Intake broken - please help

[rraceme]

 I was installing a cobra intake on my hipo motor from car 6S2227 and while in my 3rd and final round of tighten bolts the intake end broke. I was using a torque wrench, started at 12 lbs, then 20 lbs, last setting 26 lbs and the corner cracked. (See pic). What did I do wrong? I've installed 50 aluminum intakes in my life on 302's and never had this happen.  Only saving grace, this was an aftermarket blue thunder intake.... not my original intake. Still I hate destroying my intake. Also this was my 1st time installing any intake on a 289 engine all my previous intakes are 302's. Prior installing intake i knew 289's have slightly shorter head mating surface, weaken mounting area, & exposing the bolt. But I assumed by following same torque sequence would work just fine.  So before I destroy another intake please advise me what I did wrong? Lastly thank you for your assistance I've found this forum incredibly helpful and friendly. Fred

BTW - i can load more pictures of removed intake if helpful in diagnosing issue.

[Bob Gaines]

I was installing a cobra intake on my hipo motor from car 6S2227 and while in my 3rd and final round of tighten bolts the intake end broke. I was using a torque wrench, started at 12 lbs, then 20 lbs, last setting 26 lbs and the corner cracked. (See pic). What did I do wrong? I've installed 50 aluminum intakes in my life on 302's and never had this happen.  Only saving grace, this was an aftermarket blue thunder intake.... not my original intake. Still I hate destroying my intake. Also this was my 1st time installing any intake on a 289 engine all my previous intakes are 302's. Prior installing intake i knew 289's have slightly shorter head mating surface, weaken mounting area, & exposing the bolt. But I assumed by following same torque sequence would work just fine.  So before I destroy another intake please advise me what I did wrong? Lastly thank you for your assistance I've found this forum incredibly helpful and friendly. Fred

BTW - i can load more pictures of removed intake if helpful in diagnosing issue.

If it is any consultation the New Cobra intake by Scott Drake is a dramatically historical better looking 66 early 67 GT350 repro intake compared to the Blue thunder intake copied after the 67 /68 Cobra intake..

[rraceme]

Thanks Bob.  I just purchased the Scott drake intake you suggested. Hopefully someone can tell me what I did wrong in my installation to break the intake tab. I'm doing a few cosmetic enhancements to the original intake to present better. Which is why not installed now.  I wanted break in motor and dial in first. Then later install original intake. The only error I can think of is I tighten beyond torque limits and broke end. But I had wrench at 26lbs? I'm a little aggravated too I did something dumb.

[texas swede]

If I don't recall wrong the unsupported corners of the Cobra intake according to the installation manual from SA
shall not be more than 8- and 11-foot pounds respectively and the rest 15.
Texas Swede

[TA Coupe]

I've always read it should be 22-24ft lbs. I also did the same thing about 45yrs ago because I didn't know that you should reset your torque wrench back to zero as soon as you are done. The spring inside stretches and gives a false reading. There are places that can recalibrate the old kind. I now have a Snap On digital one that you don't have to worry about. Not cheap at close to $500 but worth every penny in the long run.

          Roy

[Bob Gaines]

If I don't recall wrong the unsupported corners of the Cobra intake according to the installation manual from SA
shall not be more than 8- and 11-foot pounds respectively and the rest 15.
Texas Swede

I am surprised the front ear broke before the passenger side rear ear.  Confirmation given that what Texas Swede posted is accurate. SA instructed in their Accessories Installation Manual that all bolts except the pass side rear should be torqued to 15 pounds .The passenger side rear is the easiest one to break and should not be tightened more then 8 pounds!! That weak ear is # 11 in the factory progressive torque sequence which is probably where the #11 came from in your memory.

[s2ms]

I'm impressed you got thru your second round at 20 lbs before something broke.

The 66 GT350 owner's manual says 14-16 lbs but as Texas Swede and Bob mention the passenger rear corner needs less. The cast iron intake spec is 20-22 lbs. This is the installation manual from SAI mentioned...

[GT350Lad]

That sucks Fred. Thank the Shelby gods it was only a blue thunder. Still hurts

[rraceme]

Thank you all. So looks like I didn't do my homework prior installation. I've always used my 12, 20,26 lbs torque sequence but I've been wrong.
I will follow the correct installation instructions moving forward.  Thank you SAAC forum for your guidance.  Fred

[Coralsnake]

I wouldn't be so fast to let the intake off the hook.

[rraceme]

I wouldn't be so fast to let the intake off the hook.

you are funny coralsnake!  No it is all on me. The blue thunder intake was not at fault. I will weld the intake up and reuse at another time.

[Side-Oilers]

I'm an FE guy, and have no experience with the manifolds on SBs. 

Hence this dumb question: Why was this unsupported design approved for production?

Couldn't Ford, while designing the engine, (or the aftermarket manifold companies) have reinforced those areas better?

[pbf777]

      The original Ford production incorporated a cast iron intake manifold and for that (with proper torquing guidelines adhered to  ) it was sound engineering.  But since even this wasn't impervious to idiots working on them, I would venture that the "field-engineering" observations led to the change in later head castings which did provide the support, for most any circumstance.   

      Scott.

[rraceme]

Scott I appreciate your contribution yet must say I'm not an idiot. I did do something dumb but making a mistake does not make me (or anyone else) an idiot. Additionally I'm not a 1960's ford engineer, IMHO the design was not "sound engineering" (maybe functional engineering) otherwise they would have never changed it, yet head design was changed to something better w\the 302.  I will never make this mistake again because I learned from my mistake. As I stated before, I've installed hundreds intakes (if you include Ford, Chevy & Chrysler) and NEVER had a failure.

Thank you SAAC forum I really enjoy this amazing Forum. Fred

[pbf777]

     rraceme,

     I apologize if my statement offended you, but do understand that my statement of "idiots" was targeted at those Ford Dealership mechanics in that time period, who were held out to be of expertise in the field of such repair operations, and being compensated for that capacity, and therefore should be held to a higher standard, but who fell short of being capable in their tasks, not because they didn't understand, but rather often took shortcuts, this for several reasons and involved a multitude of alternate procedures from that as outlined. And therefore Ford Motor Co. was probably held responsible thru warranty claims for many such a repair requirement, and I was attempting to imply this which probably was the impetus for the change in the design. 

     And I'm not implying that all mechanics are idiots either, as that might include myself also.   

     Scott.