crank cap/bolts missing

[daveskatesallday]

so i have a block from a friend but he hasn't touched it in forever and i removed the crank today but there were only 4 caps and 8 bolts with it, for some reason the center cap or #3 some ppl say was missing, so i was curious if anyone else ever ran into an issue like this

i was told from someone who's been working with ae86's for pretty much their whole life told me that mix matching crank caps can be bad and i wouldn't put it past him he's a good friend but at the same time i wasn't sure if he was over exaggerating, has anyone mixed matched crank caps that were missing with other motors and had no issues?

im rebuilding a stock largeport/bluetop

any info/personal exp would be nice

[CBR_TOY]

should've bought mine for cheap with rebuild parts included

and extra piston/rod/bearings/etc

[GTSRolla34]

If you can get the missing cap from someone or a junk yard you can have a machine shop align hone the mains and it should work fine. Only reason I can see it being a bad idea is if you run a mismatched set of caps without having the bore checked or recentered.

[daveskatesallday]

true i heard that too the only bad thing though is i heard that each individual cap has a marking to differentiate it from the next and on mine i took them off in order but the markings werent there so i didn't want to get a cap and it not be the right one i know it sounds a little extreme but someone was stressing it to me how important it is to keep everything 100% right otherwise there's possibilities something could not go in my favor might just have to find a seperate block

[GTSRolla34]

The markings should be on the top of the cap (number and an arrow). Clean the tops of the caps really well b/c if they're dirty they'll be hard to find. They just differentiate the order they're to be placed in the engine, and which side faces the timing belt/flywheel. This keeps the bore centered in each cap as it was initially machined. If you know that the center cap is missing (the one with the thrust washers) then you know you need to source a #3 cap. Clean the ones you have an make sure you have a complete set. 1-5 (with the exception of the cap you know is missing).

I've seen people get blocks without caps, buy a complete set at the junkyard and have the machined and they work fine. You'll be hard pressed to find something 100% at this point that won't need a bit of machining, but that little bit will be the part that keeps your engine alive or kills it. Don't stress about it. Just figure out which one you need and buy one....or buy a complete set from someone who has a trashed block (maybe the cylinder walls are too trashed to salvage) and then have the entire set machined to fit. That way you have a complete set of mains and the discrepancy of the bore should be constant, vs having to deal with an odd ball cap. Either way will work...just depends on which is more available to you.

As another note, if you're planning on using ARP main studs you should have the block align honed anyway. If you were thinking about it down the road, now would be a good time to do it since you're going to have that machine work done anyway.

[daveskatesallday]

yea i wasn't trying to stress on it but just the person who told me has been working with ae86's his whole life lol i wouldn't put anything he says past him i don't think he would say it just to say it but i have a friend who has a seperate set of caps all 5 of them with bolts i'll see what the machine shop can do im still making up my mind

[dr.occa]

line bore as previously mentioned. happens more often than you think. the original block and caps are bored the same way except they are blanks to begin with.

it's nothing but a thang.