455 OLDS C Casting head identifiction?

[kcsteck]

Hey guys. Im lookin at some 455 OLDS C Heads supposedly off 68 Block. I know C heads was the best head but Can anyone verify & tell me what the numbers I have for these heads are good ones or not.or where to get the numbers from on the heads.they have a C on them and little number 10 by 2nd spark plug hole on both heads &the numbers 394 & 548 on top of the head in the middle of head .and some kind of stamp that also says CMD next to it. AmI lookin in the right places to be able to verify these heads? They have the big valves in them and do not have hardened Seats in the exh valve ports. guy said these were the old ones and they dont need the hardened seats in them. I had K heads and had the hardened seats. But thats what came out of my head and destroyed my piston. Just tryin to make sure im not make mistake to get these heads.
Please let me know.
Casey

[SmokinLowriderSS]

Hey guys. Im lookin at some 455 OLDS C Heads supposedly off 68 Block. I know C heads was the best head but Can anyone verify & tell me what the numbers I have for these heads are good ones or not.or where to get the numbers from on the heads.they have a C on them and little number 10 by 2nd spark plug hole on both heads &the numbers 394 & 548 on top of the head in the middle of head .and some kind of stamp that also says CMD next to it. AmI lookin in the right places to be able to verify these heads? They have the big valves in them and do not have hardened Seats in the exh valve ports. guy said these were the old ones and they dont need the hardened seats in them. I had K heads and had the hardened seats. But thats what came out of my head and destroyed my piston. Just tryin to make sure im not make mistake to get these heads.
Please let me know.
Casey
I can tell you THIS, if the heads are pre-early 70's, yea, they won't have hardened valve seats, which CAN come loose, BUT, Do you understand the reason for those seats?
With the disapearance of tetraethyl lead in gasoline, the valves used to be lubricated in head contact by that lead. Unleaded fuel caused the valves to eat into the head iron, which is much softer than the steel valves.
They don't need hardened seats in them to run high-lead content race fuel, what are you planning to burn under them?
Your call.

[DelawareDave]

Quoted per 442.com/oldsfaq
C 394548 80cc 2.000, 2.072" 1.625"
67-69 400/425/455's [except W-30 and most Hurst/Olds], including 1968 H/O with A/C. Valves commonly 2.000" and 1.625", but Toronado and 442 [except Turnpike Cruiser] heads had the larger 2.072" intakes. Presumably the H/O with C heads also had the large valves. Shallow spring seats. No hard exhaust seats. On 1967 engines, RH head will have the engine ID stamped into the front. Correct for 67-69 442's, even 68 H/O with air. Heads for 1967 W-30 or California cars had the A.I.R. passages [that boss on the exhaust port] drilled, tapped, and plugged. Some '68-9 442's with auto trans may have had small valves. This is reputed to be the best-flowing head, and is still fairly easy to find.
Our local head porting guru and engine buiding maven ("trained" by Mondello) both say that the only real difference between "B" and "C" heads is the size of the pushrod hole. Starting in 1967 there was more than one lifter angle necessitating a pushrod hole large enough to accomodate both. I have examples of both in my collection and this appears to be right. Small holes in the "A" and "B" heads. Drill out the holes in a "B" head and it will fit anything the "C" will. Don't and you may eat pushrods.
Hardended Valve Seats
Before 1971, all Oldsmobile street engines require lead. An engine uses lead for valve seat protection and octane boosting. GM states in the 1971 Owner's Manuals that all 1971 GM engines can safely use unleaded fuel. You might want to consider that 100,000 miles on an unopened engine wasn't a common occurance back then.
The lead (actually tetraethyl), when burnt in the combustion process is deposited on the valve seat. This cushions the softer metal of the pre 1971 heads. Without the lead the harder valve slams into the unprotected seat and will cause seat recession. This leads to burnt valves. Heads with soft seats are A - F. Heads with hard seats are G - K. Although some Ks might have the soft seats.
To distinguish the hardened valve seat heads from the earlier, non-hardened seat heads, Olds cast a small capital-letter "A" along with the larger casting number/letter. This letter is smaller, and down to the right from the main casting number/letter; hence, it is designated by the lower-case "a", even though it is cast as a capital "A".
Heads with the small "a" designation are guaranteed to be hardened seat heads. Such as Ca, Da, Ga and also Ka and J heads. The J is the exception due to being a smog head from 73-76. Other heads (such as E and F) are rumored to have hard seats, but only your budget, gut feelings, and eventually the heads will know for sure.

[kcsteck]

hi delaware dave. These heads def do not have the hardened seats like my k Heads did and which fell out and destroyed #2 cylnder. Do I Have to put in the hardened Seats in the heads if like your quote said that OLds manual said they could burn unleaded?Cant I add somethin to the gas or somethin and leave the seats alone?or is race gas only if you leave the seats and not install hardened seats.

[SmokinLowriderSS]

Your skittishness is understandable, but consider how many hardened seats EVER get loose in the heads, over hundreds of millions of cylinder heads, over 35+ years, of all makers, in normal automotive AND performance aplications.
1%?
1/2 of 1%?
1/10 of 1%?
1/100 of 1%? (1 seat every 1250 heads)
I don't have numbers, but I can safely say it is uncomon, rare even. Absolutely anything CAN happen, but how often DOES IT?
Heck, if $$$ is no object, run them as is for 5 or 7 years and just use them up and throw them away.
If $$$ is no object, you can spend a small fortune every year on things like:
STP Lead Substitute
QX-500 fuel lubricant
Quantum VS
104+ Real Lead
Dur-Alt
Gunk Lead Substitute
Sim-U-Lead
TK-7S Super Octane Power Booster
Valve Saver
Unocal 76 Valve Saver
C-5 Fuel Additives
Alemite CD-2\
etc.
How many bottles per tank, and how many tanks per weekend?
How many tanks per season?

[kcsteck]

I must be 1 of the lucky ones then!! Happened to me last year and now last weekend. last year seat only poped out and ruined the valves on #6. this year popped out and broke and ruined the valves on #2 cylnder and the piston. Im gonna look into the additives instead of installin the hardend seats then. I only take the boat out maybe 6-8 times a summer.thanks for the info and the additves.
Casey

[oldselmn8tr]

How often do you run the boat? I don't run hardened seats in my olds because of the possibility that they can fall out. I just run a lead additive, big diff between a daily driven car and a seasonal used boat, you will get years off use before a prob. will arise. Besides one less thing to worry about. Your choice.

[SmokinLowriderSS]

Maybe Olds' have a tendancy. My Chevy heads are 29 years old now and I can't remember when I last heard of one getting loose in a big chevy.

[DelawareDave]

If it was me, I would run what you have available. Considering we are talking boats, and not cars that would be expected to go for 100,000 miles, I would not worry about hardened seats. In a boat, it would probably take at least 5 years of running every weekend, before you might see a valve sink into the head from "soft" seats.