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all about torque plate

Engine Building Fundamentals

Discussion and questions related to the course Engine Building Fundamentals


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how important to use the torque plate in ring gap.. it was mention in of the module that there is a need to use a torque plate but it was never show how? and why is necessary to use???

Ideally if you have had the engine torque plate bored/honed then you should also use the torque plate while set the ring end gaps since the torque plate can result in some distortion of the bores. It does really come down to how tight you're going with your ring gaps though. If you're really aiming for tight ring gaps then you should use a torque plate to ensure that the end gaps are where you need them to be under real operating conditions. If you're using the ring manufacturers recommendations then these are normally a little conservative so it's not in my opinion an essential step and I've set ring gaps multiple times without a torque plate fitted with no ill effects.

Andre i have always thought torque plates arnt the best method.

my concerns are: is the torque plate actually going to be the same stiffness as the cylinder head? if not wont your torque plate clearance be different than clearances with the head on? which is again different to clearances with nothing bolted on.

and also temperature, in an ideal world the head and block expand together at the same rate. this how ever isn't possible especially with an aluminum head on cast iron block. so again how accurate is the torque plate on a cold block going to be vs a hot block with a head that has a different rigidity?

I'm not saying a torque plate isn't better than no torque plate, I'm merely asking at what point is the torque plate going to give inaccurate clearances compared to real world?

The torque plate really replicates the distortion caused by the localised load from the fasteners so it's not strictly essential that the torque plate is identical to the head in terms of stiffness. It's definitely not a perfect world sadly and I've found that even with a torque plate the distortion will change a little bit every time you tighten the torque plate down. It is however a case of getting whatever improvements we can.

Taking the torque plate honing concept to the next level is having the engine block 'hot honed' where coolant is run through the block to take it to operating temperature. I think your last statement really nails it - A torque plate is undoubtedly imperfect but still going to give you a better bore finish than no torque plate at all.