New head bolts a MUST?
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  1. #1
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    New head bolts a MUST?

    I'm doing a head gasket for my kids 88 1.5 DX. Are the head bolts an absolute must replacement?

  2. #2
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    Yes. The stock ones stretch and cannot be reused.

  3. #3
    HC Racer H5 jaje's Avatar
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    depends on how long you will keep the engine and do rebuilds (i.e. racing efforts) you may want to get a set of arp head studs as they can be reused up to 6x (they cost more but if you have multiple rebuild plans they quickly become cost effective)
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  4. #4
    Civic2Scooby's Avatar
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    as answered above, factory head bolts are what are known as tq to yeild bolts...meaning you are actually stretching the bolt inside the thread bore to make sure they are extremely snug. Once they are backed out they are useless and will snap off in the block if you try to re-use them.

  5. #5
    Senior Member jlicrx's Avatar
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    Quote Originally Posted by Civic2Scooby
    as answered above, factory head bolts are what are known as tq to yeild bolts...meaning you are actually stretching the bolt inside the thread bore to make sure they are extremely snug. Once they are backed out they are useless and will snap off in the block if you try to re-use them.
    Honda head bolts are not torque to yield and are reusable - i have been working on these cars for many, many years and have always reused the head bolts with no problems - if the bolts were torque to yield, they wouldn't have a torque value listed in the manuals - the following is from leading maker of TTY bolts:

    "How to Identify an Engine with Torque-To-Yield Head Bolts?
    Early TTY bolts were easy to identify by their undercut shank. Since then, many new TTY designs have been employed. Many of these do not use an undercut shank and therefore cannot be easily recognized as TTY. The most accurate method of determining a TTY engine is based on the head bolt tightening procedure outlined by the manufacturer. If the installation procedure requires tightening the bolt to an angle (vs. torque) specification, the engine requires new TTY head bolts. If torque values are used for tightening, new bolts are not required."
    ZCspeed Racing

  6. #6
    Civic2Scooby's Avatar
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    Quote Originally Posted by jlicrx
    Honda head bolts are not torque to yield and are reusable - i have been working on these cars for many, many years and have always reused the head bolts with no problems - if the bolts were torque to yield, they wouldn't have a torque value listed in the manuals - the following is from leading maker of TTY bolts:

    "How to Identify an Engine with Torque-To-Yield Head Bolts?
    Early TTY bolts were easy to identify by their undercut shank. Since then, many new TTY designs have been employed. Many of these do not use an undercut shank and therefore cannot be easily recognized as TTY. The most accurate method of determining a TTY engine is based on the head bolt tightening procedure outlined by the manufacturer. If the installation procedure requires tightening the bolt to an angle (vs. torque) specification, the engine requires new TTY head bolts. If torque values are used for tightening, new bolts are not required."
    good to know I have been taught that pretty much all head bolts these days are TTY bolts and that as a rule of thumb they should never be re-used...even if the Honda ones arent TTY for the money they cost to replace I would prob replace them anyway just in case there was any stretching despite the fact that they are not TTY.

  7. #7
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    I reused my head bolts with terrible results. I really would recommend against it even if they can be reused.

    The stock bolts are surprisingly expensive from the dealer ($13 a piece), so it may be worth the extra few bucks for some ARP studs instead.

  8. #8
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    Thanks for the info. I started and broke both my 3/8 ratchets,1/2 torque wrench and my compression gauge doesn't work. So I'll have to wait to get some new ones tomorrow. If I can save +/- $100, I'll save it because there's always something else I'll NEED to buy. This is only a 1.5 stock motor, no rebuilds are planned.
    A couple of days ago I found out my 85 BMW head bolts are TTY, I reused them 6 years ago with no problem. Ignorance is bliss. But now I can worry about those.
    I haven't even tried to get the crank hub nut yet-that should be fun and will probably require another trip for more tools.

  9. #9
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    ok so im going to replace my head gasket on my 2001 Acura EL, AKA Honda Civic. The Haynes manual lists the following head bolt torque specs for this car
    1.7L engines
    Step 1.....168 in-lbs
    Step 2.....36 ft-lbs
    Step 3.....49 ft-lbs
    1.8L engine
    Step 1.....29 ft-lbs
    Step 2.....Tighten an additional 90-degrees
    Step 3.....Tighten an additional 90-degrees
    New bolts.Tighten an additional 60 degrees
    These torque specs are for SOHC engines.

    The DOHC engine lists torque specs as below
    1.8L engine*
    Step 1.....29 ft-lbs
    Step 2.....Tighten an additional 90-degrees
    Step 3.....Tighten an additional 90-degrees
    Step 4.....Tighten an additional 90-degrees
    *Bolts Must be Replaced

    From what I can tell it looks like the 1.8 SOHC engine uses TTY bolts while the 1.7 SOHC engine uses non TTY bolts
    From this I would say you can NOT resuse the 1.8 TTY bolts but you could reuse the regular 1.7 bolts.

    When reusing any head bolts it is important to use a tap and clean the threads in the head and a die and clean the threads on the bolts and oil the bolts before installing using a NON click type torque wrench, instead use a good quality beam or dial type and follow the manufacturer torque specs. If any binding is felt while torquing a head bolt, remove it and start again, possibly even cleaning the threads again.

    As a rule is the manufacturer lists a final torque spec numerical value for a head bolt then it is not TTY and can be reused, if the manufacturer lists an initial torque numerical value followed by some additional degrees of turning then these are definitely TTY and should not be reused.
    I have a 1.7L SOHC in mine and will be reusing my original head bolts after they are cleaned up and oiled.

    Just my 2 cents
    Last edited by wpenno; 12-23-16 at 07:00 PM.

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