MickyG's MX-73 to 7M-GE Swap

[mickyg]

I have decided on basic black for the block. This is due to some advice and some general logic. As much as I want something a bit "different" for my build, I can't deny a few advantages of black, not the least of which is thermal characteristics. If I go anything but black, the block ends up retaining a bit more heat. Does anyone know if this is a bad thing? Jake mentioned this is a great advantage of black (that it becomes a heat emitter) and it certainly is a well known fact.

Another thing I've been wondering is where people in australia get their assembly lube? Sounds like a simple question but I haven't been able to find it at any auto parts store. The only thing I can find is this stuff in a tiny bottle that costs like $15! It looks like tranny fluid (red) and is not at all what I'm used to seeing. The stuff I remember seeing is in a tube and is almost a paste (moly lube?). Anyone know if it exists or if I should be using the stuff in a bottle?

 

[IHI-RHC7]

The red stuff is awesome! It litterally disolves into the oil once pressure is built and doesn't destroy the filter like moly lube does. That said, I've never used it and I always have a large tube o' moly lube at my side...

Ian...

There is "Cast Iron" Colour VHT Engine enamel!

Tisk tisk mister anal retentive.
Looks good bro, I'm going to go play jenga.
Tomorrow nite is burger and a brew nite for $6 at the local bar and grill!
Thats a tastey bacon burger with pepperjack, cheddar, saute'ed onions and mushrooms, guacamole, thick fries and your choice of dipping condoments as well as a tall brew of your choice. Last week I had a guinness on tap, very stout.
Stock getting sick. I'm telling you, it's those damn roo's.

 

[mickyg]

Mind if I stop by? $6 is an absolute bargain for such a massive meal! Wait... (does mental conversion) that's like 9 aussie dollars. That's still a bargain!

 

[mickyg]

Today:

Made some progress! I found the elusive moly assembly lube and it didn't cost me half an arm! I did a test fit of oil clearances for the main bearings and was happy to find they're all within std tolerance (a bit less than .050mm) across all 7. I'll button up the main bearings tomorrow night hopefully and move on to the rods as soon as I'm able.

Pics (last one is with the plastigauge smashed and is only visible on no2 bearing - silly camera flash!):

 

[Allan_MA70]

Are you geting this engine balanced?????

 

[mickyg]

You just had to ask that, didn't you?

I spent the morning researching engine balancing and can now, with some level of understanding say "no" and actually tell you how I've come to that conclusion!

Reasons why I'm not going to balance:

1. Not building a race engine
2. Probably will see RPMs above 5grand 10% of all my driving
3. I've got no money
4. Pistons are originals
5. Rods are (hopefully) going to be OEM parts

Reasons why it'd be smart to balance:

1. .50mm was taken off the big ends - thereby throwing rotating mass off by that amount
2. bearings and rings might not weigh the same amount as OEM

So in short, it comes down to money and I don't have enough reason to suspect any issues with what I've done to the rotating assembly. If I were replacing with aftermarket pistons and rods, I'd be silly not to balance.

By the way, I found a lot of useful info on engine balancing from here.

 

[Allan_MA70]

its REALLY silly IMHO to goto all the trouble of a rebuild and not get it balanced!

 

[Mr.PFloyd]

its REALLY silly IMHO to goto all the trouble of a rebuild and not get it balanced!

not necessarily.. if he is using oem and is tight on cash, he doesnt necessarily need it.

 

[Allan_MA70]

cutting corners on a 7M will bite you on the ass!!!! then you will get the "I TOLD YOU SO" posts

 

[mickyg]

I looked into the how's and why's of balancing and it really doesn't make a lot of sense on a straight six if you're going with stock parts. Like I mentioned before, the only parts that aren't are the rings and bearings. Plus, from what I absorbed in the articles I read, a straight six is subject to balancing problems in a less critical way when compared to other engine formats. In other words, it's a big deal if the reciprocating assembly is out of balance (like if the pistons aren't matched in weight to each other) but nowhere near as critical if the counterweights on the crankshaft are not tightly balanced with the aforementioned reciprocating assy.

It's good advice on a high end build Allan, don't get me wrong, it's just that I'm not going for every ounce of performance I can squeeze out of this engine and I'm a firm believer in the inherent internal balance of the 7M when it's in nearly stock form like mine is.

