Hi Folks.
Another question. Series 3 1.3 engine. What's the torque setting for the head bolts.
another question.....torque
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P. de R. Leclercq
Re: another question.....torque
Hello.
The figures given in by Lancia, say for FIAT bolts, 19 lbs/ft and for the S1-type bolts, 23.8lbs/ft.
I have written elsewhere about head bolts. After having had two snap on different engines - not through twisting - they just snapped, I avoid if possible using the old bolts. I replace them with 110mm 12.9 grade socket cap screws (popularly called "Allen bolts") which are easily obtainable.
The procedure is to use the two 8.5mm dowel bolts (bottom left top right viewed from exhaust side) to locate the head correctly. Then "nip up" some of the new socket cap screws. Remove the dowel bolts and replace them with the cap screws. Then I torque them in order at 15lbs/ft. Then again at 20lbs/ft. Wait half an hour and then go round at 25lbs/ft. It's probably worth checking again with the engine warmed up.
For the three short screws at the front I don't worry, the bolts being short, they are less likely to fail. I do use cap screws sometimes but just for appearance's sake.
Paul
The figures given in by Lancia, say for FIAT bolts, 19 lbs/ft and for the S1-type bolts, 23.8lbs/ft.
I have written elsewhere about head bolts. After having had two snap on different engines - not through twisting - they just snapped, I avoid if possible using the old bolts. I replace them with 110mm 12.9 grade socket cap screws (popularly called "Allen bolts") which are easily obtainable.
The procedure is to use the two 8.5mm dowel bolts (bottom left top right viewed from exhaust side) to locate the head correctly. Then "nip up" some of the new socket cap screws. Remove the dowel bolts and replace them with the cap screws. Then I torque them in order at 15lbs/ft. Then again at 20lbs/ft. Wait half an hour and then go round at 25lbs/ft. It's probably worth checking again with the engine warmed up.
For the three short screws at the front I don't worry, the bolts being short, they are less likely to fail. I do use cap screws sometimes but just for appearance's sake.
Paul
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john tynan
Re: another question.....torque
Thanks. That's the info I wanted. I will be using the lower figure for the series 3 engine, Is the recommended setting related to the type of screw used, or the engine type? If I decided to use capscrews in a series 3 engine, could you just decide on a higher torque setting? And if so, what are the advantages. Does the gasket fail with enough frequency to warrant a greater torque?
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Huib
Re: another question.....torque
The original torque settings depended on the quality of the bolts.
Mind you, it is not just cap screws that Paul recommended but 12.9 grade cap screws. The reason for choosing that type of bolt is simply that hex bolts do not go over 100mm in 12.9 grade and you need 10mm bolts. They can be torqued to 3.8 kgm. Make sure you use very good quality steel washers. The original ones are good enough.
For a number of years I have been using the 12.9 cap bolts in all cases. Initially I re-used original bolts if still "good". However, bolts which have been stretched should not be used again. This is theoretically true for all bolts but in practice only valid for head bolts
It may be open for discussion if the 12.9 bolts are the correct way to go. Bolts are fastened by streching. In this case there is the added factor of the aluminium of the head expanding with temperature. I estimate the coefficient of thermal expansion of the aluminium to be at least twice as high as of the steel of the bolt. On one hand you don't want the bolts to snap if the aluminium expands and on the other hand you don't want the streching force to reverse which is disastrous for any bolt connection. If anybody wants to do the calculations (or the graph), I look forward to receiving a copy.
Mind you, it is not just cap screws that Paul recommended but 12.9 grade cap screws. The reason for choosing that type of bolt is simply that hex bolts do not go over 100mm in 12.9 grade and you need 10mm bolts. They can be torqued to 3.8 kgm. Make sure you use very good quality steel washers. The original ones are good enough.
For a number of years I have been using the 12.9 cap bolts in all cases. Initially I re-used original bolts if still "good". However, bolts which have been stretched should not be used again. This is theoretically true for all bolts but in practice only valid for head bolts
It may be open for discussion if the 12.9 bolts are the correct way to go. Bolts are fastened by streching. In this case there is the added factor of the aluminium of the head expanding with temperature. I estimate the coefficient of thermal expansion of the aluminium to be at least twice as high as of the steel of the bolt. On one hand you don't want the bolts to snap if the aluminium expands and on the other hand you don't want the streching force to reverse which is disastrous for any bolt connection. If anybody wants to do the calculations (or the graph), I look forward to receiving a copy.
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P. de R. Leclercq
Re: another question.....torque
It relates to the bolts - even though both types are marked "10"!
In 25 years of Fulvia ownership I have never had gasket trouble - although I have fixed many. Probably best to check the tightness every now and then
Paul
In 25 years of Fulvia ownership I have never had gasket trouble - although I have fixed many. Probably best to check the tightness every now and then
Paul
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P. de R. Leclercq
Re: another question.....torque
One more thing: there are two types of hardened washer used on Fulvias. the thick ones are not good; I have seen them burst apart when exceeding 25 lbs/ft. Even more embarrassing, I once built an engine that was sent as a unit to the client. He found pieces of washer inside. They had burst after dispatch!
The thinner ones are fine.
Paul
The thinner ones are fine.
Paul