Re-torque of RAJO head
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rnkugel
Topic author - Posts: 43
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- First Name: Reuben
- Last Name: Kugel
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Re-torque of RAJO head
I recently put the RAJO head back on the motor and ran it twice for about 15 minutes each (on jack stands) in the shop. My question is, when I go to re-torque the head bolts, should I do this cold or after allowing motor to come to temp? I'm going to 45 ft lbs as a final setting. Thanks
1915 Touring
1926 RAJO Speedster
1926 RAJO Speedster
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RajoRacer
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Re: Re-torque of RAJO head
There will be other opinions BUT I run through at least 3 heating (block operating temperature) & cooling cycles and torque dead cold @45 lbs. - I also run a BB RAJO and did that same drill near 30 years ago on my Racer and haven't touched it since !
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Kerry
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Re: Re-torque of RAJO head
Re-torque cast iron heads hot and aluminium cold.
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D Stroud
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Re: Re-torque of RAJO head
Why would you re-torque cast iron heads hot. I'm by no means an expert, but I have been around and/or worked on everything from heavy equipment, hot rods and helicopters, in the last sixty years and I have NEVER heard of that being done. Makes no sense to me. JMHO Dave
1925 mostly original coupe.
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Kerry
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Re: Re-torque of RAJO head
Gasket sets usually have instructions to do so and like many spec/tech books also but with out giving the reason why.
The types of metal expansion rates, example, in older engine design of a cast iron block and steel bolts/studs, you have about 15% stretch on the bolt when getting up to operating temp, if not allowed for in a re-torque when hot then when cooled down then you have less torque on the gasket which gives the posibility to leak or blow the gasket prematurely.
The types of metal expansion rates, example, in older engine design of a cast iron block and steel bolts/studs, you have about 15% stretch on the bolt when getting up to operating temp, if not allowed for in a re-torque when hot then when cooled down then you have less torque on the gasket which gives the posibility to leak or blow the gasket prematurely.
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RajoRacer
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Re: Re-torque of RAJO head
That "might" be good information BUT clearly specific to "studs" - no way I'm pulling a 7/16" Model T head bolt to 55-60 lbs.
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Kerry
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Re: Re-torque of RAJO head
Steve,
Nothing clearly specific at all that it refers to studs, clearly reads bolts and as for the 7/16" at 55/60 is not a bolt problem on a T, we all know or should know it's the failure of the cast iron block that's the weak point, it strips well before a good 7/16" bolt breaks at 60lbs.
Nothing clearly specific at all that it refers to studs, clearly reads bolts and as for the 7/16" at 55/60 is not a bolt problem on a T, we all know or should know it's the failure of the cast iron block that's the weak point, it strips well before a good 7/16" bolt breaks at 60lbs.
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RajoRacer
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Re: Re-torque of RAJO head
Sure appears that the chart you posted a photo of states "recommended bolt tensions" but just below under the size chart, it refers to "studs" - perhaps that might be a language difference between our English & yours ?
So, why would anyone pull a Model T head bolt to that torque ?
So, why would anyone pull a Model T head bolt to that torque ?
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Kerry
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Re: Re-torque of RAJO head
Yes you are right Steve, 100% in reference to what a head bolt or a stud is capable of. Shouldn't have used it in relation to a Model T 
As for a model T, as far as I'm concerned, the tension wrench belongs on the tool board collecting dust. a ring spanner and ones feel is more than addequate. Cold then hot a couple of times, unless a Z head then then only cold a few times.
As for a model T, as far as I'm concerned, the tension wrench belongs on the tool board collecting dust. a ring spanner and ones feel is more than addequate. Cold then hot a couple of times, unless a Z head then then only cold a few times.