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mark tucker
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PostPosted: Sun Jun 04, 2017 9:29 am    Post subject: Re: seat change Reply with quote

all, used or new. I bought a new set of heads and they were staked and there was cracks where they were staked and the aluminum fell off whn I picked it with my FINGER NAIL.so..my statement stands, if you wish to know the brand of the usa made heads Ill be gladd to say so.
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nsracing
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PostPosted: Sun Jun 04, 2017 4:57 pm    Post subject: Re: seat change Reply with quote

I don't mind staking the seats. It is probably a good idea. The factory ones are all staked. Maybe they know something.... Very Happy
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mark tucker
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PostPosted: Sun Jun 04, 2017 7:29 pm    Post subject: Re: seat change Reply with quote

maybee they dont. maybee they do it diferently. Ive seen way tomany effed up heads by some morons that thought cracked cast would actually do something....I think you would be better served by counter sinking the seat then welding around the top to hold it in if you cant seem to get the interfearance right. fractured cast needs to be removed
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PostPosted: Mon Jun 05, 2017 7:31 am    Post subject: Re: seat change Reply with quote

mark tucker wrote:
all, used or new. I bought a new set of heads and they were staked and there was cracks where they were staked and the aluminum fell off whn I picked it with my FINGER NAIL.so..my statement stands, if you wish to know the brand of the usa made heads Ill be gladd to say so.


You go right ahead and say what brand Made in the USA heads they were Mark(that you got 2 decades ago) BUT you are just flat out wrong on this. You know a lot but you don't know more than I do on manufacturing brand new aircooled heads. I've built more heads with my own hands than you've ever even seen in person. I've staked every single seat I've ever installed, never seen a crack and never had a seat fall out.
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mark tucker
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PostPosted: Mon Jun 05, 2017 2:04 pm    Post subject: Re: seat change Reply with quote

yes they were yours, less than 2 decades ago, 1 had to be replaced when new....probably like...15 years ago.yes there were cracks, yes my fingernail picked some off,I too have installed many seats in aluminum heads and never had any fall out or fail as well as many in iron heads. remember that butcher knows the cuts of beef.
those heads have around 120000 miles and over 80000 with the larger valves I put in them and lotsa port work.and still the same guides. there good heads I just wish they were not on pourpose cracked from the "staking" prosess that isant needed. I wonder why dart, brodix,canfield,and somany other aluminum head manufactures dont do it...hmmm my cb heads arnt done either.....and yes I have worked in manufacturing, but mostly aerospace/aircraft/otomotive prototype&small run stuff.(1000 piece lots)and much more.but almost exclusively billet materials. Im not clueless.
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PostPosted: Mon Jun 05, 2017 2:23 pm    Post subject: Re: seat change Reply with quote

mark tucker wrote:
yes they were yours, less than 2 decades ago, 1 had to be replaced when new....probably like...15 years ago.yes there were cracks, yes my fingernail picked some off,I too have installed many seats in aluminum heads and never had any fall out or fail as well as many in iron heads. remember that butcher knows the cuts of beef.
those heads have around 120000 miles and over 80000 with the larger valves I put in them and lotsa port work.and still the same guides. there good heads I just wish they were not on pourpose cracked from the "staking" prosess that isant needed. I wonder why dart, brodix,canfield,and somany other aluminum head manufactures dont do it...hmmm my cb heads arnt done either.....and yes I have worked in manufacturing, but mostly aerospace/aircraft/otomotive prototype&small run stuff.(1000 piece lots)and much more.but almost exclusively billet materials. Im not clueless.


I know you know a lot Mark but in 30+ years of us manufacturing cylinder heads, I have NEVER heard one person tell me the staking process cracked their heads. I stake the seats with a special made tool and a hammer, not a machine or a press. The staking folds the metal over the edge of the seat to prevent the seat from falling out and yes a flake of aluminum will come off. Maybe we had The Hulk working here the week your heads were made?

This is what makes me just sit back and laugh sometimes. We've used a process tens of thousands of times over multiple decades and I get told that "it doesn't work" Really? Why are we still the only company to make aircooled street performance cylinder heads 100% in the USA? Why hasn't anyone else done it if it's so easy and we don't know what we're doing? Why aren't all the heads cracked?
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modok
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PostPosted: Mon Jun 05, 2017 8:53 pm    Post subject: Re: seat change Reply with quote

I'd say about 30% of people.... I would consider experts, do believe in SOME form of additional retaining feature besides just press fit.

ALL OE vw heads have a chamfer atop the seat and the aluminum rolled over into it, all 50millon+ of them, so, there might be something to that.

Compared to other similar aircooled engines the OE VW heads do rarely lose a seat, so they are doing something right. What part of that is right, is the question.
There are several ways to do that and that could be a subject in itself, I think, but I don't feel like discussing it at great length, with you guys.
None of us are having any problems, no interest in changing what we are doing. Not worth typing a thousand words to fix an imaginary problem.
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PostPosted: Tue Jun 06, 2017 7:22 am    Post subject: Re: seat change Reply with quote

Roy,
Since you more then likely do have more experience installing seats then anyone else in our industry, would you mind sharing what you use for your interference fit on the seats? Do you install them at room temp or heat the head?

In this thread alone there are numbers from .005" to around .015". That's a big spread in a small hole.

Whatever you are doing works, and if you want to keep your process disclosed I understand 100%.

Thanks, Brian.
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PostPosted: Tue Jun 06, 2017 10:15 am    Post subject: Re: seat change Reply with quote

Brian_e wrote:
Roy,
Since you more then likely do have more experience installing seats then anyone else in our industry, would you mind sharing what you use for your interference fit on the seats? Do you install them at room temp or heat the head?

In this thread alone there are numbers from .005" to around .015". That's a big spread in a small hole.

Whatever you are doing works, and if you want to keep your process disclosed I understand 100%.

Thanks, Brian.


I install them at room temperature. .008" for the seats we stake and .010" for the 050 seats(we don't have a staking tool for those since I changed the seat size a year ago) In my experience, anything less and they can fall out and any more and you can break the seat while installing it(it's really good to have safety glasses on when a seat explodes while installing it)
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PostPosted: Tue Jun 06, 2017 1:16 pm    Post subject: Re: seat change Reply with quote

Thanks Roy!!

Keep up the good work!!

Brian
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modok
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PostPosted: Tue Jun 06, 2017 6:28 pm    Post subject: Re: seat change Reply with quote

Brian_e wrote:


In this thread alone there are numbers from .005" to around .015". That's a big spread in a small hole.


I guess we have to be careful what we say Laughing
It depends on the surface finish of the hole and also the seat material.
If you were replacing a small exhaust seat without re-machining the pocket, then .005 could work

If you were putting in a BIG mild steel seat then .015 could work, if the steel is soft enough to give. The chrome alloy cast seats I like to use, do not give at all, so either they would crack or the head would give. There are limits.

I agree .008 is probably the average, but if you remove the seat and measure again, I think you will find it is now .001 bigger, so IMO that is actually .007 press
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PostPosted: Tue Jun 06, 2017 11:01 pm    Post subject: Re: seat change Reply with quote

I just did my first seat install last week. I put 37mm intakes in some old but solid 113 dual port heads. i think I got lucky cause my bore had a near perfect finish. I turned the seats for a .007" press fit with a nice round bottom chamfer.
I heated the head to 380deg, and drove them in with an air hammer on a piloted driver. They went in surprisingly well. I was a little nervious about not enough press. It's going in a 1915, w/kads in an early bug. It is a weekend
cruiser. If it was going into a bus I would probably redo them.

Next set will have way more press now that I have a little more experience.


Brian.
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PostPosted: Sun Jun 11, 2017 9:00 pm    Post subject: Re: seat change Reply with quote

i went ahead and fabricated my own cutter. I took a 3/4 bolt and removed the head and thread and faced the ends in my lathe. I then brazed a bit on as suggested in an earlier post. Seems very rigid. I am having a bit of a problem with the blade loading up as the pic shows. I tried some tap oil but it seemed to make the shavings stick to the bit and left a few small scores in the finish. I might need to check my cutter angles and a few things. All in all im very happy with the results. thanx guys for your help
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PostPosted: Mon Jun 19, 2017 1:38 pm    Post subject: Re: seat change Reply with quote

Brian_e wrote:
I just did my first seat install last week. I put 37mm intakes in some old but solid 113 dual port heads. i think I got lucky cause my bore had a near perfect finish. I turned the seats for a .007" press fit with a nice round bottom chamfer.
I heated the head to 380deg, and drove them in with an air hammer on a piloted driver. They went in surprisingly well. I was a little nervious about not enough press. It's going in a 1915, w/kads in an early bug. It is a weekend
cruiser. If it was going into a bus I would probably redo them.

Next set will have way more press now that I have a little more experience.


Brian.


So... 0.007" press, huh? Okay if you say so. But you have to be honest though when it does fall off you will come back here and say so. Very Happy

Is that for both intake and exhaust?

