[DeTomaso] Another header question: bolts

[Charles Engles]

Dear Mike,


                     I agree that the Stage 8 bolts seem to be a good idea, but the space and access restrictions of a real-world installation make the fiddle factor seem to be too high.

                      The Percy Split lock header bolts seem to have the ARP style small head without the fiddle factor of the Stage 8.   There is some fiddle factor to them, but it seems less than Stage 8.   The testimonials support the attractive prospect of install them and forget them without the retightening ceremony.

                     I do agree after, at least, four header removals and installations here at the Pantera Research Institute that the small ARP header bolt heads should reduce the head-ache of the normal hex head bolts.  The Split lock seems like it would combine the best of ARP and permanent tightness  with no concerns for header bolt loosening.   That is very attractive to the lads in the Engine Department here at the Institute..........!   (of course the Split locks at a bit more than twice as expensive as ARP bolts)


                                  Warmest regards,  Chuck Engles



  ----- Original Message ----- 
  From: MikeLDrew at aol.com 
  To: cengles at cox.net ; detomaso at realbig.com 
  Sent: Sunday, December 28, 2008 5:39 PM
  Subject: Re: [DeTomaso] Another header question: bolts



  In a message dated 12/28/08 15 07 26, cengles at cox.net writes:



                 On the topic of header bolts, does anyone have an opinion about either Percy's Split Lock header bolts or the  Stage 8 Locking header bolts?   



  I've seen the Stage 8 bolts, and they seem pretty neat, although I think they require a bit too much fiddling around, and of course since you need to tighten header bolts after the engine has been through a couple of heat cycles, that requires a lot more work.

  Personally, I am advocate of ARP small-head header bolts.  These are special bolts made with a smaller-than-normal 5/16" head (rather than the more conventional 3/8").  You wouldn't think that a lousy sixteenth of an inch would make a difference, but brother, I'm here to tell you that it does.  Some headers have the pipes exiting the flange at a slight angle, which can sometimes interfere with your ability to place a wrench on the bolt head.  What follows is an agonizing ritual of turning the bolt 1/32nd of a turn at a time, constantly having to flip the wrench to get even a slight purchase on the bolt head.

  These smaller heads make short work of this.  The additional clearance can be enough to let you get a box-end wrench in there, or a socket--either one makes a huge difference.

  And they are ARP quality, nothing to sneeze at there.  Once the engine has gone through a couple of heat cycles, you'll need to go back and snug them up again, and then they should be good to go forever.

  Here's a photo from the Summit website:

  http://tinyurl.com/8dokeh

  Summit doesn't specifically list these bolts as 'small head', so I was only able to find them by first looking in my ARP bolt catalog for the part number, then typing that number in the 'search' box on the Summit website.

  These bolts are available in two lengths; either .750" or 1.00".  My Euro GTS headers (and the headers on my other cars as well) have fairly thick flanges so I always go for the longer bolts.

  They are available in either 6- or 12-point, black oxide or stainless.

  Part numbers:

  Bolt kit, 5/16" wrench, length .750 

  Black oxide 6-point: 100-1108 
  Black oxide 12-point: 100-1208 
  Stainless 6-point: 400-1108 
  Stainless 12-point: 400-1208

  Bolt kit, 5/16" wrench, length 1.000 
  Black oxide, 6-point: 100-1110 
  Black oxide 12-point: 100-1210 
  Stainless 6-point: 400-1110 
  Stainless 12-point:  400-1210

  Entering any of those part numbers in the 'search' box will bring them right up on the Summit website.  Cost is $24.69 for the black oxide, 1-inch six-point bolts.  Plus Summit charges a flat handling charge, which I believe is $11.95 now?

  I have actually found that it's cheaper to buy ARP bolts directly from the factory.  If you call them up and tell them what you need, they just pop 'em in the mail to you, saving on shipping, and the retail price from them is usually about the same or even a bit less?

  Contact info can be had on the 'contact us' link on the ARP website:  http://www.arp-bolts.com/

  Cheers!

  Mike


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