195.6 ohv performance engine build

the previous build was [what i thought was] a decent and solid rebuild. static balanced the pistons and rods, polished and smoothed ports and trough, Weber 32/36 carb, and an "RV" regrind cam from Galvin's AMC. EDI6 6 ignition, etc. ran great, from 2010 til august 2016.

the exact cause of the failure isn't exactly known, but probably too tight bearing clearances, and as it turns out, sloppy machine work. 

the new engine will have custom-forged pistons, compression raised to about 9:1, with a modern ring set. adequate and careful clearances. rotating parts balanced. careful 3-angle valve seats, and mainly, good work done with care by a pro.

Pete took a small scuff cut off the top of the block and the damn thing ain't flat at all. said the head was the same way. when we pulled the head there were signs of headgasket leakage between the siamese pairs where the gasket area is small. i'd been doing annual compression tests so no gross error/failure.

i found a NEW, not rebuilt, not NOS, oil pump. my old one seemed fine, but i assume there's got to be some slight ware on the pump body bore. though we determined (here, in another thread) that the partial-flow filtration oil pump system is actually fine, i'd already changed mine over to full-flow, with a custom pump top cover, and i'm adding a big fat oil cooler with thermostatic fan. it occurred to me that this engine was intro'd by Nash as a 75hp flathead, stroked a couple times, then AMC put the OHV on it, more than doubling the power output yet keeping the same oiling and cooling setup. and i measured 230F+ oil temperatures on one quite ordinary LA 70 mph freeway run. t'aint adequate as-is. and i've got a big aluminum radiator and a computer-controlled electric water pump, head stays solid 188F plus/minus 4F no matter WHAT.

so the pistons have arrived, i will go take pictures of them tomorrow, the block will be done this week or so, then the heads.

on bearing clearancing: since there's not a wide range of .001" over/under bearing sets available (surprise) the crank will get ground, installed, measured, and re-ground if necessary. Pete's got some solid machinist who can reliably take .001" off all journals. all i have to do is, umm, pay for it.

Frank: yes, all this old stuff has been run so long, rebuilt so many times, that i'm now reassessing some of my 'iron pile'. for example, that T96-OD i was running, and broke the 2-3 synchro on. it's been rebuilt twice by me, maybe once before that. its worn out! i had been assuming i'd save it for someone as a core or parts, but i'm not sure that's doing anyone any favors. the 3.78 axle and driveshaft, same thing. other than bent, what could go wrong with a driveshaft?!! well the yoke bearing cup bores bell and stretch, and are slightly loose. i never could get the vibration out of it. even with new parts it had play. if you saw my web page on it you can see i spent some effort on it. 8" and even 9" clutches, no new parts.

also this stuff was "light duty" then used 2X, 3X past product life. it's worn out. and unlike Chebby and Furd, there's just not that many cores/parts to go through to cherry pick. 

granted i'm doing unreasonable things now. for a sunday driver this is less of a problem (though still not a cake walk). s'ok, i'm having fun. i think (lol).