Dino 246 engine rebuild

My beautiful '74 Dino lost half it's cylinders this week. Time for an engine rebuild. I speculate that my timing chain jumped and knocked out valves and or pistons. Car has 40000 miles on original engine. Any recommendations on qualified mechanics in California. I live near San Luis Obispo, so Northern or Southern Ca. is equidistant.
Thanks for responding.

 

With out a doubt call Kevork Hazarian @ (818) 755-9555. He is in North Hollywood and comes highly recommended.

 

Ditto on Kevork, I have called him several times on problems and he has always been spot on with advice, very helpful!

 

Ditto again on Kevork. He did work on my Mondial t's cooling system. Temp wise, she runs like Kimi talks and drives - - even when it's 105 outside

 

I think I'll give Kevork a call. Thanks for the lead.

 

Steve:

You might want to talk to Jack Bianchi in Santa Barbara. Jack has worked in past on Ferraris for me. He has been around for a long time, is honest and knowledgeable.

Jack used to own and run the business, but now I think he just does mechanical work although he must still be a silent owner. Others are managing the business now.

The number is 805-965-5261. He is on Haley Street in SB.

Again, I am sorry this happened to you on the way to my party!!

Tom Elerding

 

Thanks Tom. I'll try Jack as well. I want to check out various options. I'm still considering doing it with myself and Rich. Could be a good experience.
Enjoyed the gathering. Wish I could have had a bit happier demeanor. I greatly appreciate your hospitality and aid in getting my car back home.

Steve

 

Wow Steve,

To have your Dino upchuk one side of lunch - and on the way to a party!!!
Well, thank the powers of the universe, it wasn't an accident. Good luck with her engine restoration.

Cheers, Hank

 

If you have the time, doing it yourself is lots of fun. And if I managed to do the 2.4 motor out of my old fiat dino coupe with help of a more knowledgable friend, you can too. FYI, my machine shop bill (Lonnie Jensen in San Francisco: They did good work, but I don't recommend them if you want it back anytime soon!) was about $1500 which included some repair to the head, new seats, guides installed, block prep for new pistons, and balancing of various items. I got lucky that my crank didn't need work (they just cleaned it out). The high comp pistons, big valves, guides, springs, bearings, and other parts came from Superformance.co.uk and ran about $4-5k. I disassembled myself and then a friend assembled while I tried to help. Estimated hours for disassembly and reassembly (not including pulling it from the car or putting it back) was about 24 hours (and about an equal number of beers!).

As for mechanics, if you decide to go north rather than south, I recommend Johannes at Dino Motors in San Mateo.

p.s. i have some photos of the rebuild process here:
http://www.3jar.com/fiat/fiats.php?p=rebuild

 

Steve,

I can sympathize with you. My Dino dropped a valve as some do at a track day. It isn't very pretty when they open up the motor. I was lucky, new valve seat, new valves, pistons and machining etc. The head was ok. I found the offending valve head in the muffler! You may be lucky.... I've included a scan of a picture taken at the time - sorry for the poor quality, it is over 20 years ago now.

cheers
Peter
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I feel for you as well, but the bright side is that you will learn so much about your little gem. I have had reports of the valve heads popping off of other Dino's, it seems that it was a batch problem with sodium filled exhaust valves. Do replace them with stainless as this fixes the problem. I had a dealer who told me not to drive my Dino period until valve replacement. He said that they had two Dinos drop the valve heads, one at idle and the other at 3,000 rpm. I sure was nervous until I replaced them. Good luck with the rebuild.

 

I believe Patrict Ottis in Berkeley may be one of the best, if not the best, in the US.

 

Thanks to you all for your advice and sympathy. I appreciate it greatly.

 

I replaced mine with stainless - no problems since. The week before my episode, another club members' Dino did the same. Driving home on the freeway at 100kpm, it just dropped a valve and all but destroyed the combustion chamber in the head. Both cars must have had that bad batch of sodium filled valves. A few months later, a 400i (same sodium filled valves) did the same idling in its owners driveway..... This was back in 1984/5 - most Dino's by now probably have had their heads off - if not or if you dont know whether your car has, find out. After 30 years and if the motor hasn't been touched, you may be lucky or.....

 

talk to lm2504me on this board, he lives up in Nipomo (I think) but either way he is not far from you. His name is Richard and he has a 246GT that he is rebuilding as I type this. He should know people in your area that can do the work, even though he is doing his own rebuild.

 

I have owned 4 Dinos (all 246Gt), the first acquired in 1978 (still owned). I have rebuilt 5 engines over this span of time(3 of my own, 2 for friends). I have never had a valve break, nor have I invested the necessary dollars to exchange perfectly good valves for other perfectly good valves. I have exchanged valves when the valve stem diameter has worn below specification.

