| [GMCnet] Piston rod stretch in the 455 [message #279831] |
Sat, 13 June 2015 20:06  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
|
Senior Member |
|
|
Hi Chris,
You may want to call S&J in Spokane and talk with the owner whose name is Johnson. I think you will find that they are well aware of these and other issues associated with remanufacturing Olds and other engines using numerically controlled machines. I would agree that it is hard to find really good machine work done manually with worn out tooling. I can’t imagine anyone would have still in-spec manual tooling for a low volume engine that has not been made for 40 years. That said, I would assert It is not hard to find really good machine work using state of the art computer controlled tooling. So long as the programming was correct to begin with, it stays that way.
Normal disclosures, no affiliation with S&J, no compensation, etc.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
===============
Message: 8
Date: Sat, 13 Jun 2015 15:37:20 -0600
From: Chris Tyler
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Piston rod stretch in the 455
Message-ID:
Content-Type: text/plain; charset="utf-8"
Bob, I think you'd have to agree all GM rods arent the same. Your Chevy rods in your Yenko were a better design even before you massaged them I would
bet.
Olds rods arent the best, but at least they arent the cast junkers that Pontiac used. Ask me how I know.
Rod stretch is more of a problem with RPM, and more with free reving without a load from what I have seen
Id have to agree that lugging is a bigger problem for our application. Piston speed [discussed elsewhere today] is higher with a longer stroke, and
energy being a function of mass x velocity it goes up exponentially, but not a problem with our RPM range. True, there is more friction, but via more
leverage and a longer burn time, more torque.
When were talking about lugging, its really about preignition or detonation that spikes the cyl pressure or worse, creates too much pressure while
still compressing BTDC. Plays hell with rod bearings and pistons, especially cast
Once the bearing goes, the rod follows.
Guys that worked for GM I knew swore Olds engines were more precisely assembled than other GM marks. I would bet their tolerances were on the mark,
and most rod failures are either high milage or after a shoddy rebuild on the rod. The clearance is critical, and the bearing is held in place by
proper crush. I dont know if olds uses tabs, but I have seen a lot of poorly resized rods that were not recut correctly and failed
Hard to find really good machine work anymore.
--
76 Glenbrook
======================
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jerry & Sharon Work
78 Royale
Kerby, OR
|
|
|
|
| Re: [GMCnet] Piston rod stretch in the 455 [message #279856 is a reply to message #279831] |
Sun, 14 June 2015 00:12  |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Jerry,
I agree that experience is beginning to show that S&J appear to be building quality engines for our GMC's and I agree "that it is
hard to find really good machine work done manually with worn out tooling."
However, there are lots of small time engine machine shops that can't justify the expense of numerically controlled (NC) machines
whose skilled machinists use properly maintained manual tools to obtain just as good results as the ones with NC machines.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Gerald Work
Hi Chris,
You may want to call S&J in Spokane and talk with the owner whose name is Johnson. I think you will find that they are well aware
of these and other issues associated with remanufacturing Olds and other engines using numerically controlled machines. I would
agree that it is hard to find really good machine work done manually with worn out tooling. I can't imagine anyone would have still
in-spec manual tooling for a low volume engine that has not been made for 40 years. That said, I would assert It is not hard to
find really good machine work using state of the art computer controlled tooling. So long as the programming was correct to begin
with, it stays that way.
Normal disclosures, no affiliation with S&J, no compensation, etc.
Jerry
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
|
|
|
|
| Re: [GMCnet] Piston rod stretch in the 455 [message #279927 is a reply to message #279831] |
Mon, 15 June 2015 01:45 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
|
Senior Member |
|
|
"However, there are lots of small time engine machine shops that can't justify the expense of numerically controlled (NC) machines
whose skilled machinists use properly maintained manual tools to obtain just as good results as the ones with NC machines. "
Absolutely. Plus having the latest and most expensive equipment is no guarantee of precision if the operation is slipshod.
Locally, the one machine shop I trusted for many years just closed down. Joe was meticulous almost to a fault.
Have visited several for the LS6 engine Im about to build. Havent found one yet.
76 Glenbrook
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
