Worn Rod Journal
Thread Starter
|
New User
Joined: Apr 2019
Posts: 10
Likes: 0
Option 1 it is. I put it all back together and put the pan on. Its ready to go. I decided to paint the chipper now that the engine is out of it, so it will be a while before engine results are known. I will post back on how it runs. Thanks for all the advice guys. It has given me some confidence. Weather it works or not, I think it is the best choice at this time.
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
I once re-bearing'd a Triumph TR7 4-cylinder - the lower-end in those things were built like the proverbial brick outhouse 
Forged everything, crank, rods and pistons.
Without using plastigauge, I put a dial-indicator on the rod cap while the piston was at BTDC and moved the rod up and down to get an idea of the clearance. Was way over factory spec, probably 2 or 3 times as much as yours are. That dang thing ran right up to 7K RPM for over a year before I pulled it to put a total-rebuild in it's place.
When I took it apart out of curiosity, it looked like the day I put it together, and that cheesy clearance check with the dial indicator still showed the same clearances... I was running 20W50 and had shimmed the oil pump pressure relief valve so the pressure was on the high side at around 80lbs at cold idle though
Forged everything, crank, rods and pistons.Without using plastigauge, I put a dial-indicator on the rod cap while the piston was at BTDC and moved the rod up and down to get an idea of the clearance. Was way over factory spec, probably 2 or 3 times as much as yours are. That dang thing ran right up to 7K RPM for over a year before I pulled it to put a total-rebuild in it's place.
When I took it apart out of curiosity, it looked like the day I put it together, and that cheesy clearance check with the dial indicator still showed the same clearances... I was running 20W50 and had shimmed the oil pump pressure relief valve so the pressure was on the high side at around 80lbs at cold idle though
Thread Starter
|
New User
Joined: Apr 2019
Posts: 10
Likes: 0
I once re-bearing'd a Triumph TR7 4-cylinder - the lower-end in those things were built like the proverbial brick outhouse Forged everything, crank, rods and pistons.
Without using plastigauge, I put a dial-indicator on the rod cap while the piston was at BTDC and moved the rod up and down to get an idea of the clearance. Was way over factory spec, probably 2 or 3 times as much as yours are. That dang thing ran right up to 7K RPM for over a year before I pulled it to put a total-rebuild in it's place.
When I took it apart out of curiosity, it looked like the day I put it together, and that cheesy clearance check with the dial indicator still showed the same clearances... I was running 20W50 and had shimmed the oil pump pressure relief valve so the pressure was on the high side at around 80lbs at cold idle though
Forged everything, crank, rods and pistons.Without using plastigauge, I put a dial-indicator on the rod cap while the piston was at BTDC and moved the rod up and down to get an idea of the clearance. Was way over factory spec, probably 2 or 3 times as much as yours are. That dang thing ran right up to 7K RPM for over a year before I pulled it to put a total-rebuild in it's place.
When I took it apart out of curiosity, it looked like the day I put it together, and that cheesy clearance check with the dial indicator still showed the same clearances... I was running 20W50 and had shimmed the oil pump pressure relief valve so the pressure was on the high side at around 80lbs at cold idle though
I wish there was some test data on clearances vs oil viscosity vs bearing life. I am sure engineers have done extensive testing on this subject. The recommended allowable clearances in the engine specifications are surely the result of tests. The high side allowable must be the point where the bearing will deteriorate with use but the rate is unstated. Adding more oil pressure and viscosity should stabilize the additional clearance so long as the other bearings can survive the new conditions. Without test data we are guessing. Your experience is an excellent example of viscosity, pressure and clearance. If only there was a chart showing the extended relationship.
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
I think another thing that determines how much oil stays on the bearing is rod big-end end-play. The more room around the sides of the rod, the more oil will exit the gap. But maybe I'm overanalyzing at this point 
Thread
Thread Starter
Forum
Replies
Last Post
v8only
335 Series- 5.8/351M, 6.6/400, 351 Cleveland
16
Aug 1, 2010 11:27 PM
KJKozak2
Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460)
12
Aug 5, 2003 02:47 PM
