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By yblock32 - 16 Years Ago
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I know that this has probably been done to death , but I'm going to ask anyway. I have a set of ECG-D heads and am wondering what mods should be done ??
I'm building a fairly mild street 272 and want to know what can be done porting & valve wise to get the best out of them. Do I need to go bigger valves ?
Block is .040 , cam - intake 0.4201 lift, 282' - exhaust 0.4186 lift ,281' and will probably be running my offy triple carb manifold with 3 "94s"
Also could somebody please tell me what the go is with posted & unposted heads ??
Thanks David
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By Ted - 16 Years Ago
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Here are some links to past threads about posted heads. Advantages of posted heads Identifying posted heads Performing a search will bring up some more.
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By 46yblock - 16 Years Ago
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Yblock32, If the memory is right, the ECG D heads have the combustion chamber that "wraps around" the valves, something like 220 or so degrees. Looking down on the head's bottom side the deck portion of each chamber forms something similar to a letter m. Check and see. If correct the design looks like it shrouds the valves significantly, possibly offsetting gains of larger valves. I recall looking at the chambers and thinking that with the wrap around they may have a relatively small volume, so it would be good to cc and find out where you will be on CR, and if you do please let us know the results.
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By glrbird - 16 Years Ago
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Ted Have you ever seen any of the non posted heads fail? I have only seen one head on a small block chevy fail, but it was cut .120 on the deck and the compression ratio was 12 to 1.
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By pegleg - 16 Years Ago
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Gary, The faiures first appeared on Blown cars, which is why the posts were added. I doubt if it ever happened on a normally aspirated motor unless somebody milled them a quarter inch or so!
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By Ted - 16 Years Ago
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glrbird (6/15/2009)
Ted ... Have you ever seen any of the non posted heads fail? I have only seen one head on a small block chevy fail, but it was cut .120 on the deck and the compression ratio was 12 to 1.The heads technically do not fail by breaking but they will not hold an adequate seal at the head gasket when milled excessively. At 9½:1 CR, the gasket seal is marginal at best with moderately milled non-posted G heads but at 10½:1 CR, the head gaskets fail consistently on those same cylinders that were later posted in the heads. Detonation was the root cause in a recent instance that comes to mind but the milled non-posted heads simply forced a much quicker head gasket failure as a result. Using a pair of posted heads and slightly lowering the compression ratio solved all issues in that particular case. Talking scrub and Yblock regarding head construction is analagous to comparing apples and oranges in this case. The non-posted G heads have two cylinders in each head that have large areas of unsupported head deck surface that with any significant milling to these heads simply allows too much flex at the gasket seal and results in a head gasket failure. The posted heads pretty much eliminated this problem while also permitting a much deeper cut or mill to the heads without the aforementioned gasket problems. Here’s a link to previous discussion on how much head milling is generally acceptable. http://www.y-blocksforever.com/forums/Topic16300-3-1.aspx Performing a search using head milling will bring up other threads on the subject.
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By yblock32 - 16 Years Ago
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Thanks to everyone who set me straight on "posted & "unposted" heads. I'm a novice with much to learn - thanks. I also asked about porting these heads , has anybody got any tips ?? Thanks david
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By 46yblock - 16 Years Ago
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I wouldnt do anything to the heads, even rebuild them, until the combustion chamber volume is known. With the cam duration you will need as much CR as the 272 can give. To throw out a number, say the volume is 78 cc. Then the CR is going to be way down, and it would be best to look for other heads, C's, G's or 113's. If the piston to deck clearance is excessive, that compounds CR problems of high volume heads. A really low CR matched to a 280 duration cam is going to be a dog below 2500 rpm, maybe 3000, and you wont be happy. What compression does the cam maker specify?
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By PF Arcand - 16 Years Ago
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David: According to the Mummert/Reese Head chart, those ECG-D heads were std on 55 Ford cars & were advertised at 7.6 C.R. on a 272, and that was likely optimistic. The footnote says that C.R.s with modern head gaskets are even lower. As previously mentioned, those heads are not likely the answer on a modified engine.
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By PF Arcand - 16 Years Ago
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David: Further, I forgot to mention, that while Offenhauser is a storied name in racing, if really looking for a performance boost, their intake has been analyzed and is likely the poorest internal design of the Tri power setups available. Sorry to rain on your plans, but thought you should know..
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By yblock32 - 16 Years Ago
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46yblock , thanks for your input ( greatly appreciated ) I will check the combustion chamber volume and when we do the trial assy we can check the piston to deck clearance. The block has been decked ,but only to clean up. As for looking for other heads ( maybe Aussie Bill or Lon may be better able to advise on this ) I don't believe that we had the options that you have in the states. This particular motor came out of a '56 Mainline Ute and a mate of mine picked up another 272 out of a '60 F100 that had the same heads ( I realise these could have been retro fitted some time in its life ). Ours was a small market and I believe our motors came out of Canada and our casting No's don't neccessarily match the US ones.Which brings me to another question - The ECG-D heads have expansion plugs in the ends but the heads on the272 in my '32 ( out of a '58 F100 ) don't. I cant see any casting No's on them ( maybe underneath or under header plates ) - any clues as to what these would be ? If so should I use these in stead of the ECG-Ds?
Paul - I realise that the Offy manifold is not the best, but I have 2 reasons for using it ; 1-I have it and 2- nothing looks cooler than 3x2s on a Y-Block. Sorry I don't mean to be flippant here but in Oz there just isn't the volume of yblock speed equipment as there is in the states.
I really do appreciate any and all input.
Thanks David
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By LON - 16 Years Ago
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David I have "D" heads on both of my motors 272 & 292 .According to my engine builder (Jeff Cooper in Toowoomba QLD ) "D" heads are about the best that was on offer in Au . You are correct in saying we didn't have a great choice about the heads .I have pulled apart about 6 motors in the last couple of years and not one motor had a set of matching heads .The heads I had on the hot rod were ECZ-A .Big valves ,ported ,faced etc,etc. Only problem was I had way too much shaved off . ( .080 th).I couldn't work out way I kept blowing off the radiator hose ???.The heads were lifting on the block . Send me a PM and I will give you Jeff's # .He is a real whiz on Y-blocks Lon
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