The manual grinder will work just great...

That top ring just might be a steel ring and not the typical cast iron. If it is you get a nice bonus of about 10% better heat transfer through the ring.. the top is very important at transfering heat from the top of the piston.

You may also want to consider running a wide gap on the second ring. I know it sounds wrong but the wide gap insures that the top ring has a good pressure differential so it seals well. It's the pressure behind the ring that gets it to press against the wall and seal.

If the second ring holds too well the top ring does not develop a good pressure differential. This reduces how well it transfes heat and seals.

GM and Ford now recomend wider second ring gaps... More power and better oil consumption. On a blown motor with a wider top ring gap its even more important. Why? The wide top ring gap prevents ring end butting under boost. The rest of the time the top ring runs with a bit more end gap than normal.

That wider end gap reduces the pressure differential across the top ring as the second ring does more work. With the thin low drag rings reduced cross section you may not have enough force to get the top ring to work correctly when the motor is not under boost.

Bottom line is a wider second ring gap helps the top ring do its job. This is based on my own testing as well as groups that have a bit more credability. <img src="/forums/images/graemlins/wink.gif" alt="" />

Kevin C

Kevin -

The grinder is scheduled to be delivered sometime today, so I'll see how it works.

The rings supplied by Wiseco are Sealed Power. The second ring is iron, the top ring is steel - and very, very hard steel at that.

I'm following the Wiseco "Street-Moderate Turbo/Nitrous" recommendation for end gap on the rings Their supplied chart indicates .005"/1" bore dia. for the top ring, .0055"/1" bore dia. for the 2nd ring. So, with a 3.602" bore, I need .018" gap on the top ring and .020" gap on the 2nd ring.

I'm a little concerned that since I'm not running an intercooler I should increase the gap a little more, but I guess if it was an issue, I would have experienced broken rings on the original engine that had factory standard ring end gaps.

Wiseco claims that the wider 2nd ring gap helps reduce top ring lifting or flutter.

Wiseco

Frank

With the rings you are installing now you will not break one if something is wrong but they will take the lands off the piston. The spring steel rings are very durable. The only issue I see in long term is the plasma rings do not like dust or other contaminates. But they are the only ring I install, I do however use Total seal rings allot.

My mistake - the rings aren't Sealed Power brand. I was looking at a set we took out of the original package and put back into a Sealed Power envelope. These are packaged with the Wiseco label - I don't know who made them, but the ordering info did say plasma moly.

Frank

They are still "good stuff".

That is a claim I believe and learned about the hard way... A few years before it became common knowledge.

Good stuff....

Kevin

There was a large/deep grrove in the crankshaft seal area, so I installed a seal surface repair sleeve.

The ring filer worked fine - it made short work of the job. <img src="/forums/images/graemlins/kewl.gif" alt="" /> All top rings are gapped at .018", the 2nd rings are at .020" and the oil rings have at least .010". The pistons are installed, but the piston/deck clearances aren't as good as I'd like:

#1 = .019"
#2 = .017"
#3 = .020"
#4 = .018"
#5 = .018"
#6 = .016"



The dealer tells me that MLS gaskets are not available from Mitsubishi - not sure if he knows what he's talking about, though. So, I ordered some Nippon-Reinz MLS gaskets - should be here in a couple of days. I just hope they're at least .050" thick..... if so, that'll give me a quench height of .030" minimum - not great, but it should run fine. I don't like the piston/deck variances, but I don't want to grind the crank/resize the rods and/or mill the piston tops at this point. Aside from the quench distance, the variances are better than the original engine, so I'm going to run it like it is.

If I ever build another blower engine, I'll sure start by indexing the crank and use custom rods..... in hindsight, it would make a much better engine than what I see with (some) factory parts.

Frank

Well, I'll be durned! Some puzzles take me a while to figure out. Maybe it's old age. <img src="/forums/images/graemlins/lol.gif" alt="" />

I sat for a long time last night and contemplated those piston/deck clearances and refused to believe that after all of the measurements I took and the calculations I made.... that the variances could be so large.

So, I got out the original list of crankshaft throw and rod length measurements and compared them to the installed results. I kept saying..... "That's impossible!... that's impossible! The expected shortest combination of rod and crankshaft throw can't end up being the longest and vice-versa". It's impossible!!"

I finally realized that the only way the results could show a .004" variance was if the table under the crankshaft grinder was not correctly aligned (not likely).... or the machinist made an error in reading his dial indicator. The lightbulb went on when I remembered that he was reading the dial indicator upside down and had maybe reversed the numbers and gave me (+) numbers when the indicator read (-) and (-) numbers when the indicator read (+). Ya think? Nah, nobody would do that, would they?

This morning, I removed #3 & #6, swapped rings and then swapped bores. Yup. Then I did the same thing with #1 & #2. Yup. Now the piston/deck clearances look like this:

#1 = .0175"
#2 = .0175"
#3 = .0180"
#4 = .0180"
#5 = .0180"
#6 = .0175"

It doesn't get much better than that and I've gone from not liking it at all to lovin' it! <img src="/forums/images/graemlins/kewl.gif" alt="" /> Now, the only variance is the very slight difference in swept volume due to the crankshaft throw differences - not enough to be at all concerned with.

I haven't yet gone back to visit the machine shop, but I expect we'll have an interesting conversation when I do. <img src="/forums/images/graemlins/lol.gif" alt="" />

What a lesson in assumptions!!! <img src="/forums/images/graemlins/kewl.gif" alt="" />

Frank

That is purdy durn close on them thar numbers.
Makes me think of each time I installed one oversize cylinder on an aircraft engine, kept mumbling it isn't right it isn't right.

Charley -

I'll take those numbers any day! <img src="/forums/images/graemlins/kewl.gif" alt="" />

The Nippon-Reinz MLS head gaskets arrived from statracing and they're very nice:



My best efforts at measuring thickness indicate .050", so they should work fine and give me a piston clearance of .032"..... just about right - particularly since the engine has fairly short rods and won't turn over 6000 rpms. <img src="/forums/images/graemlins/kewl.gif" alt="" /> The slightly reduced deck clearance just might help make up for the the loss of quench pad area on the circular dished pistons.

It's interesting that they have MD199239 printed on the package, so I guess Nippon-Reinz was the OE manfacturer for Mitsubishi. It's also interesting that I find that same part number in CAPS for a '95 Diamante DOHC engine..... were there 12v DOHC Diamantes? IIRC, the 24v heads have a completely different oiling pattern and require a different gasket.

There is a bore limitation on these gaskets. I measure them at 3.610" or maybe a hair more, so I wouldn't want to tempt fate with more than a .020" overbore.... that'd be 3.607" and I would be afraid that anything more would have the gasket overhanging the bore.

Tomorrow, I'll install the heads and see what the cams look like.

Oh, I did find another difference between the Montero and Diamante SOHC blocks.... the machine screws that hold the oil pickup braces to the main bearing girdle are different between the 2 engines. The Diamante girdle threads are 7mmx1.00. I don't know what vehicle used those holes (Diamante SOHC did not), so I'll try to find some cap screws at Home Depot..... most anything the correct size with a split washer should work.... particularly if I use a little LocTite on them.

Frank