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?)

[vjb206]

Again, really, really great advice. Thank you @technicalninja , @Superhawk996 , and @cgnj

I went to my FLAPS and picked up PG. Since I'm checking the mains I needed to thread it in between the crank and the bearings (on all but #2 obvi) but I couldn't get it to go through without breaking. Perhaps there's some trick to "par-flatten" it just enough to get it in between the mating parts, but I couldn't do it.

So I called my local machinist and he said that he wouldn't take any material off the crank because it's chromoly and it'll lose some sort of protective coating. He told me to call the folks I got the parts from (AA Pistons).

Then I called AA and spoke to a very helpful person on the phone and he reassured me that the STD/STD Silverlines are the right bearings for the crank in the 2270 kit. He recommended I wet-fit it and "feel" if it spun freely and/or if there were any binding spots.

So.... I just did a wet fit and stopped futzing about ¯\_(ツ)_/¯

Here's the result:
(IMG:http://www.914world.com/bbs2/uploads_offsite/media.giphy.com-23760-1703800335.1.gif)

I mean... the darn thing spins that's for sure. I still have no idea whether I need to do anything to the crank/bearings/line bore/etc. since I don't have reliable measurements to backstop me.

FWIW my machinist really doesn't want to be bothered with this job so perhaps I'll call around for someone how does? I did want to do this myself (and learn in the process), but I'm just not sure what my next step is other than to send it and hope.

[Superhawk996]

So I called my local machinist and he said that he wouldn't take any material off the crank because it's chromoly and it'll lose some sort of protective coating. He told me to call the folks I got the parts from (AA Pistons).


FWIW my machinist really doesn't want to be bothered with this job so perhaps I'll call around for someone how does? I did want to do this myself (and learn in the process), but I'm just not sure what my next step is other than to send it and hope.

Time to find a real machinist

chromoly cranks can be ground if needed. How exactly does he think it was made in the first place?

If the crank needs to be heat treated and / or nitrided that’s a whole different ballgame typical of Porsche 911 crankshafts but to say it cant be done is moronic and I wouldn’t trust that guy at all.

The fact that he doesn’t want to be bothered with the job of measuring - fitting doesn’t bode well for him either. I wouldn’t expect it to be done for free but that’s different than doesn’t want to be bothered. Jeesh! (IMG:style_emoticons/default/ar15.gif)