warrior Posted March 14, 2011 Share Posted March 14, 2011 Hi All Just about to replace the head on my jimmy, can any of you guys tell me the correct head bolt torque and the cold tappet clearance??? Cheers all. :laugh: Quote Link to comment Share on other sites More sharing options...
Lewis Garner Posted March 14, 2011 Share Posted March 14, 2011 I believe it's 72 ft lb for the head bolts Quote Link to comment Share on other sites More sharing options...
Degsy Posted March 14, 2011 Share Posted March 14, 2011 When you dismantle the engine you will find a pipe leading from the oil filler or the rocker box to the inlet manifold just below the carb. This line has a valve fitting in it which needs to be dismantled and cleaned, be careful when it comes apart, it contains a small steel ball and a spring and note needs to be taken of position of these parts. The pipe fitting at the manifold is taper thread and when reassembling I have found it is best to use some PTFE tape. Make sure that the spring is not broken or deformed and thoroughly clean the parts before reassembly. From memory I think the TM lists this job at every 1000 miles and if it is not kept clean it makes a big difference to the running of the engine. Hope this is of some help to you. Quote Link to comment Share on other sites More sharing options...
deadline Posted March 15, 2011 Share Posted March 15, 2011 (edited) Torque for head bolts is 70ft/lbs Please see: http://www.tm9-801.com/searchTM9/tm9_pages/237.pdf The valves are adjusted to INTAKE .012 EXHAUST .016 with the engine HOT (above 160F). Please see: http://www.tm9-801.com/searchTM9/tm9_pages/229.pdf Engine must be running.. I guess you can do it with it off if you index the valves, but the special tool makes doing it at idle very simple. Also, 'Degsy' is referring to the crankcase ventilator. I do not believe it is simply a steel ball and spring. Its actually a metered orifice. There is a GM Service Bulletin that talks about it. And not all motors have it. Its should be on the top of the valve cover and run run into the intake manifold casting. Please see: http://www.tm9-801.com/searchTM9/tm9_pages/242.pdf You can download a FREE copy of TM9-801 from: http://www.tm9-801.com/tm9-801/index.php Or I have an online version for searching: http://www.tm9-801.com/searchTM9/searchfiles.php Edited March 15, 2011 by deadline Quote Link to comment Share on other sites More sharing options...
deadline Posted March 15, 2011 Share Posted March 15, 2011 You will find that having the special tools make this an easy job. They can be found online with a little luck, or maybe they are more common overseas than in the US. The valve adjusting tool: http://www.tm9-801.com/searchTM9/tm9_pages/230.pdf And wrench socket: http://www.tm9-801.com/searchTM9/tm9_pages/237.pdf Quote Link to comment Share on other sites More sharing options...
Degsy Posted March 15, 2011 Share Posted March 15, 2011 The crankcase ventilator is indeed a metered orifice, the ball and spring opens and closes the orifice as necessary and as I said can be fitted in 2 places, either from the oil filler tube or from the top of the rocker cover. It is possible that the oil tube fitting could be a european post war mod. Quote Link to comment Share on other sites More sharing options...
deadline Posted March 15, 2011 Share Posted March 15, 2011 NATO countries may have moved it around.. I cannot say where they put it. Initially the motors did not have any ventilation.. then it was added from the valve cover to the intake. I don't think the oil filler tube would work, as that was the air intake. The ventilator must be connected to a vacuum in order to evacuate the blowby gasses, and the oil fill tube (which also has the oil breather) would not supply any vacuum... if anything it would recirculate the blow by gasses right back into the crankcase in a loop. Please refer to this page from the TM9 http://www.tm9-801.com/searchTM9/tm9_pages/242.pdf There is no ball. There are two metered orifices that open depending on the pressure in the crankcase. Quote Link to comment Share on other sites More sharing options...
deadline Posted March 15, 2011 Share Posted March 15, 2011 You may be thinking of the jeep. That DOES have a connection from the oil fill tube to the carb air intake crossover tube.... but its a straight tube.. no valve. Quote Link to comment Share on other sites More sharing options...
