1G Engine Blueprint Data Check - Main Journal Oil Clearances and path forward

[athlete3344]

Good evening,

Im currently in the process of blueprinting my block, and Ive finished up the main journal oil clearances. Goal for now is to support a 20g and have a fun to drive car. Based on the data, I do have a few questions:

• Overall, things look great, but Im wondering if I should be picky about #4, 3, and 2 oil clearances? I dont mind spending a little extra on a line hone if its worth it w/ the above goals in mind.
  • Plastigauge and dial bore mostly agree on taper for #4. I do think my dial bore/mic error is in the 0.0005 range, so the difference make sense. Also for #4 and #3 the plastigauge was just a hair outside the 0.0020 range.
• Is it normal for these bearings to be egg shaped? I saw this mentioned in a Jafro video but wanted to double check.
• Other machine work Im looking to include is a bore/hone for new pistons, fitting 1g rods to new pistons, deck, cleaning/hot tank, and crankshaft galley ball removal (maybe rod work depending on clearances but Im expecting them to be spot on). Is there anything else I should be asking for to get the block ready to start my build?

y = vertical main measurement (parallel to cylinder)
x = horizontal main measurement (other way to cylinder)

oil clearances w/ new acl bearings	5​	4​	3​	2​	1​
y1	0.0025​	0.0024​	0.0019​	0.0024​	0.0023​
y2	0.0025​	0.0024​	0.0018​	0.0026​	0.0024​
x1	0.0034​	0.0031​	0.0032​	0.0031​	0.0030​
x2	0.0033​	0.0031​	0.0030​	0.0032​	0.0027​
plastigauge	0.0020, no taper	0.0018-0.0019, no taper	0.0019, no taper	some slight taper 0.0018 <-> 0.0019	0.0020, no taper

Also for fun I grabbed some measurements with the original bearings. Looks like #3 was still showing some taper, and maybe #2 and #1 were wearing a little faster. #5 and #4 look to be pretty close to the new ACL bearing measurements above. Also egging was a bit worse in #3, 2, and 1.

oil clearances, original bearings	5​	4​	3​	2​	1​
y1	0.0026​	0.0025​	0.0025​	0.0029​	0.0027​
y2	0.0028​	0.0025​	0.0023​	0.0029​	0.0029​
x1	0.003​	0.0029​	0.0037​	0.0041​	0.004​
x2	0.0029​	0.0031​	0.0034​	0.004​	0.0039​

 

[athlete3344]

Figured I should follow up with rod oil clearances as well. I think these are going to be a big on a loose side (Im betting #4 is closer to 1/2/3) and Im leaning towards ordering an oversized bearing and having the shop open up the rods to get closer to 0.0022 for the clearances. Does this make sense or should I go with looser than 0.0022 for rod oil clearances?

rod oil clearances	4	3	2	1
y1	0.0019	0.0026	0.0027	0.0024
y2	0.0022	0.0026	0.0026	0.0024
x1	0.0046	0.0046	0.0034	0.0047
x2	0.0046	0.0046	0.0021	0.0043

I want to make sure I get everything done at the machine shop in 1 stop if possible. Heres the current list of things I have:

• Check main oil clearances and hone/polish if needed, target 0.0022
• Replace STD ACL rod bearings with 0.001 oversized, hone/polish to 0.0022
• Bore cylinders to 85.5mm pistons, target 0.0035-0.0040 PTW
• Rings gaps top = 0.020, bottom = 0.024
• The crank is basically perfect, should it just be cleaned or should I have it polished?
• Should the rotating assembly be balance?
• Hot tank, surface deck - anything else?

 

[1990TSIAWDTALON]

Here, you need one of these.
Print and fill out EVERYTHING you measure. Then you have a "Blueprint Sheet".
Pops

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[athlete3344]

Thank you!

 

[1990TSIAWDTALON]

Oversized bearings will make your oil clearance larger. Undersized bearings will make them tighter.

 

[athlete3344]

Youre right, I definitely had that backwards and Im glad I didnt order anything else yet.

I actually decided to take a big step back since I wasnt too confident with my measurements and the time between measurements (crank was taken over a year ago when I was just learning to use mics). Ended up buying an ultra sonic cleaner for the head, and tossed a couple sets of 1g rods in there to too. Going to remeasure crank, rods, and check w/ plastigauge again. I may end up just getting a set of Eagle rods and call it a day.