Editing Big block Chevy heads

==BBC L29 Vortec heads==
[[File:ChevyBigBlockL-29vortec chamb.jpg]]
[[File:454 vortec head.jpg]]

==Mark IV cylinder heads on later Mark V block==
There are gaskets made specifically for this swap. Use other gaskets at you're own risk- these are what you want (from a V/R press release, '''presumably prior to the Gen 6 engine release'''):

'''General Motors 7.4L Head Gasket Issue:'''<br>
General Motors (GM) 7.4L (454 CID) engines use two types of engine blocks: the Mark IV and Mark V. The Mark IV is found on 7.4L engines in model years from 1965 to 1990, and the Mark V is found on 7.4L engines in model years from 1991 and newer.

Often, installers will attempt to adapt a Mark IV cylinder head for a Mark V block. This conversion can be made if attention is paid to the coolant circulation. Mark IV and Mark V have different coolant flows and were originally designed for different head gaskets. If the conversion is not performed correctly, the engine will overheat, causing premature engine wear and damage.

'''Resolution:'''<br>
Victor Reinz has designed two Nitroseal® head gaskets to specifically allow for this conversion. The installation requires Victor Reinz part number 4918 be installed on the right cylinder bank to maintain proper coolant circulation, and part number 4923 to be installed on the left cylinder bank for the correct coolant flow.

'''Application:'''<br>
Victor Reinz part numbers '''4918''' (right bank) and '''4923''' (left bank) are available for GM 7.4L (454 CID) engines.

==Torque sequence for big block aluminum heads==

[[File:Bbc head bolt tightening sequence.jpg]] 

===Special considerations===
Aluminum heads require parallel ground hardened steel washers under the bolt head or nut to prevent galling the aluminum seat. Some or all bolts/studs are often a different length than the bolts used on the stock cast iron head. If aftermarket hardware is used, follow the manufacturer's instructions for lubrication and torque specs. Otherwise, tighten the hardware in at least three steps. New hardware should have the threads burnished before final torque is applied (see manufacturer's instructions).

Use anti seize compound on all threaded aluminum bolt or sender holes, especially the spark plug threads. Only remove fasteners or senders when the head is cold. 

[[Category:GM]]
[[Category:Engine]]
[[Category:Cylinder head]]
[[Category:Undeveloped articles]]
[[Category:Undeveloped Engine articles]]
[[Category:Undeveloped Cylinder head articles]]