Degsy Posted March 15, 2011 Share Posted March 15, 2011 No , I am not thinking of the jeep, my own GMC had the fitting as stated and I i have seen others, as you say there is a breather on the oil filler tube but crankcase pressure would occur at the at the filler tube and I have tested the pressure at the valve to check it was working. As regards the valve I have dismantled several and they have all been the same , a steel ball and a spring. Quote Link to comment Share on other sites More sharing options...
deadline Posted March 15, 2011 Share Posted March 15, 2011 (edited) You must be seeing a foreign modification. At no time was an in-service US CCKW ever modified with an oil fill tube that accepted a breather connection as you claim. If you have a document, please post. There is also only ONE valve, GM-15433412. This is from ORD-9-SNL-G508 August 45. My ORD-8 (supply allowances from 1947) also lists this single part... it was never superseded. I can also refer you to the GMC Technical bulletin, it lists one part number. I have seen a LOT of funny do-dads and mods made by foreign governments to CCKWs given to them. The 1945 French tipper (-H1) I have ran the oil return into the bottom of the oil fill tube (it should return into the special bolt that holds the fuel pump on) and they welded a water temp probe into the steel radiator supply tube. Those wacky french. If you read a vacuum at the oil filler tube on a US CCKW then you read the gauge wrong. There is nothing inside the crankcase to create a vacuum. There is lot of blowby gasses from the pistons. These gases contain water and can cause sludge in the oil. They also pressurize the crankcase. The way the ventilator works is vacuum is provided by the intake. This draws air in from the oil breather (located on the oil fill tube) through the filter, into the crankcase, through the valve and into the intake to be burned. Otherwise, why have a filter on the oil fill tube? Who cares if you filter air that is being pushed out of the engine??? I do believe that you have seen what you claim.. but its not a GMC part, nor is it a proper CCKW ventilator setup. Edited March 15, 2011 by deadline Quote Link to comment Share on other sites More sharing options...
Degsy Posted March 15, 2011 Share Posted March 15, 2011 If you had read my earlier post properly I said I suspected it to be a European mod. It's all very well quoting TM's and I assure you I have read them thoroughly when working on trucks but theory and practice are two very different things and I have come across lots of differences , some, but not all being European mods. I have also seen arguments go on on other forums over similar things and I find it a little pointless.Assuming this is not one of the earlier trucks without the valve the important thing is for it to be checked however it is fitted. I understand that you are keen on authenticity but sometimes it is easier to run things as they are , it depends how keen you are on perfection but in some cases it represents the true history of the vehicle and as such can be perfectly legitimate as long as the vehicle is not purporting to be something which it is not and never has been. Incidentally it would be interesting to know how many of these valves you have dismantled and rebuilt. Quote Link to comment Share on other sites More sharing options...
deadline Posted March 16, 2011 Share Posted March 16, 2011 The only reason why I "quote TM's" is because that's how the systems are designed. PVC valves (aka ventilators) can cause major headaches (poor engine performance, poor idle, poor fuel economy, sludge, etc) and GMC designed a pretty good system that has worked well. Start rerouting tubes, using parts that 'fit' instead of proper parts and then you start chasing problems that have no clear cause. People (and governments) do all kinds of wacky things to CCKWs. Vendors also give out some really bad advice from time to time. The only point of reference you have is the TM. Although I can't read it, the 1960s Norwegian CCKW TM I have still references the GM ventilator valve.. even uses the same TM pictures. How many ventilator valves have I taken apart? I'm gonna say about 9. Most were from parts trucks and most were full of crud so I screwed them back together and left them behind. Not that it means anything... you can take apart the wrong ventilator valve 9,000 times and still not know anything about the proper one. If you read the TM there is a very specific spring test you need to perform to ensure reliable ventilator valve operation. And I post the proper TM references so people can have them for their own use. Share the knowledge, you know, help someone out. Quote Link to comment Share on other sites More sharing options...
warrior Posted March 16, 2011 Author Share Posted March 16, 2011 Going back to my original question , i need to set my tappet clearance cold as i replace the head, does anyone know the gap ?? Cheers all :laugh: Quote Link to comment Share on other sites More sharing options...
deadline Posted March 17, 2011 Share Posted March 17, 2011 My first post gave the clearance and TM page. You can set them cold.. then get the engine running for the proper gap. Quote Link to comment Share on other sites More sharing options...
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