Noddle Posted October 31, 2011 Share Posted October 31, 2011 (edited) Hi, I'm wanting to press some exhaust valve guides, I need to move them about a inch so I can remove some meat in the head, so I'm wonder what is the best way to do it, at the moment I have made a tool to fit into the guide with a square step, I was planing to use a tube with a fat washer on it, to sit where the spring would be, to keep everything square to the bed of my press I assume this should work ? do I need to heat anything up, or cold pressing will be ok ? Nigel Edited October 31, 2011 by Noddle Quote Link to comment Share on other sites More sharing options...
ozconnection Posted October 31, 2011 Share Posted October 31, 2011 Looks like a P90 Nigel, did you get that off ebay? Quote Link to comment Share on other sites More sharing options...
Noddle Posted October 31, 2011 Author Share Posted October 31, 2011 (edited) Looks like a P90 Nigel, did you get that off ebay? No, not from eBay, from the US Yes, its a P90A Edited October 31, 2011 by Noddle Quote Link to comment Share on other sites More sharing options...
josh817 Posted October 31, 2011 Share Posted October 31, 2011 (edited) Well... I tried using one of those tools with some grease, oil, and a 12 ton press, and it crushed the old guides. Took it to my machine shop and instead of using a press they simply used an air hammer and got all 12 out and 12 new ones installed in about 10 minutes. I suspect like an impact tool, short bursts will ease it in rather than applying 12 tons of steady force. They used the same tool you pictured by the way. I say get yourself a cheap harbor Freight air hammer and some lube. Mind you, they didn't heat the head or anything like that. EDIT: This is exactly what they used http://www.harborfreight.com/super-duty-air-hammer-with-chisels-47868.html Edited October 31, 2011 by josh817 Quote Link to comment Share on other sites More sharing options...
inline6 Posted November 1, 2011 Share Posted November 1, 2011 I worked for a long time Nissan engine builder for one summer when I was in college. He uses an air hammer just like Josh said. No heat, no lube. I even used it once to drive some guides out and put new ones in. Is very easy. I don't think you can drive them out a bit and back in and use them though. All kinds of problems with that. Quote Link to comment Share on other sites More sharing options...
duragg Posted November 1, 2011 Share Posted November 1, 2011 (edited) All the guides I ever pushed in or out were some type of relatively soft material (Manganese Bronze). I pushed a few set in and out dry / no lube and they were all fould up. mushrooming of the soft material and poor alignment. Instead now we heat the aluminum and press out the old guide. Then the guys measure and clean the ID of the hole and adjust the guides if needed. Heat the head to 375 with the guides immersed in a bath of rubbing alcohol and dry-ice. This way the guides nearly fall right in and lock down a fraction of a second later. Vast improvement in bore quality and alignment. Got to be careful where the putter-inner tool contacts the guides. Some guides we work with have a very thin upper section where the seal rides. Pushing on there is very weak and the deform easily when beaten with a powerful device. Edited November 1, 2011 by duragg Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 2, 2011 Share Posted November 2, 2011 (edited) I'm in the same boat as Duragg...coming out (you don't 'move them an inch'---they are coming out, getting thrown away, and being replaced...) a shot of CO2'd Alky down the bore (or LN2) will shock-shrink the guides free to easily knock them out with a hammer and the tool shown (remember stock guides are iron/steel based.) The most important thing is when coming out they don't gall the head requiring oversized guides for the way back in! Going in, some more freezing, a little heat, and they go in like nobody's business. Actually the tool shown and a small hammer lightly but quickly tapping them will seat them to the limit-ring easily with little fuss. I've seen guys drive them in with Moly and a Press...but I like chilling and less force. But you aren't simply going to "move" them...once the process starts, it's all the way out and replacement time. Edited November 2, 2011 by Tony D Quote Link to comment Share on other sites More sharing options...
