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GM Gen 5 14097088 Cylinder Heads
Posted: Fri Feb 20, 2009 2:02 pm
by Marty Ester
Can these Gen 5 heads be put on a Gen 4 block? If so, does it take a specific head gasket to mate the two together? These heads, I believe are 91 & up rectangular port heads that came on the 502. Bolt holes are correct for the block and intake and will mate with an edelbrock 454r. Its the block to head water passages I have in question.
Thanks
Marty
Posted: Sat Feb 21, 2009 9:45 am
by jamie
I have done it lots of times with gen 5 heads to mark 4 block and the other way around.I haven't had leaks on any of mine but have heard some castings have.I would put the head on with no gasket and come up through the lifter valley and scribe a line following the block all the way across the head.Take the head off and check to see how close the tear drops come to the edge of the block.My closest one was 3/32 and it sealed fine.I use victor #4918 left and #4923 right performance gaskets for up to about 11:1.We have also used a regular felpro mark 4 gasket and it worked fine.
Posted: Sat Feb 21, 2009 11:30 pm
by Marty Ester
Thanks Jamie. Appreciate the info.
Posted: Sat Feb 21, 2009 11:51 pm
by hitchcock
Yes it can be done. You just have to use the correct head gasket and it will be fine. There was an article in Hot Rod called "A Game or Rat and Mouse" They used a 505 bbc gen. IV block with the 088 casting heads. And they covered this very same issue in detail. If you want I will go through my magazine stash and find the part number on this gasket they used to to this.
Posted: Sun Feb 22, 2009 7:48 am
by Marty Ester
That would be great. I may still have the back issue.
Thanks again
Marty
Posted: Sun Feb 22, 2009 9:45 am
by PWMAX
Like said above, it works fine. I do A LOT of Hp marine engines, Mercruiser HP500 502's are like a## holes, everyone has one, and they all have 088 heads on them. I have right now 5 sets of take off heads on the shelf, and will do them up from time to time for a budget bracket deal, and use them on a Mark4 block, you just need to use a gasket intended for the Gen5 or6. The gasket will match the heads water ports, which are way different than the Mark4 stuff. The water holes are in the right spot on the block, so, it doesn't matter what "printo seal" is on the gasket, it will just seal on the flat deck. It works fine.
Frank
Posted: Sun Feb 22, 2009 3:09 pm
by jdavis
Anyone got advice on going the other way, putting a set of 990's on a gen 6 block. Or is there no issue there. I've got a set that were on a gen 4 454 in a boat that wasnt winterized properly and when it froze the block expired and left me a forged rotating assembly and 990 heads in fine shape.
sorry for the hijack.