head bolt holes & studs

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Seight-V8
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head bolt holes & studs

Post by Seight-V8 »

hello all,

Just dry assembling a few things while waiting from some head gaskets from America to turn up.

I notice when I put one side of the engine cylinder head on it doesn't sit flat with the block, and seems to be under some tension, it will go flat if I push on the head.

I notice that two of the bolt holes in the head that have ARP studs in are really tight, while the others all turn by hand....

If I remove these two studs, then the head sits flat with the block straight away.....but the studs in question are then too tight to install.

So not sure whats causing the problem, but what worries me is both heads leaked last time I assembled everything, and this might have been a cause, certainly wont help anyway.

So whats the fix?

drill or dress an edge of the holes that are tight to allow the studs to install freely?

Or open the dowel holes up on one side to allow the head to float a little?

The holes studs in question are at the front either side of the middle one, and its a 10 hole head.

Anyone had this before?

Glad I found another problem, just something else to get around.

cheers

scott



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Post by unstable load »

I wouldn't open the dowel holes up, personally.It sounds like someone has fitted the studs incorrectly to me. Get an engineer's square and check if the bolts are vertical to the deck surface.
Cheers,
John

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Post by DEVONMAN »

I believe that ARP head studs are now available with longer thread length into the block. I have had two of the shorter version studs pull out slightly in service and their nuts were found to be relatively loose when I dismantled the engine. Like yours the studs were tighter in the block.
I fitted double length helicoils to those holes. (7/16" UNC)

I extended the thread length on the studs by 1D before using them again. They are tough so a top quality die is needed.
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ratwing
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Post by ratwing »

Are ARP stud threads rolled or cut?
I just wondered, I've heard they don't really go deep enough into the block and thought cutting more thread with a die might give a weak point if they're rolled? (which is why I went for JE studs which have enough thread to almost reach the bottom of the block holes).
Mind you, I've never heard of 'modified' ARP's breaking either so I suppose it must be ok.

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Post by DEVONMAN »

ratwing wrote:Are ARP stud threads rolled or cut?
I just wondered, I've heard they don't really go deep enough into the block and thought cutting more thread with a die might give a weak point if they're rolled? (which is why I went for JE studs which have enough thread to almost reach the bottom of the block holes).
Mind you, I've never heard of 'modified' ARP's breaking either so I suppose it must be ok.
I would think they are rolled. Cutting an extra length of thread is probably not ideal but the weakness is the penetration into the ally block not the stud. I'm not convinced that the short threaded ARP studs were not originally intended for a cast iron block.
1950 A40 Devon Hotrod with 5.0 twin turbo RV8.
EDIS8 wasted spark, Holley Injection.
Been as far as the Moon and back in 57 years of driving. Same Car, 5 engine upgrades !!!


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Post by stevieturbo »

So it's basically that the holes in the head do not appear big enough for the studs ?

Are these standard replacement ARP studs ? ie same size ?

I'm sure there are many casting variations here and there, if the hole needs a little reaming out or a drill run down it, I'd just do that.

As long as thread engagement is good, the dowels are not physically holding the head away from the block etc etc then I dont see a problem.

When I DIY'd some 1/2" studs on an old RV8 years ago....some ended up at all sorts of angles lol.
No poop I had to beat the head on with a block of wood and a hammer. But it went on and torqued up great and never once gave a problem. When it did come apart, heads lifted off fine, so torquing things up pulled them straight.

Needless to say...I wouldnt DIY drill/tap a block again that same way lol
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Post by mgbv8 »

I've had this before on a block that had helicoils fitted in the block for the head studs. The Helicoils were all at various angles. It was nightmare to get it sorted as I had to open out the bolt holes in the heads by 3mm?

Perry Stephenson

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9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

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Post by Seight-V8 »

found the problem tonight, the sizes of the bolt holes at the head side where 12.25 to12.5mm.

Size of the bolt holes at the stud nut end 11.75mm...

So looks like all those head on-offs and re-tightening has shrunk the hole sizes at that side.

Drilled them out to 12mm....

And now can install all the head studs with no binding....

Another job done...and something less to worry about....

Now where's those head gaskets from America.....oh 4wks away yet...hmmmm

cheers all.

scott

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Post by mgbv8 »

What head gaskets are you waiting for??

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

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Post by Seight-V8 »

Ordered some cometic 1mm thick ones from Burton power..... Delivery was quoted at 4-5wks, but hoping for a little quicker..... Not cheap at £180.....but we're £210 from summit with tax added....

Overkill maybe....

Just looking forward to getting it back in the car after a 2 year..... Rebuild...

Regards

Scott

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Post by stevieturbo »

Why not just a regular composite 4.6 gasket ? They'd be around 1mm ?
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http://www.youtube.com/watch?v=XgWRCDtiTQ0

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Post by Seight-V8 »

i wanted a little more compression ratio, should be about 9.9:1 if my calcs work out, struggled to find any other gaskets that where listed with actual compressed sizes.

I'm not sure they are worth 180 notes, but they are supposed to be good, just hope they are worth it.

My last build was plagued with problems during running, and I've spent 2 years doing this build, I really hope this time I can get to do more than 475 mile on the engine, and all this expense is worth it.

scott

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Post by mgbv8 »

Scotty!
I used Cometics on my last RV8 build. When I had finished with them we chucked them onto my Sons Escort RV8. Those gasket came off and back on at least 5 times while we swapped them from engine to engine as we blew our poop up on the 1/4 mile. Even with being re used many times they never leaked?

Pel

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

mgbv8
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Post by mgbv8 »

Scotty!
I used Cometics on my last RV8 build. When I had finished with them we chucked them onto my Sons Escort RV8. Those gasket came off and back on at least 5 times while we swapped them from engine to engine as we blew our poop up on the 1/4 mile. Even with being re used many times they never leaked?

Pel

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

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