Why not simply make up copper head gaskets and use o-rings around the water passages??
Not a great weekend for working so far…baby duty most of the day yesterday and the power was out until 3pm today. Here’s what I’ve got so far though. The one side is pretty much done. It will need a finish cut on the deck and I still need to cut the bores but that has to wait until I actually see a 348 liner to know what I’m cutting. I also gave some thought to the o-ring concept, but I don’t see a practical solution there. The reason is the tops of the liners do not seal to the block and there is no way to make them seal, so the o-ring would have to go around everything as I’ve drawn in the second picture….I’m really liking the 518 idea….. Off to start the second side. Once I finish cutting what I cut on the machine, I'll get into the water passages with a die grind and smooth them out...they have to make a little bend at the bottom of the hole and I'll have to finish that by hand. Image Unavailable, Please Login Image Unavailable, Please Login
Side 2 almost done. The oil feed hole is right where an old oil return hole was and I didnt get it welded deep enough I didnt realize they where going to be in the same place. Ill re-weld it all the way to the bottom tomorrow. Then re-drill the feed hole and hopefully no more break throughs. I also need to clean up the 2 oil return bungs I welded on, I didnt do it tonight because I didnt want to change the set-up and its late anyway. I have a plan for the oil feed, but I need a longer drill bit than I have. Ill get it on order and move on to the timing cover while Im waiting. A little progress anyway. Image Unavailable, Please Login
Want to share something I saw on a an all out race motor. The o-ring grooves for water sealing had been machined in a spacer plate about 1/8" thick similar in tool path to what you traced out . .. if the spacer plate was thick enough you could machine grooves in both sides . . .. wasn't the case with this setup so "other side" grooves were machined directly in the head. . . . the sleeves stuck out the deck of the block the thickness of the spacer plate and had there own individual combustion seal on the top of each sleeve . . think they were called Cooper seals . .. twin turbo motor ran 100 psi boost on alcohol Sean
It sounds like the spacer plate was there to raise the deck height to accommodate a longer stroke. I definitely could cut the o-rind groove into the block and make the length work out to some standard size .I see mcmaster has a 412mm OD, that would be 1294mm long and that would be right in the ball-park but its a 6mm cross-section an I think I would want 2-3mm . Im sure I could find something but it seems like it would be a bugger to get it to sit in the groove and not pop out while Im putting on the head. It think that will be the back-up plan if the 518 springs a leak. I am planning to use 12 individual copper rings (vw bug is the right bore) to seal the combustion chambers. I think I will cut the groove into the liners only so they will sit nicely in the grooves.
Could've been . .. got the impression at the time it was just easier to machine a spacer plate than fixture the block in a mill.
I machined a 1/16" o-ring groove (actual groove is .093/.098 wide x .055 deep from memory . .. see Parker o-ring book for correct #'s) all the way around the lip on the cam covers . .. getting the o-ring to stay in there during assembly wasn't an issue . .. regarding length I just trimmed the o-ring lengths from stock (couldn't be continous o-ring anyway).
Duhhh!! I was talking about spark eroding in an earlier post and forgetting this was an alloy block. Of course machining a 1/16th groove of any shape in ally is easy and effective. Our cutters were snapping on an iron head which is why we had to go that route. I'll try to be more alert before I do my next post...
Youre probably right, 1/16th does sit pretty well, a little grease and it good to go. Id be a bit nervous about anything that small for this job though. I was thinking 3/32nd or 1/8th which would still probably stay in with a little grease, vacuum grease is about as sticky as it gets. This would need to be a continuous o-ring or it would leak at the ends. I know they do glue the ends together, but that is pretty scary to me. The o-ring will be the back-up plan. I think if this were a race engine that would be coming apart on a regular basis, I would move the o-ring to the top. In this case though Im hoping the next time it comes apart is at about 100k miles 30 years from now and I think the 518 will give a better seal and I know its less work for me.... today anyway
I just ordered 12 VW bug head gaskets, I think they will do the trick. It's an 85mm bore and they have 87mm overbore kits, so right in line with what I'm planing and they cost $1.85 each..right in budget Also in budget is the free loaner extra-long drill bit I got hold of today so I can finish up the oil passege tonight if nothing else comes up.
