2270 Build thread, Looking forward to making all of the mistakes! Options

[vjb206]

Hey folks! I've got...

• Case halves from an old 1.7 (cleaned as best I could)
• 2270 crank + P&C kit
• #163/86b Web Cam
• 2.0 heads with 44X36 valves, where I'll be installing dual springs and 38mm exhaust valves
• Upgraded oil pump and other goodies

So my first question for the community has to do with ensuring the rotating mass is spinning freely/correctly…

I started by measuring all of the the main journals on the crank and I got a range from 2.358” - 2.360” (I used a digital caliper and I'm pretty sure I did this correctly).

Then I “dry-fit” Silverline STD/STD main bearings into the case (sans crank), torqued everything down, and got 0.003” in radial play (I used a cylinder bore dial gauge for the first time, and I think I did it correctly).

The spec-sheet says radial play should be between 0.06” - 0.10” (0.03” - 0.09” for #2); and I have 0.003." I'm a MINIMUM of 0.057" off, is that normal? What's my next step?

1. Stop pretending I know what I'm doing and take it to a machinist for test-fitting and honing (I'd like to keep cost down so this is my less preferred option)
2. DIY: hone 0.06" off all bearings (what's the right honing tool / approach here?)
3. Order different bearings (if so, which?)

[Superhawk996]

Yeah - hit pause. Something is wacko - probably measurements.

Technicalninja’s technique suggestion is good to minimize error swapping back and forth between devices.

There is also an aspect of these methods (snap gauges, dial indicator bore gage) that is overkill. The main reason to use gauges like you are is to determine roundness of the main bearing bore.

At this stage in the game - let’s just focus on bearing clearance.

Since you have all parts, you can use Plastigage. Plastigauge is a more direct measurement and avoids the math and multiple gage use issues.This method will give you a good rationality check on the math you’ve done. Plastigage will measure clearance very precisely but won’t tell you much about roundness. For now, that’s fine.

I’m not going to spell out the whole process to plastigage parts here. Google and YouTube will fill in the details. Get a couple strips each of Plastigage in red and green from your local flaps. The only trick to using Plastigage is to make sure the crank doesn’t move while you’re tightening the case or re-splitting the case. If the crank moves, it will smear the Plastigage and you’ll get an erroneous measurement. Overall, a much simpler, direct way of measuring bearing clearance.

Green =.001” - .003”
Red = .002” - .006”

This will cover any plausible range of clearances you should be playing with. If you truly have zero clearance, you’ll squish out the green to a width way wider than the .001” marking on the paper package / gage.

Under no circumstance will you ever hone a T4 bearing to size.