RandyR Posted July 19, 2016 Report Share Posted July 19, 2016 Thanks for the helpful tip about exhaust gas velocity. Hadn't thought of it that way before. So you're saying I should back off on the 6" dual smokestack idea? A co-worker has replaced the entire 2.25" exhaust on his late model Toyota car, and donated his old stuff to me just for scrap metal. I may get out the hacksaw, some clamps and hangers, and spend some time under the 720 to fab my own setup. This can wait until after I successfully change the head gasket, of course. I may also find out if there's any scrap value in my old cat. I am ashamed at how cheap I can be at times. 1 Quote Link to comment
datzenmike Posted July 19, 2016 Report Share Posted July 19, 2016 Before you dive into a head gasket change find out how to prevent the timing chain tensioner from falling out,iif you don't already know. Failure to secure it will add 4-6 hours more work and some more gaskets to fix. 1 Quote Link to comment
RandyR Posted July 19, 2016 Report Share Posted July 19, 2016 Yup. Been reading all the advice on the forums about the timing chain tensioner springing out. I wouldn't have suspected that would happen, but I'm glad I did some reading before it did! I ordered an Alltrade 648832 tool https://www.amazon.com/Alltrade-648832-Nissan-Timing-Holding/dp/B0002Q8TVO/ref=sr_1_2?ie=UTF8&qid=1468957945&sr=8-2&keywords=timing+chain+tool+nissan but I'm only about 90% confident in it, only because it lists the 1984 Z24 motor as one of its applications. I'm about 85% confident in using the Alltrade 648831 https://www.amazon.com/Alltrade-648831-Nissan-Timing-Holding/dp/B0002Q8TV4/ref=sr_1_1?ie=UTF8&qid=1468958036&sr=8-1&keywords=timing+chain+tool+nissan although it is for L-motors, and for years up to 1983 ...and about 75% confident I can carve a piece of wood the right size and shape that will sufficiently hold. I suspect that at TDC and the gearbox in neutral, there shouldn't be much natural tendency for the crank to rotate either direction, so just enough friction to keep the spring compressed should do it. (?) I won't die as a result of the chain coming loose, but I don't want the consequences of the chain falling down. 1 Quote Link to comment
datzenmike Posted July 21, 2016 Report Share Posted July 21, 2016 This one... https://www.amazon.c...ain tool nissan Chain can't 'fall down'. There's no where for it to go. Don't worry. 1 Quote Link to comment
RandyR Posted July 21, 2016 Report Share Posted July 21, 2016 Mike, is that tool jammed into a Z24? If so, I will have Amazon send me that one asap. That picture says it all. Lesson learned: Never trust the item description on Amazon. 1 Quote Link to comment
datzenmike Posted July 21, 2016 Report Share Posted July 21, 2016 The tool pictured reaches down to the tensioner and just blocks it. Some don't reach but wedge in and hold the chain from moving. I believe the picture is from an L18 but only the tops of the guides change (if at all) the guides where the 'wedge' is don't change so it will work just fine on a 'taller' Z24.. I made my own wedge from a wooden plank. Bottom 1 1/4"... top 1 3/4".... length about 6". Whack it in good. Set TDC and mark the chain/sprocket so there's no guessing when you put back together. The cam sprocket has three holes in the back for the dowel on the cam to fit onto. It should be on the #2 (from the factory), or middle one. Recently had my L20B head off and it was on the #1 so someone was in there before. I set it back on the #2. 1 Quote Link to comment
RandyR Posted July 21, 2016 Report Share Posted July 21, 2016 Gotcha. I had read your other material on HG replacement, but your advice on the #2 hole on the cam sprocket is a new one I believe. Thanks! HG replacement parts to arrive next week. As a side note - I decided to "go with the flow" (pun intended) and use the stock exhaust manifold back to the cat. I began disassembling what was left of the exhaust, and miraculously I was able to unthread the bolts that held the cat-back exhaust system to the cat! I was pleasantly surprised to learn someone had done the service of busting out the guts of the cat, so it's essentially a free-flowing little box. I then started the truck, which PROMPTLY told me I had better order the cat-back exhaust (including muffler). To be installed as soon as it arrives on Friday. 1 Quote Link to comment
datzenmike Posted July 22, 2016 Report Share Posted July 22, 2016 The insides may have just disintegrated and blown out.. A header should be low on your list as the stock manifold is fine. At some point in the future, if you add enough modifications, this may change. 1 Quote Link to comment
RandyR Posted July 22, 2016 Report Share Posted July 22, 2016 Just the sound it makes as it first starts up (due to the miss in one cylinder until the coolant is purged out) similar to machine-gun fire. Neighbors surely thinking a drive-by is taking place. No, I'm not interested in modifying the truck in any way (other than the Weber, and already removed all the unnecessary vac lines). Just happy with stock, as long as it's cheaper than aftermarket "improvements", and can still be found. I like to keep things as simple as possible - I believe simplicity results in dependability. If I'm told by someone who knows more than I do, that the manifold is not the weak link in the chain of air flow, I'll take his word for it. The manifold stays, and the money goes to the carb replacement fund. I'm getting old. 1 Quote Link to comment
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