It is the most accurate way to determine the correct pre-load in the rod bolt. Unfortunately there are shops out there that will sell the community on anything they can make money on with only their self preservation in mind and not what a person realistically needs in order to achieve a certain power goal. The one that snapped is the front driver side bolt. This helps prevent blown head gaskets, and assures optimum engine sealing! Studs also provide more accurate and consistent torque loading. To achieve accuracy it is also best to cycle the fasteners five times before either calibrating or installing. The stretching is a sure indicator that the bolt has been compromised and taken past its yield point. They seem to be all the same stud, but before I go too far I figured Id check in first from people who have done it first hand.
Simple calculation of bolt stretch based on thread pitch is not accurate. The friction factor changes from one application to the next. This also allowed them to sell the kits at a significantly lower price while increasing profit margins. Alternatively, anyone know where i could find them? Going too slow will cause starting and stopping of the nut rotation and can cause false torque readings. We have seen fluctuations of as much as ten 10 foot pounds of torque from wrench to wrench. I will retorque them to 85 lb ft again once the engine is broken in after 500 miles. This procedure ensures complete heat penetration and the results are far superior to those lesser quality studs from other manufacturers who just dump pieces in a basket and hope for the best.
If the torque value has been specified for a particular fastener on the basis of low friction lube, installing the fastener with motor oil will result in insufficient preload; the torque has to be increased to compensate for the extra friction caused by the motor oil. Hardened and parallel-ground washers are included with each kit to ensure even load distribution and accurate torque readings. Your only supposed to screw it in hand tight. The lubricant used is the main factor in determining friction, and therefore, the torque for a particular installation. All he asked me was if we used moly lube, did we finger tighten the studs or tighten them with a torque wrench, and did we lube up everything studs, nut, washer. After the engineer looked at all the data, they determined that the fastener would roll the threads around 83 Foot pounds. It shows the above stud part number is in fact a Chromoly 8740 part number! I need to know if there is any way in particular to install these things? Im not saying its going to fail.
As for gasket sealant at the honda dealership, they supply the same stuff that you can buy at canadian tire, but at twice the cost. Make sure you soak up any oil that may be in the head stud holes before installing the new ones. It would simply add a little more head room to the point where a stud would break. Im not saying its going to fail. This would fix the dimple issue and spread the clamping surface out to an acceptable level. The kits that are being sold are recommending you torque the studs to 90 Ft Lbs.
Make sure you lube the washers too. The engine is a 1. Hackish made a post on how he likes to install the headstuds hand tight, then loosen it just a bit, then fallow torque specs in 3 steps. It costs a lot more to do it this way, because its tough on tooling, but the results are well worth the extra effort. When you tear the engine down for maintenance, again measure the length of each rod bolt — being careful to keep everything in the proper order.
The important thing is to prevent the bolt from failing due to fatigue by tightening it to a load greater than the demand of the engine. All operations are performed in-house and closely monitored. If a bolt is installed without sufficient preload or pre-stretch , every revolution of the crankshaft will cause a separation between the connecting rod and rod cap. When you use the molylube, surface friction affects are minimized and stud tension is much more consistent stud to stud. For example, black oxide behaves differently than a polished fastener. Most applications have undercut short bolts that can help eliminate head gasket failures through providing more stretch to compensate for the additional compression of gaskets.
L19 is not a stud that is commonly used as a head stud in other platforms! So 1 Where does each stud go? For example, for the same degree of rotation, the actual amount of bolt stretch will be critically different between an aluminum cylinder head and a cast iron cylinder head — or a steel main cap on an aluminum block and a steel main cap on a cast iron block. In other types of bolted joints, this careful attention to tightening is not as important. A much weaker stud that is not to ever be used as a head stud on a high power engine! Simply read down to the correct fastener size, then across to find the torque value for your application. If there is a permanent increase of. So if you torqued them to 90 as advertised, you have stretched the bolts past yield and have rolled or galled the threads on the studs.
Because the thermal expansion rate of aluminum is far greater than that of steel it is possible to stretch a fastener beyond yield as the aluminum expands under heat. We recommend you maintain a chart of all rod bolts, and copy down the length of the fastener prior to and after installation. The actual swapping of the head should be easy once I fill in the information gaps. Just ask anyone who has ran it and used a catch can. That is an added cost and a waste! These 8740 head stud part numbers are for a ford Cosworth engine.