Landracing Forum Home
November 17, 2017, 08:05:27 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
News:
BACK TO LANDRACING.COM HOMEPAGE
 
   Home   Help Search Calendar Login Register  


(Note: Donations are not tax deductible)







Live Audio Streaming and Archives of Past Events
Next Live Event: TBD
Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 [25]   Go Down
  Print  
Author Topic: Inline-four crankshaft  (Read 102494 times)
0 Members and 1 Guest are viewing this topic.
RidgeRunner
Sr. Member
****
Offline Offline

Location: Ashfield, in the Territories of Western Massachusetts
Posts: 718




Ignore
« Reply #360 on: August 13, 2017, 05:36:09 AM »

     Great news!  All the best for everything to continue to  go well now.

     Great chat with you at Loring, looking forward to another one when I'm not quite so busy.

               Ed
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 64
Location: backwoods Oregon
Posts: 4438





Ignore
« Reply #361 on: August 13, 2017, 09:45:26 AM »

This was explained to me while I was in my early 20's so some things are sorta vague now.  Picture in your mind two moving smooth plates with one laying on top of the other and an oil film between them.  One plate is moving to the right at the same speed the other plate is moving to the left.  The oil at the boundary where it touches the plate is moving at the speed of the plate in the direction the plate is going.  The average speed of the oil halfway between the plates is zero.

The relationships between distances and velocities are "shear."  The shear increases when the plate velocities increase.  It also increases when the plates are closer together.  Lubricants have a limit of shear they can withstand.  The clearances between the moving objects need to be wide enough to keep the shear within acceptable limits.

Flexure can cause clearances to decrease between a shaft and a journal during operation beyond their values when the mechanism is static.  This can lead to lubrication failure.  The specific instance where I learned this was the outside crank journal bushing on a BSA A-65 twin.  There is no center journal on these cranks and they flex.  The clearances at the ends of the journals would be tight in some places due to this flexure.  Sometimes it would occur on the edges of the rod bearings.

What I did was to build the engine, break it in fairly gently, run it hard for a short time, and then tear it down.  Then, I would look for signs of overheating or galled spots on the journals and bushings, scrape them, and put the engine back together.  What I was trying to do was to keep the oil film shear within the limits the lubricant could withstand.   

   
Logged
Jack Gifford
Hero Member
*****
Offline Offline

Age: 77
Location: Phelps, NY
Posts: 1049





Ignore
« Reply #362 on: October 24, 2017, 11:26:18 PM »

No excitement here... which is good news- nothing gone "bang", broken, etc. grin Engine has been test-run a few times now. Still tweaking the fuel system for a reliable idle- it's down to about 1,700 RPM but air/fuel isn't optimal yet.
Firing it up has been troublesome. The cam-driven Enderle pump doesn't want to draw fuel (about 30" above the tank) when cranking. I've had to manually fill the tank-to-pump line for it to begin pumping. My alky experience has all been with a tank above the pump for gravity feed, so I don't know whether this is to be expected with such a slowly-turning gearotor pump (half of cranking speed)? Pump is new and seems to function okay once engine is running. I'm in the process of mounting a test setup tank up at the pump level, but in the lakester I won't be able to put the tank quite that high. And I won't have the option of push-starting due to the full-centrifugal CrowerGlide clutch.
« Last Edit: October 24, 2017, 11:33:02 PM by Jack Gifford » Logged

M/T Pontiac hemi guru
Crackerman
Full Member
***
Offline Offline

Location: Alvord, Tx
Posts: 182




Ignore
« Reply #363 on: October 25, 2017, 12:07:24 AM »

An electric primer pump and check valves installed in a certain configuration does help it start. If you can find a small electric pump tha will stand up to alcohol.
Logged
Jack Gifford
Hero Member
*****
Offline Offline

Age: 77
Location: Phelps, NY
Posts: 1049





Ignore
« Reply #364 on: November 14, 2017, 12:12:38 AM »

If it's a problem after situating everything in the car, I guess I could look for a high-flow check valve (equivalent flow of -12 lines) to keep fuel from draining out of the pump feed line when not running.
« Last Edit: November 14, 2017, 12:14:42 AM by Jack Gifford » Logged

M/T Pontiac hemi guru
Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 [25]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!


Google visited last this page October 25, 2017, 03:43:31 AM