Starfighterpilot Posted October 20, 2008 Report Share Posted October 20, 2008 I did a search but could not come up with anything that answers this question. I just bought a good used '88 T cylinder head. I have been thinking of "welding" up the jet valve hole, fairing the "weld" into the combustion chamber and eliminating the shroud during rebuilding of the head; rather than doing the JVE. Has anyone done this? Did you experience any cracking in the head after prolonged use (provided the initial welds were good)? Thanks for you answers. KEN Link to comment Share on other sites More sharing options...
Dad Posted October 21, 2008 Report Share Posted October 21, 2008 After removing the Jet valve you will need to press out the metal shroud. Biggest problem I see is you have to do it all a few steps at a time to reduce overheating the head, especially around the seats. you don't want to shrink them and have them fall out do you? I would just do a Jet valve elim and be done with it. Dad Link to comment Share on other sites More sharing options...
Indiana Posted October 21, 2008 Report Share Posted October 21, 2008 if you don't want to buy the jvek just remove the valve from the tube and weld up the end of the jet tube and reinsert it back into the shroud and leave it, the tube is steel and if you can weld save yourself the money for the jvek Link to comment Share on other sites More sharing options...
Dcrasta Posted October 22, 2008 Report Share Posted October 22, 2008 I got my JVE kit from Goodson and Co for less than 30 bucks shipped. I would think by the time you prepped, and welded, and materials and time consumed, you would end up ahead by just buying the kit and throwing the 4 bolts in.. But , If you are trying to eliminate the shroud to improve the head's flow, this solution may not be for you.. http://www.goodson.com/store/template/disp...ebaf4b82a6729b7 Link to comment Share on other sites More sharing options...
marso Posted October 24, 2008 Report Share Posted October 24, 2008 (edited) I have a T head that had the holes welded shut. Can't tell it had a JV in it by looking at the combustion chamber. The holes on top have bolts in them. I run a Marnal now but I still have the T head. Edited October 24, 2008 by marso Link to comment Share on other sites More sharing options...
Professor Posted October 25, 2008 Report Share Posted October 25, 2008 Just food for thought. I knocked out the steel plug in the head out that the jet valve screws into and duplicated it in aluminum, without the through hole. I then put the plugs in the jet valve holes from the combustion chamber side and put a bolt in from the top side. I just machined a groove in the bolt just below the head of the bolt and put an o-ring on. I then took the grinder and smoothed the plug off to match the combustion chamber. I do have pictures of it if anyone wants to see. I have 45K miles on the one head and no problems. The other head is on an engine I just rebuilt and only has 30 miles on it. . Link to comment Share on other sites More sharing options...
Tim_C. Posted October 25, 2008 Report Share Posted October 25, 2008 That sounds a bit risky to try plugging it without welding the plug in. The hot-cold, hot-cold for thousands of times can easily loosen it up to come out. Too many bad heat characteristics to trust that method. Maybe if perfectly machined with aluminum that expands and contracts the same, etc..., and it could work like yours has so far. However, what if the engine gets hot and comes close to overheating, etc... Maybe doing the plug thing like that, and tacking it in too? Instead of doing a big weld that heats it up to cracking. It is very hard to properly weld these heads without cracking. It must be heated to 230 degrees F or so, before welding on it. You really need to be a pro to weld it. I've seen a pro chase a crack so much it ruined the head. Link to comment Share on other sites More sharing options...
Indiana Posted October 25, 2008 Report Share Posted October 25, 2008 steel and aluminum do not make for good friends when put together, hard to say what will eventually happen maybe nothing, maybe they will crack and fall to pieces Link to comment Share on other sites More sharing options...
Professor Posted October 26, 2008 Report Share Posted October 26, 2008 Perhaps you didn't understand what I tried to explain. I turned the plugs out of 6061-T6 aluminum. They are held in the same as the steel plug the jet valve screws into. I used a grade 8 bolt screwed in the same hole as the jet valve with lock tight. It is NOT comming out. The JVE kits are steel bolts screwed into the steel plugs or the steel jet valves screwed into the steel plugs which is possibly contributing to the cracks between the valves, because of the different expansion rates. I really don't care if anyone else tries this or not. I started my first post on this subject as "Food for Thought". I just wanted people to think about other options. I have the only two Conquests in the world with this mod and they work. Link to comment Share on other sites More sharing options...
Tim_C. Posted October 26, 2008 Report Share Posted October 26, 2008 Perhaps you didn't understand what I tried to explain. I turned the plugs out of 6061-T6 aluminum. They are held in the same as the steel plug the jet valve screws into. I used a grade 8 bolt screwed in the same hole as the jet valve with lock tight. It is NOT comming out. The JVE kits are steel bolts screwed into the steel plugs or the steel jet valves screwed into the steel plugs which is possibly contributing to the cracks between the valves, because of the different expansion rates. I really don't care if anyone else tries this or not. I started my first post on this subject as "Food for Thought". I just wanted people to think about other options. I have the only two Conquests in the world with this mod and they work. Please be a bit less defensive. My response was just food for thought about your post, no offense meant. I understood you used the aluminum. All aluminum doesn't expand the same. 6061-T6 is different than the cast. It might be fine to do it that way, but I don't trust just grinding the plug to match the chamber without a weld to ensure it won't come out. I don't think any shop could do it that way and stand behind it. However, your theory and subsequent experiment sounds great! I'd have to think they will not come out either because aluminum galls together to bind like no other metal, and pressing the correct sized plug into the hole, and grinding it will surely create that galling adhesion effect. I just wouldn't bet my $5,000+ performance long block on it. Maybe my stock bare bones rebuild block would be a better choice to try that method on. Link to comment Share on other sites More sharing options...
slowquest Posted October 27, 2008 Report Share Posted October 27, 2008 this is a welded head off of a car I picked up. I chased this problem for a month..... http://www.26liter.us/gallery/albums/userpics/10108/car_pics_008.jpg http://www.26liter.us/gallery/albums/userpics/10108/car_pics_007.jpg Link to comment Share on other sites More sharing options...
Recommended Posts