Installing valve guides in aluminum heads

[dhidaka]

I am forever having difficulty getting concentric valve seats after installing replacable valve guides in aluminum heads. When seats are not concentric I have to grind deeper than should be necessary to get a good valve seat. How are you guys installing replacable valve guides in aluminum heads? Is there a more "efficient" way than heating the head (200 degrees) and using a conventional guide driver?

[ProPower engines]

NO
Depending on the guide ID I just go to a +.002-.003 larger stem diameter.
There is hardly a generic bronze replacement valve guide that is concentric.

PPPC in north Carolina does have the best made guides as far as accuracy from ID to OD goes but you have a bit of a wait.
It not like calling a jobber store or parts warehouse and getting the sealed power guides off the shelf
The PEP guides are the same way off center.
The larger stem helps to keep the same center line and just ream close and hone to finished size. This is a really big help if using Ti valves that are getting replaced anyway.

[user-3597028]

I machine the top of the guide off flush if it is a stepped guide. A piloted 3-4 flute cutter works well. Then, I warm the head and push them out from the spring side to the port side. I do this in case the guide is out of shape on the port side.
Pushing it out back through the port may gaul up the guide bore and cause the new guide to be out of round with the seat. This is extremely important with Harley heads.

I have been using SBI replacement guides and they are excellent. They make them for many popular heads with the .562" seal boss on top. Many times I just buy universal ones and machine them to fit. I double check them for runout using a pilot held in a vice and a dial indicator. Slide the guide on and spin it with the indicator on the OD of the guide.

Another tip; If the guide has an extended part into the port, machine the press fit off of this area. This reduces the amount of surface contact to just the press fit part of the guide. The head will last longer without wearing the guide bore from installation. The turned-down area will act as a lead-in pilot for installing. I chuck the guides in a collet in the mill quill and turn them down against a bit held in the vice. Use the power down feed for a nice finish. This is way faster than a lathe and more accurate.

[GOSFAST]

I'm assuming you have some type of head machine, if not I would farm the job out!

If you take the time and have the "correct" tooling you can get the guides out almost "by-hand" and you will not "hurt"
the original holes, you will also be able to install the new "pressed" guides in (almost) "by-hand" also! As I stated
above, it should be done on a head machine!

Here's our procedure: (this info is based on a "standard" bronze .502"/.343" guide with a .530" top for the seals)
(The tools needed are a 3/8-16" tap, a 15/32" core drill, a 15/32" conventional drill, the 1/2" (piloted) reamer used for
reaming new guide holes, a guide driver that fits through the 15/32" hole, a hammer (or an air-tool), and (8) 3/8"-16
bolts 1/2" long.

1-Tap the top (seal-side) with a 3/8"-16 tap deep enough to get the 1/2" long bolt in place.

2-Leave the bolts in position, core-drill most of the guide from the bottoms till the drill-tip (pilot end) hits the bolt.

3-Using the conventional 15/32" drill bit, drill down again till the drill hits the bolt.

4-At this point MOST of the guide is "gone" and you have not disturbed the original hole, most of the press-fit is now
also gone.

5-Using the guide-driver (through the guide "shell") against the bolt, you simply drive the remaining "shell" out, either
by hand-held hammer or with an air hammer.They WILL come out with very little effort!

6-Using the 1/2" guide-reamer BY HAND, turn it through the guide holes. All this does is "clean-up" the existing holes.

For the install we place the new guides in a small "cooler" with "dry-ice" for a about an hour. We heat the head in a
"barbeque" for about 1/2 hour (near 300*). The "temp" here isn't a critical number.

Using gloves we now lay the head on the bench, take the (ice-cold) guides one at a time, dip the tip in some oil, and
push into the head. They will go in at least half-way by hand, finish them with a driver. Here, the hand-held hammer and
correct installation driver will do. This won't the be the same driver used for the initial removal.

This procedure will maintain the seat/guide alignment accurately, assuming all was good/concentric in the beginning?
I've finished these on occasion and have been able to "quick-check" the concentricity by "lapping" the valves.

The "prepping", heating of the head and freezing the guides, is important. This sounds like a really time-consuming
deal but it goes fairly quick, just takes some good tooling. The drilling of the bronze (material) guides takes the longest.

(Add) I've never tried using a conventional freezer for the guides, we have easy access to "dry-ice" here.

Thanks, Gary in N.Y.

P.S. We normally use either Ferrea or Brodix for the guides, both are top quality so far!

Double P.S. WE NEVER "HAMMER" ON ANY GUIDES DURING REMOVAL WITH ALUMINUM HEADS/BRONZE GUIDES
WITHOUT PREPPING THE ORIGINAL (worn-out) GUIDES FIRST AND WE NEVER "JUST HAMMER THE NEW ONES IN".

[MotionMachine]

It doesn't sound to me like your issue is with installing the guides, you're concern is valve seats not lining up with the guides after new ones are installed? Are these just stock type heads, import or domestic? If so, join the club. The guide od's are not concentric with the id's from new on a lot of heads because of the production methods. I first noticed it with Mitsubishis and Hondas way back (and Yamaha's and Kawasaki's), what a nightmare. That's why I went to liners, no change of the seat/guide alignment. I found a video on Youtube a while back that showed some import head being manufactured and it backed up my suspicion. The head was on a 4th axis and laid over horizontally when a spindle came in from the side with the all in one guide boring/reaming/seat cutting tool. Works great until you come along 100K miles later and change that guide to one that is concentric od to id and introduce seat alignment issues. This is just my personal conspiracy theory, I'm open to other explanations.

[jsgarage]

FWIW, my low-tech method for guide removal involves a pilot that fits the guide's valve bore & top (at the valve end), 150-200F of oven heat and an air hammer set on medium pressure. Using a hydraulic press with a hot head and polyangle valves is just too much trouble setting up. There's really no guarantee the old (or new) guide's bore is concentric as received, either.
Note- guides with the ends thinned for PC seals will crack if brutalized with too high air pressure in the gun, but do not normally tear up their bores coming out of a hot head. One time I got fooled by a Ducati head- their guides are retained by wire rings at the valve side and the cleaning didn't remove all the crud so I missed seeing them. But when the first guide didn't move with my usual air hammer setting, a closer look spotted the retainer before any damage occurred.

[BrazilianZ28Camaro]

I'm assuming you have some type of head machine, if not I would farm the job out!

If you take the time and have the "correct" tooling you can get the guides out almost "by-hand" and you will not "hurt"
the original holes, you will also be able to install the new "pressed" guides in (almost) "by-hand" also! As I stated
above, it should be done on a head machine!

Here's our procedure: (this info is based on a "standard" bronze .502"/.343" guide with a .530" top for the seals)
(The tools needed are a 3/8-16" tap, a 15/32" core drill, a 15/32" conventional drill, the 1/2" (piloted) reamer used for
reaming new guide holes, a guide driver that fits through the 15/32" hole, a hammer (or an air-tool), and (8) 3/8"-16
bolts 1/2" long.

1-Tap the top (seal-side) with a 3/8"-16 tap deep enough to get the 1/2" long bolt in place.

2-Leave the bolts in position, core-drill most of the guide from the bottoms till the drill-tip (pilot end) hits the bolt.

3-Using the conventional 15/32" drill bit, drill down again till the drill hits the bolt.

4-At this point MOST of the guide is "gone" and you have not disturbed the original hole, most of the press-fit is now
also gone.

5-Using the guide-driver (through the guide "shell") against the bolt, you simply drive the remaining "shell" out, either
by hand-held hammer or with an air hammer.They WILL come out with very little effort!

6-Using the 1/2" guide-reamer BY HAND, turn it through the guide holes. All this does is "clean-up" the existing holes.

For the install we place the new guides in a small "cooler" with "dry-ice" for a about an hour. We heat the head in a
"barbeque" for about 1/2 hour (near 300*). The "temp" here isn't a critical number.

Using gloves we now lay the head on the bench, take the (ice-cold) guides one at a time, dip the tip in some oil, and
push into the head. They will go in at least half-way by hand, finish them with a driver. Here, the hand-held hammer and
correct installation driver will do. This won't the be the same driver used for the initial removal.

This procedure will maintain the seat/guide alignment accurately, assuming all was good/concentric in the beginning?
I've finished these on occasion and have been able to "quick-check" the concentricity by "lapping" the valves.

The "prepping", heating of the head and freezing the guides, is important. This sounds like a really time-consuming
deal but it goes fairly quick, just takes some good tooling. The drilling of the bronze (material) guides takes the longest.

(Add) I've never tried using a conventional freezer for the guides, we have easy access to "dry-ice" here.

Thanks, Gary in N.Y.

P.S. We normally use either Ferrea or Brodix for the guides, both are top quality so far!

Double P.S. WE NEVER "HAMMER" ON ANY GUIDES DURING REMOVAL WITH ALUMINUM HEADS/BRONZE GUIDES
WITHOUT PREPPING THE ORIGINAL (worn-out) GUIDES FIRST AND WE NEVER "JUST HAMMER THE NEW ONES IN".

Very nice tips, this is the best way I ever seen to remove guides. Thanks for share it.

[Gary terhaar]

I'm assuming you have some type of head machine, if not I would farm the job out!

