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When I took my heads to the machine shop, I told the machinist it was likely the guides would need replaced as they felt rather loose. The heads have 270,000 miles on them. I bought new ferrea valves along with new springs and etc. I asked him when I picked them up if he had to replace the guides, he said "no, they checked good, we check them using a vacuum method, if it holds vacuum the guide is okay" I never heard of this method, and I`m not about to throw this thing together to have the guides leak like hell and have to take the heads right back off, It`s hard for me to believe the guides aren`t shot after 270,000 miles. However when I did remove the heads, they showed little sign of oil on the valves, even so the valve seals were hard and brittle, anyone want to offer any insight on this?
 

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DoubleVision said:
When I took my heads to the machine shop, I told the machinist it was likely the guides would need replaced as they felt rather loose. The heads have 270,000 miles on them. I bought new ferrea valves along with new springs and etc. I asked him when I picked them up if he had to replace the guides, he said "no, they checked good, we check them using a vacuum method, if it holds vacuum the guide is okay" I never heard of this method, and I`m not about to throw this thing together to have the guides leak like hell and have to take the heads right back off, It`s hard for me to believe the guides aren`t shot after 270,000 miles. However when I did remove the heads, they showed little sign of oil on the valves, even so the valve seals were hard and brittle, anyone want to offer any insight on this?
Please SPLAIN this vacuum method to which you refer.

If I were in doubt , take a retainer off and see if you can wiggle valve back and forth, should not be sloppy side to side.
 

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He didn`t give me any details on how it`s done, that was all he told me so it`s all I got to go by unfortunately.
 

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Find you a new builder. They apparently is interested more in mass producing junk than making a quality product.


Loose guides cost big time power and invite broken and bent valves. Not to mention the seat's get hammerd oblong and that cut's the valves ability to seal.


You can suck any valve shut with enough air.
 

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DoubleVision said:
When I took my heads to the machine shop, I told the machinist it was likely the guides would need replaced as they felt rather loose. The heads have 270,000 miles on them. I bought new ferrea valves along with new springs and etc. I asked him when I picked them up if he had to replace the guides, he said "no, they checked good, we check them using a vacuum method, if it holds vacuum the guide is okay" I never heard of this method, and I`m not about to throw this thing together to have the guides leak like hell and have to take the heads right back off, It`s hard for me to believe the guides aren`t shot after 270,000 miles. However when I did remove the heads, they showed little sign of oil on the valves, even so the valve seals were hard and brittle, anyone want to offer any insight on this?
Vacuum is usually used to check the seal of the valves to the seats. Not sure how vacuum test could apply to guides. Guides are usually measured and compared to valve stem size.

Chris Laarman
Ottawa Engine and Performance
 

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I agree with the guys here...There is the so-called precision wiggle test whereby you extend the valve flush with end of the guide & measure the "throw" of the valve head...but really one should measure the inside of the guide for more precise numbers. The spec manuals have very specific numbers to deal with and have stock ranges and have service limits.
Guides are of two types as far as I know, one is made of the same material as the head ...say Iron, and is a simple precision hole...the other is an insert which needs to be used on an aluminum head as aluminum is too soft for the valve to ride in. The insert version can be replaced, the Iron version has a few ways to be redone. The first and worst version is to "Knurl" the inside of the guide...this decreases the diameter to fit but the surface area is reduced & should never be an acceptable repair.
The others are a swedged "split" collar type, The heli-coil type....and there are a few others I can't recall at this moment............avoid the Knurl type like the plauge(sp?).......
______________________________________________Rick...........
 

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like was said in one of the other replies. Pull off the retainer and slide the valve about an inch out. Then try and wiggle it and see how much "play" it has. If its really loose it needs fixing. If its just barely wiggles then you should be fine.
 

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Seems funny that he would not want to replace the guides...............More money in his pocket. I would get another shops opinion.

What ever happened to bronze guides?
 
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