Re: Crankshaft Drag Revisited - (Joe, Voyce, Bidonde and Purcel)

Posted by DJ.Voyce on March 08, 1998 at 13:13:05

In Reply to: Crankshaft Drag Revisited - (Joe, Voyce, Bidonde and Purcel)
posted by Gordon Biggar on March 08, 1998 at 01:13:20

G'Day Colonel,
Glad to hear your problem's sorted. The object of this posting is just to point out that under NO CIRCUMSTANCES WHATSOEVER should the bearing caps be switched around on the conrods (I'm sure Gordon meant nuts & not caps) as they are machined as a unit & will not form a perfect circle with a foreign rod. The same will apply if the cap is reversed when fitted to the rod. If the bearing caps are causing an increase in drag when tightened, I would seriously consider re-checking the clearance with Plastigage & look for any shiny spots on the bearing surface just as a matter of course.
Regardz
DJ.
OutOfAfrica A's

: Many thanks!

: The delay in my response is not one of disinterest, by any means.I can now understand why Ford used electric motors to break in engines.It appears that my shoulders are not as strong as they used to be...

: I reached Les Andrews in California.His 35 foot-pound guide is only a rule of thumb from many engine rebuilds.He noted that a figure in the neighborhood of 45+ foot pounds was nothing to be concerned about.(He did note that his measurement of piston-to-sleeve clearance should have read, "as taken at the base of the piston skirt."Good catch, Monsieur Voyce!There was barely .001 inches on all four of my readings, which made me feel better.)

: I followed DJ Voyce's approach of loosening the connecting rod bolts, one by one.The increase in drag, contrasted with just the main bearing caps torqued to specs, very definitely appears to be related to the connecting rod caps themselves.(I have included a table of torque readings below for your bedtime reading.)One of the problems may relate to the fact that the positioning of the castle nuts after torquing left the "towers" of four of the nuts squarely in line with the cotter pin holes.This required additional torque -- it turns out -- of 12-15 foot pounds to line up the nuts appropriately.I had initially assumed that backing them off -- with only 35 foot pounds of torque to begin with -- might be too lenient, providing too much play in the caps.I have since learned that one trick to solve this dilemma is to switch around the caps.The other, if that doesn't work, is to mill down very slightly the base of the nut.(The latter came from Les; I can't say that I would have thought of that.)

: I'm not sure what the following table proves, but it (as well as your comments) has given me confidence to proceed.

: Original Torque after Initial Rebuild = 58 foot pounds
:
: Torque after Loosening and Retightening all rod nuts,
:using the procedure described above for
:aligning castle nuts = 49 foot pounds

:
: With Conn. Rod Cap #1 Loosened:48 ft. lbs.
: #1 " :35
:#1-3 " :27
: With all Loosened: 26

:
: The reverse procedure was used for the tightening (e.g., starting with #4 and working forward).The table below is reversed to correspond with that above

:
: With all Tightened:49 ft. lbs.
: With #2-4 Tightened: 53 ft. lbs.
: #3 ": 40
:#4 ": 30

:
: The only explanation that I can provide for the 49 foot-pound reading is that by that time the crank had been getting a good workout -- as had my shoulder.

: Thanks for your collective inputs.

: Regards,

: Gordon Biggar
: Houston, Texas


Follow Ups:



Previous PageE-Mail Comment to WebmasterPost New MessagePrint MessageClose Window

© 1996-2010, Ahooga.Com

Anti Spam