Hot Rods How Difficult & Expensive to Replace Valve Guides at Home? Do a Valve Job?

Ordered them both! Thanks!!!

 

Time for some light reading!

 

Neway cutters have arrived, too!

 

Ok, I have one head that may be junk. Waiting to see if if will p*** a pressure test.

Thanks again

 

Made some progress today.

To review the bidding, my valve guides were at .3885" or so, depending on the guide. On some of the valves, the guide to valve stem clearance was as tight as .0005", and several exhaust valves were galled. I could have polished the galling out of the stems, but I ordered new exhaust valves instead. Tough to find with .015" oversize stems, but I found some.

So, in a perfect world, I'd get to .3895" or so on the intake (.0025" clearance) and about .3900" on the exhaust (.0030" clearance).

I got the exhaust valve guides on one head to .3900" today using a K-Line piloted reamer and some cutting fluid. Easy-peasy, since it only needed to enlarge the guide by .0015". That'll give me .003" clearance on the exhaust. Afterwards, I used the flex hone - one stroke down and up using some honing oil - to get rid of any burrs and to leave a crosshatch pattern in the guide.

I also hit each of the intake valve guides with two strokes with the flex hone. However, in reviewing my data, I'm seeing that the clearance on three of the intake valve guides was .0005". None of the intake valves were galled, but that's too damn tight in my opinion. From the factory, they're set up at about .0021" and the max allowable is .0055". I'm inclined to open up the intakes to .3900" with the piloted reamer as well, giving me .003" clearance on the intake, which would be the same as the exhaust. Only other option would be to polish the valve stems a bit and hit the guides with a few more p***es of the hone.

From there, I put the Neway cutters to work. Took a bit of getting used to, but when I was done, I had a three angle on all the seats, all the Prussian blue was gone, and the seat width was within spec - .065" - .095".

I still need to lap the valves, but my new exhaust valves haven't arrived yet, and my intake valves need to either be replaced or ground and I don't have a valve grinder. I'll either ask the machine shop to take care of these or order a new set unless I find a good deal on a valve grinder locally.

 

Is that a "good" head? I haven't used the cutters before, only stone grinding. When I do the seats I have all my valves ready to go first and mark them to keep track to each cylinder. Then I machine the seat to match the valve so that the seat contact is in the center of the valve face. I think there is some performance gains by moving the contact area to the edge of the valve face, but most of my stuff is regular equipment. Not sure how the cutters work that guarantees the seat will match the valve face, e****ially if you have old valves refaced causing the valve to become smaller.

 

Yes, it's a good head. The valves are going back in the same holes that they came out of unless I source new ones. I don't think there's any guarantee that the seat will match the valve face; the cutter just gets the angle right.

EDIT - in reading one of the books that was recommended above (yes, after the fact), I realize I should have checked valve contact on the seat with some Prussian blue after I made the 15 and 60 degree cuts.

Thanks

 

Probably not the best idea I ever did, but on a recent set of heads that had been apart for years, I cleaned up the valves in a drill press to get rid of carbon and rust. Then I spun them and used a small hand stone to dress the seats. It wasn't that hard to get the right angle, the valves were much harder than the stone. I lapped each one in the head and checked for leaks. Heads are still working good with no issues.

 

I went ahead and ordered new valves; not terribly expensive for OEM stuff.

 

I'm looking for some sort of attachment so I can better use the valve guide reamer with a hand drill. You can use it directly in the hand drill chuck, but I have seen some sort of swivel attachment that should help keep reamer straight if you're not 100% lined up. Anyone know what this is called? Tried to find it myself, but my Google-fu must be weak today.

 

Mocked up some new exhaust valves today in freshly cut seats - how does this look? Looks like I have full contact on the seat, unless I put the Prussian Blue on too thick.

 

Your contact looks pretty good. Is the width to specs? One trick I use is I cut my seat angle then take a permanent marker and and color it. Then when I cut the top and bottom angle the seat angle will stand out and it’s a little easier to measure. Also I always lap the valve to seat. This will help check for proper seating and make the seal even better.
Also regarding your question on the reamer drive I use a speed reducer that has a handle. I was going to bring it up when the guid liner conversation was goin on as it take a bit of torque to make the oversized cut to bore out for the liner. Also reaming the aluminum bronze gets tuff. The unit I have is a Babco 821. It’s a 5:1 reduction. I thought for sure Goodson would offer something but it doesn’t seem so.

 

The width of all the seats are to spec - IIRC, it's .065" - .095" and they're all well within that range. Good tip on the permanent marker; can be a bit tough to get the measurement when it's difficult to see the edges.

I'll definitely be lapping all the valves.

On the reamer driver, the reamer has a square end like a regular tap, so I'm guessing it's designed for a tap handle. I'm only reaming out .001" or so to get the guides to the right size, so it should be fairly easy to do by hand.

Thanks for the input,

Scott

 

Sorry that I didn’t clarify better. The gear reduction setup has a .250 square drive that is purpose built to drive the reamers. It also has a bit of slop built in to compensate for not having it perfectly inline with your drill. I have another setup that is on a right angle which also makes it easy to get a feel for the ream as it is goin down through the guid. Also I’d like to give you some kudos for wanting to do this yourself and not just take it to a professional as was recommended. It’s pretty much how I got my start.

 

Ahhh, now I understand. What I'm looking for is something along those lines with "slop built in to compensate for not having it perfectly inline with the drill." Anyway, I found some of the Babco 821's on eBay. Will have to pick one up.

As for doing stuff myself, I spent 3 hours in the garage today with a crankshaft, a shoestring, strips of 600/1000/1500 grit sandpaper, and some metal polish.

Thanks!

Scott