ok guys im gonna be ordering rod and main bearings for my build here before too long and i wanna make sure i understand every aspect of the bearings ie: clearances, tolerances, etc, etc. i have been reading on bearings for a couple weeks now and thanks to turbols over on teamintegra.net i have learned tons and have a much better understanding of the whole selection process as a whole. but there is still one area that i am not totally convinced on. I dont understand what a desireable clearance is. How much is too much, how much isnt enough. i dont wanna order $1000 dollars in bearings and try them all just to9 only end up using $100 worth of them and have a bunch of bearings left over that i probably wont ever use. according to this post: http://www.team-integra.net/forum/19-projects-diy-article-talk/136781-crank-rod-bearing-sizing.html the desired clearance for the rod bearings should be 0.0012 across the board and the desired main clearance for main caps 1,2,4,and 5 should be 0.0013 and for main cap 3 should be 0.0016.
is this clearance what he decided would work best for his motor or is this a general clearance and thats what you should shoot for with all motors ( of course there is allways and exception but u get the idea)?
Using his formula that he posted seems to be an accurate way if determining what bearings would give the desired clearances… but that was for HIS motor. You’d need to know YOUR exact journal clearances, and cap clearances etc.
As far as his clearances go… each builder has their own preferences for clearances (tighter for turbo, mire loose for NA, etc)… but as ling as you’re within spec you won’t have any adverse issues.
When I had mine built everything was zeroed out, that way every journal used the same bearing. No color coding necessary. But as long as your math is correct, the OEM system works like a charm.
ive had my rods align honed because of arp rod bolts so if im not mistake that takes the OEM system out of order correct? you say as long as im within spec i wont have any issues… what exactly is spec? thats what im trying to find. im building the motor for NA for right now but eventually i do hope to see low boost if that matters
I mean as long as your oil clearances are within the OEM limits…
Main Bearing Oil Clearance .0008" to .0017"
Rod Bearing Oil Clearance .0009 to .0018"
As per my Haynes manual.
No, having your rods line-honed doesn’t take the OEM system out of the equation… Because you still do the same process… find out your crank journal thickness, and your rod/main-cap inner diameter, then select the proper OEM bearing size/color that will facilitate the oil clearances you’re looking for.
I’ve read about people using their old bearings as a guide… plastigauge each journal, with the old bearings, see what the clearance spec is, and adjust which bearings you need to buy based on those results. But I really don’t like the idea of old bearings on a newly machined crank.
It’s a bit of a headache for sure. Like I said when mine was machined, it was done in a manner which let me order a set of Calico standard size bearings and slap them in… all the clearances were nearly identical, allowing the same bearing to be used for all mains/rods. It all depends on what machine work was done, and with what goal in mind. I gave it all to my builder and he took care of it.
I’m assuming you have a Haynes/shop manual? I know there is a good 3-4 pages explaining the system in mine.
i do indeed have a manual… its for a dc but should be the same in this department however i just moved 3 days ago so its packed away somewhere and i havent come across it since i started researching all this about bearings. but thank you for spoon feeding me there that was exactly what i was looking for