torque-to-yield bolts query

Ken Haase · 10-30-2008, 01:34 AM

I just picked up a used Chev 454HO crate motor. Does anybody know if those come with torque-to-yield head bolts?

Also, any idea how much increase in lift can the stock hydraulic roller lifter set-up tolerate? I'd like to get to the .580-.600 range if possible. Or am I going to need the retro-fit lifters? Thanks for any help.

Ken

Moparteacher · 10-31-2008, 01:25 AM

TTY fasteners are usually used where an aluminum part (cylinder head ) is being fastened. Aluminum expands and contracts greater than cast iron. This expansion requires a bolt that will stretch and retract while maintaining clamping force.

I doubt your 454 utilizes TTY bolts if it has iron heads. Are the heads iron?

Ken Haase · 11-02-2008, 02:42 AM

Yes, Gary, the heads are iron. And, my recollection regarding the appearance of single-use bolts is that they are dull looking, almost like they have been bead blasted. Am I correct on that?

I was disappointed that these Gen VI head bolts still go into water, unlike the aftermarket blocks.

Thanks for the reply. Ken

BillK · 11-02-2008, 09:23 PM

Ken,
They are not torque to yield, however ......

Most of the later model 454's use the "torque plus angle" method of tightening the head bolts.

There is a big misconception that any time a fastener uses the "torque plus angle" method of tightening ( such as 30 ft lbs plus 90 degrees) that it means the fastener is torque to yield. This is not always the case !!! This is simply a more accurate method of getting the required stretch on the fastener.

There are a lot of fasteners (Oliver rod bolts for one) that use the "torque plus angle" method of tighteneing, but are definitely not torque to yield.

Then there are some Honda head bolts that are strictly torqued to a certain ft lb figure, but those bolts are torque to yield and have to be replaced after each use.

Also, torque to yield bolts are certainly used on cast iron heads.

Ken Haase · 11-05-2008, 01:46 AM

Bill K., thanks for the info. Very informative. Maybe I'll just buy ARP fasteners.

Along the same lines, is there a steel shim head gasket for the Gen VI blocks?

Thanks again. Ken

10-30-2008, 01:34 AM	#1
Ken Haase Member Join Date: Mar 2007 Posts: 233 Likes: 0 Liked 1 Time in 1 Post	torque-to-yield bolts query I just picked up a used Chev 454HO crate motor. Does anybody know if those come with torque-to-yield head bolts? Also, any idea how much increase in lift can the stock hydraulic roller lifter set-up tolerate? I'd like to get to the .580-.600 range if possible. Or am I going to need the retro-fit lifters? Thanks for any help. Ken

10-31-2008, 01:25 AM	#2
Moparteacher Junior Member Join Date: Nov 2007 Location: Boise Posts: 49 Likes: 0 Liked 0 Times in 0 Posts	Re: torque-to-yield bolts query TTY fasteners are usually used where an aluminum part (cylinder head ) is being fastened. Aluminum expands and contracts greater than cast iron. This expansion requires a bolt that will stretch and retract while maintaining clamping force. I doubt your 454 utilizes TTY bolts if it has iron heads. Are the heads iron? __________________ Gary Weaver Moparteacher@yahoo.com

11-02-2008, 02:42 AM	#3
Ken Haase Member Join Date: Mar 2007 Posts: 233 Likes: 0 Liked 1 Time in 1 Post	Re: torque-to-yield bolts query Yes, Gary, the heads are iron. And, my recollection regarding the appearance of single-use bolts is that they are dull looking, almost like they have been bead blasted. Am I correct on that? I was disappointed that these Gen VI head bolts still go into water, unlike the aftermarket blocks. Thanks for the reply. Ken

11-02-2008, 09:23 PM	#4
BillK Member Join Date: Nov 2005 Location: Waldorf Md Posts: 230 Likes: 12 Liked 30 Times in 17 Posts	Re: torque-to-yield bolts query Ken, They are not torque to yield, however ...... Most of the later model 454's use the "torque plus angle" method of tightening the head bolts. There is a big misconception that any time a fastener uses the "torque plus angle" method of tightening ( such as 30 ft lbs plus 90 degrees) that it means the fastener is torque to yield. This is not always the case !!! This is simply a more accurate method of getting the required stretch on the fastener. There are a lot of fasteners (Oliver rod bolts for one) that use the "torque plus angle" method of tighteneing, but are definitely not torque to yield. Then there are some Honda head bolts that are strictly torqued to a certain ft lb figure, but those bolts are torque to yield and have to be replaced after each use. Also, torque to yield bolts are certainly used on cast iron heads. __________________ Bill Koustenis

11-05-2008, 01:46 AM	#5
Ken Haase Member Join Date: Mar 2007 Posts: 233 Likes: 0 Liked 1 Time in 1 Post	Re: torque-to-yield bolts query Bill K., thanks for the info. Very informative. Maybe I'll just buy ARP fasteners. Along the same lines, is there a steel shim head gasket for the Gen VI blocks? Thanks again. Ken

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