Mercury Rod Cap Alignment

[pbxcomm]

Conventional type bolts? Meaning other than SPS, TTY or OEM? Sorry didn't register..

[pbxcomm]

Where can I purchase the SPS Bolts?

[FORBESAUTO]

Sorry for not being clear. The OEM bolts are tty. All your performance bolts (SPS and ARP)are normal hardened bolts better suited for performance and won't give you that mushy feel when tightening and have very little stretch. The Performance bolts will be torqued without using any additional angles being they don't go into a plastic phase as the tty bolts do and can be used over and over. I get mine from pro-marine.

[FORBESAUTO]

Ya gotta slap me upside my head sometimes. I get to bablin on and don't make no sense sometimes. Ya just gotta reel me back in

[pbxcomm]

Perfectly clear... Thanks much, I learned something new and absorb!
One more question related.. Is the manufactures name TTY and makes these bolts exclusively for Mercury? If so, can you purchase TTY Bolts outside of the Mercury markup?

[pbxcomm]

Additionally, would you use SPS and/or ARP over TTY in all of your rod applications? I assume by your name your involved with auto engines as well as Outboard Motors.

[FORBESAUTO]

Tty (torque to yield) is just the type bolt ( high tech bolt designed to stretch at certain stress point) works great for production due to accuracy during torque process and in auto industry used them because they can use a smaller od bolt and less of them to save weight for economy. Problem with them in performance situations is under load you could exceed the point where it's designed to stretch. There are many companies that make the tty bolts, only one in aware of for Mercury is the oem bolts. I don't have a problem using them in stock applications, but prefer the non tty just (SPS seems to easier to find)

[FORBESAUTO]

Yeah, my profession is with autos. I don't know crap about an outboard, which is why I like em so much . In the auto industry it's filled with all kind of fasteners that you have to be well aware of for liability purposes. The real main reason the auto industry went to tty type bolts was weight savings, now they have taken it even a step further as to using aluminum bolts( also throw away bolts as you can imagine). In automobiles I prefer ARP, in marine they are a little harder to come by. SPS has been great and have no complaints

[Chaz]

The torque spec is determined by the stretch.
Thats basic engineering for all bolts.
The nuts never fall off chev rod bolts do they because the elastic bolts keeps then snug.

Nope , the nuts never fell off . The bolts usually broke off at the shank / first thread junction . ( remember , I am talking circa 1975 on 1960's era BBC's )

In situations where you can measure the stretch then the spec will be to a stretch to a spec.
If you keep the stretch in spec you can reuse the bolt as you stay in the elastic zone.
Torque to yield goes into the plastic zone so its single use.

So if the bolt cant be pulled up to elastic or the quality doesn't warrant it then you find the spec says loctite etc or it has a spring washer etc.

I've owned a set of ball and pin point mikes for 30 years and a torque to angle gauge for 20 ( when Tom Molnar was at Oliver he made me buy one ) but thank you for the refresher course ...

[powerabout]

were you reving the bbc's over the original redline, shock horror?

[Chaz]

were you reving the bbc's over the original redline, shock horror?

16 year old kid , SS396 / 4-speed ..... you tell me .

[FORBESAUTO]

Just for info for anyone that cares or wondering why we even have the little tty bolts. If doesn't interest you or make you curious then ignore this post. The theory behind the tty bolts (theory is a fancy way for engineers to convince ya they need to be paid more) is that a standard bolt can only be torqued to 20% less than its yield rate without potential failure and tty bolt is torqued above its yield rate. This allows the manufacturer to use a size smaller bolt and sometimes fewer bolts to get the same clamping force ( I sometimes really wonder about this)to save weight. In mercury's rod bolt case I suspect it was more cost effective to use a tty bolt over a more expensive hardened bolt to get the needed clamping force of such a small diameter bolt. Figured I would throw that out there to help some understand the tty bolt more clearly and why in the world a manufacturer would use a "throw away bolt" in the first place.