Noddle Posted November 2, 2011 Author Share Posted November 2, 2011 .... Going in, some more freezing, a little heat, and they go in like nobody's business. Actually the tool shown and a small hammer lightly but quickly tapping them will seat them to the limit-ring easily with little fuss. I've seen guys drive them in with Moly and a Press...but I like chilling and less force. .... So, it's the same principle as fitting liner into a diesel engine.. mmm, It maybe a little out of my expertise with the gear I have at home. What is the flow from a stock P90A head ?, I may just do a value job and leave it at that, but there is a heap of material in that exhaust port that needs to be removed. ( around the guide area ) Looks like I'll have to find a workshop shop to do some work for me... ( more money ) btw, does anyone know off hand where I can buy guides from. Nigel Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 2, 2011 Share Posted November 2, 2011 Dry Liner, without o-rings, yeah. Detroits slip in and out (same as White Superiors) without any heating or cooling. But if you have dry ice, alcohol, the proper punch/hammer you can do this. But porting doesn't mean you have to remove the guides. Just give a slight berth, and maybe slip some fuel hose tightly over the exposed portion of the guide if you are all that paranoid about nicking them and doing damage with a burr. A small piece of copper/brass/steel/stainless steel tubing may also serve the same protective function to allow burr work close to the guide without hurting it. No need to pull them if they are concentric with the valve seats already. You can do it! Quote Link to comment Share on other sites More sharing options...
Noddle Posted November 2, 2011 Author Share Posted November 2, 2011 I was wanting to to do something like this ( see picture ), It would be a lot easier to do with out the guide in there.. I have been looking into "freeze sprays", I might have a play with on of my old heads ( E31 / N42 ) But I still need to find guides to put back in. more "Googling". Tony, you may have talked me into it. but I need to practice first as I have spent a lot to get my P90 head ( postage was a killer ) Nigel Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 2, 2011 Share Posted November 2, 2011 Make sure the exterior of the guides are clean. Any carbon or fouling left on the guide when you drive it out will scratch and gall the bore,and cause you heartache. I used an air hammer to remove mine, after making sure they were very clean. Warmed the head up to about 140F, then knocked the guide out with the air hammer and punch. Make sure you go easy, any misalignment will snap one off, and almost any radius at the step in the tool will shatter the guide...cast iron is shitty in tension, and if there is a radius at the step it'll expand the guide, putting it in tension and it will start crumbling away. I have two heads that have crumbled up valve guides like this. Quote Link to comment Share on other sites More sharing options...
josh817 Posted November 3, 2011 Share Posted November 3, 2011 If you screw up the guide bore and have to oversize I believe I have 25 oversized guides. Bought them but figured it would be cheaper to get the proper size and do them the way I want (shortened...). I'd have to check how much over they are. Don't plan on using them though; do it right the first time! Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted September 30, 2016 Share Posted September 30, 2016 After reading this I'm considering replacing my stock guides with manganese bronze guides myself. I've seen them for sale on ebay but does anyone have a better source? Thanks. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 10, 2016 Share Posted October 10, 2016 They are all pretty much the same, any good CNC Shop can take a pair of stock uninstalled guides and make you a couple hundred in any dimension you desire.... Couple it with an oversize reamer and a cheap driver tool with an instruction sheet... Then you, too can offer cheap Manganese-Bronze valve guides on eBay and become the King of L-Guides! Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted October 10, 2016 Share Posted October 10, 2016 I've been trying different methods of removal on a spare head. It seems the intake guides come out fairly easily however I broke two exhaust guides. They seem to get stuck. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 12, 2016 Share Posted October 12, 2016 Try shocking them in the center with dry ice chilled alcohol. Use a silicone stopper on the non-driven end and fill the guide. It will bubble like crazy and sometimes you hear a distinct "tink" or "pop" - start driving then. Heating around the guide non-driven (top) side with an acetylene torch to expand the aluminum immediately befor e installing the stopper and chilling the interior of the guide (a plastic tirkey blaster works but gets brittle at semicryogenic temps) Quote Link to comment Share on other sites More sharing options...
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