This engine still uses the (rare) factory aluminum block, copper clad head gasket.
I already did one head gasket retorque, right after initial start-up and a couple of heat cycles... it took another 5 ftlbs to get back to the 60 ftlb setting I am using with the ARP studs.

I will report back on how much additional retorque it takes after 1000+ miles and some intense heat cycles / hard running.
DD

Checked the head gasket torque and it was about were we left it, except for 3 stud nuts that may have lost 3-4 ft lbs. We tightened them all to 65 ft lbs... that's about as tight as I want to go for this combination.

Also re-checked the valve lashed and loosened the intake valves more, from .020 to .022... the exhausts were still at .023. Tried going a little wider on lash and things start to clatter so I am convinced that we are right at the end of the lash ramps with this cam profile.

Doing this work (running engine, valve cover off) reminded me about the small groove we added to the rear cam bearing journal... that modification puts a bunch of oil up top. I have mixed feelings about doing that... now valve adjustments will always be messy work with Twiggy. I find that this all aluminum engine has way more valve lash change from cold to hot, about .004 on the exhaust valves.

We also did an oil change and the oil that came out looks good. There was more lint and grit then I usually see, My lack of cleaning or may-be because the engine sat for 8 months before installation... but it's a "datapoint" and something I need to pay more attention to.
The oil change pointed-out a problem with the dip stick's calibration, it shows "Full" at 4 quarts. The oil pressure was 5 psi higher when we put in all 5 quarts so I changed dip sticks to show the correct "Full" level.
Using the high volume oil pump was the right decision, after break-in, hot idle shows the oil pressure at 35 psi, that quickly goes to 55 psi at just over 1000 RPMs.

The biggest assembly mistake was my sloppy use of block filler.... I had to have the radiator "rodded-out" and we are currently using a screen to trap flakes of filler, as it makes it's way out of the engine. With the cleaned-out radiator, the engine temps are under control... as long as I keep the screen "trap" clear.... and that cleaning is becoming less frequent.
Another bad decision, I added a timing chain tensioner to this engine and now I hear the chain rubbing on it at slow idle. Another one of those "live & learn" things.

Power and performance is good, this is a very good street performance combination over-all. This set-up feels like it will really "wake-up" with more carb and exhaust... or a shot of N2O (I may do that later)

I do have a few moments of engine rough running, right upon cold start-up... worse then the iron engine that came-out of the car. The missing "clears-up" after the first 60 seconds of running and a blip or two of the throttle. I need to chase that problem down. (Mis-adjusted choke, bad plugs or wires?? May-be some oil or water is getting into a cylinder as it sits and cools?)
For now, I keep on driving it.
DD

Well, I found the start-up miss, coolant is getting into #5.

The start-up miss was the first bad sign and I was seeing more "color" on the #5 spark plug. The engine was also putting-out a lot of tailpipe condensation on cold mornings, during the first 5 minutes of running.

I finally pulled all the plugs, after the car sat for a few days and gave the engine a crank with the starter, that produced a pretty good shot of water mist out of #5. I poured-in a can of radiator sealer thinking that would plug any head porosity or a small crack but that has not helped.

Off with her head!
I think I will pull the head tonight to see what the problem is.
About now is when I hate myself for using head studs.
I sure hope the aluminum head is not damaged.
I will let you know what I find.
DD

Aw, that blows. Hope it's just a small/simple issue that turns out to be little more than a nuisance.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Should I call Cometic again and try to start up a MLS gasket project??

Bummer.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Not just yet, Lou — I just got a PM the other day suggesting MLS gaskets are days away from ready availability from another source. Gimme those couple days to nail down details.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Whoa. OK. What design parameters are these using? Work for both Fe and Al blocks? Australian??

Thanks,

Lou

_________________
Home of Slant6-powered fun machines since 1988

Those are all the questions I immediately fired back, except for the last one: Australian = yes. I am sort of caught flat-footed on this one; I don't recall there being a call for input on the design of such gaskets, so I am _hoping_ that either the ones now in stock are AL-compatible, or that a second AL-compatible variety can be made.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Any aftermarket gasket should have the external profile cut to be aluminum block compatable, those blocks have more curves along the lifter gallery and using that profile will not impact sealing on an iron block.

The "claim to fame" for the Auzzy head gasket has been the larger bore / fire ring.
That feature is in conflict with the Aluminum block, which needs a small bore "fire ring" with an ID of 3.440 to 3.450 max. in order to seal on the narrow cast iron bore liners
DD

I'm pretty sure the small bore version are the ones I'm talking about with Ray over there, they are not the large-bore fire-ring gaskets...but should know more soon.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

The other big bore Oz gaskets have been standard materials/design.

We need a true MLS (multi-layered steel) design to hopefully fix the Al block problems, and yes 3.450 is what I would spec.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Yes, we got the head off the Twiggy engine in about 90 minutes. Having to "double nut" and remove 14 head studs took 1/2 of that time.

The head gasket stuck to the head and came off clean on the copper (engine block) side, which was good. We left the manifolds, carb and other "bits" bolted to the head, just to do the job as fast as possible. Being mostly aluminum parts, the assembly was a one person removal job.



I was thinking that the head gasket would be "breached" or that a valve seat insert could be leaking or may-be we would find a crack.
The only obvious thing is that this casted-in top deck on this engine has shifted and in places, it is being pushed down deeper into the block's water jacket. You can see seam lines and cracks in various places of the closed deck and some areas are now .005 to .008 lower.



Live and learn... I did this block repair over 10 year ago, while I was doing the Hyper-Pak reproduction project... basically, took a badly corroded aluminum block to the foundry one day, sandblasted all the corrosion, fill the water jackets with casting sand, leaving 1 inch at the top to pour-in molten aluminum. In hind sight, the small amount of draft in the die casting, combined with the corrosion pits and some welding is not enough support for the new top deck.

The pressed-on ring repair we just did on Buster has way more support but after seeing this... and seeing how much pushing force the head / gasket can put on this surface... I now worry about the likelihood of success with the Buster repair.

Well, this engine will have to come-out and I need to re-think and do some testing on how we can get a good long-term repair on a badly corroded aluminum SL6 block.

Some "good news - bad news"... the head gasket did seal well on the head side. It's going to take some work to get that surface clean.
DD

Doc
Is that a hole in #5 intake valve??? Whats the scoop.
Thanks,
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Looks like a missing (removed) valve

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

WOW looks different with my glasses on?????
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered