V-12 Engine into 308 Build, over on Grassroots

How could they seal right?

But I'm honestly shocked to here you NOT suggesting aviation sealant

 

You funny

Seal right? With silicone?

I like aviation sealant for composite and MLS. Copper.... I don't like copper, even 'O' ringing has it's issues. It's the floating liner design that complicates the whole thing.

 

I meant how can a slab of copper seal anything....its a shim. The sealing had to come from somewhere else, silicone, aviation sealant, copper spray...somewhere

 

Ahh ..
It can in 'theory' because it's a soft material. It's useful as we know for 'O' ringed engines but that's a different beast.

So yeah silicone is the better option for sealing. It's all that dynamic movement that needs to be accounted for.

Setting aside torsional flex and looking at only Z axis movement. Frame of reference the block. The liners move up/down with ring drag, the heads lift under pressure and the studs are the springs keeping it all together. That micro movement makes it a fun job of getting the sealant just right. Composite gaskets have "crush" and rubber silicone tracings, MLS uses "spring" embossing, but the movement is such that even those have issues, hence my choice of sealant to insure it doesn't leak.

You've got such a unique build and custom fab, it might really be worth doing a sensitive film pressure test to see what is actually going on.

Evans is also a surfactant, that stuff migrates thru the tiniest of gaps. That's it's one downside in my view.

 

Not to be Debbie downer, check to see how many cycles the studs can take. The development mules we used ate thru studs as we only got 4-5 cycles. You might be running into head stud clamp load problems as well. Wait.... Do you re tq after a heat cycle? Or check the tq?

Checked my notes, mfg recommend only 3 cycles but suggested we might get more by checking stretch. We hit the limit at 5 every time. A couple stretched out at 4.

 

Are the studs you use factory dimensions and torque values? I'm honestly not sure how I'd know if they stretched. They are nothing crazy, just 4140 at RC45 iirc I settled on after talking with a bolt guy who offered to help. and it was a huge help. I think the 328 and newer use the same torque but 10mm instead of ther 308 11mm I'm using so I that might be a factor? Don't know.

There really is no good way to retorque but this was basically 1 heat cycle....Sunday I only ran in 45 seconds so Thursday was the first time to bring it up to temp

But none of this is going to matter once I install the copper gaskets

 

Yes and no, factory tq spec and metric threading in block, however the top end was imperial and right PITA on the QV heads. These were mfg in bulk so it was what was in hand before I got involved in the engine dev. That bolt mfg is no more. So I don't have to deal with that funky miss match. Currently we're in talks with 2 companies for getting head studs mfg. But in either case I had the length spec to work from and the notation that they can only be brought to tq 3 times before they start to just yield. ARP also only has 3 tq cycles. Same for Conrod bolts.

 

I'm still not replacing the studs or rod bolts, all of which must be pushing 10 cycles now.

I spent the morning discussing sealing strategies. I'm certain the issue here is being caused by distortion of the block and heads on the ends which are not supported the same as the centers....the end blots are acting on 1/2 the area and the end liners are touching block on a 3rd side so they must tilt a bit....and then leak.

Part of me believes the basically non-compressible gasket aka shim will sort it by not letting the ends over compress. Another part says o-ring the liners to lock them in place and yield the cooper to match whatever deformation there is. I'm leaning toward going with sealant as o-rings the liner gives me even less fluid sealing area plus i can always try that next but can't undo it....so for today that's the answer, slather RTV on a copper shim and pray.

 

I thought I threw out the old gaskets but found them and was measuring while the oil drained. They are about 0.055 throughout, but the ends are as low as 0.053. What is confusing me is the fire rings are all about .057....I think that just means they never enter a yield state and recovered....or it means the liners are dropping below the deck height but I don't like that answer so I choose recovered

 

Liners sit on register shelf? O ring seal. Without O ring, how proud of the deck are they at register?

I'll have to spark up the ol PC but I've got a study on liner deformation under clamp load... Interesting results.

 

The liners sit on a shelf on the deck. I measured tham at 0.0015" proud but I'll see if I can find another way to measure and see if I get a different answer.

For sure the gaskets are compressing 0.002" more on the end so its not a surprise the end cylinders are having issues. The is clearly a reason ferrari designed their gaskets with metal ends. For sure this is an issue needing a solution.

The liner height may also be and issue, not sure but I'll what I can figure out while I wait for gaskets.

 

I would add stop leak and retorque then go through a few more heat cycles. Worth a try. I coated my gaskets with high temp silicone around the water passages, torqued a little and then torqued fully after 24 hrs.

 

I went the stop leak path last time, it didn't seem to even slow the leaks down and just looking at the coolant as it came out there was still quite a bit of it in the system. It could be the stuff just doesn't work very well with the evans coolant or maybe the leaking cumbustion chamber blows out whatever seal the stuff made vert cycles? don't know.

