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?)

[technicalninja]

I'm a big believer when making a "comparison" measurement try to keep all of the readings on a single tool.

here's how to do bearing to journal comparisons the normal way.

Bearings installed in block dry, torqued up.
Use "snap expanding" gauge set to find inner diameter. You have to be stupid centered and straight. Lock gauge. Measure with micrometer. Measure crank journal with same micrometer.

Even if you have a low-quality tool the difference between the two readings on that singular tool will be more accurate than using both a dial indicator and a micrometer together any day.

How to do it with a floating bore gauge: Mic crank, lock mic. carefully affix in vice and zero dial indicator to the micrometer. You have now zeroed your dial indicator to the crank journal and what you read inside the bearings bores is your actual clearance.

Both methods are using a single tool to actually take the measurement.

Hope this helps.

Never in my life have I had to have a set of main/rod bearings honed to size.
I've used specific +/- .00025 stuff to blueprint.
I'm hunting tenths at that point. PIA!

You're way off IMO. Too far off for a bearing screw up.

Try different techniques.

I wouldn't take that to the machine shop yet...