landcrush Posted March 10, 2017 Share Posted March 10, 2017 Finally getting my block back together. Picked up everything from the machine shop he micd my mains and rod bearings. I reused my crank which checked out a-ok, but my clearances are on the loose side. I am already planning on running a heavier weight oil and the car will eventually be seeing north of 350 to the wheels so i went with the race bearings. It's my understanding they have a little extra clearance built in. My mains were kinda all over the place with number one being tightest i think around .016 up to nearly 2 thou. I'm using STD size, should i get .025 bearings and mix and match to get a tighter clearance or is 2 thou okay? Link to comment Share on other sites More sharing options...
birkhoff Posted March 11, 2017 Share Posted March 11, 2017 Finally getting my block back together. Picked up everything from the machine shop he micd my mains and rod bearings. I reused my crank which checked out a-ok, but my clearances are on the loose side. I am already planning on running a heavier weight oil and the car will eventually be seeing north of 350 to the wheels so i went with the race bearings. It's my understanding they have a little extra clearance built in. My mains were kinda all over the place with number one being tightest i think around .016 up to nearly 2 thou. I'm using STD size, should i get .025 bearings and mix and match to get a tighter clearance or is 2 thou okay? That's what I did -- shooting for the low teens all down the line. From the numbers, I expect you are fitting STD size and if you check, they mic pretty much right on to what the factory spec is in terms of shell thickness. So there is no extra clearance in the ACL race line STD size that I could detect, although they do make a 1 thou bigger bearing that can open up the oil flow if you are looking for that. I wasn't. I ended up with good oil pressure on standard 10W30 from first startup. No complaints at this end. Link to comment Share on other sites More sharing options...
landcrush Posted March 11, 2017 Author Share Posted March 11, 2017 Interesting yea they were standard size bearings.. my crank was polished maybe that's where my clearance is coming from. I'm no expert engine builder maybe i'd be best suited to try and mix "over size" bearings to get my teens clearance. I know it's better to be on the looser end rather than too tight Link to comment Share on other sites More sharing options...
landcrush Posted March 11, 2017 Author Share Posted March 11, 2017 Browsing around other forums, most seem to think 2 thou clearance is okay and some even think that's ideal. I guess if the car is going to see abuse and track use the extra oil clearance wouldn't be a bad thing, however mine will mostly see street use, definitely looking to do some track days though Link to comment Share on other sites More sharing options...
Darth SpecB Posted March 11, 2017 Share Posted March 11, 2017 The spec for main clearances are .0004-.0012. It seems you are getting around .0016 The problem with too much clearance on the mains is that you will lose pressure going to the rod bearings and ultimately the whole system all together including avcs and turbo. EJ25 are notorious for rod bearing failure so this can get risky. I would recommend trying to get as close to spec as possible on the mains. A little loose on the rod bearings would be better than say the mains theoretically. Now there are many high hp cars out there that run "tight" clearances from .0005-.0015 with no issues at all in fact they run tight main clearances on purpose for more pressure. Your best bet would be to mix and match the shells to get within spec on #1. Possibly ask if anyone else has spares laying around since you only need 1. Like I do but they are standard. I don't believe being a little over spec will be detrimental. I am running a .0025 clearance and I haven't had any issues because it is just on 1 journal. The benefit of running all journals in spec is that you can use the recommended 5w30 and get better gas mileage. Which you still may be able to do. Just check your oil pressure upon start up, and if it's a little low than simply choose a higher viscosity oil until you have sufficient pressure. Good luck! Sent from my SAMSUNG-SM-G900A using Tapatalk Link to comment Share on other sites More sharing options...
birkhoff Posted March 11, 2017 Share Posted March 11, 2017 Interesting yea they were standard size bearings.. my crank was polished maybe that's where my clearance is coming from. I'm no expert engine builder maybe i'd be best suited to try and mix "over size" bearings to get my teens clearance. I know it's better to be on the looser end rather than too tight Polishing probably didn't take off much. I expect if you had measured the crank before it was cleaned up you'd find it was down already. Also the bores in the case seem to open up over time and you don't get the full amount of bearing crush, so the bore ends up bigger. Especially on the narrow webs at #2,4. There seem to be a few things going on at the same time that contribute to what you are observing, but it is very common. If I understand your description, your smallest running clearance is 16 tenths, with the others closer to 20. If you used a full oversize shell on the big ones (that brings it down almost a full thou) and a half shell on the 0.0016 bore, you'd be in good shape. How are you measuring your clearances? Link to comment Share on other sites More sharing options...
landcrush Posted March 11, 2017 Author Share Posted March 11, 2017 The machine shop has been mic'ing everything. He said the crank was within spec. The motor only has 50k miles And yea, my smallest clearance was on #1 as expected Looks like I'll have to get a full set of .025 oversize. It'd be ideal if someone had extras but I don't have the patience to seek it out lol. Measurements were taken with a bore gauge/ micrometer he didn't use plastigauge. Link to comment Share on other sites More sharing options...
birkhoff Posted March 11, 2017 Share Posted March 11, 2017 I have extras, but you wouldn't like the wait for them to be shipped from Canada, and I probably don't have enough anyway. Just pick up the oversize/undersize set. If you don't have the tools to load the shells, torque the case and check your actual diameters with a gauge, then you should proceed carefully. Assume your machine shop gave you accurate numbers, figure out for each journal how much you want to add to the shell thickness, either 5 tenths or 10 tenths. Install the bearings accordingly and write the location with a soft sharpie on each shell. 1-L, 2-R and so on. The final check will be trial assembly, dry, with plastigauge to make sure something isn't wildly out. Torque the case to spec (important), then take it apart and try to estimate your clearances. The smallest official measurement on the wrapper is 15 tenths, so you have to interpolate (extrapolate?) from that. Now you are ready for final assembly, with lube and sealant. Double check that you haven't shifted any of the shells from the trial assembly -- you were right earlier: you can live with a little more clearance, but the block will die if you have less than the minimum spec of 4 tenths. Link to comment Share on other sites More sharing options...
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