emwmarine
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| posted on 14/3/13 at 01:56 PM |
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ARP bolts
I have a cheap blacktop and was baulking at spending a lot on ARP blots, whilst I build, slowly a better one.
I have read that cheap black cap 12.9 bolts are nearly as good as ARP bolts and cost peanuts.
Any views on the need to use ARP bolts (and then have to also ream out the cap) or cheaper locost alternatives?
Building a Dax Rush.
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Alfa145
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| posted on 14/3/13 at 02:18 PM |
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Dont bother, leave it as standard. Especially as you're building a replacement engine anyway.
Most tin tops survive fine without them so why should your use break them? ARPs are £65ish? Replacement Zetec can be got for £50+
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mcerd1
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| posted on 14/3/13 at 02:22 PM |
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correct me if I'm wrong but arn't ARP ones reusable as long as you check for any increase in untorqued length?
(see the arp instructions below)
8mm ones:
http://arpinstructions.com/instructions/151-6003.pdf
9mm ones:
http://arpinstructions.com/instructions/151-6005.pdf
but if your not that bothered for the cheap engine why not just use the ford ones - my 1.8 blacktop in the tin-top see's 6500rpm nearly every
day and its still going (well almost... its got some issues at the moment, but the bottom end is fine  )
-
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Paul Turner
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| posted on 14/3/13 at 03:32 PM |
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I used 12.9 spec bolts instead of expensive Cosworth bolts in 2 x-flow engines. It was a standard fitment for the oval racers who revved their 1.3
x-flows far more than I did. The 2nd one revved regularly to 7800 and never let go.
But there is a problem fitting them in Zetecs.
In a x-flow the caps are registered to the rods with small pins, these ensure that they are aligned correctly, the bolts only job is to provide the
clamping force. In a Ztec there are no locating pins, the bolts are a tight fit in the cap and rod and provide the exact location as well as the
clamping force.
Even if you found 12.9 bolts with the correct thread length and pitch you would not find any with the correct shank diameter to provide the exact
location.
Not bothered with ARP's in my Blacktop, the standard bolts are good to 7200 according to Raceline and mine is limited to 6800.
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whitestu
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| posted on 14/3/13 at 04:32 PM |
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My blacktop has standard bolts and I have not worried [rightly or wrongly] as long as I'm keeping under 7500 rpm.
My dash logs max rpm and after one track day it said 8100 after the throttle got stuck! It survived though!
Stu
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perksy
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| posted on 14/3/13 at 06:20 PM |
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As above, use the standard ones
Unless your revving the nads off it on a regular basis the standard Ford offering will be fine
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snapper
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| posted on 14/3/13 at 06:52 PM |
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In order of preference I fit
Flywheel bolts
Rod bolts
Head bolts
Main bolts
Head bolts are worth it if you replace the head gasket more than once or pull off the head for any reason
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Grimsdale
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| posted on 15/3/13 at 08:25 AM |
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quote:
Originally posted by emwmarine
I have read that cheap black cap 12.9 bolts are nearly as good as ARP bolts and cost peanuts.
In terms of tensile strength they may be similar, but the design of the waisted shank, the thread rolling process and the quantity and size of defects
in the bolt means the fatigue resistance of the ARP bolts is superior. There's much more detail on the arp site, if you're as sad as me to
read it all
I'd stick with stock bolts instead of cheap 12.9 bolts.
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atomic
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| posted on 15/3/13 at 02:03 PM |
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It all depends on which bolts really. If you are just wanting generic HT type bolts of a high quality then I would personally use Unbrako, if you
require something more specialised for example Rod bolts or Headstuds then that's when things can get a little more tricky.
ARP do have a very large catalogue but over the years we have seen numerous issues with poor thread quality on ARP's and they generally seem to
not accept there could ever be any issue with their products. We now exclusively use Northbridge Motorsport (Pankl) & A1 Technologies for our
specialist requirements. The quality of product coming out of Northbridge Motorsport is absolutely second to none but you do get what you pay for and
by that I mean they are not cheap.
There are other manufactures that have a good reputaiton too like SPS Technologies & MSAerospace but I've never used their products.
[Edited on 15/3/13 by atomic]
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