Adoom Posted April 1, 2015 Share Posted April 1, 2015 Due to the passing of time and a lack of labeling... I have a CA18DET block I intend to use. The only machining I think it needs is to surface the deck and hone the bores. But I have two sets of main caps.... one set is from an earlier block that I am not using. I am 100% sure which caps belong in which set, and I know what order they go in since their numbers are cast in. Buuuuut, I don't know which set of mains caps belong to the block I am using :/ Is there a way to work this out by measuring? Both sets are standard size. Or will I be in for a line bore and over size bearings? Quote Link to comment Share on other sites More sharing options...
Testament Posted April 2, 2015 Share Posted April 2, 2015 bolt them up and measure the diameters at multiple angles on each bearing and look very carefully for how well they match up I guess. if they measure up right and look right then it's probably ok. the other one is bolt it all up with bearings and crank in there and it should turn over nicely/not bind up anywhere. how worried are you about the motor? Quote Link to comment Share on other sites More sharing options...
Spencer Posted April 2, 2015 Share Posted April 2, 2015 Mixed up caps is a recipe for disaster, get them measured up properly when you get the machine work done. Then get them honed or align bored as needed. Quote Link to comment Share on other sites More sharing options...
Adoom Posted April 2, 2015 Author Share Posted April 2, 2015 how worried are you about the motor? Enough that I don't want it to fail prematurely. Mixed up caps is a recipe for disaster, get them measured up properly when you get the machine work done. Then get them honed or align bored as needed. I thought as much. Quote Link to comment Share on other sites More sharing options...
Spencer Posted April 2, 2015 Share Posted April 2, 2015 If you want to keep an engine its best to get the crank and main bores measured. Then decide if/how much to take off the crank and if the bore needs to be honed/aligned, then after that order bearings to suit. Quote Link to comment Share on other sites More sharing options...
Testament Posted April 2, 2015 Share Posted April 2, 2015 if the crank doesn't need grinding and you already have the bearings id measure and trial fit both sets of caps with the crank and see if one is tight. In reality cranks flex all over the show in operation so if the clearances are right so the correct oiling happens and it turns freely then I would be satisfied it was sufficiently aligned unless you know it's a type of motor that is very particular in that respect for some actual factually documented reason. Quote Link to comment Share on other sites More sharing options...
Spencer Posted April 2, 2015 Share Posted April 2, 2015 Yea all true Tom, easy to get the clearances correct and have the wrong cap in place and its not round though. I doubt he has the gear to measure this properly. Couple hundred bucks while its at the machine shop will ease your mind. Quote Link to comment Share on other sites More sharing options...
Seedy Al Posted April 2, 2015 Share Posted April 2, 2015 come spend more money with us! Quote Link to comment Share on other sites More sharing options...
Adoom Posted April 2, 2015 Author Share Posted April 2, 2015 come spend more money with us! That's the eventual plan Just as soon as I have some. I finally got my head all together because gf was overseas for work for 2 weeks. I only had to install the valve springs 3 times! The initial install. The, FUCK, how did I forget the valve stem seals, reinstall. And the, WTF do you mean the springs only go one way around reinstall. I should have read the manual. HAHA Now I'm pretty good at installing valve spring collets though. Quote Link to comment Share on other sites More sharing options...
Testament Posted April 2, 2015 Share Posted April 2, 2015 Yea all true Tom, easy to get the clearances correct and have the wrong cap in place and its not round though. I doubt he has the gear to measure this properly. Couple hundred bucks while its at the machine shop will ease your mind. thats why you check everything is round and the right sizes then install the crank and turn it to see that it turns free with no tight spots could even put a dti on it, but that will probably just tell you that the factory crank machining is a littel shonky and make you go crazy because you dont actually know what an allowable number for that is. also he said the caps are all numbered so they wont be in the wrong place. 98% chance the 1980's nissan maching is probably good enough that either set works fine ultimately. it's not some silly old british engine where everything was fitted and hand machined or a flimsy american v8 cathedral with thin bendy walls everywhere 2 Quote Link to comment Share on other sites More sharing options...
Spencer Posted April 2, 2015 Share Posted April 2, 2015 You are correct jap bottom ends are sweet, I'd still get it measured personally. Don't get me wrong I've done lots of plastigauge rebuilds, just not on things I plan to keep for long. Old Philly did a rebuild with the wrong caps that measured up fine and turned over OK, nek minute. 1 Quote Link to comment Share on other sites More sharing options...
Testament Posted April 2, 2015 Share Posted April 2, 2015 old smoky phil 2 Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted April 4, 2015 Share Posted April 4, 2015 you really need an inside micrometer to measure it accurately. if you don't have one, talk to a shop. (most shops will try and fit you into a line bore etc because thats how they roll. Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted April 5, 2015 Share Posted April 5, 2015 Run a straight edge through the caps? Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted April 5, 2015 Share Posted April 5, 2015 No Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted April 6, 2015 Share Posted April 6, 2015 It's a pretty common way to measure mains for alignment. Usually using solid bar, not your old bent ruler.. What's you expert opinion on what he should do? Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted April 6, 2015 Share Posted April 6, 2015 Id bolt one set in and measure it up with internal micrometer. Then do the same with the other set. Then fingers crossed one set is obviously the correct set. 4 Quote Link to comment Share on other sites More sharing options...
Testament Posted April 6, 2015 Share Posted April 6, 2015 Id bolt one set in and measure it up with internal micrometer. Then do the same with the other set. Then fingers crossed one set is obviously the correct set. exactly. if you can do this then fit the crank to check it turns free its as good as its going to get. You are correct jap bottom ends are sweet, I'd still get it measured personally. Don't get me wrong I've done lots of plastigauge rebuilds, just not on things I plan to keep for long. Old Philly did a rebuild with the wrong caps that measured up fine and turned over OK, nek minute. was that with plastigage or with mic's ? was there some other cockup? chances are the barry at the machine shop could cock it up worse and machine it wrong too. 1 Quote Link to comment Share on other sites More sharing options...
Spencer Posted April 6, 2015 Share Posted April 6, 2015 Phil probably measured it with cheeseburgers. You think this guy has internal mics sitting around? I would say if he did he wouldn't have asked us the question. its going into the machine shop anyway so get it measured, this doesn't seem very hard to me Tom? other option is to buy some gear to measure it properly. By the sounds he is sending it to grotty's so its going to steer him in the right direction. 1 Quote Link to comment Share on other sites More sharing options...
Adoom Posted April 7, 2015 Author Share Posted April 7, 2015 Phil probably measured it with cheeseburgers. You think this guy has internal mics sitting around? I would say if he did he wouldn't have asked us the question. its going into the machine shop anyway so get it measured, this doesn't seem very hard to me Tom? other option is to buy some gear to measure it properly. By the sounds he is sending it to grotty's so its going to steer him in the right direction. I don't have any micrometers(or cheeseburgers/bananas/cellphones), it would be nice, but the amount of times I'd use them doesn't really justify buying any. I assume cheap ones are not worth buying. The most precision measuring tool I have is vernier calipers. I am taking it to the guys at Custom Works eventually, when I have some money. But because I have no money yet, I did try installing both #5 caps and they seem to be exactly the same. I cannot see or feel any misalignment where the cap meet the block on either of them, so their machining seems to be pretty consistent. Quote Link to comment Share on other sites More sharing options...
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