Wow Mark, I just found out about this thread 2 days ago and it has taken me this long to catch up. Amazing.
This has got to be in the running for thread of the month or most outrageous thread of the year!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! JIM
I got oil to the second side tonight. I was a little nervous drilling the hole...it was 4" deep, a compound angle and had to slip the deck, which isn't all that thick without breaking out, but it came out fine. Tomorrow I just need to weld shut the ends where I had to drill through the outside to get to the inside. Then on to the timing cover and head part.....where I though the project was going to be starting. Stupid head studs in the wrong places........ Image Unavailable, Please Login
That's still a good question. My experience with copper gaskets is that they need a very smooth surface and glue to seal. It's hard to get a nice surface finish on aluminum weld, so I'd really be relying on the glue part, which makes me think it might be best to just skip the copper gasket and go straight to the glue. The advantage of a gasket on a non-drop-in liner engine in general over the rings and glue I'm planning is it's easier to grind/mill the deck flat and drop on a gasket then it is to mill 6 pockets per deck (nearly) exactly the same depth for the rings to work. On this engine through because of the drop in liners I need to machine the pockets for the liners perfect, so I have to do the hard work anyway. I figure I might as well save the extra effort of making the copper gasket on top of it all. Hopefully is wont prove to be a mistake ..
518 should do the job, sealing metal flanges against pressure is what it's made for. As for tacking o-rings into place. The MAZDA Rx7 WSM instructs you to tack o-rings down with Hylomar. After fighting with some of those o-rings, I broke down & got some. What a difference, IMHO you can't get a rotary to go together w/o using it. I use the Permatex Hylomar because it comes out of the tube in dense tacky form & that's as hard as it gets. BTW, The Valeo Hylomar comes out fairly liquid, has a solvent that has to evaporate before it gets dense. Problem is that if you're working on something large & complex (like a head or cam cover), the solvent evaporates & it sets up very firm before you've got things together. Also, I've glued o-ring stock (nitrile) with crazy glue & the result was a very strong bond, as far as I can tell, the bond is as strong as the rest of the 0-ring. In one case, the o-ring was being used as a replacement for a broken drive belt. The belt broke again (eqpt problem), but the break was NOT along the bond. Tricks for bonding o-rings are: 1) use a razor blade & get a very smooth cut. 2) Use a jig that ensures the ends are exactly aligned when they go together, basicly just a slot. (I bought an o-ring repair kit from HF that had a nice plastic jig, but it wouldn't be hard to make one.
finally 1 vote in favor....I thought I was going this one alone Crazy glue or cyanoacrylate is great stuff, but it breaks down with exposure to water. In looses about ½ it’s strength in 2 hours at 100F and will generally be undone in 24 hours on the stuff I’ve ever tried to glue with it such as SS and assorted FDA approved polymers. I may try it on an o-ring that seals oil, but not water.
From all the reading and talking to different people I have done the last few years, including Norwood, I found there is a great deal of confusion and misinformation about copper headgaskets. I havnt gotten up the guts yet to try it myself, at least not on the 308, but I do know they have been used on them. I have thought that if the surfaces were micro polished, and o-rings were used around the coolant and oil passages, leakage shouldnt be any more of an issue than with a standard gasket. Guys decades ago use to just cut them out on a work bench at put them in, it was common practice. Seems today everyone is trying to turn it into rocket science and overcomplicate it.
On a 308 you can't easily oring the coolant because there is no block between the cylinders. You need to use a long oring that at least goes around the all the cylinders. The copper seals the combustion chamber well and drag guys who run a dry block just love them. If you are running coolant though, sealing the water is a challenge and everyone I found who was successful used sealant of some type on the copper.
First thing tonight was to weld shut the open ends of the oil holes I drilled last night. Then the moment of truth, set the heads on the block and see what I've got. Much to my delight the alignment pins lined-up as planned and the heads dropped right on into their official location. I still need to add oil return bosses to the heads to match what I did on the block, but that should be pretty straight forward. Next came a quick look at the timing cover situation ..and it looks like Ive got a wee bit of work ahead of me. Tomorrow. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
I think you need more oil returns, looks great though. The timing cover mis-match made me laugh out loud, just a little fabrication there, lol, anything is possible though so keep the pics coming.
