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Tell me what you know about assembling a bottom end!

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#42 ·
Sorry to bring this back up, but I could use of clarification on thrust bearing alignment. I have searched and search but I still don't get it. When I install the crank I pry on it forward and check the clearance with a feeler gauge, then pry it to the rear and check the clearance. If it checks within spec I just torque it down or do I need to pry again to the front and torque down? Sorry for the dumb question I just can't afford to mess this up once my block comes back from the machine shop, so if someone could dumb it down step my step it would be much appreciated.:eek:
 
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#44 ·
DSM Loki said:
I usually snug the mains, pry it back and forth, torque the mains and pry it to one end and check the thrust.
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Alright, thanks for the clarification. Not going to lie I'm nervous to put this block together as its my first time. Trying to convince myself to save $250 by assembling it myself, but its a hard choice because the machinist has done it alot more. This thread is very helpful and has alot of good info, so it give me hope.
 
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#46 ·
It is not hard to assemble the engine as that is the easy part. The hard part is knowing how to use proper measuring devices to be absolutely certain you have your clearances within specifications.

I personally just built a Evo VIII motor Wednesday, Put it in the car thursday and with the engine having about 5 miles on it breaking it in just made 862AWHP at 42 PSI.

Finding a set of clearances that work is the hard part because unless you have someone that is already knowledgeable on 4g63's and can tell you what clearances should be used for x amount of HP then most people have no clue what to do.

You may ask what clearance's am I running for a 900whp 4G63?

.005" PTW
.0025" Main bearing oil clearance
.0035" Rod bearing oil clearance

I am running a much larger rod bearing clearance due to the fact that I am running aluminum rod's. Clearance for steel rods will be .001" smaller in most cases.

I only use Brad Penn 20w-50 and it gets changed after every track event.
 
Discussion starter · #47 ·
90BLACKAWDTSI said:
It is not hard to assemble the engine as that is the easy part. The hard part is knowing how to use proper measuring devices to be absolutely certain you have your clearances within specifications.

I personally just built a Evo VIII motor Wednesday, Put it in the car thursday and with the engine having about 5 miles on it breaking it in just made 862AWHP at 42 PSI.

Finding a set of clearances that work is the hard part because unless you have someone that is already knowledgeable on 4g63's and can tell you what clearances should be used for x amount of HP then most people have no clue what to do.

You may ask what clearance's am I running for a 900whp 4G63?

.005" PTW
.0025" Main bearing oil clearance
.0035" Rod bearing oil clearance

I am running a much larger rod bearing clearance due to the fact that I am running aluminum rod's. Clearance for steel rods will be .001" smaller in most cases.

I only use Brad Penn 20w-50 and it gets changed after every track event.
Click to expand...
What do you use to measure?

Also, great point about oil clearance. Normally, the manufacturer of the internals has the specs so the assembler doesnt always need to blow up a couple motors before he/she figures it out.
 
#48 ·
Something that I think is relevant and haven't seen yet. Say you build a long block and its going to sit for a little before its first start, is there anything that needs to be done to maintain it until its first start? Ex: put oil/WD-40 in the spark plug wells and rotate crank etc...

What do you guys do or recommend?
 
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#50 ·
When I assemble an engine for long term storage I use STP oil additive for assembly lube, and coat the cylinder walls, valve stems, seats, inside the crankcase, cams, rockers, etc. If it's only going to be sitting for a month or so I like to use a 50/50 mix of STP and oil, or if it's going to be run right away I just use oil.
 
Discussion starter · #54 ·
It still takes skill to measure a clearance. With just a caliper a user has stability in just one axis. With a dial-bore, a user has stability in two axes. No measuring device affords stability in all three it seems, are you guys measuring with an initial reference from the block deck when measuring cylinder bore?

How about when measuring the torqued bore of a rod journal? Even with a dial bore gauge, how do you make sure your z axis is stable?

Things like this that are immediately apparent to professionals, are not to those who have no experience with the equipment (me).
 
#55 ·
A dial caliper is not accurate enough for most engine assembly processes so that throws that measuring device out completely. A dial-bore doesn't matter on rotation and trying to find center you are simply looking for the smallest value to make sure the gauge is square and centered in the bore. There is some practice in precision measuring and a bit of a touch, but it is not rocket science.

You need to measure cylinder bore in multiple places to make sure it is the correct size, not egg shaped and not tapered. For anything small like a rod bearing you can loosely clamp the stem of the rod in a vice or something and then you just go back and forth with the bore gauge to find the smallest measurement, then you turn 90* or so and measure again to check for circularity.
 
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