If you take the time and have the "correct" tooling you can get the guides out almost "by-hand" and you will not "hurt"
the original holes, you will also be able to install the new "pressed" guides in (almost) "by-hand" also! As I stated
above, it should be done on a head machine!

Here's our procedure: (this info is based on a "standard" bronze .502"/.343" guide with a .530" top for the seals)
(The tools needed are a 3/8-16" tap, a 15/32" core drill, a 15/32" conventional drill, the 1/2" (piloted) reamer used for
reaming new guide holes, a guide driver that fits through the 15/32" hole, a hammer (or an air-tool), and (8) 3/8"-16
bolts 1/2" long.

1-Tap the top (seal-side) with a 3/8"-16 tap deep enough to get the 1/2" long bolt in place.

2-Leave the bolts in position, core-drill most of the guide from the bottoms till the drill-tip (pilot end) hits the bolt.

3-Using the conventional 15/32" drill bit, drill down again till the drill hits the bolt.

4-At this point MOST of the guide is "gone" and you have not disturbed the original hole, most of the press-fit is now
also gone.

5-Using the guide-driver (through the guide "shell") against the bolt, you simply drive the remaining "shell" out, either
by hand-held hammer or with an air hammer.They WILL come out with very little effort!

6-Using the 1/2" guide-reamer BY HAND, turn it through the guide holes. All this does is "clean-up" the existing holes.

For the install we place the new guides in a small "cooler" with "dry-ice" for a about an hour. We heat the head in a
"barbeque" for about 1/2 hour (near 300*). The "temp" here isn't a critical number.

Using gloves we now lay the head on the bench, take the (ice-cold) guides one at a time, dip the tip in some oil, and
push into the head. They will go in at least half-way by hand, finish them with a driver. Here, the hand-held hammer and
correct installation driver will do. This won't the be the same driver used for the initial removal.

This procedure will maintain the seat/guide alignment accurately, assuming all was good/concentric in the beginning?
I've finished these on occasion and have been able to "quick-check" the concentricity by "lapping" the valves.

The "prepping", heating of the head and freezing the guides, is important. This sounds like a really time-consuming
deal but it goes fairly quick, just takes some good tooling. The drilling of the bronze (material) guides takes the longest.

(Add) I've never tried using a conventional freezer for the guides, we have easy access to "dry-ice" here.

Thanks, Gary in N.Y.

P.S. We normally use either Ferrea or Brodix for the guides, both are top quality so far!

Double P.S. WE NEVER "HAMMER" ON ANY GUIDES DURING REMOVAL WITH ALUMINUM HEADS/BRONZE GUIDES
WITHOUT PREPPING THE ORIGINAL (worn-out) GUIDES FIRST AND WE NEVER "JUST HAMMER THE NEW ONES IN".

A bit entailed but effective I guess. Aluminum changes heat treat at 300 degrees,if you hit a head that is heat treated it rings,one that's not it has a dull thud and is soft as peanut butter.when you drill it the chip will tell as we'll.
My concern would be a head with lost heat treat when done the interfearance on the seat are effected. When I weld a head I try to keep the head no hotter than 250. The welded area is obviously hotter but it was junk until I struck a arc.

[GOSFAST]

This is "far & away" the safest way to get the guides done on this platform, been doing it this way for "eons", or so it seems anyway!

Thanks, Gary in N.Y.

P.S. That "near 300*" number is direct from Brodix some years ago! We actually aim closer to 270*, but "tech" assured us 300* was no issue. Brodix aside, personally I would have trouble believing that 300* is going to sacrifice the integrity of the casting??

[Gary terhaar]

This is "far & away" the safest way to get the guides done on this platform, been doing it this way for "eons", or so it seems anyway!

Thanks, Gary in N.Y.

P.S. That "near 300*" number is direct from Brodix some years ago! We actually aim closer to 270*, but "tech" assured us 300* was no issue. Brodix aside, personally I would have trouble believing that 300* is going to sacrifice the integrity of the casting??

You may have trouble but when you use a heat treating oven to bring aluminum to a t6 heat treat you start at 300 and time it as it goes up in temp and slow time the cool.
Is this a educated guess or have you Rockwell tested the part after your cheeseburger achieved med rare.

[bmcdaniel]

Doesn't a head get hotter than 300* during normal operation?

[jdperform]

On some heads the seat counterbore and the guide bore are not very concentric to each other. Certain brands of heads are better than others in this regard.

[machine shop tom]

I quit replacing guides in aluminum heads unless they are damaged. I reline them. That way there is no problem with concentricity. If the guide is damaged, I push them out out and push in a new one, then use the guide and seat machine to bore the new guide for a liner, centering the reamer with a seat centering piece. That aligns the bore concentric to the seat.

tom