Hey guys so I have been checking casting numbers on my engine to verify what I have in my 68 Riviera. Checked my block, casting number shows to be a 67/68 430, casting # on intake shows to be 68 430, pulled a valve cover off and found head casting #1240149 with S1 nearby which from my online research I have found to be a 70-71 455 factory replacement head, now from my understanding the 1970 1240149 head is 69cc and the 1971 1240149 head is 71cc, I am hoping to have the 1970 heads for the higher compression, is there a way to determine the build date of these heads? Also is there anything else I should be checking via 70/71 455 heads on 430 oiling/cooling wise? I tried to search for more information online but have come up empty handed, any help would be much appreciated! thanks guys.
Only way to know for sure is to do a CC check -- it can be done at home pretty easy, do a youtube search for DIY burette or DIY head CCing but requires the head to be removed for obvious reasons -- it's best not to assume they haven't been milled for any variety of reasons especially if you have a replacement on one side of the engine. Others might chime in and have some info on your casting #'s as I do not.
Thanks for the responce, I only pulled the drivers valve cover so far, will pull the other today and make sure I have a matching set of heads, as for the cc check yes I would have to remove heads I was just hoping there would be a production date casting code/number aswell.
Isn't there a date code cast in? A budget way for cc'ing can be found at a Farm-Fleet type store. They have large syringes for maybe $2.50 each. Get a few.
Yes there is another cast consisting of: D / 6 but that just means April 6th from what ive read. How do I determine if that is april of 70 or 71? Unless I missed something, again this is info from the left side head I will pop the right side valve cover off today and check its numbers.
You've probably already looked at this, but here goes anyway. http://gasalley.thetumbleweeds.net/tech_archive/buick/heads.htm My interpretation is if there was a run of heads made, casted, then they had to of been done in 1970 and there were some left over that were also used in 71. If it was cast in 1971 then how did they use it in 1970.... see what I'm getting at? So it has to be that it was cast in 1970 and is at the 1970 specs and not the 71.
Ah, your interpretation does make very good sense indeed sir! Haha :laugh: And it does seem plausable for the head cast charts to be basing the cc's off heads for those years but some 71's could have recieved the 1240149 as a replacement so that number made its way into the chart under the 1971 year! Anyone else with information or theories reguarding this topic please chime in! And I will definitely post my findings of numbers cast on the other head in a couple hours when I make my way to the shop!
Time has revealed many reasons for "inconsistencies" in castings. Things like labor strikes, end of production runs, etc. One of the best things I've read is from a guy that supposedly worked at a foundry that supplied GM... The fabled 010 020 (chevy) blocks were either not (or not always) with higher %'s of nickel or tin. The explanation was that when they were pouring, they would grab ANY core needed to complete the pour, and that they weren't always marked well on the outside of the core...or organized on racks. The markings face inwards. (The cores are racked prior to pours, and done long before final quantity projections, supposedly) I can imagine Buick having better control of this though, due to smaller quantity and efforts justifying higher pricing. Cadillac sure had interesting foundry processes... Many myths have been busted over the years regarding all makes. Things like "thin walled" later years or material composition have found to be suspect info. When I machined castings we were always dealing with various issues. We were told that they can harden up a bit more when they are pulled from the molds too quickly, as an example.
69cc vs. 71cc is too small a difference to be deliberate. First Guess: They're all "the same" within production tolerances--and production tolerances back then were pretty generous. Way more generous than two CCs. You'd be lucky if all the combustion chambers of a single head were that close. My Oldsmobile heads (C castings) were "supposed" to be 80cc according to the books and online info. After being shaved twice, and having larger valves installed (so the valve seats were on virgin metal) they were mostly around 83cc.
You all make great points the engine runs great so I'll just not worry about the cc's of my head untill I tear it apart for an overhaul, I pulled the passenger valve cover and my heads have the same casting # and same date code. Are dual valve springs factory? Cuz I noticed I have dual valve springs and the valvetrain is very clean/nice looking, please correct me if I'm wrong but Im thinking the valve train has been upgraded? Update, I also found a Stage 1 link that does mention my head cast # as one of the "Important numbers at a quick glance" and does refer to stage 1's using stiffer spring pressure via. duel valve springs, do I have stage 1 heads on my 68 430???? For what its worth here are my engine numbers: Block 1381625 Heads 1240149 Intake 1386681
If you are interested to know the compression ratio and you want to leave the engine together your best bet is to take compression test readings... Although you cannot nail down the exact compression ratio the readings will tell the general story. For example if you have 140 PSI compression tests it is likely not 10:1 and if it is reading 190 PSI then you likely have close to 10:1.
No way to know for sure, if they are actually replacement heads. I suspect that more than a few 149 heads were actually installed at the factory, I have just seen too many of them over the years to believe they all came thru the service department, especially with an engine family that had no commonly know cylinder head issues back then. They had quite a bit of issues with head gasket failure in development, but larger diameter bolts eliminated that before production. If it's a production engine, That has never been opened, or has retained the OE heads, and left in the frame rails of a car, it has a VIN number on it. IN that vintage, the number is stamped on the deck of the block. Second digit is the model year. 149 heads can vary a bit, I just CC'ed a set that went 75, with small valves and a couple of valve jobs, so the valves were sunk a bit. As was suggested, a 430's biggest issue is excessive deck clearance. I just shipped one back to Oregon that was build some years ago, but could not be used, it detonated so badly. Static and dynamic compression calculations would not indicate this, but it detonated so bad, the customer pulled it out and set it aside. A 400/430 has a particular deck height/aftermarket piston issue. Pre- release specs for the 400/430 list the deck height at 10.540. Even today, you can find that spec is reference books and catalogs. But the production engines were 10.570, just like the 455. But that early spec dictated the compression distance on the 400/430 pistons for the aftermarket. And all 430 cast replacement pistons I have seen are built for that deck height spec. This makes the already generous factory deck clearance of right around .050 into a soul crushing .080 and is the major contributor to poor performance and detonation. The 67 I just dynoed here last month was this type of deal, and we cut .070 off the deck of that one, as the customer opted to do that work, vs the custom piston route. With the aforementioned 75 cc heads, this brought our compression up to 9.89, which was similar to what his cracked 430 heads yielded, but reducing the deck height is key to engine operations. I am rambling a bit at this early hour, but to bring this back to a point for the original poster.. No need to quibble over a couple CC on the heads, you need to pull a head and see if it has the factory pistons in it still, and measure how far they are down from the deck surface, at TDC. And extra .030 on the deck height is a full half point of compression.. JW
Ah lots of great information thanks, as of this evening I have found what appears to be blue paint on the block and heads so at this point I am confident to assume this engine has once been rebuilt, probably at the same time the 455 heads were installed, guess I wont know what I have untill I tear into it, but as of now it runs and sounds great and I happy with that, plus if I dig into the engine I have a wish list of parts I will need to purchase :TU:
