Thinking of DIY instead of machine shop

Wrong, re balance crank is needed as it is worn, if bores are untrue they need machining. If they need machining then you may need special spec rings .... just let the professionals do it ...do it right once so you don't have heartache afterwards. Most reputable workshops can do what you need at a reasonable cost.

 

New pistons do not mean you need to rebalance the crankshaft !! As long as the pistons are a balanced set in themselves then its all good . As for the bores , you need to measure them properly both for size and oval . If they are within size and oval tolerances then a quick deglaze with tool meant for the purpose will be perfectly ok and will provide the correct surface for the new rings to bed in on . If the wear on the bores is excessive then your only option is a good machine shop for reborn etc . It might be worth balancing the rods whilst they are out but this is a real easy DIY job .

 

bore it out and do it right or you will be buying my spare 2.0 engine because you broke yours.

This is not a time to try and save some pennies.

 

With a good machine shop you are not only buying their considerable expertise and experience but the use of precision machinery.
You cannot overbore with a glaser; it will only follow the contour of the oval bore and you will have a larger oval bore.

Find a good machine shop, treat them right, and you will never have to look again.

I took a very expensive/onobtainable Mecredes head to a idiot for a resurface and he turned it into scrap aluminum.

I took an "unrebuildable" M-6 head to another and they found a way to make it work.
A new head would have been more expensive than that used car.

Find a good machinist.
Ask around.

 

Do it yourself machine work is not a good idea. Dont know where you are located but there are many competent machine shops in the Indy area. VDS racing engines is one

 

If you don't want to spend much money, de glase and new stock rings with original pistons, with a valve job and seals will give you some more good engine life. But since the value of a Dino is very high, I would do a complete rebuild. You should not need to rebalance unless you are changing major components. Just remember most of engine wear is in the cylinders, and a correct rebore and a thorough rebuild of the rest of the engine will give like new performance. I read a book about what you can live with on slightly worn components on an engine. An engine can still perform surprising well with some wear.



Ago

 

+1. Expertise and experience are highly under-rated...

 

Do it right or don't do it at all. Cobbling it together with loose-fitting pistons on oblong (and probably tapered) bores, will be immediately unsatisfactory. I doubt the rings would ever seat properly. You will have just spent quite a bit of money to have "not fixed" anything. Connecting rods are suspect (especially the bolts) and should be at least crack-tested if not replaced with new.

Don't forget the cylinder heads. Your Dino likely still has sodium-filled exhaust valves (a ticking time-bomb) and worn-out guides. The valve seats might need replacing as well.

Some things are optional and some are not. Don't make the mistake of cutting too many corners.

Find someone there who knows what they're doing, and let them do it.

 

Remember the Chevy Vega, the cylinders became oval at about 30K miles. I am not comparing the Dino to a Vega. The only cure for the Vega was to install steel liners, or send it to the scrap yard. 99% went to the junk yard. If you are keeping the Dino!
Do it right the first time.

 

I can sympathise with the OP and his situation. He has already stated that this is not a "cost saving" exercise; he simply had a bad experience with a "reputable" machine shop that cost him a lot of money to fix and he wants to avoid a repeat of this at all costs with his Dino motor. I've been there & done that too, as I'm sure many others here have.

IMO, we shouldn't be ragging on him for trying to save money because that's not his goal. We should be helping him to find a machine shop who are well equipped and knowledgeable in Ferrari.

 

Assuming that you are in London, England, I can recommend South Cerney Engineering Ltd. They did some excellent work for me on an older V12 engine and at the time they had at least three other Ferrari engines, including two Dino's being worked on. They have the experience, equipment and skill that you need and they are very approachable. Good luck.

 

I suggest a call to Tim at Emblem sportscars
http://www.emblemsportscars.com/home.aspx
He is very reputable on the early cars, I worked with him many years back, and can vouch for his expertise. Even if you don't use him for the engine work he will certainly be able to offer you some advice or recommend a good company for the machine work...

