How to change Valve guides In a 4G63T head

[BogusSVO]

How to Change Valve Guides In a 4G63 Cylinder Head


The first thing is to remove the valves, springs, retainers and locks.



The guides are cracked from the bent valves…
(Sorry about the pic,)



The tools needed for this is an air hammer, a regular hammer, venire calipers, and the proper sized guide driver.
Also the replacement valve guides are shown.



Have the head with the deck side up.
With the guide driver in the air hammer, knock out the broken guides.
Take care on not letting the driver get into the head casting.



Once all the guides are removed, flip the head over. Spray lube/oil in the guide bore (not shown), also lube up the replacement guide. Lightly tap the new guide to start it.



Once the guides are started, use the air hammer to get them “close” to where they should be.
I would not recommend trying to hand drive the guide fully into place, damage may occur to the tool, the guide, and/or the head casting.



Once the guides are close, finish set the guides to the proper height. By measuring from the top of the guide to the valve spring pad using the venire calipers.



Once all the guides are set to proper height, The head will move on to the next part of the repair, Having the seats cut, so the valve seat will be index to the center line of the guide.

[Delta Cam]

ohh ohh I see a mazda cam in the back ground ! strike 1 lol

[dave99gst]

You told us to set the guides to the proper height but didn't bother to tell us what the proper height is ?

[gofer]

I assumed that when you removed the valve guides from the head you heated it up first. Then before putting in the new valve guides you freeze them so they contract and keep the head heated so it expands, making it easier to press the new ones in.

Is this true?

Originally Posted by dave99gst

You told us to set the guides to the proper height but didn't bother to tell us what the proper height is ?

Don't quote me on this but I think its 19.5mm between the top of the valve guide to the valve spring pad.

[RvlutionMtrsprt]

19.2-19.8mm is what the service manual calls for.

As for heating the head up, I've been told that's a good way to warp the head. A pretty smart machinist told me his secret to doing guides was to freeze them before tapping them out (c02/liquid nitrogen) and also freezing the new ones before they go in.

[silicosys4]

I have this question going in another thread, but I think this might be a more appropriate place for this. Right now I'm looking to have all new bronze intake, copper exhaust guides put in a 1g head I'm building.
My problem is, the machine shop I'd like to go with is telling me that if I don't go with oversized valves after installing the new guides, my valves will be misaligned, won't seat properly, and/or will be "sunk" into the seats. This is apparently due to unavoidable misalignment between the new guides and the original seats. Apparently this can only be solved by going with oversized valves, and milling new seats in the head to match the valves and guides. So anyone on here, what kind of issues have you had with Stainless Steel standard size valves with bronze guides?

[gixrman]

I just had my head done and it was $80 to replace the guides and $240 to recut the seats and valves and the seats were replaced. I also had the head decked which was an additional $60. I was told and believe that when vavles wear into the seats and you replace the guides it will mis-align the valve to seat contact surface and this is the reason to have the valves reseated. The reason to upsize the valves sound scetchy.
This was also for a standard 3 angle valve job.

I appuade the OP for the DIY but this was the least expensive job on my head rebuild and seems like the one of the easiest ways to FUBAR the head.

[arrowhead]

YES, YES, to alot of stated before

This is called concentricity when you have to put in new guides, freezing or not or driving them in it depends on the machinist preference, both work.

the problem arises then with the seats being concentric with the new guides.

More than likely the original seats will be in bad shape, from the abuse,or plain worn out, pitted or cracked.

Why not just replace them,since new valves are going in anyways, then take this opportunity and spend a little bit more money, and go to next size valve.

Many a times I have heard, I just had a valve job done and it is running shitty.

It is blamed on the machine shop when the real couse


is the customer was advised
of this and said do the best you can with what I have I can not afford it.

Valve jobs are not cheap on any 16v heads.
I have turned away many customers becouse they wanted cheap valve jobs.

DO it right do it once.
Go to cedar rapids web or kwik way for more info.

[9!'clipseDOHC]

Shouldn't this be a tech article?

[BogusSVO]

gixrman.... I have installed several sets of oversized valves on the factory seats, after installing new guides, it is not a sketchy thing to do, as long it is done properly.

you can do new guides and factory seats as long as you adjust the rest of the valvetrain accordingly. IE Valve tip height and spring installed height

Also you are correct, if the old guide removel goes wrong, you can junk a head quick. I learned that on a 4G head back in 1992/1993, I knocked the guides out the wrong way and tore up the guide bores in the head.

