|
|
| Re: [GMCnet] Head bolt torque [message #67875 is a reply to message #67874] |
Sun, 20 December 2009 16:41   |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
|
Senior Member |
|
|
| Gary Casey wrote on Sun, 20 December 2009 16:32 |
What is the correct head bolt torque for the 455? Just about to put mine together.
Gary
Gary,
The manual says 85 (eighty five) ft lb after cleaning and dipping in engine oil.
Dennis
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
Dennis S
73 Painted Desert 230
Memphis TN Metro
|
|
|
|
| Re: [GMCnet] Head bolt torque [message #67889 is a reply to message #67874] |
Sun, 20 December 2009 19:37 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
| Gary Casey wrote on Sun, 20 December 2009 17:32 |
What is the correct head bolt torque for the 455? Just about to put mine together.
Gary
|
Gary,
Do yourself (and the engine) a real big favor at a couple of places here.
I know the manual says dip the Bolts in engine lube oil, but they say that just to get past the people that would lubricate only the threads. The fact is that lubrication under the head is just as important. The problem with dipping the entire fastener is that you then should wait long enough for most of the lube oil to run off. You can do better by putting a small amount of under the head and a line down the thread and drop it in. Then run it down with a socket on a long extension spun between flat hands. If your not good at that, a 3/8 speed wrench is OK, but be careful. You do this to be certain that there is nothing in the threads. You should be able to spin the fastener home with very little effort. If it catches, this is the time to find out why.
The stock head bolts do not include a hardened washer. If there is any visible deformation of the bolt boss, that can cause a significant change in the torque/tension relationship and the tension in the fastener is the real reason for using a specified torque.
Next thing, and this is big.
Pull all the bolts to tension(torque) and let the engine sit at least a day. Go back and pull on them all again. Most of then will move. You can do this after the valve train is installed, but I usually find that setting heads and pulling all those bolts to load makes a good place to end a day.
This is a result of the low temperature creep of the gasket's body material. They all have some creep. This amounts to free (as in zero cost) additional tension in the assembly. This can't hurt anything.
It is even better if you can do the re-torque after a few thermal cycles, but that is just not realistic in a coach installation. I don't CARE what Henry (aka Smokey) Yunick said... Retorque is always good if you can do it. Less important in hard joints, like drive axle flange screws, but it can save a marginal gasketed joint from failure. (Most head gaskets are marginal.)
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
| Re: [GMCnet] Head bolt torque [message #67890 is a reply to message #67874] |
Sun, 20 December 2009 19:35 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
|
Senior Member |
|
|
If your using the factory head bolts the manual says,"Clean and dip
the entire bolt in engine oil before tightening to obtain a correct
torque reading". The torque 85 FT/LBS for the 455 Cu/in and 130 FT/
LBS for the 403 Cu/in engine using the correct tighten sequence show
in Fig 28 in Engine 6A-39.
J.R. Wright
> What is the correct head bolt torque for the 455? Just about to put
> mine together.
> Gary
>
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
