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]

I should have been more clear. You can only use Plastigage on the split bearing.

However, it is pretty reasonable to use that single split bearing as a proxy for the others while still being able to use it as a double check to your measurements.

Here’s the problem with assuming a free spinning crank equals success, too much clearance is as bad as too little clearance. Too much clearance results in low oil pressure.

Since you assembled and spun it here’s what we do know. You don’t have a zero clearance condition as your 2nd set of measurements was indicating.

What to do next?

I’d suggest going back and learning how to get your bore gage, micrometer measurements to agree with what Plastigage indicates on the split bearing.

I’d also spend some time measuring and Plastigage’ing the connecting rods.

At this point it’s just time to assemble & disassemble parts. The opportunity to learn here being the primary goal. The secondary goal is that you should eventually be confident that you know what your bearing and rod clearances are.