@arrowhead....

you bring up alot of valid points....

Originally Posted by arrowhead

YES, YES, to alot of stated before

This is called concentricity when you have to put in new guides, freezing or not or driving them in it depends on the machinist preference, both work.

the problem arises then with the seats being concentric with the new guides.

More than likely the original seats will be in bad shape, from the abuse,or plain worn out, pitted or cracked.

Why not just replace them,since new valves are going in anyways, then take this opportunity and spend a little bit more money, and go to next size valve.

Many a times I have heard, I just had a valve job done and it is running shitty.

It is blamed on the machine shop when the real couse
is the customer was advised
of this and said do the best you can with what I have I can not afford it.

The valve guide MUST be index to the valve seat, just not the insert, that is why the valve seat is cut after the new guide is installed.

The cost of having new seats installed can get costly quick, around my part of the country, to R&R a valve seat will cost between $7-$10 per seat in labor, and then about another $6 for the seat insert.

The 4G63 head has a sinterd metal or Powder Metal seat insert, and are rather hard, and a true PITA to cut/grind with older equipment (valve seat stones such a a Souix or B&D or the neway cutter) with these hard seats the valve takes the wear more than the seat.

Some shops still in operation have equipment still in use from the 1950s, 1960s, and the 1970s.. this equipment is too out of date to work on modern alum heads and the seat inserts they have. They will still work just fine on older cas iron heads like small bocks and such.

Another reason he have heard "I just had a valve job done and it is running shitty" is beacuse the machinist did not check the specs, or perform a simple vacuume teast to check for valve to seat seal.

A properly spec head that is rebuilt will be good as factory or even better. The installer will know with in 5 mins of fire up after the install if the head is done properly.

Originally Posted by 9!'clipseDOHC

Shouldn't this be a tech article?

It probly should be, I was a noob to the board when I first wrote this, plus it is not in the proper format for a tech article, nor are the pics used saved at DSMTuners.

I tend to post these on a few diffrent sites.

If you go here, and check posts # 10 and #17 you will find more links to machine shop write ups I have done.

http://www.dsmtuners.com/forums/repu...-bogussvo.html

[arrowhead]

Exactly what I stated, but I have never really seen any gains from larger valves on a stock seat on the contrary on a flowmaster I have seen the opposite, think about it and you will see it makes sense, the largest restriction to cylinder fill is the valve and if you place a larger valve on a non proper seat you will get reversion we even smooth and round the edges of the valve faces to have a better drop of the mixture into the cylinder.

This has been my experience. Please do not take this as an argument only that
less experience guys will benefit from this info.


Thanks
arrowhead

[BogusSVO]

Arrowhead, I understand what you are saying. I have seen a good amount of OS valve installed improperly.

Some shops are lazy, or do not want to spend the time to do it right.

The big thing I see is that they do not do a throat cut and open that up, so that becomes the "choke point" and will flow no more than a stock valve.

The other over looked point is valve unshrouding in the combustion chamber, and that will case the reversion, from the air flow coming off the back of the valve and bouncing back of the CC wall

When you talke about smothing the valve face, do you mean back cutting the valve? Or polising the valve margin?

Why to have your Valves back cut

[arrowhead]

Originally Posted by BogusSVO

Arrowhead, I understand what you are saying. I have seen a good amount of OS valve installed improperly.

Some shops are lazy, or do not want to semd the time to do it right.

The big thing I see is that they do not do a throat cut and open that up, so that becomes the "choke point" and will flow no more than a stock valve.

The other over looked point is valve unshrouding in the combustion chamber, and that will case the reversion, from the air flow coming off the back of the valve and bouncing back of the CC wall

When you talke about smothing the valve face, do you mean back cutting the valve? Or polising the valve margin?

Why to have your Valves back cut

OK I think I understand your question if not please let me know.

I do smooth the valve face to get as smooth finish as i can, I do the same to the valve stem up to the guides mark there I just polish very lightly not to upset
my clearances.

I do very light polish on my transition steps but not on my seat angle.

I like to do 44 degree cut on the valve and 45 on the seat, interference angles,
The valve face edge is the one that I try to sore of smooth out.I think I am running out of space. PLUS doing all you mentioned before your question.
Look at all the research by all oem to try disk or flappers or valve opening by selenoids to eliminate that big blockage.I can go further with more but I am at the bottom of the page, I am not very good at this . If this clarifies your question
Please let me know if not I will try some more.
thank you
arrowhead