Cylinder Head Bolt size

[macdeb]

Sardonicus said:

Wouldnt know I never use yield bolts on the RV8 only ARP

This I don't know why anyone would consider using stretch bolts over the fitment of ARP studs. I've even heard of some re-using the old stretch bolts
For the extra couple of bob do it right.

[BeastMaster]

macdeb said:

This I don't know why anyone would consider using stretch bolts over the fitment of ARP studs. I've even heard of some re-using the old stretch bolts
For the extra couple of bob do it right.

A couple of years ago needed to remove the heads because of a damaged valve stem caused by the breakup of a rocker pad. Looked at all the options for refitting the heads as very nearly soiled myself with the crack sound breaking the grip on each bolt.

After researching the different ways to fit the head down decide to stay with stretch bolts because they are a more reliable way to get the correct pressure and are fit and forget, but would be interested to know why some on here decided to change.


Am really worried about the guy on here moaning about the info he has received and the time it is taking him to get the job done, and suggest :-

It would appear that a spark plug has been cross threaded which is why he wants to remove the heads, if it was this guy who damaged it I would advise him to seek a competent mechanic to sort out the problem because removing and refitting heads is a planet away from changing a plug.

Secondly don't buy a single socket from Amazon, just go and buy a complete set of quality sockets and breaker bar because you will need more than one.

Then one weekend to remove both heads and deliver to a competent engineering company to be refurbished. Purchase a pair of head gaskets, four exhaust gaskets and a valley gasket along with two sets of long and short stretch bolts, clean up and inspect all that has been revealed

Collect refurbished and repaired heads.

The second weekend to refit and job is done.

Cost involved 450.00 to 500.00 plus tools plus whatever additional cost for the engineer to repair the damaged plug thread., this figure based on my own experience.

[Sardonicus]

Because after a couple of head pulls you are likely to do just that pull the threads from the block which sods law will always be the last couple of bolts you degree no doubt when final angle tightening is achieved there is an obscene amount of strain going through those block threads well over 100 plus ft pounds I am lead to believe not forgetting its rotational stress i.e the fastener is moving in those threads while being strained unlike ARP for example where that end is fixed and the rolled finer threads on the higher tensile studs rather than cut threads are doing all the work, its not just a flaw with the RV8 the BMW M54 six cyl ali blocked motor can do the same thing apparently when angle tightening HB's

Edited by Sardonicus on Tuesday 21st March 13:16

[e635815]

Discopotatoes said:

I would have thought if you were attempting to remove the heads you would be competent enough to measure the head of the bolt yourself and have a full set of imperial and metric sockets a breaker bar and a torque wrench. if not how to you expect that jobs going to end up, apart from in tears?

I consider myself competent enough. And no, I don't have a full set of Imperial sockets but Yes, I do have breaker bar and torque wrench and everything else.
But I reserve myself the right to have other things going on in my life which occupy my brain and by the time I walk from the garage to the house, that 16 mm socket became a 14 mm in my brain.

The engine benefited from a cam change, re timing etc.... which ended-up me driving to Le Mans and back faultlessly. No skills shortage here. Thanks for asking....

[BeastMaster]

Sardonicus said:

Because after a couple of head pulls you are likely to do just that pull the threads from the block which sods law will always be the last couple of bolts you degree no doubt when final angle tightening is achieved there is an obscene amount of strain going through those block threads well over 100 plus ft pounds I am lead to believe not forgetting its rotational stress i.e the fastener is moving in those threads while being strained unlike ARP for example where that end is fixed and the rolled finer threads on the higher tensile studs rather than cut threads are doing all the work, its not just a flaw with the RV8 the BMW M54 six cyl ali blocked motor can do the same thing apparently when angle tightening HB's

Edited by Sardonicus on Tuesday 21st March 13:16

Thanks for your information Simon

I will look at putting in studs if the heads need to be taken off again, because it was a big deal using the stretch bolts – needing to buy them, clean out the threads in the block, use a thin engineer oil to act as lubricant and be very pedantic about the whole thing which is where it can go very wrong, and as you say a scary amount of force required on those aluminum threads in the block.

When using studs is there enough room to get the heads off with the block in situ, seem to remember not a lot of room to lift up over studs ?

And do you need to re-torque the heads at service intervals ?

I do take on board what you are saying regarding older engines which have had the heads off a few times but would not say that stretch bolts are flawed, in a perfect world they are far superior for this type of application when all is new, but the risk of damage on older stuff may not be worth it – as I put the last 90 deg of turn in everything was crossed, my breathing and heart had stopped and my wallet was twitching in my back pocket.

Thanks for your help

Andy

[Sardonicus]

BeastMaster said:

Thanks for your information Simon

I will look at putting in studs if the heads need to be taken off again, because it was a big deal using the stretch bolts – needing to buy them, clean out the threads in the block, use a thin engineer oil to act as lubricant and be very pedantic about the whole thing which is where it can go very wrong, and as you say a scary amount of force required on those aluminum threads in the block.

When using studs is there enough room to get the heads off with the block in situ, seem to remember not a lot of room to lift up over studs ?

And do you need to re-torque the heads at service intervals ?

I do take on board what you are saying regarding older engines which have had the heads off a few times but would not say that stretch bolts are flawed, in a perfect world they are far superior for this type of application when all is new, but the risk of damage on older stuff may not be worth it – as I put the last 90 deg of turn in everything was crossed, my breathing and heart had stopped and my wallet was twitching in my back pocket.

Thanks for your help

Andy

Your welcome I'm not knocking yield bolts they are very good as you say & working on modern stuff daily I appreciate the benefits... no re-torques being one its just that I dont thing they need to be as tight as LR state for the RV8 when stud nuts are happy at 75 ft pounds, the ARP studs need to be removed when removing cyl heads in situ but then they are only screwed into the block with either small nip or just finger tight with the supplied moly lube no chance of seizing IMO and yes I would be inclined to do one re-torque with ARP's on cyl heads say after 500/1k Miles, this is my experience anyway

Edited by Sardonicus on Tuesday 21st March 18:33

[macdeb]

Sardonicus said:

Because after a couple of head pulls you are likely to do just that pull the threads from the block which sods law will always be the last couple of bolts you degree no doubt when final angle tightening is achieved there is an obscene amount of strain going through those block threads well over 100 plus ft pounds I am lead to believe not forgetting its rotational stress i.e the fastener is moving in those threads while being strained unlike ARP for example where that end is fixed and the rolled finer threads on the higher tensile studs rather than cut threads are doing all the work, its not just a flaw with the RV8 the BMW M54 six cyl ali blocked motor can do the same thing apparently when angle tightening HB's

Edited by Sardonicus on Tuesday 21st March 13:16

Logically a no-brainer. I would NEVER use stretch bolts