Jump to content
The mkiv Supra Owners Club

Valve guide oil clearances


GTR RGT
 Share

Recommended Posts

Hi,

 

Does anyone know what the oil clearances are meant to be for Ferrea valves and guides on a 2jz-gte head?

 

Upon checking mine, I believe they should be stock clearances but mine are right on the limit. I think my machine shop may have reamed these guides and they are meant to be drop in's - that's my theory anyway.

I need to make sure i am correct before I start making them buy me new.

 

Or, does anyone know if there tuner normally reams their guides once they've been pressed in?

 

Many thanks

Edited by GTR RGT
Can't spell apparently (see edit history)
Link to comment
Share on other sites

NEVER fit new guides if at all avaoidable. the hole in the guide will not be concentric to the OD of the guide, so if you fit a new one the valve seats will need a ridiculous amount of cutting to get them concentric to the centre of the new guides. I ALWAYS liner the original guides with a phosphor bronze liner, reamed to suit. Photo shows original guides in a Skyline head, not lack of concentricity between hole in guide and OD of guide as they are drilled by a machine with the guides in the head... Toyota do the same.

concentricity.jpg

Link to comment
Share on other sites

Perfectly normal for modern heads and their manufacturing methods. The seats and guide are cut and drilled as one, concentricity of guide bore to seat is ensured, concentricity of guide bore to guide OD is random. You drop a new (concentric ID to OD) guide in and you can see how far out of concentricity the valve head will be to the valve seat, and how deeply pocketed it will be to restore concentricity, which is terrible for flow and may bring the tip height out of range of normal shims. (You reading this Stu...... :))

Edited by Chris Wilson (see edit history)
Link to comment
Share on other sites

That's what i don't understand, if the hole for the guide to press into is machined at

the same time as the seats how can the stem bore in the center of the guide be out of center

 

I'd expect it to look like this head

DSC_0092.jpg

Link to comment
Share on other sites

http://speedtalk.com/forum/viewtopic.php?f=1&t=34583 MotionMachine post a some way down:

 

[h=3]Re: Installing valve guides in aluminum heads[/h] http://speedtalk.com/forum/styles/prosilver/imageset/icon_post_target.gifby MotionMachine » Wed Feb 13, 2013 12:19 pm

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.

Link to comment
Share on other sites

You was right Chris, I had mentioned this to another well known machinist and had them check my local machinists work. There was problems everywhere.

 

From now on, I will sleeve and hone the original guides.

 

For future search reference, for anyone in Essex - do not use elmsliegh in benfleet manor trading estate for any head work. Block work is ok because the bottom end work in taken care of by a different guy who is great.

 

I owe you a drink Chris :D

Link to comment
Share on other sites

No worries, I have seen perfectly good heads made effectively into boat anchors through this, by the time you get a concentric seat again the valve's about an eighth of an inch down into the port! Who told you I drink..... ;) (Plus you turn a cast iron, wear prone guide into a nice phosphor bronze one with no gotchas by linering). If only I was as good with IT stuff I'd be dangerous

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.