Valve Guide Bosses

[JDMfantasy]

Some engines simply have casting that extends down into the airway (port) which you can grind down fairly easily. In our engines, the steel sleeve extends down into the port almost a half inch....

....can these valve guides be removed? I would like to take them out and cut them down flush with the port wall. Is this possible?? Are the sleeves just pressed in?? Anyone with info jump right in...

 

[Zuffen]

My heads are being ported at the moment and the guides will not be ground flush.

The guides will be tidied up by tapering them toward the end.

The attached grainy photo shows a ported head and the guides are still there.

According the the Toyota repair manuals the guide is a press fit but it would probably cost more to replace 16 guides than purchase a good used head, if not a whole engine.

 

[SCV8]

My four cylinder Corolla engine has that pretty bad, ground them down a bunch, helped a lot. I had also stream-lined the guides as well.
If I ever had a chance to remove the heads on the V8, I would start by doing the same, without removal if the stem to guide fit was still decent.

 

[cribbj]

The guides do press out; the seats have to be cut out. Here's a shot of one of my heads minus guides & seats getting prepped for new SiBr guides and tool steel seats (I'll be running LPG). Rod's right, it's not cheap; the guides were $500 and the seats are around $350.

Having a 32 valve engine can get expensive at rebuild time (this was an eBay SC400 motor that cost me $400, plus $300 to ship.)

John

 

[MikeMan]

John

Have you specced those heads for over size valves?

If not do you mind measuring the heads valve center to center and the meat between the seat edges?

 

[JDMfantasy]

I can get you a presice measurement tomorrow, but there is plenty of room for oversized valves...I want to say at least 5-7mm of clearance. We will be using +2mm (2jz +1mm valves) in our motor.

 

[cribbj]

MikeMan, sorry for the lateness in the reply. To answer your question, no I'm not going with oversize valves as my HP goals shouldn't require them. Also, my builder just replied with "some" of the info you requested:

"The intake valve center to center measurement is: 1.540 the head diameter is 1.320, the exhaust center to center is 1.500 the head diameter is 1.105."

I've asked him again to get the "meat" measurement you requested. You can infer some of what you want from the C/C and diameter measurements above, but we don't know the thickness/width of the seats. Better to get an actual measurement......

John

 

[MikeMan]

MikeMan, sorry for the lateness in the reply. To answer your question, no I'm not going with oversize valves as my HP goals shouldn't require them. Also, my builder just replied with "some" of the info you requested:

"The intake valve center to center measurement is: 1.540 the head diameter is 1.320, the exhaust center to center is 1.500 the head diameter is 1.105."

I've asked him again to get the "meat" measurement you requested. You can infer some of what you want from the C/C and diameter measurements above, but we don't know the thickness/width of the seats. Better to get an actual measurement......

John

John

Thanks for that information.

It will help a lot.

 

[Lextreme II]

Here is some information on the 3uzfe valve guide.

 

[mycarhasposessedme]

I narrowed down the guides on my heads when I did them, with a die grinder as part of the porting process.
The only problem I have encountered with this practise over the years is, if it is left too thin at the top it can get hot and fold in on the valve stem (not good).
Pics below.

 

[rarson]

It looks to me from that head picture that the limiting factor for valve sizing is going to be the gap between the valve and the spark plug. It doesn't look like there's a whole lot of room there... of course, with a 1mm oversize valve, you're only getting .5mm closer to the plug... Should be able to get at least a mm or two extra in there.

 

[rarson]

Just to clarify, I was talking about cribbj's head picture.

mycarhasposessedme, is that a 1UZ head?

 

[mycarhasposessedme]

Yes rarson it is, 1st gen.
Slightly modified.

 

[slyalfa]

oversize valves and too close to spark plug can be bad..
this is what happened on my alfa with oversized valves.
I have to index them or use a non 'J' type plug like the bosh +4