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]

Hopefully this doesn’t come off as condescending - that is not my intent .

Slow down - you’re not ready to do that build yourself based on what you’ve written and the questions you’re asking.

I’m not saying you can’t do it. Just that you’re not ready.

Read Tom Wilson book. Watch Raby DVD. Keep asking questions.

1st - Don’t measure crank journals with a caliper. It doesn’t have the accuracy and repeatability for the job. A Micrometer is the proper tool, is repeatable, and is 10 times more accurate than a caliper. You shouldn’t be getting a variance of 0.002” when measuring journals. Not within a single journal nor .002” across all journals. If you had .002” of variance across journals - the crank would need to be reground in order to get proper bearing clearance.

Sanity check: rule of thumb for automotive main bearing clearance is 0.001” per inch of journal diameter. So about 0.0024” - 0.0025” would be the expected target clearance based on that rule of thumb.

Edit: a digital caliper is only accurate to about .001” which is almost 1/2 of the target clearance. Not accurate enough for the job. A micrometer is accurate to about 0.0001”. This is the “why” behind the need to use a micrometer for journal measurements.

2nd - you are confusing bearing clearance with some other radial play measurement.

3rd - no automotive engine bearings are run with 0.06” - 0.1” of clearance. Not sure what the “spec sheet” is that you are referring to. Are you confusing specs between inches and millimeters? Post details of where you are getting info from and make sure it is correct information before proceeding.

I would suggest having machinist confirm measurements if you don’t have proper tools.

4th - any talk of honing bearings and what tool to use is crazy talk.

Slow down - learn more. Props for coming here with the questions before doing anything rash. (IMG:style_emoticons/default/beerchug.gif)

You’ll find help and lots of folks here willing to help you succeed. I’ll apologize in advance if it seems I’m being harsh and not trying to help.