WELL AS SOME OF YOU ALL KNOW I HAD TO TEAR DOWN MY 302 IN MY 71 CAUSE OF A ROD KNOCK. AND WHEN I TORE IT DOWN IT WAS WAY WORSE THAN EXPECTED -THE CRANK WAS UNUSEABLE- SO I PULLED A CRANK FROM ANOTHER ENGINE AND HAD IT CHECKED, POLISHED AND BALANCED. I STARTED RE-ASSEMBLY OF THE ENGINE TUESDAY AFTERNOON FROM 7-10 AND FOLLOWED UP ON IT LAST NIGHT FOR ABOUT THE SAME AMOUNT OF TIME (SINCE I DONT GET HOME TILL 6PM AND I HAVE TO WORK IN MY DRIVEWAY). WHEN I GOT THE CRANK BACK HE CHECKED OUT OK BUT HE SAID IT SHOWED 'NORMAL WEAR', SO I ORDERED NEW ROD AND MAIN BEARINGS WITH A .001" OVERSIZE, AS HE ADVISED. I PLASTIGAGED EVERYTHING WHEN PUTTING IT BACK TOGETHER AND IT COME UP .0019 COMPRESSED. ANYONE ELSE THINK THIS IS KINDA ON THE MINIMUM SIDE?:16suspect AT THE TIME I JUST NEED TO GET THE CAR BACK TOGETHER AND GOING SO I WENT AHEAD AND PUT IT ALL BACK TOGETHER AND EVERYTHING SO TONIGHT ALL I HAVE TO DO IS SOME BOLT TIGHTENING HERE AND THERE AND PUT THE FRONT OF THE ENGINE BACK ON (IE. TIMING COVER, WATER PUMP, ETC.) WISH ME LUCK ON DRIVING THE CAR BY SATURDAY (WEATHER PERMITTING FOR WORK)
Is it hard to rotate by hand? Thats a bit tight on the clearences,, .002-.003 is optimum. It will wear in sure, but will be hard on the bearings. Before you fire it up,,, once you have primed the oiling system, rotate the engine a few revolutions, maybe 15-20 times,,, that will help set the wear pattern in the bearings and the crank,,, if you do this upon start up, the initial thrust from start up will be harsh,, and can start to spin a bearing before you even get to fire up. Id put in a stock bearing before you put the pan on,, check the clearence,, if its .002-003 area,,, run it,, If the journals are that far off,, best to get a reground crank and start over. Its gonna score the journals and the bearings being that tight if its not broke in properly,,, watch for shavings in the oil,,, if you got alot of em withint the first 20 minutes of running, you got trouble. JMHO,, Chad
my engine kit i got from coast high performance was about 0015. And, last time i had it out i checked the bearings and thay look great so that should be just fine.
Plastigage is not my choice of measuring, set of good micrometers will tell the true clearance if they are calibraided correctly. Have seem too many tore up cranks and bearings, using .001 clearance. You will have to run some 5W-20 oil for safety, if you only have .001 on the rods. Drive easy and after a few thousand miles, change to 10W-30. Make sure you have good thrust clearance and side rod clearance too. .0025 would be minimum for me, and .003 for hard driving. JMO
That .0019" he posted is pretty close to .0020". I have never gauged this stuff, so I am just wondering if that .0001" is that big a deal. I use the 'rotate it' method... If it isn't too tight, go with it. Real technical like... Dave
Well Im Gonna Spin The Assembly A Few Times Before Startup And We'll See What Happens.... Ill Keep Everyone Posted
I'm new here, but I build a lot of engines including SBF's. A good rule of thumb: You want .001" of clearance for every inch of journal diameter. This is what I shoot for on all of my engine builds. If I'm below .002 on a SBF rod journal I usually have the rod journals polished again and it takes care of it. Good Luck. -Dan
Well I Got It All Back Together And Fired Up. So Far So Good. Everything Is Looking Great And Sounded Great. Oil Pressure Is At 55-60 Psi Cold And Is Now At About 22-27psi Warm. Im Gonna Drive It Around Town For A Bit To Get Everything Broken In And We'll See What Happens From There. Thanks To All For Your Advice And Help, As Always!
Glad to hear it. Since you mentioned it, I was wondering where others see their oil pressure. I have always been around 55-60 cold but never lower than 40-45 hot. That is running a melling pump. Just curious..(not a thread highjack!)
Mine are .0015 according to plasti-gage, and I am told that it's fine. I know race-engines need to be looser, but this is for the street, and I am running a standard-volume oil pump...
