Connecting Rod Bots

[roanokeSpider]

Do the con bots and nuts need to be replaced after i have put my new rings in or can i just simply reuse them,

[manoa matt]

Guy Croft recommends replacement, granted he is building race engines that sometimes go to 9000 rpms. It somewhat depends on the mileage and history of the engine. Those bolts have to deal with a lot of repeated stress cycles. The Haynes or Chiltons manuals may say its OK to reuse them, but don't hold me to that. However as a general rule of thumb with critical fasteners like flywheel bolts, cylinder head bolts, and connecting rod bolts: "When in doubt, replace it." Ultimatly it will be cheaper if something goes wrong down the line, and you will have piece of mind. Important part is making sure they are pressed in correctly.

Was that vague enough?

[htchevyii]

On my 1438 two of the main cap bolts stretched during torquing as did two or three head bolts. I couldn't find replacement main cap bolts, so I got a set of studs from ARP, the head bolts were new stock replacement. I replaced the rod bolts with what may have been the the last set in existence, (for the early 1438, 1608), from Bayless. I'd be leary of reusing the stock bolts based on my experience, (at the very least pay special attention while torquing for stretching).

[maytag]

The way we used to determine this was how long the bolt is, compared to how long it should be. Sounds strange, but the torque-ing of the bolts is actually causing them to stretch, and bolt-stretch is what provides the "stay-put" in the bolt.

The real-world / practical rule of thumb is if they've been re-used (re-torqued) twice, throw-em out.

[htchevyii]

You're correct, a bolt stretch gauge is way more accurate than torque!

[mdrburchette]

At least buy new rod bolts. I just went through this mess with my 1608 and ended up having to wait for new rod bolts to come in to finish the job. Why take the chance? Now, if your threads are good on the nuts and you oil them they should be good to go and they don't come with a set of bolts when you order.