engine builders

braindamage

braindamage

Member +
Hey guys,if i am fitting a new crank form Toyota ,how do i know what mark bearings should i use? or how do i calculate what size i should use?
 
sx_turbo

sx_turbo

Lifer
there are numbers on the main caps they range from 1-4

i think there are also numbers on the rods ranging from 1-4
 
350ep70gr

350ep70gr

Member +
You need to mesure all the crank journals with a micrometer. Then you need to close all the main caps and torque them down without the crank inside and mesure with a bore micrometer the diametre. Then you need to calculate each cap diametre with each journal diameter so you are in the right clearence. The other more faster (but not as accurate is the plastigauge method). Same procedure for the rod bearings. If you dont know what you doing down there or dont have the special tools to make the mesurments call a pro to do the job. Clearence issues dosent forgive mistakes and new crank is way expenssive.

Chris
 
finx

finx

Member +
chris's advice is spot on.
bearing clearances are not something you can just guess and hope it will be ok. 5thou out and you will have a knock which will result in low oil pressure and not long after a dead engine so you will be back where you started from.
same goes for all engine clearances if there is to much tolerance something bad will result.
if you dont have the equipment or expertise get a pro to do it for you. its money well spent.
 
JasonGlanza

JasonGlanza

Lifer
when doing a rebuild, you just need to measure up before you buy bearings? what sizes does ACL do? and how to choose the right ones?
 
finx

finx

Member +
JasonGlanza said:
when doing a rebuild, you just need to measure up before you buy bearings? what sizes does ACL do? and how to choose the right ones?
Click to expand...

when doing any rebuild you need to determine what size parts you require before racing out nd telling the parts guy you need this this and that. stock or oversize are basically what you are looking for. this will be decided on how worn the original parts and components are or if it has been previously rebuilt or not and weather any oversizng was done at that time.

on bearings most of the time it is easy to tell via the part number or code on the bottom of the bearing. STD means its a stock side bearing. .25 or .50 thou means it is oversize by that amount.

rings are harder. you need to work out the reason for failure. then measure the piston and bore for clearances and wear measurements. and then measure the ring gap of the rings that you have removed and based on these results you choose what needs to be done. re bore/oversize pistons and rings or just oversize rings or whatever.

you then need to consider why the engine is out of the car and in bits. had it run the bottom end or had you fried a piston from a bad tune.
depending on the engines cause of failure you need to be looking in that area very carefully for what components are worn or worse wrecked and decide what needs to be done to rectify it and make it work properly again and most importantly last the same distance that it managed since Toyota built it.

if the engine has been previously rebuilt and oversized you need to be checking things like crank journal measurements and rod big end cap clearances so that you end up with the correct bearing to suit. for example when a crank is oversized the rods are also re bored at the same time during normal practice.

thats how you determine the parts sizing in a fairly simple wight up...



ACL supple STD (standard) .25 or .50 oversize parts


AzE_B what is all this 2s and 3s your talking about? sounds more like toyota piston sizes more than anything bearing related...
 
350ep70gr

350ep70gr

Member +
finx said:
AzE_B what is all this 2s and 3s your talking about? sounds more like toyota piston sizes more than anything bearing related...
Click to expand...

AzE_B probably talking for standard rebuilt for the originaly supplyed crank with the engine and numbers 2,3 he said are probably the stamp numbers near the flywheel for the main and big ends bearing size. Even in this situation i stongly recomend that a mesurment have to take place before assembly.
Braindamage is in more complicate situation cause he will use a new crank and not the original one and the clearence have to be CHECKED. Even by a plastigauge and 2 old bearings to determine the size for order the right number.
With the new bering the clearence must be checked again at least 2 times in every journal in 180 degrees angle. (The caps may not be a perfect circle after 15 years.)

Chris
 
finx

finx

Member +
ahh that makes more sence haha been a hard day..

once again Chris well put about the measurements etc on the new crankshaft. :) you summed it up much better than i did in my overdone last post :p. i was talking more in general than to his specific case which is guess wasnt allot of help haha
 
350ep70gr

350ep70gr

Member +
finx said:
ahh that makes more sence haha been a hard day..

once again Chris well put about the measurements etc on the new crankshaft. :) you summed it up much better than i did in my overdone last post :p. i was talking more in general than to his specific case which is guess wasnt allot of help haha
Click to expand...

Naaaa always your posts are good,helpfull and extensive. I am watching you I hope i could explain myshelf as good as you.!:p

Chris
 
finx

finx

Member +
haha cheers bud :)
im no master of explanation i personally think you get the message across much better than myself haha
i find its always a bit odd using text as a direct medium of communication when all day every day im in the workshop trying to explain things verbally
 
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