V6 valve guides

Some of you may know that a nut fell into my intake from the air cleaner hold down and then past a valve into the cylinder and destroyed a piston on my engine. It most likely bent a valve or 2. Maybe not, haven't taken apart the head yet.

Question is, how do I remove valve guides and re install them? Do they need reaming? Can I machine the valve guides for viton or similar seals before pressing them in?

I never did anything but lap the valves when I built the motor, so I might want to replace valves and springs. Don't have a bunch of money to throw at a machine shop so of course I am looking to do it myself.

Yes I have a lathe, press etc. I also have several extra heads that are probably in similar condition or worse.

Thanks!

 

You sure you have valve guides? Typically in cast iron heads the valves ride right on the casting metal. There are no press-in guides from the factory.

You can have your head machined for rubber-teflon "Perfect Circle" valve seals. The factory style is likely an umbrella seal, which can come in rubber or hard plastic, and requires no additional machining.

When cast iron heads are reconditioned, the valve guides can be reconditioned in a few ways. The cheapest is knurling, which raises the iron in the valve guide. Then the guides are reamed to spec. Otherwise, there are several types of replacement guides. I don't know of any advantage to one design over another - each shop will have a preference. They could be bronze or cast iron, press in or screw in. Lastly, you can buy valves with oversized stems and ream the guides to the new size.

Do you have the equipment to grind the valves and seats? If not, you may as well take them to a shop and get them rebuilt. They will assess the condition of the valves and guides. Likely they will recommend knurling the guides and surfacing the head at a minimum.

 

When i was rebuilding my engine (225 V6) i had the heads rebuilt. Chances are the valve guides are worn due to normal use. The shop i used was able to install bronze liners in the existing guides. They ream the holes oversize and install the bronze guides then do a final ream after installation. I belive this is a better option than knurling the guides and will last longer. The machine shop will have to cut the OD (Outside Diameter ) of the existing valve guides for the Viton type seals. After the bronze guides are installed the valve seats and valves will need to be machined to align them and the machine shop will do this also. Mine cost around $300 if i remember correclty. They also had to machine the valve stem where the rocker arm touches to get the correct height (since the valves are not adjustable). You will probably want to have them surface ground too for a nice mating surface to your block.

Good luck!!!

 

Re knurling, it's true that a knurled guide will not last as long as an insert. Functionally I believe they are equivalent. But, if this is a hobby car, it may not matter that the knurled heads will only last another 80K or 100K miles...

 

I had all my guides knurled and passed on adding the seals.
Yes bronze guides could be superior to knurling especially if you run high rpm's.
I expect that good job of knurling should last about as long as the rest of the valve train.

 

Thanks guys. I was looking at parts prices and listed are valve guides. I didn't think they were the press in or out kind, thought they were cast integral, but I can remember wrong. I may just find a good head in my pile of engines, but they might all be garbage.