By the way, what sort of "balancing" are you having done? I'm assuming getting all parts matched (material removed from pistons to match each other) as well as having crank balanced to reciprocating assembly? How much does that sort of work cost?

 

[Allan_MA70]

the ross pistons come within a gram of each other, the rods have been previously balanced so hopefully only the crank needs to be looked at!

I still say your crazy for not balancing it! makes it much more refined in any engine... im yet to see a cheap 7M build last more then a week I hope you have not wasted any luck buying lotto tickets!

will you drag your ass to the bbq this weekend? ill bring along the crankies quote...

 

[mickyg]

When is it? I think this weekend might be the first time I've been free in months!

Edit:

I found it! Doesn't say what time but I should be able to make it. I really should visit that section of the forums more often...

 

[IHI-RHC7]

Allan, every race shop I've visited out here in the states has laughed at me when I ask them about balancing the 7m crank.

With the inherent design of a straight 6, every pair of pistons moving upward has two other sets of pistons moving up or down in perfect harmony to balance the overall load on the crank. That said, as long as the crank is balanced to itself, and the recip assy is balanced to itself, you can swap cranks and recips as you please. I know people see not balancing an engine as cutting corners, but with the 7m in particular, it really isn't a big deal. Also, any decent shop is going to check internal balance on the crank when they mill it.

 

[mickyg]

I forgot to mention that this was done when the crank was milled in my case as well. I'll weigh the recip assy before it goes back together - just to make sure there's a reasonable amount of symmetry.

 

[mickyg]

Today:

Got to use a bead blaster for the first time! Sweet machine and very simple as well. The shop next door does radiator/cooling systems work and rarely use it. I used it on 4 exhaust valves, as they were the worst. Took me about 30 minutes to do all 4 so multiply that by 6 and it'll take me about 3 hours to do 'em all!

The valves are in excellent shape - no pitting at all. A quick lapping job and they should be perfect!

Also got some good news from the machinist when I went in to pay off the rest of my parts - he said I should bring in the pistons at some point and he'll get all the carbon crap off of them for free!

 

[IHI-RHC7]

Nice! Having a chum of a machinest will save you tons in the end.

 

[miggles]

you finnished it yet mickyg? lol. Mates cressida passed engineering but 3 weeks later he's still waiting for the report....

 

[mickyg]

Mik, not even close! I'm just now getting things put back together so it'll be a few weeks before the motor's even close to finished!

Today

Went out to the Melbourne Toyota BBQ today and finally put a few faces to some names - sorry I didn't hang aroung a bit longer, had a busy day planned.

When I got back home, I got stuck straight into the motor. Removed the pilot bearing on the crank, cleaned the crank up thoroughly (machine shop did a really good job so not much required). Popped the crank back in with some assembly lube and buttoned it all up. It was nice to get that out of the way, finally feel like I'm making some progress!

On the subject of pilot bearing removal, I grabbed the advice of a fellow SM member (I'll have to find the link and thank him) and used a home-made hydraulic pusher. One of the easiest things I've done on this motor and I'm quite impressed with how quickly it did the job! I grabbed an 8mm socket, popped a reducer on the end, filled the socket with wax to make it grease tight, filled behind the bearing with high temp grease, tapped the socket with a hammer, kept topping up with grease, and in about 5 minutes, the bearing popped out!

Anyway, random pics. Meet today (mines the one that doesn't look like it belongs there), my "super duper bearing pusher" results:

 

[mickyg]

As usual, the day was not without a few items that I had questions about! I popped a freeze plug off to assess how bad they were and was pleasantly surprised to find they're almost totally corrosion free! There was rust on the back of the plug but it wasn't from the plug, just deposited there by the cooling system from somewhere else.

What had me curious though is what's behind the plug. Between each cylinder is a small metal "finger" for lack of a better term. It is about an inch long and "points" to the steam hole. Any idea what these are for? My first guess was that they are just the remains of the casting process.

 

[miggles]

to show the way young grasshopper, the way of the bhg.
I think your rite, they are leftovers from casting, though i dont remember any fingers in my blocks (soo long ago)