Guest 4.3L 280z Posted January 9, 2005 Share Posted January 9, 2005 Well you all helped me with the knocking in my motor and it was the number 6 rod bearing. I replaced the bearing because I was hoping the crank wasn't to mared up but I guess it was cause its starting it again. I need some advice, 1. Is it ok to get the journal reground or should I just buy a new crank? I'm going to take it to the machine shop anyways to make sure it hasn't been reground before so I don't have trouble and use the wrong bearings for the new crank 2. I'll get the rod checked but if I need to replace it they have to press the rod into the piston right? 3. Is it ok to reuse my rings I have or is it a good idea to replace them when I take the piston out? 4. What do you think about just taking off the one head and leaving all the pistons in the motor except the one that was knocking cause the others look fine? You probably read my other post but the motor was rebuilt when I got it but I guess he used the wrong size bearing or torqued this one down to much which caused it to fail. I'll be following the haynes manual when I do this, is there any other advice you have that may not be in the book? I really don't need to screw this up but I don't have enough money to have someone else do it. I just hope it doesn't end up costing even more than a new motor! lol Quote Link to comment Share on other sites More sharing options...
jbk240z Posted January 9, 2005 Share Posted January 9, 2005 Yo, Depending on how bad the journal is, you may be better off just getting another crank from the salvage yard. As common as these engines are, you should be able to get one pretty cheap. As cheap as new rings are just replace them while you have it apart, trust me it's cheap insurance. It would be best to dis-assemble the whole motor anyway so you can inspect the rest of it. Would be a great time to add a hotter cam to........lol Good luck. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted January 9, 2005 Share Posted January 9, 2005 IMO as a 'for now' motor, I'd do exactly what you said... Pull just the one head, pop out the one bad rod/piston, and reuse the rings/piston as long as they arn't in rough shape. Yes replacing parts is insurance, and I don't have all the knowlege a lot of folks here have, but it's what I'd do.. Besides..you said you'll be droping in a V8 'down the road' right? I'd try to get this motor back together, and not spend too much time/money on it. Quote Link to comment Share on other sites More sharing options...
Guest Magnum Rockwilder Posted January 9, 2005 Share Posted January 9, 2005 Your cheapest option will probably be to get another used, running, 4.3 or SBC. Labor at a machine shop gets expensive. I recently GAVE a friend a running 305 for his Nissan truck, and another friend GAVE me a running 305 for a Jaguar XJ6 I sold. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 9, 2005 Share Posted January 9, 2005 It depends on what you want to do, now and in the future. To do it right the first time and only once, the engine should be completely disassembled, cleaned, honed. rods resized, crank reground or newer crank used, use new bearings and rings, check the guides and seats in the heads and reassembled as necessary, and you can take this time to upgrade cam. Undersize cranks aren't that big of a deal as long as they are not less than .020 undersize for performance applications. Most people shy away from alot of undersize ground cranks, but in this type of application it'll probably work fine for quite some time. If you want to patch, then patch, just don't expect all the metal that's circulating in the oil passages to be removed and expect the potential for the same problems again. When you buy a gasket set they come with both so why not pull both heads, tank the block or at least wash it by hand and do the oil galleries while your there. But you will have to resize the one rod for sure. IMHO I'd wait, you seem to have the capability to do it well, scrape up a few bucks, do it right and have a smile on your face longer, rather than posting here again on what went wrong. Quote Link to comment Share on other sites More sharing options...
skipzoomie Posted January 9, 2005 Share Posted January 9, 2005 If you are new to this arena, the old adage is: Pay me now or pay me later. Do it right the first time!!!! You can either enjoy the car or you can spend your time working on it. The later is always much more expensive. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 9, 2005 Share Posted January 9, 2005 Look into an aftermarket crank. They are usually stronger than the stock ones and work out cheaper than doing the machine work to the OEM one (at least with the 350 chevy cranks). Also, when you have a crank ground down you usually lose the hardened surfacing of the journals as they are usually only surface hardened. Not the end of the work, but something to keep in mind. At least look into the price of an aftermarket stock replacement crank. Tim Quote Link to comment Share on other sites More sharing options...
Guest 4.3L 280z Posted January 10, 2005 Share Posted January 10, 2005 Ok but what about cam bearings if I clean it out myself with soap and water? I don't think I'd have a problem with anything except the book doesn't go into it, just says its hard and should be done by a professional. Do I have to remove them to wash the engine? Or could I just clean them and regrease them or is it something I will be able to do on my own. I'm going to check the local maching shops because I'd like to do it right and get it bored out. My parents want to buy me a new motor but I really don't want them to because although they do pretty well, there not rich, i think they want to see me drive it as much as I want to cause I've been working on it from rust to finish for the past 4 years since I got it for $300 when I was 16. I looked at all the rod bearing again and there all starting to show lots of wear and I checked to make sure the crank was getting oil and it is. He must have used all wrong bearings or something. Now that I see that I'm thinking of taking it all apart (again let me know about the cam bearings) and just getting a full rebuild kit with a new crank. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 10, 2005 Share Posted January 10, 2005 If you are taking the block in to get bored, the the machine shop can remove and reinstall the cam bearing....it's cheap, and bad economy to try and reuse the old ones. Usual price to install cam bearings is ~$30, plus bearings---another ~$30. Let the machine shop hot tank clean the block...the results will be far better than driveway soap and water...... Tim Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted January 10, 2005 Share Posted January 10, 2005 Before adding a hotter cam I would add the 2 extra cylinders first. Quote Link to comment Share on other sites More sharing options...
Guest 4.3L 280z Posted January 10, 2005 Share Posted January 10, 2005 If thats all it costs I guess there isn't a reason not to. If I'm going that far I might as well do that to. I've finally decided I'm going to keep the v6. It only takes an hour to take it out and put it on the stand and performance heads aren't that expensive on ebay. Quote Link to comment Share on other sites More sharing options...
jbk240z Posted January 30, 2005 Share Posted January 30, 2005 Yo, 4.3 280Z, Just wondering if there has been any progress on ur rebuild? Maybe ur just busy making it totally bad A$$! There is some brodix heads for a 4.3 on ebay. It is refreshing to be different. Quote Link to comment Share on other sites More sharing options...
jbk240z Posted February 3, 2005 Share Posted February 3, 2005 Hi, I was just wondering if you made any progress on the rebuild, or maybe you switched to a sbc? Quote Link to comment Share on other sites More sharing options...
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