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Broken retainers is not rare with these cars and its due to piston-to-valve contact. Ever since Porsche started using sintered retainers (instead of machined ones), those have proven fragile when the engine is overreved, even momentarily. All of our cars used for track events get better springs & titanium retainers, simply for insurance against these kinds of events.
FWIW, I prefer CP over JE pistons since I can specify precisely what I want. Off-the-shelf ones do make noise so we avoid using them.
Originally Posted by Steve Weiner-Rennsport Systems
Broken retainers is not rare with these cars and its due to piston-to-valve contact. Ever since Porsche started using sintered retainers (instead of machined ones), those have proven fragile when the engine is overreved, even momentarily. All of our cars used for track events get better springs & titanium retainers, simply for insurance against these kinds of events.
FWIW, I prefer CP over JE pistons since I can specify precisely what I want. Off-the-shelf ones do make noise so we avoid using them.
For longevity, Mahle is the best choice.
I only have 700 miles on this engine. It's possible it was something the previous owner did that eventually let go. The car was on the dyno when it happened but at a rest. The files showed nothing over 6000 rpm that day but it could have been a weak spring.
The JE's were the wrong parts for my build and reading reviews I came to the same conclusion. I might be able to pick up the cylinders NIB minus the pistons or buy them and try to sell the pistons. I plan to go custom as you suggest. The damage ended up making its way to the other cylinders thankfully the remaining heads are repairable. Leak down numbers were scary bad all through the exhaust valves where the shrapnel landed. Upwards of 60% in 4&6 the other 3 were not as bad with less obvious damage. Finding a replacement cylinder head is proving to be tough. Would prefer used in good condition and reworking it with the rest. I have decided not to attack the bottom end at this time. I hope I don't regret it but everything checks out perfectly.
One question you might know the answer to. The cylinder that failed the hash marks were very different than the remaining 5 cylinders. The 5 looked as though it was done yesterday but the failed cylinder #5 was not as pronounced and almost a bit fuzzy. Is this common and if so attributed to?
So After further examination I found the valve guide for the failed intake valve is sitting .150" further into the head than the other intake valves. Not sure if this happened first or was result of.
After the help of many including Steve (thank you) I was put in touch with Charles Olson of Olsen Engines in Nanuet NY. https://www.google.com/maps/uv?hl=en...oiowEHoECAoQCQ
He is used by a friend Pino from RSR Autobody and restoration and Gaspare from Gaswerks Garage amongst many others who all swear by him.
I am meeting with Charles tomorrow and he is confident he can repair my heads and reline and hone my cylinders for what I consider reasonable money (at least compared to buying new) Once this is done I will have custom pistons made for my application. So all is not lost and I am learning more each day witch is never a bad thing.
Steve has great knowledge with amazing achievements. No doubt what he has forgotten over the years is more than I know.
I truly enjoy every aspect of ownership and that includes mechanicals. The only way I know how to learn is get my elbows greasy. There was a lot I should have done initially but was in a hurry to get back on track. In hindsight I should have. I got the car done quickly and had a sudden change in life plans so it sat and I ended up having the time after all.
After 40 years ownership and 35 PCA I have made a lot of friends with a wealth of knowledge and experience. I am not looking forward to the expense but before i do anything I have numerous pros and cons to weigh before making any solid decisions.
So I went and met with Charley Olsen. A small world as we have many mutual friends and at one time customers. He machined all the parts I made for Joe Nastasi of Nastasi racing and his Typo 33/3 Alfa that won Mile Miglia showing Porsche and Ferrari its back end.
Most all the magnesium parts in the yellowish color on this car I made amongst others over the years and Charley did the machining. IMO that is good enough for me and his knowledge and experience is priceless.
He had numerous McLaren engines, Ferrari and 996 Cup cars waiting to be worked on amongst numerous others.
He will be getting back to me soon on cost to rework and or replace the damaged parts. His opinion is it has something to do with the hydraulic lifter which i will be replacing with solid. I noticed that there seemed to be a bit of dirt in the lifters so that might have had something to do with it.
I decided to break the bottom end and inspect everything. In hind sight it wasn't necessary but why not install Pauter rods, ARP bolts and have everything inspected prior to building it.
I don't recall if it was intake or exhaust. Tracked some, but at the time of the fail, really not that much. I've had the car awhile but had a string of bad luck during the summers: injury, trans needing rebuilt, and I forget what else. So it really hadn't been tracked much. Still a bit of a mystery as to why. The shop doing the rebuild said just bad metallurgical luck, but like K2SO said in Star Wars, "I find that answer vague and unconvincing". But it's whats I gots. Now I gots a 3.8 as the heat damage that ensued warped a cylinder or 2.
08-08-2018, 01:56 PM
I totally missed that typo.
I would have to see it for myself to tell you anything..
