017 6:42 pm Post subject: Re: Removing guides |
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you can make your own modock......you have the techknoligy. just a step drill with 1 step... or you could use a step drill and make a bushing to center the tip.  and of corse grind the last size to size. |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Sun Feb 26, 2017 7:01 pm Post subject: Re: Removing guides |
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Good guess Mark. I did that! Just not as good as the real thing.
yeah i could probably make one, but not as nice as I'd like.
I have been buying a lot more valve guide and seat tools for myself but that one is low on the list. Most wanted was a 8mm diamond reamer, and I got one, not as good as sunnen but I'll make it work. |
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mark tucker
Samba Member
Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sun Feb 26, 2017 7:30 pm Post subject: Re: Removing guides |
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| I got the sunnen pg set up(valve guide hone) although not the diamond stones the low volume I do for my self kinda dont need to spend the extra on the stones as Ill never wear out these stones.. Im also making a arbor/mandrill for the lifter bushing size, so i can hone them with the sunnen hone too. also modifying the mandrels for the 'Y" stones..I got it all for my 7mm stuff then started getting more size mandrels. any size I cant find on flebay at a good deal Ill just make my self. |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Sun Feb 26, 2017 9:34 pm Post subject: Re: Removing guides |
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That's fine too. Or the solid carbide reamers, any of the three should be good enough. but if I had to choose I'd take the one pass hone. That's what happened.
I would think thoughts like that, think "if i had to choose.....which way would I go?" One pass hone, .375 top carbide pilots, cutters and stone holders modified to work with the same size pilots.
talked myself into it, subconsciously
My buddy got a sunnen seat cutting machine and converted it to sioux pilots. Go figure. You can make it all interchange. .375 tools can be reamed to .385, and .385 tools can be k-lined to .375 |
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