Installing 7.3 head bolts/studs into a 6.9 block

[riotwarrior]

Is there enough material in the deck to drill and tap one of the newer 6.9 blocks to utilize the 7.3 headbolt or studs?

Better yet how about upgrading to a 9/16 stud size, does anyone think that this may be viable?

Might be nice to use same size studs as those Top Fuel drag engines eh?

 

[icanfixall]

The diameter of the 7/16th bolt is .3680 and for the 1/2 inch bolt is .4219... That only gives you about 54 thousands worth of material to make a 1/2x13 thread in. Not nearly enough. Drilling out to 9/16th will be .5156. This will give you about 94 thousands worth of material to tap in a 9/16th thread where a 1/2x13 thread was. The factory head bolt outside diameter of the threads is .495. So you see that gives us about 30 thousands of material to cut the 9/16th threads in.. Not looking good at all... Now drill out a 7/16th to 9/16th and you have about 147 thousands worth of material to get a thread in so thats a good thingbecause the 7/16 thread is completelt gone and you have a good pruchase for cutting a complete thread but... Now you need to be sure the block and head can handle this much machining without cutting into a water jacket. Then the nuts need to clear and the washers will probably need to be modified to fit the heads or the heads massaged to fit the washers or a little bit of both.... A bad block and heads would be a great place to test this out on and of course a good shop too....

 

[riotwarrior]

Gary, Thanks for the info....it was just something I have pondered since in a previous "Head Stud" thread you mentioned Top Fuel engines using 9/16 studs.

Whats your take on upgrading a 6.9 block to accept the studs....From what I see you think it's ok numerically, whats your thoughts on material thickness...like Deck thickness, bolt bosses etc. Do you feel that a newer 6.9 block could handle being massaged to the larger side?

Oddly, I am re-thinking building a 7.3 because of the cyl wall thickness issue. I am thinking going to a 6.9 and have already made contact and am waiting on info about a set of custom 6.9 slugs that take the larger 7.3 turbo wrist pin using teflon Pin buttons instead of circlips or spirolocks as well as adding a 4th ring for added durability.

Gas ported pistons would be ridiculous for everyday driving I think but hey...what do you think?

Perhaps with custom For

 

[Joejohn]

Skip the extra ring, just use "total seal" piston rings. They are second to none. I used them in my rebuild and the pressure leak down was next to nothing.

 

[icanfixall]

I don't feel changing the bolts in the 6.9 to 9/16th would be a good idea but... Installing a set of studs is a better idea just like it is for the 7.3 motors. Ken is making his studs with a 220,000 psi breaking strength now as some have reported. My set from him are the first ones and they yeild at 270,000 psi. I tested the new 7.3 bolts and they broke at 153,000 psi on the pull test. I really wish I had an extra stud to have it tested so everyone would have proof what it yeilds at. Also I should have tested a 6,9 bolt so everyone had that yeild strength too. I figure the 6.9 is somewhere around 110,000 psi. Milling a block to install bigger head bolts or studs is a big jut. Too bad we can't get a block that hasen't been drilled yet. A CNC mapping and things could be done easily....

 

[zigg]

Is there enough material in the deck to drill and tap one of the newer 6.9 blocks to utilize the 7.3 headbolt or studs?

Better yet how about upgrading to a 9/16 stud size, does anyone think that this may be viable?

Might be nice to use same size studs as those Top Fuel drag engines eh?

I did a lot of research on this, and finally decided to just got with a newer('87) 6.9 block, and install turbo pistons, and rods, and use studs instead of the factory bolts. I think it is the ideal combination. 30,000km on mine, runs perfect so far, gobs of power, smooth as silk, and doesn't burn a drop of oil!!

I have heard of one guy who got a 7.3 sleeved down to 6.9 specs, but I don't really see the reason for that, other than having the thicker bolts...?!

Anyway, here's a pic to compare the 6.9 stud to the factory 6.9 bolt, you can see the diff for y'self...

Zigg

 

[riotwarrior]

All this (cough) research is more or less hypothetical anyway. Just thinking of how to get MORE boost safely and not have the heads become one with the hood!

Gary whats your thought on cryogenic conditioning of materials? I understand that this can really have a significant impact on axle strength and wondered about doing same to Head Studs?

According to an article I read in a magazine the treatment can increase the torque an axle can take upwards of 40% which is significant. Now how does that ability to handle increased torque translate in to a strength increase in regards to a pull test I have no idea...

...anyone want to chime in here?

As for Sealed Power rings I have used those in several gasser engines over the years with complete satisfaction.


Joejohn, if what you say about studs and commetic gaskets is for real, and that we can see 30lbs boost, then I for one would consider custom slugs because I want to see a good seal and a 4 ring piston offers better longevity in regards to life with higher boost levels.

I am still awaiting a response from my email regarding custom slugs.

zigg, I had considered the studded 6.9 route but I do not like the smaller dia studs and you cannot as far as I know get 6.9 pistons that utilize the larger diameter wrist pin in the 7.3 Turbo engine. Thus negating the overal strength increase I am looking for.

I doubt we will see 30lbs boost but nice to build for it just in case....still concerned about Bottom end though....rofl thats just me though....

 

[subway]

cryogenicly treating parts dousent neccisarilly make them any stronger but it takes out internal stresses in the materials that cause parts to fail. from what i remember about the process is it takes materials down to a extreemly low temp (obvously ) shrinking the parts and that atomic structure. when the parts are made this structure is not neccisarily even hence some of the built in stressors from the start of its life from forming machining or whatever. as the part comes back up to temp the atoms all expand back out evenly from each other then releaving the built in stress.

you can also do this with vibrating a part at a certian frequency......of course if you hit it with a resonating frequency you can explode one to. like a singer with a wine glass

 

[riotwarrior]

Hmmm....singer...wine glass.....ah heck....make that Karaoke and beer and broken ears and headaches...

Sounds like that may be an idea to try then to treat head studs

Joejohn...you willing to send a few studs out to get treated then have pull tested as a comparison to the non treated ones?

 

[icanfixall]

I have done some reading up on the parts freezing and I really like it. I know its done to brake rotors in some of the NASCAR teams and if it works for them it will work for us. Its almost like majic the way it works. The parts are cleaned, then taken down to a specific temp and held there for a specific time. Then its brought back up to room temp over several days and thats it. The company I was reading this about does it for any part of the motors and break systems like rotor and several others parts. I just can't remember who it was.... Gees...

 

[riotwarrior]

Well I reread the article I have on the Cryo stuff and there is a company mentioned http://www.cryoscience.com/ I see the do quite a selection of engine parts, though I don't see bolts or studs listed.

I'll contact them and see what they say for curiosities sake.

Prices are not too bad either.....heck...do a whole block for $650 I wonder what the benefits for a part like a block are? Cylinders likely wear better for one I suspect.