 

You probably should rebore it and put in a set of oversize pistons. Bores don't wear evenly and you should get them true and straight. There really should be no worry with a competent shop.

That said, a piston to wall clearance of .005 is what you see in small bore racing engines using forged pistons. These commonly have piston slap when first started, but as the pistons heat up they are fine. Forged pistons grow a bit more than cast pistons, and you want to build an engine with forged pistons a bit looser, so that you don't stick it when it gets hot. A bit of piston slap on startup isn't a big deal, it goes away and doesn't really effect life. If you were talking a .001 or .002 oversize that might be a viable route, but I'm thinking you would be on the hairy edge trying to do that with were you are.

I built a 2 liter BMW engine with .006 piston to wall clearance with forged pistons and it had good compression 40,000 miles later when I sold it. Yea, it had piston slap on startup, but it went away and was fine as the engine warmed up and was gone in 15 or 20 seconds. And it did burn some oil, but it was liveable if you used 50 wt racing oil.

If you really don't want to properly rebore it, you might hone it measure the bores and see where you are when you get a cross hatch pattern. At that point look at your piston to wall clearances, and then decide on a plan. You might be able to use a set of forged pistons, or even have a set of custom pistons made a bit larger to give you the right clearance. Bore wear of .002 isn't very much, I've seen engines with a lot more bore wear than that that still ran fine. I wouldn't expect it to last 200,000 miles if you start a bit loose, but if the car isn't a daily driver and isn't going to see a lot of miles it might work out.

 

It looks like you weren't paying attention.

What you are proposing is almost certainly worse than doing nothing.

Good luck.

 

I concur. Despite your reservations seeking proffesional expertise, you should look down this route if you want 30,000 miles out of that engine...Hope it works out for you.

 

One thing I have done to find a good amchine shop-that knows the engine in question, is to contact well regarded shops that specialize in the marque and ask them which machine shop they use. then you find a machine shop that is familiar with the brand engine you are repairing.

 

Building an engine that small with that much clearance will produce piston slap when cold and it's going to consume some oil. That's a lot of clearance, in my experience. Running hotter heat range plugs and thicker oil may well let you get away with it, but you also might expect some plug fouling and more frequent plug changes than a tighter engine. Other than that you won't know it's built that loose. It will run just as strong and it isn't going to be noticeable other than a puff of smoke on the first start and some clatter when cold.

If the workshop manual says that's a big as you should go, then they are probably being generous. I'm curious as to what the min build clearance is, but I probably wouldn't go that big as a build clearance. JMHO

 

Wow, that's a big clearance, are you measuring at the bottom of the skirt, 90 degrees to the wrist pin??? If so that's bigger than anything I've seen. I'm thinking that you will be somewhere near .008 to .009 if you hone it? I think you need to talk to some folks who have experience with that particular engine and dial into that knowledge base. You are getting outside of my experience base. I've built a good number of engines and never built a engine with clearances larger than .007, and that was a pure race motor. Typical stock engines in that size class (that small a piston) are generally half that or less.

 

I went thru an engine re-build on my 2.0 Dino. I feel for you - really. I also wanted to watch costs having heard many stories about these things costing a fortune to do right. I tried to read thru your post, and I think you are saying the bore varies 2-3 thou beyond? That means the rings will be doing a dance as they travel the bore (granted only a few thou). Or they may hold into the ring groove by friction and skate acoss low spots. I suggest you talk with the folks at Superformance. They have done many and could have a feel for what you could get away with. I couldn't bear the thought of this work being done wrong as nightmare previous experiences with goofed machining literally doubled the cost and time of the project. So for my Dino, I went to a Mach Shop that has aircraft engine re-furb on their resume. They hit me up with components being .0005" out and wouldn't allow it! 10 years later, I still regard the engine as a jewel, and don't begrudge anything I paid for nice work. It went together smoothly, started immediately, doesn't consume oil, and tuned easily. Wish you the best. Happy holiday & New year!