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Old 10-18-2017, 02:59 PM   #1
DaveWright
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Default Modern Valves - cutting?

I’m beginning to assemble my A engine with the guidance from Les Andrews handbooks, and I have a question: when installing the modern valves, he instructs to cut the valve so there is only a 1/16 reveal below the keeper. What is the best way to cut the valve stem? Is this something I should have a machine shop do? Any advice is appreciated. Thanks!
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Old 10-18-2017, 05:30 PM   #2
J and M Machine
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Default Re: Modern Valves - cutting?

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I’m beginning to assemble my A engine with the guidance from Les Andrews handbooks, and I have a question: when installing the modern valves, he instructs to cut the valve so there is only a 1/16 reveal below the keeper. What is the best way to cut the valve stem? Is this something I should have a machine shop do? Any advice is appreciated. Thanks!
Yes: The bottom of the valve stem is not something you can do yourself.
Take it to a machine shop and have them grind it to your specific dimension.
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Old 10-18-2017, 05:40 PM   #3
denniskliesen
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Default Re: Modern Valves - cutting?

Consider when that book was published. I believe a lot has changed since then regarding modern valves. I have installed modern valves and all were different. Never had a reason to cut any of them.
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Old 10-18-2017, 05:49 PM   #4
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Default Re: Modern Valves - cutting?

Don't do it! At least until you have demonstrated the need to do so. With your cam in place, determine if the recommended valve lash can be achieved by lifter adjustment. Then you can proceed either by lifter adjustment, valve stem grinding, or maybe a combination of both. The out come as to which path, is dictated by the choice of components.
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Old 10-18-2017, 07:25 PM   #5
glenn in camino
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Default Re: Modern Valves - cutting?

Have a machine shop do it.
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Old 10-19-2017, 01:58 PM   #6
hardtimes
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Default Re: Modern Valves - cutting?

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Hey Dave,
Russ/40 has good advice here.
However, if you do have valve stem 'cut', have you considered whether that same stem needs to be hardened, against wear, again ?
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Old 10-19-2017, 03:52 PM   #7
100IH
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Default Re: Modern Valves - cutting?

1. magnaflux for cracks
2. replace guides
3. install seat rings as needed, then grind or cut seats
4. install camshaft and lifters, then valves
At this point you can figure assembled spring height and see if but end works as is or if it needs to be shortened on the valve grinder.
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Old 10-19-2017, 10:26 PM   #8
DaveWright
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Default Re: Modern Valves - cutting?

Thanks for all the good info, Gents. You all gave this rookie things to consider... I’m sure I’ll be back with more questions.
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Old 10-20-2017, 07:47 AM   #9
Dave in MN
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Default Re: Modern Valves - cutting?

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Originally Posted by Russ/40 View Post
Don't do it! At least until you have demonstrated the need to do so. With your cam in place, determine if the recommended valve lash can be achieved by lifter adjustment. Then you can proceed either by lifter adjustment, valve stem grinding, or maybe a combination of both. The out come as to which path, is dictated by the choice of components.

Agree! (Only if necessary and then by a machine shop.)
Good Day!
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Old 10-20-2017, 11:23 AM   #10
George Miller
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Default Re: Modern Valves - cutting?

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Agree! (Only if necessary and then by a machine shop.)
Good Day!
Plus 1
The end of the valve has to square with the valve stem. If not you are going to side load the guides.
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Old 10-21-2017, 01:38 AM   #11
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Default Re: Modern Valves - cutting?

Do not rely on Andrews' 1/16" number as the final measurement. That is .0625 as a reveal and is quite a bit to take up. Presumably you are using adjustable lifters. The proper clearance depends first on which "modern" valve is used and its length. Most important is to measure the deck height, ie, that is the distance from the pan rails to the top of the block. That will affect the clearance of the valve stem to the lifters. 1/16" from the keeper may or may not be right depending on whether some one in the past has shaved the deck, installed hard seats, how deep the seats are, etc. It is probable that the deck has been shaved--you need to know by how much. As noted, adjustable lifters leave some room for variations. Measure, measure, measure.
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