I am building a 24v P pumped engine, and have gotten soooo much conflicting information from forums and even diesel shops regarding the two methods. My question is this, can FR's be used on a daily driver w/o any issues? I do realize that proper torquing of the studs (I'll use ARP studs either way) is important after several heat cycles. I have had one very prominent diesel shop tell me that fire rings would be fine for a daily driver if the machining was done correctly and I torqued properly after 5 heat cycles. I have also heard horror stories of the fire rings breaking off and tearing up the head or scoring the cylinder walls. O-ringing seems to be the way I am leaning however I have yet to find a shop in the state of TN that does this service. I am trying to avoid the freight charge of sending a head out to a shop for O-rings. I am not wanting to constantly be re torquing the studs all the time, but then again, depending on who you talk to some people say after 5 heat cycles they have never touched them. Has anyone put 100K miles on a fire ringed DD w/o any problems? I am not building a sled puller, just a dead reliable engine for a little play and heavy towing capabilities. I have heard enough opinions already, please limit these responses to people who have actual experiences with either of these methods. No offense taken I hope. Thanks in advance for your help.

 

I'd lean to o-rings. Easy to install, and uses OEM head gasket. So if there are ever issues, its easy to sort out. I've never dealt with fire rings. I'd think any shop capable of machining the fire rings would be able to do o-rings. 110mm diameter, 0.039" wide groove, 0.029" deep, 0.041" stainless wire.

 

I have yet to find too many machine shops in TN that are even familiar with O-rings, and none as of yet that are capable of machining them. Pro tech tools in Lebanon, TN is supposedly the best as far as fire rings go, but they ONLY do fire rings and said they will not do O-rings...I kinda figured if you could do fire rings O-rings should be able to be done as well, but I guess not.

 

In have a 12 valve that I did the head on almost two years ago now. I put fire rings in it. Have used it as a driver / work truck since. No issues at all (with this mod anyway ), always let motor warm up be for each drive. Only down fall is the expensive gasket if u have to remove in the for any reason.

 

you can buy the tool to put "O" rings in the block, from summit , for `bout $150 or so. do it your self. I`ve done `bout a dozen blocks ( for different racers) back in my sand dragging days, never had ANY head gasket failures. also did it to my SD22 Diesel in my vega when I turbo`ed it, 30 years ago, still NO head gasket prob`s. check out summit.

 

thats good information to know, I wasn't sure if it was possible to DIY. I did a search of Summit and found nothing like that, do you have the specific name of the tool or the brand I can do a better search for? I googled it and found some cutters but they did not offer a price, and they looked to cost several thousands I'm sure....

 

in the summit web site it is called ISKY Engine block O-Ring tool # 200-GRM. I lied, when I bought mine years ago, it was in the $150 range( as well as I can remember) todays price is in the $300 range. the kit comes with a small coil of copper wire, but I`ve used .040" stainless or .040 galvanized tie-wire. the stainless and steel leaves a deeper groove in the head gasket. I`ve also used the galvanized steel tie wire on dead soft copper head gaskets. hope this helps. I just rechecked and it is $329 with free shippin`.

 

Is there any disadvantage to O-rininging the block verses the head? I found the tool and am thinking about buying this, very cool idea!

 

there`s no advantage having the "O" ring in the head or the block. it`s just easier to mount a head in the machine to cut the gruve for the "O" ring. the pressure on the head gasket will be the same with the "O" ring in the head or in the block.

 

I wouldn't do the oring the block. I would do the deck the block so its straight and true surface. Same goes for the head. The shop that I use for all my head work, will pull all of the valves out of the head. The head is deck on the valve surface and on the backside. Once everything is trued up, then you can install o-rings into the head.

Which head gasket are you going to run? If the block has been decked, you should measure the piston protrusion. 0.029thou protrusion is around the max spec for the 0.065thou head gasket.

True Fire rings is usually has a cut into the block and the head. There is a small ring/cylinder that goes in-between the head/block. Its alot tricker to machine and really not required for street daily driver.

Cometic has a MLS head gasket for the 12V/24V, but I have never run one.
http://www.cometic.com/default.aspx

 

If the head has to be completely rebuilt (guides and needs machine work for the valves/seats). I would start with a new CR head (cummins pn#4931564RX 06/07 CR head). Its a new casting that's been re-engineered to more resistant to cracking. Its pricing is cheaper than rebuilding an old core. I've decked a few of the new heads, all have straight surfaces. The new head can be run out of the box.

If your going to run on a VP injection pump, you will need to machine the VP cross tubes so they will fit in. I can post pictures showing how.

If your going to run on a P7100 conversion, buy CR to P7100 pump lines. Buy the 6.7L cross tubes. They flow more fuel and are less likely to leak like the VP stuff. I've drilled out the edge filters on a set of 6.7L cross tubes they flow way more fuel than stock.

 

mike,

You have an abundance of knowledge, thank you for the insight. I do have an almost new 24V head I think I will use just because ordering a CR head would make this project more of a money pit than it already is. The 215 pump is in great shape and was taken off a running motor, I just figured if I was going to have a shop install the 4GSK and the .191 DV's I would have them go ahead and bench it to make it a little more precise and accurate....not looking for huge HP gains, just a great running motor that my grandkids will be driving someday! I am leary of attempting to O-ring the block myself, and since I don't have a crap block to practice on I might just go with studs and a quality head gasket for now. I can always upgrade to O-rinds later but honestly I doubt I'll need them for what I am using this for. Thank you for the great responses