Id try moving the stainless o-rings to the block and possibly going to 1/2 studs. I had a similar setup with the o-rings in the block and a shallow receiver in the heads. It was a stock block application that only saw 30psi. But it was surely bulletproof then. Then again i wasnt dealing with Siamese bores. Im sure it gets plenty hot there at 60psi after a couple seconds. The compression is acting like a cutting torch.
Anyone Tried 1/2" Head Bolts??
- Thread starter BlownV6
- Start date
Mike
Have you thought about converting to a MLS type gasket?
O-RINGING ENGINE BLOCKS - Yellow Bullet Forums
Billy T.
gnxtc2@aol.com
Have you thought about converting to a MLS type gasket?
O-RINGING ENGINE BLOCKS - Yellow Bullet Forums
Billy T.
gnxtc2@aol.com
Whew, only 3/4" thick and I'm sure you have a 1/16" or so chamfer at the top to keep from raising a thread and making a high spot so your engagement length is really only 11/16" or so. I found the formula for shear area, it's 0.5 * pi * Le * (D - 0.64952 / p), where pi is 3.14159, Le is the engagement length (11/16" here), D is the major diameter (7/16 and 1/2"), and p is the # threads per inch, 14 for 7/16-14 threads and 13 for 1/2-13 threads. Running the numbers gives 0.4224 square inches and 0.4860 square inches for 7/16 and 1/2" studs, respectively. That means the 1/2" stud can give 15% more clamping force when both are stressed to the same point (actually in this case when the threads in the block are stressed to the same point since the block is weaker than the stud material is going to be). I'm not sure what the yield tensile strength of a stage II block is but cast iron is typically 30-45 ksi so the threads would pull out at (using 40,000 psi tensile strength) 16,900 and 19,440 lbs of clamping force, minus some derating for thread imperfections in the 1/2" threads from tapping over the 7/16" threads. That corresponds roughly to 160-170 ft-lbs of tightening torque with oil on the threads so I'd stay well below that. (If you have a junk block you could tap a hole and tighten down on a spacer block until it strips out and find out the limit for sure, just don't reuse that stud and nut.) I assume you also go through at least three torque/loosen cycles before the final tightening - you can really feel the threads getting smoother and you finish with much more uniform clamping across the gasket. ARP recommends five cycles but that gets boring and I can't feel the difference past the second or third 
. Anyway, see what ARP says about stud material and tightening torques and clamping force compared to the maximum obtainable that I estimated. Looks like it should be well worth the effort.
. Anyway, see what ARP says about stud material and tightening torques and clamping force compared to the maximum obtainable that I estimated. Looks like it should be well worth the effort.At this point in my journey , head gaskets/torching heads seems to be the weak link!! I am seriously looking into installing 1/2" head studs in the 2 center rows to keep the heads clamped down. Anybody eles tried this?? This is on a stage 2 block with stage 2 heads.
Mike
it will be an exercise in futility-------most of the time the problem is not the head bolts (assuming they are torqued correctly)------the problem is that the deck surface and mating head surface seperate by flexing apart BETWEEN the bolt spaces-------they don't remain flat under excessive pressure-------bigger/stronger bolts can't do a thing to help with this problem.........RC
8 years ago or so when I was first working on this combo I had this same thing happen and I thought the same thing!! So I filled the heads with hard block , it has helped up till this boost level. I have been designing a billet head with a few minor changes from the stage 2 design and this is in part why I would go to this expense (When I can afford to have them machined)
If I do ever get the billet heads made the bigger head bolts would certaily help with those. So my thinking is its time to try this experiment. I can see no reason whatsover that it would hurt anything and just may help. Mike
Too bad you don't have more room between those bores to run separated o-rings. I think the thinness there is not helping that gasket dissipate heat much.
I chose to run the groove in the top of the sleeve on a TA block so that movement of the gasket couldn't work on the groove as easily as it could if the groove was in aluminum material (the head). With the groove in aluminum, after awhile the sharpness of the groove starts to go away affecting head to gasket contact and the ability for heat to dissipate.
