Hey i was looking at the edelbrock website and cames across the Performer RPM 454 R pn 60559 and noticed that all the specs are exactly the same as my GM performance Signature Series Bowtie heads pn 12363400. The chamber size, int/exh/ port and valve sizes and everything else are exactly the same. Does anyone know for sure if these heads are the same like edelbrock casts them and puts GMs name on them? ANy insight would be great.
Also Edelbrocks heads have this little disclaimer under their head ad- The spark plug has been moved closer to the center of the bore and will interfere with high-dome pistons designed for stock Chevy open chamber heads When i go to the SRP website and look up the pistons i ordered it says it will fit edelbrock STD series heads so Im not worried if my GMs really are Edelbrocks, but SRP has a series high dome pistons and they say designed to fit the above mentioned Edelbrock heads and to use w/ the GM heads Ihave for high compression so Im pretty sure both these heads are edelbrocks but mines stamped GM. Lame, wish i had known, either way my head looks good, just wish i had known since before since I paid to have a GM logo stamped on.

 

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I have wondered that myself.Alot of parts for gm are made my other aftermarket companies through contracts.Here are just a few examples that I know of and I know there must be more.

GM 845 camshaft made by crane for GM.
I have heard that the Gm roller rockers are very similar if not the same to the crane gold race.
zz4intake-made by edelbrock for gm,its a performer intake
GM846 camshaft by crane and I have also heard that the hotcam is done by crane to but not sure on this one.

Thats all I can think of but aftermarket companies also use things like GM shortblocks. Edelbrocks crate engines start with gm shortblocks zz4 with the 410,435 version and the goodwrench block with the performer package same goes for there over priced zz383 version.The list goes on and on but you get the point.Alot of work nowdays is subcontracted out to smaller coperations because of all the normal economic reasons that we here about everyday.
I think the edelbrock and gm head is the same but I know that I have seen the oval port version side by side and I would bet they are the same casting.

 

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Your best bet is to go ask the guy on Chevytalk.com. Someone there will def. know what you are talking about.

 

Hey guys,
There is no question, 100% those cylinder heads are produced exclusively by Edelbrock for General Motors.
I have purchased a set from GM found documentation that came with them in the box. For technical support call Edelbrock.
I also use a camshaft and rockers from GM performance parts. When I opened up the GM packaging I found Crane Cam packaging with their documentation and cam spec. card.
I run the GM performance parts gauges as well and found half of them came in GM boxes and the rest in Autometer boxes.
So now you know!

Fastcars
Technician at GM dealership.