I didn't work very fast or very consistently yesterday but I'm about 1/2 way through ready to pull it. What I'm trying to get my head around whether I'm just going to try the copper with sealant or going to pull out the cylinders to cut 0ring grooves and know they are locked into the gasket....and heads can be oringed too or have a receiver groove to accept the copper deformed by the bottom oring.....but I really don't want it to leak again

 

Something worth checking is the torque settings for the head bolts should be with or without lubricant. This can effect the ultimate torque achieved and could deform the head or block if outside the design envelope. I don’t see a problem with using a proper sealant with a partial torquing and then to final torque after the sealant cures to form a gasket.

 

That would be the path if I decide to NOT oring.....I'm trying to convince myself its the right approach. I would feel better on this path if I used aluminum instead of copper I think so I know it would move naturally with the heads & block .

 

I have been following your work throughout this thread and it is impressive. My two cents after building multiple race engines for funny cars and SCCA road race cars 30 years ago is that you could be trading one problem for another by putting o-rings in the heads or block. We would do o-rings on high compression aluminum engines because nothing else worked to contain the compression on an aluminum block and heads. For engines that didn't have coolant it was an easy solution. For those that did have coolant running through the block.....we fought leaks around all the cooling channels because no matter what we did they would leak after a while. Back then we tried everything to seal the cooling channels but coolant under pressure has a way of working its way through RTV and every other sealant we tried. Maybe there is a better sealant today?

This is the sealant we did have good luck with on non-oring installations:
Valco Cincinnati 71283 Hylomar Blue

The other issue we had was retorquing the heads. Stainless steel wire is much harder than the block or head and as a result dug witness marks into the aluminum as it compressed. Multiple heat cycles caused the heads to lose torque and leak cylinder compression. Not a problem with a no coolant engine (other than HP loss) but a much bigger problem with one that had coolant.

I guess this is a long way of saying......I would try your gasket approach one more time before I put o-rings in. Once you do o-rings there is no going back. Also.....don't put stop leak or any other nonsense in your cooling system.....that is also trading one problem for another in your radiators.

I also like the fujifilm idea to see what is really going on. I wish we had that stuff 30 years ago.

 

Thanks. The copper gaskets would be my 1st attempt with them, I've been using a composite material with soft steel flame rings crimped on.

I could change the order to another set of these and buy some steel to wrap around the ends to try and duplicate the factory approach...how much to use would be a guess but its possible to try...these did ALMOST seal with the sealant on them.

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Who's the gasket mfg?
While I like Evans in specific applications, the stuff eats thru some composite gaskets, iirc Chevy had this issue for a bit with the coolant system and gasket corrosion due to the coolant.
It's why I'm forced to use an MLS gasket with Evans.

I checked the report on the liner study I did a couple yrs ago. Ductile iron liner compression under tq was deformed ~ 0.0025mm. fairly uniform with the inner dia showing more deformation into the bore. The study design was for a 308 with factory register and liner profile.

 

I'm using cometic and I don't SEE any sign of the material degrading.

Right now I'm certain the ends are over crushing. My thought with the copper was that won't happen....but I more thinking got me to , yeak it probably still will because the liners are proud, which go me to wire...but maybe a step back is in order.

I should also dig back through oll plug photos to see if anyhjitng looks like coolant from the first run 4 years ago....this might be an Evans issue

 

Can't find that I took any plug photos, that's unhelpful.

 

Ok cometic is the go to.
Evans is just so damn hard to contain on these engines.

O ringing does introduce whole bunch of other issues.

Is your stud and bore center different from the factory 12? I don't recall that you changed it. Surprised cometic doesn't have an MLS option for you. However that was also a bit of back and forth with them to get it right on the 3x8 with stock liners.

Another option if you're not to far into removal. Run the engine with just distilled water before switching to Evans. That initial thermal cycle before everything is set is where Evans just migrates and weeps. All our engine Dyno testing is with water, no choice as the facility is setup that way. But I've noticed less issues with starting with water for break in and tune, re-tq heads etc, before switching to Evans.
And admittedly we did have one engine that simply would not hold Evans, nothing worked. Thankfully it wasn't a 3.5L build.

 

Cometic has very few ferrrari options....308 and 250 I think? But yes, my bore is offset 1mm from stock TR location and much larger. The offset let me keep 10 400i stub locations and also allowed larger intake valves so win-win.

Day is done and the engine is out....time for more drinking.
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Hustle'n...

 

Retreat I did....called and changed the order to another set of composite. I will guess as how much metal to add to the ends...I'm leaning toward coping the flame rings basically but still pondering.

Also retreat from Evans coolant I will....I love no corrosion concerns but yeah, it has very low surface tension and just gets everywhere.

 

I'm out of town till Friday/sat... When I get back I can measure the thickness of the metal shim used on the OEM gasket if you'd like.

Run the engine for break in on straight distilled water. If that holds with no issues you can opt to switch up after. I find Evans to be most useful in the Siamese liners of the 3.5L. otherwise the German blue coolant is my go-to. I can get you mfg if you'd like, it's not cheap but it's not anywhere near expensive as Evans.