I chose to run the groove in the top of the sleeve on a TA block so that movement of the gasket couldn't work on the groove as easily as it could if the groove was in aluminum material (the head). With the groove in aluminum, after awhile the sharpness of the groove starts to go away affecting head to gasket contact and the ability for heat to dissipate.
I have to agree with RC. Although, I'm sure there is a point where you must move up in fastener strength.
Mike, you need to get that billet head done.
Here's something else to think about.
We all know that stainless steel resists heat transfer much better than copper and aluminum. With the stainless wire firmly embedded in a groove in the head, any heat put to the wire will be thwarted by the stainless material and the transfter of heat to the large surface area of the groove in the head is also thwarted by the stainless wire. Hence the stainless wire tends to protect the groove in the aluminum material from heat. Less heat has to be handled by that critical area of the head.
With the stainless wire in the top of the block, the heat is rejected by the stainless wire as previously explained and is forced to be reflected or contained in the copper gasket. The heat searching for somewhere to travel looks at that increased surface area of the groove in the head, loose fitting at that, and also the material being aluminum says, 'Oh yeah! I know where I'm going.' The concentration of heat weakens the aluminum making working the groove by the gasket even more of a possibility, continually losing more and more head to gasket contact and...
We all know that stainless steel resists heat transfer much better than copper and aluminum. With the stainless wire firmly embedded in a groove in the head, any heat put to the wire will be thwarted by the stainless material and the transfter of heat to the large surface area of the groove in the head is also thwarted by the stainless wire. Hence the stainless wire tends to protect the groove in the aluminum material from heat. Less heat has to be handled by that critical area of the head.
With the stainless wire in the top of the block, the heat is rejected by the stainless wire as previously explained and is forced to be reflected or contained in the copper gasket. The heat searching for somewhere to travel looks at that increased surface area of the groove in the head, loose fitting at that, and also the material being aluminum says, 'Oh yeah! I know where I'm going.' The concentration of heat weakens the aluminum making working the groove by the gasket even more of a possibility, continually losing more and more head to gasket contact and...
Maybe that Im looking at a different problem than you. My bore size is 4.030 what size is yours?? Bore spacing is 4.280 so with that bore that leaves 4.250 thick between the bores , a .060 wide receiver grove just looks looks dangerous to put in the block. Im no engineer but I still think if there is going to a problem I want the weak link to be the repairable part, which is the head. But im still open for ideas!! All other forms of engines Im looking at that are under extreme conditions have evolved to larger/stronger head studs!! Im pretty sure Im there, and it certainly cant hurt that contact area. I can back the boost / timing /or load fuel to it, or try to fix the weak link. Mike
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
I think the blown alky cars use double o-rings rather than a reciever groove.
Run o-rings in the block and head with an .080-.090 copper gasket
Run o-rings in the block and head with an .080-.090 copper gasket
The room I have between bores allows me to run individual separated o-rings with an acceptable (according to the gasket manufacturer) amount of spacing between them. That, I am thankful for. That's why I stated, too bad you don't have more room there to run separate o-rings. You're stuck having to do what you're doing because of your valve sizing too. Can't go down on the bore for interference and shrouding problems. I'm not trying to convince you to resort to a different combo, heck you're shooting for the top shelf here. I'm just saying, I feel your pain.Maybe that Im looking at a different problem than you. My bore size is 4.030 what size is yours?? Bore spacing is 4.280 so with that bore that leaves 4.250 thick between the bores , a .060 wide receiver grove just looks looks dangerous to put in the block. Im no engineer but I still think if there is going to a problem I want the weak link to be the repairable part, which is the head. But im still open for ideas!! All other forms of engines Im looking at that are under extreme conditions have evolved to larger/stronger head studs!! Im pretty sure Im there, and it certainly cant hurt that contact area. I can back the boost / timing /or load fuel to it, or try to fix the weak link. Mike
There is certainly no room for double o-rings if there isn't any for separated single 0-rings.
