Have a 68 nodular crank that is all pollished down and had bad luck several times with the engine build, the machine shop was getting the bearing clearances incorrect, the crank is turned all the way down on the crank journals, just wondering if the crank can be welded and machined back to stock spec? has anyone ever done this and how reliable is it?
thanks for any feedback.
Robert
1969 442

 

This is common practice with heavy duty truck engines (for example). Be sure you use an experienced shop. One advantage of welding is that the finished bearing surface can be hardfaced for additional wear resistance.

 

Yes it can, its expensive, but it can be done, I have seen it done on a 427 Chevy. It looks really cool when its done. and its very strong, but I WARN YOU !!! search for a very experienced shop. It doesnt matter if you have to ship it half way across the US, do it! As it sounds now, the shop you have been going to isnt the best. Good luck

 

Its funny, i have built many performance engines, and this engine is the first that i have been stumped on. i was going off of stock clearances, using the perfered crank to run via mondello, 68-69 and spinning it up to 6k. the oil was slingging off the crank journals and burning up the mains..rods and cam bearings were always ok. I had a old guy disect the engine and said that i should be blowing the doors off with oil pressure, he said that the trick to making these engines live is TIGHT clearances. told the machine shop to put the mains at .001 and rear main at 1.5-.002" and the motor is alive and very healthy. I did everything i knew to do with the oiling system and had some help from mondello and a buddy that used to build don garlands nhra engines for his dragisters. I used this shop because they were the only shop that had torque plates for the olds. It wasn't the machine shops fault, because the clearances were right at stock spec, from manual. I plastica guaged it every time. I think it was not knowing the characteristics of this engine. I have never heard of this before, but it seemed to work. the engine has a sh$t load of oil pressure even hot...@ 195 degrees and 3k rpm, its got 50-60 psi, 20 psi at idle...now when its cold i will blow the oil filter off...yes i have done this....well over 100 psi during a rev. Does any of this sound right??? The engine is doing great and has been together for about 5yrs now.. don't drive the car much though. its probable got 1500 miles on engine and oil is very clean during oil changes!
appriciate any feed back on this issue!
Robert

 

Rule of thumb is at LEAST .001 clearance for each inch of journal diameter.
http://72.22.90.30/phpBB2/viewtopic....side+clearance

Read the whole thing, especially what BTR Bill has to say.

 

his specs seam really loose, thats about what they were out ot the book and the mains were burning up? I still like tight specs.
robert