No, All Mitsu's DOHC from the mid 80's on have been multi valve. In the 70s they had some DOHC 4s that were 2 valve engines. Even the DOHC head for the 2.6 is 4 valve and that dates back to 83.
7mm in a Japanese engine would be very odd. French yes and some in German engines and gearboxes but that is the first I have heard of in a Mits. Sure someone did not tap them to a 1/4"? I am not even sure if there is an ISO spec for 7mm, not looked and probably won't. I have seen both 6 & 8 mm in the girdle.
The MLS gaskets are closer to the bore size than composite ones. They can take the heat allowing the gasket to be tightened up to the bore. Comatec wants the bore size on some of there gaskets.

There is such a hodge-podge of headgasket numbers in the Mitsubishi system, perhaps some of the parts houses have bad information..... wouldn't be surprised..... even the dealers get confused.

Tomorrow I'll try an 8mmx1.0 and see if it'll work on the girdle threads, but the 7mm tap was fairly snug. AFAIK, those holes were never touched since the factory built it.... the Diamante SOHC engines didn't use the holes for anything - the oil pickup on the Diamante SOHC has no brace legs..... but maybe they're 8mm and really gunked up with baked oil since they were open.

There is a spec for 7mm - I have the taps and dies and have used them to overtap the water pump rear housing for stripped 6mm threads when installing a new front on an old rear housing.... it makes for an easy solution to a common aluminum problem...... screws are available at Lowes or Home Depot.

Frank

[hijack]There is more useful info in this thread than in many Service Manuals. Thanks to all, esp the dude himself. <img src="/forums/images/graemlins/cheers.gif" alt="" /> Everytime I read from this page I learn something new, up until I get lost... <img src="/forums/images/graemlins/lol.gif" alt="" />
[/hijack]

Charley -

You were correct on the girdle threads. I was only cutting carbon with the 7mmx1.0 tap. The better light of day allowed these old eyes to see that the thread size is 8mmx1.25..... they were really, really coked up.

Much of today was spent disassembling and cleaning the heads, looking for lost valve train springs <img src="/forums/images/graemlins/lol.gif" alt="" />, installing the heads (on an old gasket set) and water pump... and setting up for cam readings..... maybe tomorrow.

Frank

Is time flying or are you getting the hang of this by now? <img src="/forums/images/graemlins/smile.gif" alt="" />

Still waiting to come down.. got that router yet? <img src="/forums/images/graemlins/smile.gif" alt="" />

I don't know if I'll ever get the hang of a 3.0L...... every time I solve a riddle, it raises more questions. Just because a fellow tears one down and rebuilds it, doesn't mean he knows what he's got.... or if it could be better. <img src="/forums/images/graemlins/wink.gif" alt="" /> The 3.0L SOHC is a neat engine.... one that has a lot of power lurking..... the trick is in finding it. There's a pony in it somewhere. <img src="/forums/images/graemlins/kewl.gif" alt="" />

No WAP yet.

If you can make it, it'll probably be the weekend after Thanksgiving on the engine install..... gotta go to the CU/USC game next Saturday.

Frank

It's been a while since I did any cam degreeing, so someone please check my math.

There's no place to attach anything I have as a good dial indicator mount, so here's my ghetto rig set up on #1 intake valve with a light checking spring - it appears to be stable:



The Diamante SOHC FSM spec is:

16* BTDC = Open
66* ABDC = Close

I won't be able to get the opening and closing points with a collapsed hydraulic lifter, so I've used the lobe C/L method as follows:

16 BTDC + 180 + 66 ABDC = 262/2 = 131 - 16 BTDC = 115* lobe C/L

I measured the intake opening to be 22* ATDC @ .050" lift and the closing to be 34* ABDC @ .050" lift and calculated the installed lobe C/L as follows:

180 - 22* ATDC + 34* ABDC = 192/2 = 96 + 22* ATDC = 118* installed lobe C/L.

Then, I brought the cam up to max lift and found the drop points before and after max lift and averaged both sides after several cycles.... that indicated 120* installed C/L.

I expect the difference is in lobe wear on the up ramp side, which would show a delay in the apparent C/L.

Anyway, from checking this cam and if my math is correct - it would appear to me that it's installed about 3-4* retarded - probably caused by milling the heads and deck.

Charley - have you ever checked any of these Diamante cams and if so, can you tell me what readings you got? More importantly, do you know if the lobes are supposed to be symmetrical? The variance I got due to the collapsed lifter is not the same on opening and closing angles - maybe that's a geometry thing, but it would seem to affect the calculated C/L.

Tomorrow, I'll remove the rocker assembly and try to take a reading directly off of the cam lobe. I also need to check the other cam.

Frank

I have not checked a single cam 6. I have not rechecked either of the 4 cam engines I am driving since they were setup. Not that my 3.8 has any miles on it, Damn where did I put that title, Damn.
Most of the roller cams are asymmetrical lobes. I would not expect to find wear on a cam lobe.
I would however check both sides and from what I have learned with the 4G63 the belts settle in a fair amount. I found a set of cams rolled back almost 4 degrees in the first 1000 miles. That was not a factory belt not that this matters.
I now run the engines awhile before setting the cams. That would suck with the accessory mounting and blower drive on your engine.
Also the followers run on an odd path and move a degree or two through there range, I have not confirmed this myself. If your checking spring is soft enough and the lifter has heating oil in it they should respond fine during this work. Wait delete that thought, that pertains to the DOHC engines.
Sorry your sets up the same as a 2.6, again the lifters should have fuel oil in them and I use a shortened rocker spring from a 2.6 valve train for the checking spring. They generally are soft enough.

I expect I would set your engine up with the drivers side advanced a degree or so and the passenger side 3 or 4 degrees up. Once you check the drivers cam and if it is close to what you want make sure the water pump is pushed down as low as it goes since that will advance the other side. You can elongate the WP bolt holes to dial in the passenger side cam.
Now are you going for the factory specs or do you want to move the torque band a little by rolling the cams one way or the other. Hard to do without a dyno though.

The belt I'm using was a new OE when the engine was rebuilt 5,000 miles ago, so it should be fully stretched and it'll stay on this engine.... should be fine.

I have not filled the lifter that I'm using in #1..... you think it would make any difference? I wouldn't think the diesel oil would stay in the lifter long enough, but I guess I could try it.

The checking spring I'm using is one I got from a hardware store - very light... I can squeeze it easily between my thumb and forefinger.

The water pump is also from the rebuild 5,000 miles ago, so it may have loosened up a little.

I was hoping to hit the factory specs, since they have the late-closing intake..... but I don't think I want to close the intake any later than factory spec..... that would further decrease the dynamic compression ratio. The only way I would want it later is if I had too much power under the curve and not enough above - or if I had an issue with detonation under boost pressure.

I think tomorrow I'll check the #2 intake lobe with the same method, then check both by direct read off the cams without the valves and see if I get a different reading.

I may want to make the cam sprockets adjustable.... then it would be fairly easy to make changes later if I find the need.

You agree with the math, though.... right?

Frank

The math looks right. 5K on the belt should have that bedded in so your setting will stay.
Mitsubishi calls for the lifters to be purged with fuel oil prior to installation. For your checking work engine oil my be better but for start up fuel oil in the lifters is best.
Without any oil in the lifter you are working with is just using its internal spring,it will bottom out. With fuel oil it will push your tooling spring.
You do not want to start an engine with dry lifters, not good for them.