I put a little more on the exhaust side just from small experience w/ racing heads.
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PostPosted: Mon Jun 19, 2017 2:17 pm    Post subject: Re: seat change Reply with quote

nsracing wrote:
Brian_e wrote:
I just did my first seat install last week. I put 37mm intakes in some old but solid 113 dual port heads. i think I got lucky cause my bore had a near perfect finish. I turned the seats for a .007" press fit with a nice round bottom chamfer.
I heated the head to 380deg, and drove them in with an air hammer on a piloted driver. They went in surprisingly well. I was a little nervious about not enough press. It's going in a 1915, w/kads in an early bug. It is a weekend
cruiser. If it was going into a bus I would probably redo them.

Next set will have way more press now that I have a little more experience.


Brian.


So... 0.007" press, huh? Okay if you say so. But you have to be honest though when it does fall off you will come back here and say so. Very Happy

Is that for both intake and exhaust?

I put a little more on the exhaust side just from small experience w/ racing heads.


Ya. I wish I would have done more now, but this topic wasn't started when I did mine. I did a bunch of research, and like I said before, the number ranged from .005-.015" press.

I only bumped the intakes to a 37mm valve. Exhausts are still stock. I have about 300 miles on the engine now. I have checked the valves twice, and they are perfect each time. Only time will tell. I will for sure post the carnage if it happens.

I will be doing a set of 40x35's in new T4 heads tomorrow night. What would you recommend for a press fit?

Brian
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PostPosted: Mon Jun 19, 2017 8:41 pm    Post subject: Re: seat change Reply with quote

I wouldent use a air hammer. and be carfull to not bounce the seat back up. also installing into a hot head the seats may creep out when it cooles like motorcycle cylinders pressed into a hot aluminum cylinder finn. it's recommended to put the cylinders in a press to hold it till it cooled. I like a radii on the cutter so there is not a sharp corner in the counter bore.and yes a nice raidi on the seat too.I like to have a slight chamfer on the seat top too so there is not a hot spot potential., not much but just enough to break the edge. there are many ways to do seats. some times it's as eazy as just drilling 4 holes and bolting it in and going for a ride.
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PostPosted: Mon Jun 19, 2017 11:13 pm    Post subject: Re: seat change Reply with quote

mark tucker wrote:
also installing into a hot head the seats may creep out when it cools like motorcycle cylinders pressed into a hot aluminum cylinder finn. it's recommended to put the cylinders in a press to hold it till it cooled.

Good thinking mark but you got it bass-aqward. seats down as it cools.
Motorcycle jug has flange at top, seat has step at bottom.
If you have a iron sleeve sitting on a step at the bottom of an aluminum jug it also DROPS when hot and raises when cooled.
I have done many both ways, seats and sleeves. Very Happy

BUT, let us consider this for a moment...... The head DOES expand and contract in THIs dimension.....
if we want the seat to NOT move around, then witch END of the seat do we want to stay PUT? at the surface or down at the bottom? Food for thought.

Will you be trimming the seats to fit the hole? I have a trick for you may consider, for intakes or maybe both.
Cut the OD of the seat just a bit smaller, perhaps .010 smaller, for the top .080 or so, bit less, bit more, not sure. Relieving the press fit near the chamber floor. Didn't really want to get into it, but since mark "brought it up" Razz
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PostPosted: Tue Jun 20, 2017 6:58 am    Post subject: Re: seat change Reply with quote

modok wrote:

Will you be trimming the seats to fit the hole? I have a trick for you may consider, for intakes or maybe both.
Cut the OD of the seat just a bit smaller, perhaps .010 smaller, for the top .080 or so, bit less, bit more, not sure. Relieving the press fit near the chamber floor. Didn't really want to get into it, but since mark "brought it up" Razz


Yes, I have a nice expanding mandrel, and I will trim the seats to fit the new bore. I can try your trick. Sounds like it might help keep a crack from starting right at the floor.

What do you use for lube when pressing them in? Any green locktite press fit assist?

Brian
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PostPosted: Tue Jun 20, 2017 7:28 am    Post subject: Re: seat change Reply with quote

Which Green Loctite are you using Brian?

Some of those greens are "designed" for clearances .005 and up to .015 lol. When I worked in a machine shop installing bushings in transmissions the "Walk of shame" was anyone reaching for the green loctite. Cause it meant someone screwed up bad.
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PostPosted: Tue Jun 20, 2017 8:15 am    Post subject: Re: seat change Reply with quote

I have a bottle of 620 retaining compound. I wasn't planning to use it, but I did read somewhere it was supposed to help heat transfer in press fit parts.

I agree with the "walk of shame". Only reason I bought this bottle was to help fix another guy's screw up.

Brian
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