Author Topic: Webster build some questions  (Read 3281 times)

Offline John Rudd

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Webster build some questions
« on: February 16, 2015, 03:19:51 PM »
Mine is an ongoing build, pics to follow, but in the meantime, I have a couple of concerns....

The valve seat assemblies are made from bronze, ideally or CI, but the internal bore is shown,as .219 inches....the valve head is shown as .25 inches....hmmm it won't fit..anyone else come across this?
So if I go for the .219, what have folk used for cutting the 45 degree seat angle?
More questions later...no doubt..
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Offline Jasonb

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Re: Webster build some questions
« Reply #1 on: February 16, 2015, 03:38:51 PM »
Most valve cages are smaller than the head of the valve other wise it would dissapear inside. By the time you have got the 0.015" chamfer all round that will take things upto 0.25". Don't confuse the angle of the drilled hole shown on teh sectional drawing that is 0.188 deep with the valve seat which is right at the end of the cage.

I tend to set the topslide to 45deg and cut my seats with a boring bar. Some people just use a CSK bit others make their own valve seating tool which has a guide pin that fits the valve guide hole

Offline John Rudd

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Re: Webster build some questions
« Reply #2 on: February 16, 2015, 04:02:28 PM »
Jason,thnx for the reply....but the light is out.....
I have a valve whose head is .25 dia....
It fits into a cage....the bore of the cage is .219 for a depth of .188....

I see a 45 deg chamfer at the bottom of the bore, it's major diameter too is .219.....but then the head of the valve is .25 in with a thickness of 10 thou, which then reduces to a dia of 093 for the stem.....

Summat missing?
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Offline Jasonb

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Re: Webster build some questions
« Reply #3 on: February 16, 2015, 04:08:17 PM »
The chamfer is at the end of the cage, what you are looking at is the pointed hole left by the 0.219 drill. The valve sits 0.020" proud of the bottom of the cage
« Last Edit: February 16, 2015, 04:28:35 PM by Jasonb »

Offline John Rudd

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Re: Webster build some questions
« Reply #4 on: February 16, 2015, 05:15:13 PM »
Gotcha....the valve seat is at the flange of the cage.....yippeeeeeeeeee....no problem now cutting the swat with a 90 degree cutter....

Thanks for the help Jason.. :NotWorthy:
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Offline John Rudd

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Re: Webster build some questions
« Reply #5 on: February 17, 2015, 11:14:02 AM »
Ok,got the first guide/seat done...
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Offline John Rudd

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Re: Webster build some questions
« Reply #6 on: July 09, 2017, 06:13:52 PM »
Ok,getting back to building this....
I'm sure I posted about the rocker but cant find any detail.....

Looking at the drawing, the cam for the ex valve is 3/16" thick, add 0.015 for the washer between it and the support, this adds to 0.202....
Now the rocker is thinned to 0.125 at the gear end, add to that the 0.105" thick spacer it sits against,means it fouls the gear....Summat doesnt add up....

What am I missing? I dont see  to get my head round the drawing for the rocker, as if some measurements are missing?
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Offline Jasonb

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Re: Webster build some questions
« Reply #7 on: July 09, 2017, 06:43:39 PM »
Cam gear washer is 0.063"

The 0.015" washer goes on the outside of the rocker arm, also at 1/8" bore it would not fit on teh cam stubshaft.
« Last Edit: July 09, 2017, 07:00:02 PM by Jasonb »

Offline John Rudd

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Re: Webster build some questions
« Reply #8 on: July 09, 2017, 08:04:18 PM »
Think I got it.....
The cam gear is 3/16" thick, add to that its 1/16" washer gives 1/4"....
The rocker is 0.125  thick, offset with spacer of 0.105, gives 0.230. A clearance of 20 thou...
That'll do....
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