know where i can get the flow chart for the chevy zz-4 aluminum cylinder head. part #12556463. how come i cant get through to the GMPP web site are they down or is it me. also known as the corvette design for the 350 HO service engine. 58cc. 163 intake runner. thanks for any help. bern

Your rite they did change the site to a new one. They took off the spec charts with flow. This is the only specs that I found. I'll look around for you, maybe someone else mite know.

This aluminum cylinder head assembly for small-block Chevrolet V8s is ideal for street rods, fresh-water power boats, and high-performance applications. GM Performance Parts' aluminum cylinder head assembly combines the benefits of light weight, advanced design, and an affordable price. This complete head assembly includes valves, chrome silicon heavy-duty valve springs, retainers, 3/8" screw-in rocker studs-everything an enthusiast wants in a high-performance cylinder head package! GM Performance Parts aluminum cylinder head assemblies are based on brand new Corvette light alloy castings (P/N 10088113). The Corvette cylinder head's advanced design features include D-shaped exhaust ports that enhance the flow of burned gases, high-velocity intake runners that provide crisp throttle response, and centrally located spark plugs that improve combustion efficiency. Valve seat inserts for 1.94" diameter intake valves and 1.50" exhausts are installed in the 58cc combustion chambers. Raised rocker cover rails with machined sealing surfaces virtually eliminate rocker cover gasket oil leaks. This high-performance cylinder head assembly is used exclusively on High Output 5.7-liter small-block V8 engines. Unlike production Corvette cylinder heads, it is outfitted with special heavy-duty valve springs (see part number 12551483 for technical specifications). A pair of aluminum cylinder heads offers a weight savings of approximately 50 pounds over comparable cast iron cylinder heads. (A bare aluminum casting, less valves and springs, weighs 19 pounds, versus 44 pounds for a bare cast iron head). This reduction in total engine weight of 25 pounds each can improve handling, acceleration, and fuel economy.

Part Number...Description
12555269.........Stamped steel rocker cover
10229162.........Corvette screw-in oil filter cap
12342056.........Chrome screw-in oil cap w/GM logo
12338092.........Valve cover hold-down bolts (8 required)
14094717.........Hold-down bolt washers (8 required)
14088793.........Hold-down bolt gaskets (8 required)
14088564.........Neoprene rocker cover gasket
12557236.........Composition head gasket, .051" thick
12495499.........Head Bolt Kit
12495490.........Rocker Arm Kit

Technical Notes: Technical Notes: This casting does not have intake manifold heat riser or EGR passages. The exhaust port exits are approximately .100" higher than production cast iron heads; exhaust manifolds and aftermarket headers may require modification to maximize airflow. The spark plug holes are angled; check for adequate exhaust manifold or header clearance. Use 3/4" reach gasketed spark plugs with 5/8" hex heads (AC FR5LS), 904, or MR 43LTS. In rapid fire use #8 plug. Both ends of the head are machined for alternator, power steering, and air conditioning compressor mounts. No pushrod guideplates; use rail type rocker arms P/N 10089648. This aluminum head assembly requires valve covers with central hold-down bolts and extra-long bolts with washers. A composition head gasket with stainless steel fire rings is recommended to prevent galvanic action between the head and a cast iron engine block. This head assembly is the same as P/N 10185087, except valve spring and retainer change.



[ April 16, 2003: Message edited by: 1BAD80 ]</p>

__________________
Luv the smell of NITRO in the morning.

If you scroll down this link a bit the head you're looking for is the old L98 Corvette head.

<a href="http://www.chevyhiperformance.com/techarticles/41598/index4.html" target="_blank">http://www.chevyhiperformance.com/techarticles/41598/index4.html</a>

[ April 17, 2003: Message edited by: engineczar ]</p>

__________________
B Sinc

Thank's I forgot about that site.

__________________
Luv the smell of NITRO in the morning.