Chiamac

Do they sell the banks seperate or together?

It seems that the worst that would happen is the "fix" fails in a few years, should run and work ok in the mean time, and then the new owner would be in the same place with the same options. Again, as long as it's not sold as new engine or rebuilt engine then I just don't see an issue with this. Who knows, the fix could be fine and a timing chain fails...

Flat6 Innovations

Typically that piston is about 7gr difference.
The weight difference is one reason for the vibrations, but combustion balance equates to more.
Those who have never dynamically balanced an engine to a tolerance of .2 oz./ in. and built it up, then tore back into it and balanced every chamber volume and every deck height to the nth degree can't equate to the differences I am speaking of.

The best dynamically balanced engine will still not operate as smoothly as one that also considers combustion balancing from blueprinting.

Here's what I balanced last night, dynamic assembly from a '76 930 engine I am building this month..
I spent the money for the best balance machine I could find. The balance machine isn't everything, the machinist running it and the assembler who assembles the engine are both key players. Thats why when I build something, no one else touches any part of it.

Imo000

That's nice but it's an overkill. Even the factory doesn't go to that level. Your level of expectations is higher than the factory specs so if someone does something less, it's right away not accaptable to you. Engines can and do run well without taking them to the Nth degree.

0.2os is about 5.7grams but it sounds cooler inndecimals.

Flat6 Innovations

That's .2 oz per inch of measured component radius. That's a big difference when dealing with something like a flywheel that's 10" diameter. To achieve this both measured planes must have an accumulative imbalance of less than the tolerance that's set by the user. In this case that's .2 oz / in.

Notice that I even have the crank gears fitted during the procedure.. When this pic was taken I was just getting ready to add the crank pulley to the rotating mass and correct it. This is t a race engine, it's just a street engine.

Now, that said, damn right the factory doesn't do this today, but they did yesterday. In fact this engine was all original and unmolested as a virgin when I got to it. Until I added the new pressure plate I didn't have to correct anything to have the unit balanced to tolerance. If I do this with an M96 we are whittling parts right off the bat.

So, if I were to build a stock engine and use two different Pistons in two different bore sizes you guys would accept that? Raise your standards people, we are working with a damn Briggs and Stratton here... Even if I was, Id still balance it. I balanced the engine for my lawnmower a couple years ago when I had to tear into it!

dporto

Overkill? I would say not... Just because most everything to day is built to "good enough to get it out the door/sell it" doesn't mean it the right way to build something. Jake has created a business model that allows him to build things to a very high standard and get paid accordingly. Kudos to him for sticking to his standards! His isn't the only way, but it's clearly the best way if you can afford it

aftCG

When I first got my car I joined my chapter of PCA. I'm not really that social but I thought I would be accessing a local technical knowledge base (instead of a bunch of fender polishing doctors) that would be of help when I was elbow deep in my crank case.

I recall in my early reading where someone brought their Raby engine car to a track day and let one of the club seniors drive it. It's very telling that his review stated that it was the smoothest running Porsche he had ever driven.

That is the result of mass balancing and volume balancing exactly as he describes above.

Jake's engines may be out of my price range but I understand that he is building his reputation not on "good enough" but on the best engine you can buy.

Imo000

If you can build it so that it runs good and holds up for many years then I really don't care much how you do it. The goal of repairing something (and the OP did just that) is already a compromise because a full rebuild, properly done, is always better than just fixing an old engine but it cost a lot more too.

Your OCD of balancing engines to the Nth degree is not required in every engine out there. You do it because you can't help yourself. Balancing an lawnmower engine?!?!?! Give me an Fn' break! Sure an engine should be balanced as close to perfection as possible but in many cases this is not a requirement to make them last.

Imo000

What's the definition "everything today is built to good enough"?
The cars of "yesterdays" are are built to much lesser standards than today. 30 years ago cars would last half as much as they do today. 130K miles was usually the end of most cars back then. Now look at your local classifieds or go to the local junk yard as see how many miles those cars have. The air cooled 911s yesterday have/had their fair share of major problems too but because the internet wasn't around yet, we didn't hear much of it unless someone published it and that wasn't happening much.

Chiamac

I'm sorry I jumped on the person and said morals and cheap before hearing more about what they did.

I'd work with them in a heartbeat if they were local and some work came up. Maybe not doing what they did (since I'd more than likely find the money for new parts) but I'd trust them to put everything back together and/or be a resource if I needed help on something.

It's hard to find a shop that will do that kind of work on any engine that walks in or one off projects like this.

alpine003

I attribute Jake with Mike Holmes. "Make it Right"... That's all I'll say.

Flat6 Innovations

I've said enough.

It's a sad day when it's acceptable to mismatch bore sizes and piston materials inside the same engine. I don't care if you work on Chevys, or Porsches, that's unacceptable.

Patching something up for yourself is one thing; knowing it's being done to pass it on to another unsuspecting buyer is another.

Mudflaps

my assumption is that this hodge-podged engine will beat itself to death eventually. more displacement in one cylinder bank is the largest of the issues. this sucks for the unassuming future owner.