line bore after studds? | Ford Escort Owners Association (FEOA)
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line bore after studds?

Discussion in 'Engine Tuning' started by austin86, Feb 27, 2020.

  1. austin86

    austin86 That nut who spends way to much on a escort.

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    I know not all motors are the same, but after putting in ARP main studs what are the chances of not needing to line bore a CVH motor? I know not all motors have to be line bored with ARP main studs. For example the VW VR6 and some Toyota motors very rarely need a line bore job done after ARPs mains are put in.

    And No, I'm not trying to skimp, just was wanting to know out of curiosity before I get into building my motor. I'll be checking before and after to see if my motor needs it.
  2. marclar

    marclar Moderator Staff Member

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    i cant think of anyone that has ever used arp main studs on a cvh...
    the studs just add clamping force to the main caps, they shouldnt distort the overall trueness of the block vs regular bolts..
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  3. austin86

    austin86 That nut who spends way to much on a escort.

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    thanks for the info.
    I can't find anyone even on UK boards that have done it ether. But from what I know, at lest on V8s the added clamping force can change tolerances and eat up bearings or distort the main caps. I never seen ARP studs done on a l4 or l6 myself, but from reading most cast iron l4 and l6 blocks/caps don't need honing or a line bore after studs are put in.

    Ether way I'll check before and after I install the studs. I plain to have some head work done and if I use stock rods for my build it will use ARP rod bolts so I'll be at the machine shop one way or anther.

    EDIT:
    I guess my bigger concern right now would be if the main studs will fit a 1.9l as they are for a 1.6l
    Anyway the ARP bolts are only 10 added PSI. I can't see cast iron distorting that much from 10 more PSI on the studs. But I will find out.
    Last edited: Feb 27, 2020
  4. marclar

    marclar Moderator Staff Member

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    from my understanding of the theory of the studs is that they shouldnt 'add' clamping force, but have a higher resistance to stretching.. you would have to spin the thing to 12000rpm to need that type of modification.. IMO

    specs for the bolts are available from arp.. you could measure the ones in your block and email them for specifics of that 1.6 bolts.. iirc the blocks are prety close to the same
  5. austin86

    austin86 That nut who spends way to much on a escort.

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    Wouldn't torquing them at 90ft lbs (arp recommendation) vs ford 80ft lbs recommendation add clamping force? I do agree on the needs of the mod, sure I do not need it. but why not? Whats 100 more dollars on a motor build that has already toppled 1k and will likely hit the 3k mark when done.
    Then again I don't plan to all to kind to the motor once its done so anything to make it stronger will be nice.

    I guess I'll l wait and see if things need honed or bored
    Last edited: Jun 18, 2020
  6. marclar

    marclar Moderator Staff Member

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    difference of 10ft lbs wont make much of a difference i dont think. but then again, im not an expert. the main cap is pretty hefty and has a bunch of meat to it. i dont think it will squish. i would ask arp what they think, and call a few machine shops and quiz them as well.
  7. austin86

    austin86 That nut who spends way to much on a escort.

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    That is what I plan to do. Aside from calling arp that is. The main studs came with a one size fits all sheet saying you have to line bore the motor after installing the studs.
    I'm no expert ether and I don't think 10 more psi would novk it out of round.
  8. marclar

    marclar Moderator Staff Member

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    i'm sure that's a legal note they put in after someone burned them once or twice.
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  9. austin86

    austin86 That nut who spends way to much on a escort.

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    Good point. I bet it is too.
  10. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    A minor note: Torque values are ft-lbs, not PSI.
  11. austin86

    austin86 That nut who spends way to much on a escort.

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    Doof. There I go being Dyslexic again
  12. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    Dyslexics Untie!
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  13. marclar

    marclar Moderator Staff Member

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    i just put a 912 bulb in place of a 921... stupid numbers
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  14. austin86

    austin86 That nut who spends way to much on a escort.

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    Does anyone else have any thoughts on this?
  15. marclar

    marclar Moderator Staff Member

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    i will say that ive watched a gazillion hours of engine building and dyno vids on youtube. they prety much for the most part just assemble the engines with arp studs after machining.
  16. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    I don't see why it would need line boring. They probably copied and pasted that from some instance where the main caps were replaced.

    I think it would do more harm than good. Oh, and I'm a machinist by trade.
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  17. austin86

    austin86 That nut who spends way to much on a escort.

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  18. marclar

    marclar Moderator Staff Member

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    the studs resist stretch, dont necessarily hold down harder...
  19. novanutcase

    novanutcase FEOA Member

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    Unless the bearing seats are out of round you should be fine. I would be more concerned and point my money at balancing the rotating assembly as that will allow the motor to spin easier, vibrate less and have less stress on the bearings along with having the rotating assembly and block checked for stress fractures especially since you'll be beating on the engine. Broken rods are not fun. I'd also have the block hot tanked to make sure all the fluid passageways are unobstructed. If you want to go nuts and add a little more life to the motor you can have the machine shop machine in some piston squirters and wire the car to actuate the squirters when the key gets put into the accessory position to pre-oil the cylinder walls causing less ring and cylinder wear on start up.

    As was mentioned, ARP head studs will resist stretching and keep the head where it needs to be once it's been torqued to the proper values.

    I would also look at some head upgrades like polishing the air path without sacrificing swirl along with a 5 angle valve job and new seats and guides. Don't knife edge the port wall separators as this reduces performance. Porting and larger valves will also help but that also depends on your states smog requirements. Maybe deck the head and raise the compression?

    Post the engine build. I love watching people put motors together almost as much as I like building them myself!:)

    Good Luck!

    John
  20. austin86

    austin86 That nut who spends way to much on a escort.

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    The motor was already rebuild and hasn't been used since. But if I do end up taking it to the machine shop Id like to have the crank lightened and balanced.

    But I'm hoping to avoid taking it to the shop.

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