Install connecting rod cap

Understanding the details for proper installation is important for veteran engine builders and first-timers alike. The connecting rod is designed to take the reciprocating motion of the piston's travel in the bore and turn it into rotating motion at the crankshaft, turning combustion forces into propulsion forces.

The fasteners, which holds the rod's big end together, can make—or break—your high-performance engine. Each connecting rod fastener is tasked with maintaining its clamp load whether the connecting rod is at bottom dead center BDC or top dead center TDC in the cylinder bore. At TDC, the fastener's difficult job is to prevent the connecting rod from separating at its big end and permitting the piston to crash into the cylinder head. Regardless of what you've heard elsewhere, checking fastener stretch is the best way to ensure connecting rod fasteners are installed correctly.

This is because just measuring torque does not accurately inform you how much the fastener is stretched, nor its clamp load; instead, measuring the torque simply provides you with the amount of friction it takes to turn the fastener. This can be affected by the use of lubricating oil, molybdenum lubricant, or any other liquid you've seen used over the years to install connecting rod bolts and is most definitely not the most accurate way to determine whether the fastener is providing the proper clamp load to the connecting rod.

Measuring connecting rod stretch is not difficult, but it does require the use of a stretch gauge, which is available from ARP and other sources. This could lead to a spun bearing or a broken bolt. Prior to the installation of the connecting rod's cap and fasteners, the first step is to ensure you have a notepad handy to mark down your measurements and prevent any confusion.

Each fastener must be measured before it is installed, to note its free length in a relaxed state. Each K1 Technologies connecting rod set comes with ARP fasteners, which have dimples on each end of the fastener so that the gauge can be properly centered on the fastener to measure its length. Before any torque is applied, set the stretch gauge's ball ends into the dimples on the fastener.

It will feel like the stretch gauge drops into place in the dimples. Make sure to adjust the outer ring on the dial gauge to ensure it is at Zero on the gauge face. Each fastener will have a stretch specification, which K1 Technologies provides with the connecting rod set. Two critical things to note here: you must make sure you are using an accurate torque wrench, and you must be able to snug the fastener down in one single pull.

If you stop partway through, it can provide inaccurate readings. It would prove they are fitting perfectly If you have both side with a feelable edge, try adjusting them out and it you can't, posion the rod cap to minic the less amount of both sides.

That is all you can do with cages and bearings like that. I'm convinced there is no way, no how this can be done 'perfectly' by hand.

That cost is unbelievable and I don't think it is needed for your success. JMHO though! I've also read a few posts on other marine sites and they also think it is not needed as well.

Then before tightening to torque specs, rotate the crank over about three or four times and then tighten the cap up and torque to spec. Everything will be correct according to their procedures.

And so the needle bearings would never have to cross the very slight mismatch fit of the rod and cap fit. So even a very slight edge on the alignment, the bearings will not have to cross such a joint alignment Just an idea, but others seem to think that works correct Re: Connecting rod cap install I found this old post that seems to describe my problem, which feels llike to me from the way my nail or the pencil catches, that the cap actually sprung open once disassembled.

Not sure if I'm ready to squeez the caps in the vise but maybe that's one funtion of the 'alignment tool'? We spring them inward with soft paperboard lined jaws in a bench visevery carefully until they fit with just an index finger holding the cap in place. Then assembly in the engine is easier and a sure bet! I'm always inclined to give our assembly tool away, but, now and then we get a request for it's use by a customer.

Rotate the crankshaft so that the piston is at top dead center to protect the dipper on the connecting rod. If locking tabs are used bend them to lock cap screws. K All in. K Posi-Lock in. K Cap-screw in. K, K, K, K Cap-screw in. Share this: Twitter Facebook. Like this: Like Loading Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in:. Email required Address never made public. Name required.

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