I talked to a fella that has quite a bit of blown alcohol hemi experience, and he says he's tried o-rings with and without receiver grooves. Don't know what experience he has with double o-ringing. He feels o-ringing without receiver grooves is a waste of time.
I didnt know you could use an o-ring that stuck very far out of the block without a receiver groove?? The o-ring will not penetrate the surface of the copper gasket so that raises the gasket off the surface of the block and the head?? I cant picture how that might work in my mind
Im going to the ADRL race at Columbus and then Indy in a couple weeks. Hope to get a better idea of whats in current vouge. There was a $10,000 to win Pro-mod race here at my local track last night, one the 4 turbo cars was a ford that blew a head gasket and I got to help rip it apart. He had the exact same setup I use with the exact same results!! He was on the cell phone with his engine man discussing both a tuning issue and switching from 1/2" to 9/16" head bolts. I told him I was researching do the same thing except just the 2 center rows. His engine only had the 4 bolt per cylinder setup but the ford beside him had Trick flow stuff with 8 bolts per cylinder and combination of 1/2 and 9/16" studs and said that hadnt had any problem with the head gaskets. Dusty please explain how they do this please??? BTW Andy jensen couldnt get qualified, Billy glidden showed up to the track at the call for 2nd round qualifing and made it to the staging line with 4 cars left to qualify!! He ended up #3. It was a great time!!! MikeYeah, that's tight.Correction to above post!! I stated that the bore spacing is 4.280" and that leaves .250 between the bores. I believe it is actually 4.240" bore spacing which leaves .210' between the bores!!!
My bores are only 3.83 or 3.84, and even there the amount of material between the bores was right at the limit of being able to run separated o-rings, rather than the figure 8 method. If I remember right SCE recommends .100" clearance between the o-rings when running them separated. This prevents a bunching of copper material causing lifting of the head between the bores.
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
I was about to go this double o-ring route with my SB2.2 heads.
Don. There is only one o-ring in the block, and one o-ring in the head. Not two side by side.
The gasket has to be thicker than your average copper gasket which allows both o-rings to penetrate the copper. I believe I was told to run an .090 gasket.
Looking at your o-ring set-up and where your getting the damage. I'd have to say the overlapping of the o-rings is a major part of the issue.
Don. There is only one o-ring in the block, and one o-ring in the head. Not two side by side.
The gasket has to be thicker than your average copper gasket which allows both o-rings to penetrate the copper. I believe I was told to run an .090 gasket.
Looking at your o-ring set-up and where your getting the damage. I'd have to say the overlapping of the o-rings is a major part of the issue.
If thre was .400" to .500" between the bores as with some blocks I would defenatly go with a double o-ring setup. But with what I have here Im not really seeing a better way to o-ring it. Im thinking the o-ring setup I have will work (has worked) I just need more clamping force and deck rigidity.
I know that what I have is not working at this boost level so Im looking to put a lot more clamping force on it and see if that will hold!! Also still listening to new ideas!!! Mike
I understand that Dusty, but are the o-rings on a same diameter or are they on slightly different diameters so that they end up side by side, but one above and one below the gasket?
For what you're trying to do Mike, I think your move to larger fasteners is a good one, but I'd also work on those billet heads and throw those on too. Even with the studs you're using now, the gasket isn't showing much evidence of lifting right around the studs, only between them. That tells me head deck bowing between the studs is more of the problem than anything else.
joe_schindler
Living better with carbon
- Joined
- Oct 1, 2001
I completely agree with this. There’s probably some slight increase to be had; but at a cost.
Don’t forget that as the stud gets bigger; the amount of material between the cylinder bore and the threads holding the stud are reduced. This area already cracks in stock N/A blocks that have not been bored and are using the stock head bolts.
Raising the clamping force on the head will also raise the distortion pressures working against the deck surfaces of the block and the surface of the head.