I have heard of the issue of "sodium filled" valves for years, and have read many interesting threads pertaining to the 348 and 355 valve issues - all related to "sodium filled" valves. Personal experience shapes our perception, and my experience suggests that this is either 1) a non-issue, or 2) there is a touch of folklore involved, or 3) I have been exceedingly lucky not to have had a problem (and this is definitely out of character).

Beginning with the 246, if Ferrari felt that the sodium filled valve issue was a concern, why did they continue using this technology in the 3x8, 348, and 355 series? I tend to lend more credence to the engineers at Ferrari then non-metallurgic analysis of a valve failure offered by some back-alley mechanic (I am not referring to anyone who participates on FerrariChat). While this may seem to represent a contrarian point of view, it stems from a healthy dose of skepticism derived from non-technical analysis of many things Ferrari.

Jim S.

 

Folklore or not, my engine rebuild was prompted by a snapped original sodium type valve, too. Piston got chunked up like AusDino's picture above. When buying new valves, everyone said not to get that style but to get new style.

 

Richard - did you replace all of your valves at the time of rebuild? If so, did you measure the stem diameter to see if they required replacement anyway? Finally, what was the cost of parts (valves)?

Bad things happen. My post was merely to observe that input from a metallurgist might be helpful vis-a-vis the valve fracture issue.

Jim S.

 

I would guess that the simple fact is that a hollow valve, sodium filled or not, is more fragile than a solid one. But Ferrari chose to use sodium filled rather than solid, to shed heat better. As a carb 308 owner, I almost certainly have a car with sodium filled exhaust valves (unless a PO changed them out). Given all the 308s out there, only a small number have had valve issues, so generally, I don't think they are as much of a time bomb as people think. Then again, a fair number of people on Fchat can relate an experience with losing a sodium valve, so maybe I'm wrong!!

What I don't understand is the idea that they need to be replaced with "modern stainless steel" exhaust valves. Stainless steel is not a new material. They clearly could have made the OEM valves in a 246 from stainless but they didn't. So why is it better now? They chose sodium filled to shed heat. Does "modern" stainless perform in some way better than "vintage" stainless? And if so, why does the new Chrysler 300 SRT, among other things, use sodium filled exhaust valves?

Birdman

 

Unfortunately I didn't measure the old valves. I just wanted to rebuild the engine totally with all new parts. I also wanted to upgrade to larger valves to go with the new high comp pistons (and planned cam change though I never got around to that before selling the car). I don't remember what I paid in 2000 or so when we did my engine, but the current cost of the larger exaust and intake valves is 23 pounds each (vs. 18 pounds for standard size) from Superformance in England. It's not much money considering we only need six each for the Dinos!

 

Birdman - my thoughts exactly - there does not seem to be an epidemic of valve failure.

Regarding the justification for hollow valves - perhaps it is a weight issue. One can save a few ounces with a hollow shaft. Once this decision is made, then cooling becomes a problem as the "thermal mass" is diminshed. Filling with sodium presumably is lighter and offers better heat conduction.

Finally - I believe that the failure of sodium filled valves may be related to the manufacturing technique. The valve may be filled at the junction of the stem and the valve head, and then welded closed. An alternative is to fill the open stem from the end opposite the valve head and then weld closed. I understand that those designs that are welded at the stem are subject to failure.

It would be interesting to hear from someone who understands the technical (engineering) issues of how these hollow stems are filled, the nature of the sodium (density and thermal conductivity), etc.

Jim S.

 

Patrick Ottis in Berkeley is excellent, as is Brian Crall in San Ramon.
Winston

 

When my motor was dismantled after the "dropping" of #6 exhaust, #3 exhaust had a crack at the base of the stem.This may support your first proposition. I think another factor maybe the use or lack of use of the car. I went through all the receipts etc that came with the car and to my surprise, it had only done 1000miles in the previous 18 months before I bought it. This conjures up thoughts of open valves sticking open after extended periods of no use. When the motor is then first turned over/started, the piston/s may hit the stuck open valve/s and either damage it/them or bend it/them slightly. This, plus maybe a weakness in the manufacturing process of the sodium filled valves may explain the problems had by myself and others. I have included a pic of the dead valve - notice the hole in the head where the stem was.

cheers
peter
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Aus, thanks for the photo, that pretty much exlains it. I'll bet the noise was horrific!

 

Holy crap, that thing really took a beating! I can't imagine what the piston looks like.

I figure I'm going to drive mine until such time as a valve fails or it just needs to be rebuilt due to compression issues. At that time, I'll upgrade the valves and put in higher compression pistons. Until that time, I'm not going to worry about it.

Also, the new Corvette Z06 has sodium filled valves.

Birdman