As I have been going through the heads, I found one valve guide with a crack at the top. I had to fight to get it out, but once out, the crack was isolated just to the top. But I will have to replace it.
Is there any particular value to replacing all of the guides with the newer bronze ones? This is not a racing engine and will probably only get a thousand miles a year put on it.
Thoughts?
Just go standard, 1000mls a year will last through to the next millennium:)
While we’re here, can someone please expound on the functional differences between the sintered iron and sintered bronze valve guides?
best i can say is they both are a porus matrix, maybe to provide some no sticky.
either will last many moons! when top of a guide is cracked ,may have been a bent /dropped valve seat!
ron
I wasn’t quite aware of the structure of the guide until I pulled it out. I saw and felt the crack so it caused enough concern to get it out. The valve seats are all in pristine shape but I don’t know the complete history of the engine. At least when this process is over, I’ll have an intimate knowledge of every component.
The only reason that asked about changing out all of the guides was that, from what I’ve read at least, the bronze ones are happier with modern non leaded gasoline. Not sure if that is true, just what I read.
be a good thing to run some lapping ,to be sure of the seats, and regrind the valves !
why not , simple and cheap!
Rather than pulling all the guides, you can K-Line them, mine were done this way. The K-Line is a bronze insert. Bronze has much better lubricant properties than iron.
If you are going to re-cut the seats it would be worth while to do a multi angle job, and back cut the intake valve. This will increase low lift flow by 5-10cfm, I saw nearly 10cfm at 5mm lift on my flow bench. didn’t make much difference at full lift, but the valve isn’t there long.
