gemellocattivo.com

ok its out

well....



Tis but a scratch!
https://www.youtube.com/watch?v=UijhbHvxWrA

well ...

Scheiße. Not much consolation, yet this is most similar to my project car problem. I don't have a visual on it. So, you are not alone. I have been so slow, you will likely have your car running again before I do.

About 5 years ago I was sorting out the last valve failure (tight guide) but I was also recutting the valve pockets because I could see evidence of contact, just barely.  I inspected the valves and they were all within .004 TIR but 1 needed a light smack and I had Wade regrind them.....what  do you want to bet I just found the one I smacked?  But I can't be sure so now I need to think about replacing them all I guess.

No work yesterday (no need to poke the bear) and a late start tonight but I did have time to pull the other head and for the most part all is well. Oil


So while I epoxied the huge leaks there are clearly still leaks in most of the ports waiting for me to weld shut. Over the next couple days the plan is get the piston out and see what the rod and bearing look like then I can start making a repair plan.

Ok.  If you look, like actually look at the head off pics you can see the intakes were hitting the pistons.  Here's a close up from the worst one in bank 2


So I went rolling back through pic and here is a gasket change in 2022.....if you zoom in its got the same marks


So there is an assignable cause......which leaves me very confused how the clay test looked like this before those run tests.


Once I get the a little further along I'll repeat the clay test and see what it says, I must have screwed it up somehow, I just don't know how. 

Engine off the trans


and...no spun bearing!


Its looks a little sad but its pretty cheap.

So, the valve hitting is the cause but why is the valve hitting? If the clay test had clearance, why hit? Is it too much movement for and aluminum engine?
Do you know what the valve to piston number is or just a clay test? A little loss of compression to insure no contact is a good trade off. It probably is not even a .1 of compression. I am glad you have evidence of the issue. This can be fixed and the problem solved.
How many are hitting? Did you clay all of the cylinders?

_________________
Wade Williams
Master Ferrari Tech
Restoration Tech
Engine Machinist
Fabricator
Racecar Driver

So many questions!

The clay was done in early 2021 and I checked all 12. I know I would have at least attempted to measure the thickness but I could not find a record. I did recheck the cam timing marks at that time and they were all correct.

Right now I see evidence of contact on most pistons making me thing its a they are all CLOSE so a little heat and movement is all it takes. Doing the clay test is really hard since the cam timing needs to be perfect on the 1st try as 1 rotation is all I get. Dynomation will tell me the TDC valve lift numbers so I think my next step is throw in the light test springs and measure piston to valve at TDC.....which is likely not the min clearance timing but its an easily measured timing and if there isn't good clearance there then there for sure isn't good clearance.

Long story short I'll probably be asking to borrow the piston jig again.

New thought is I'll pull the lift numbers from DM in 5 degree steps 20BTDC to 20ATDC, set the crank and measure the clearance. If that doesn't find the problem I can mount the timing cover and cams and check the same range with a feeler gage.