Strange heads 3731539 any suggestions
I have a set of heads with casting number 3731539. they have 2.02" intake valves, staggered valve cover bolt holes and camel hump casting symbols. Anyone have an idea on them.
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Re: Strange heads 3731539 any suggestions
To my eye the camel hump proportions are off and the casting number looks too clean. Books put the number as a 57 head with 1.7 intake valves and the older power pack casting mark of small triangle on top of the rectangle. That is cast iron, yes? -
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Re: Strange heads 3731539 any suggestions
Very strange indeed. I don't know why someone would try to make something like this? The part number is under the valve cover not to be seen, staggered bolt valve covers were only used on early 283s and NONE of them ever had a camel hump marking so in what application would someone attempt to use this to fool anyone?
What is the casting date of these heads and are they cast iron or aluminum?
May be an aftermarket head that just uses the same part number as a 57 head?Comment
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Re: Strange heads 3731539 any suggestions
That is NOT an original GM cast 3731539 casting.
I can easily understand an aftermarket vendor casting heads to have an appearance of an early head, but with later flow improvements. BUUUUUUUUUT, why cast a head with a 539 (57 ONLY) casting number and a double hump symbols???????????????????????
As mentioned, 539 castings ONLY had the pyramid symbol.Comment
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Re: Strange heads 3731539 any suggestions
I know all this is strange, these heads are from a may 19th 1960 283 30 over 3756519 block and it has four bolt main caps.Comment
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Re: Strange heads 3731539 any suggestions
Bob------
These are definitely not original GM cylinder heads. In addition to the differences noted by others, the style of the casting number embossment seen in your photo is not a style ever used by GM.
By the way and for what it's worth, unless these heads were manufactured under a GM Restoration Parts Program license (which is HIGHLY doubtful), they illegally display a GM casting number.Last edited by Joe L.; January 11, 2019, 03:42 AM.In Appreciation of John HinckleyComment
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Re: Strange heads 3731539 any suggestions
Look closely at the end of the head. You can see accessory mounting holes which have been filled.
Also, the shape of the raised area adjacent to the intake manifold surface is shaped all wrong for this to be an old head.Comment
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Re: Strange heads 3731539 any suggestions
Take a look at this picture with the GM casting logo on it.Comment
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Re: Strange heads 3731539 any suggestions
It looks like it may be the handiwork of these guys. They specialize in disguising various head castings.
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Re: Strange heads 3731539 any suggestions
OH YA, I HAVE TAKEN A VERY CLOSE LOOK AT THE PICTURES--------------AND SEE LOTS OF THINGS!!!!!!!!!! (I had not looked that close before)
After a closer look, the three accessory holes are VERY clear (accessory holes did not appear until the 69 model).
Grinding marks (which someone tried to make look like a cast finish) are ABUNDANTLY clear on the ends where shaping was done, as well as in the center of the head, below the "casting" number (clearly, original casting numbers/letters have been removed).
And the general, overall cast shapes of the head are for sure not as it would have been cast by GM.
Last, I still wonder why a head made to resemble an early casting would have the 3731539 csating number-------------------AND HAVE THE DOUBLE HUMP SYMBOLS??????????
Now, with all that said, I also have built an engine (SB400) for the 56 with the intent for it to sorta, kinda resemble an FI 57 283. But I have NEVER tried to pass it off as the genuine article (The NCRS community does NOT like my car---------------ask me if I care).
For example, the heads are massaged 1966 462 castings, which had double humps. The double humps were ground off and then pyramid symbols were shaped---------------then the shaped areas were HEAVILY sand blasted to sorta create an appearance of a cast finish.
I did NOT use a 400 harmonic balancer. I used a finned 327 balancer (smooth all the way around the outer ring) and had the front of the crank internally balanced.
I had additional bosses welded, drilled and tapped for valve covers with a staggered bolt pattern and then installed 9-fin valve covers.
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Re: Strange heads 3731539 any suggestions
This does not answer the original question about the OP subject heads but addresses ways to give better performance with an original look.
If you want aluminum heads with a stealth look for your C2-C3s I believe it is Trick Flow that now makes a head that has the camel hump marking. For the casual observer these heads will fool many but not experts looking directly for the trickery.
Also you can certainly use later original 327 heads ported for more power and with the bigger valves on you C1s that can be disguised to look like original 283 heads. It is simple enough to grind off the original head markings and create new ones with epoxy and a Dremel.
I know that if I needed a set of the factory twin tower marked heads that command a ridiculous price that is what I would be doing as an alternative. These things are nothing new and have been going on for years just like people changing casting numbers, dates and stamped characters on drive train items to fool the public. I have a stealth 383 that at first glace looks like an original 238/270 engine. My engine has Edelbrock aluminum heads on it with adapters for the staggered bolt pattern nine fin valve covers that I bought here. https://www.ictbillet.com/catalogsea...83+265-327+543
I have done this to satisfy myself and have no intention of defrauding anyone and in fact it will not fool any expert.Comment
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Re: Strange heads 3731539 any suggestions
[ (The NCRS community does NOT like my car---------------ask me if I care).
[/QUOTE]
I don't care what the NCRS community says Tom, I love your car - especially the coveted air box.
-Dan-Comment
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