Leakdown resuts question for the pros

you have 4 cylinders that are past their prime, and another two right on the edge. Thu, in effect, you have 2 good cylinders and 2 marginal cylinders.

Time to take it apart.

 

I have one apart right now that tested much better than yours. Doing valves and replacing a liner & rings on one cylinder.

Not a cheap date.
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Just drive it don't stress.

 

I agree...are you looking for the perfect track car? is it billowing smoke when you drive it? Half the production cars on the road newer than your will have the same results...only on a Ferrari where owners have more money than sense would this be a catastrophic issue....put the plugs back in go for a cruise

 

You need quides for sure

When crude gets into the seat it wobbles from not sealing and wears out the guide
You can see crude on the valve seat here. best to pull them and freshen it up
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Regular Italian tune ups and sea foam would probably prevent such build up? Good thing I redline mine constantly.

 

That's why you need to take it apart. You just proved even with steel guides and late model run this is a big issue.

 

Maybe there is s much build up on the stem it can't seat

 

The scale on the Matco gauge is for a Chevy. The 355 is a different animal altogether. 4 to 6% is "okay", more than 8% is a problem. The bad cylinder that I'm doing was 12%. I'm hoping for 1-2% when I'm done.

It is possible that your problem is just in valves and guides. The car I'm working on had guides replaced 5 years back. You can see a tiny scratch in the photo that is most of the problem. The liner can't be fixed, it must be replaced $$$. The OEM rings are $100 each. Fortunately it just needed a "light" valve job although 4 valves show damage on the stem inflicted by the last person that worked on it and will be replaced $$$. So much for trusting a Ferrari dealer .

I have a tool that makes it possible to leakdown just the pistons as well as the whole package.
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Thats the second liner from the top in your picture?

Did you leakdown the cyl with the head off or was it a standout issue.

EDIT. nevermind just saw your last picture

What was leakdown on the block leakdown tester

 

2NA: Have you learned anything worth sharing when it comes to refreshing these engines?

 

How do you think that valve stem damage happen?

 

For the record... A late 98 car with leak down issues.

None of these car are immune, despite what any memo from Ferrari says.

Gobble, I say just redo the top end. A marginal cost at this point considering all things.

 

On the same cylinder it was around 10%

Still a work in progress. I've built quite a few engines but this animal is different. There is more to it than I could have imagined. The parts are ridiculously expensive (even for Ferrari). I'll finish the story when it's actually done.

Follow the 45 degree angle on the valve. It was done by careless valve refacing. The relatively minor nick is in the most vulnerable part of the valve. Fortunately these aren't sodium-filled anymore. That's right where they break. Pricey little devils too.

 

+1

And the car will be documented with known fixes at that point. So worth more and since you are doing it yourself with expert help - perfect fix with less cost.

Robb

 

$5k or so to do the heads now while the motor is out. Do it!

 

I bet she runs like a stallion still.

 

I think at this point, with the engine out of the car and the LD results you cannot comfortably put it back into the car like this. As others have said, I would at least plan on doing the top end now and have the cylinders tested as per 2NA when you have the heads off.

Sucks but either you do it or you will have to deal with it if and when you sell the car.

Do you have the compression numbers?

This is exactly like the car that I was suggested not to buy on a PPI. It was a 97 with 18K miles. The Ferrari techs discussion of what he felt was going on re:build up on the valve seats, etc. is in the videos that I have posted of that PPI if you are interested in hearing it. After an Italian tune up, things improved marginally but he said no amount of sea foam , etc. was going to resolve it and that a top end refurb was at least what it needed.

 

Three of our best "pros" told you what acceptable specs limits are and how to fix your problem, yet, you debate their replies??

Go to the parts store and buy some "valveguide in-a-can" pour it in, fixed.

 

Despite their efforts no 2 cylinders ever run totally the same on any motor. They breathe different, run at different temps etc. On a 355 the middle cylinders run hottest with 2 and 7 being at the top of the list. #2 having the most leakage is exactly what you would expect to see.

They have very small valve stems so very little surface area to wear. People inside Ferrari predicted no valve guide would last a long time in the motors. So far their predictions have proven to be too pessimistic but not totally wrong.


Indications of "Good,Bad,Worse" on faces of leak down gauges was arrived at in the 50's and would not be applicable to a modern lawn mower.