Gen VI, Gen IV parts interchange?
07-03-2007, 01:35 PM
#1
Safety Car
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Gen VI, Gen IV parts interchange?
I have seen a few Gen VI engines for cheap and I was wondering if this is because the parts (heads, water pump, crank) from a Gen IV dont interchange. I thoght that if the water passages were changed between versions that it might create a problem similar to the sb400 and other sbc engines. Does anyone know? $350 for a rebuildable 454 just seems suspicious to me. 
07-03-2007, 02:12 PM
#2
Safety Car
Actually I think GM wanted to correct a lot of the interchange problems (they created in the Gen 5) when the started prouducing the Gen 6. I'm not positive on ALL the particulars thou. I have a brand new Gen 5 crate motor for my 76 and this is what I have been able to discern from comparing it directly to other MK4 BBC's I have laying around and what I have been able to find out about the Gen 6's. I think the only thing they succeded in correcting was the lack of a fuel pump provision on the Gen 5 (which has none) and the Z clutch linkage hole, but I understand only some Gen 6's have a fuel pump boss and the clutch provision.
First off - Most newer mfgr aftermarket cyl heads will fit either old MK4 or the later Gen5/6 engines. I know stock heads will NOT interchange from a MK4 to the Gen 5 - not sure about the Gen 6.
Other stuff that is different and not interchangeable. Timing covers are different between the MK4 and the Gen 5/6 (5/6 are the same). Camshaft nose is different on the Gen 5/6 (stepped nose hyd roller cam) as wellas the timing set. MK4 uses a 2 pc rear seal while the Gen 5/6 use a one peice so the crank shafts are different also. Oil pan is different rear seal area).
If you can get a good rebuildable Gen 5 or Gen 6 454/502 for $350 you better get one. There is plenty of aftermarket support for these engines. The rods, pistons, brgs, intake manifold ect are all the same as the old MK4 so you can still build a good motor.
Will
First off - Most newer mfgr aftermarket cyl heads will fit either old MK4 or the later Gen5/6 engines. I know stock heads will NOT interchange from a MK4 to the Gen 5 - not sure about the Gen 6.
Other stuff that is different and not interchangeable. Timing covers are different between the MK4 and the Gen 5/6 (5/6 are the same). Camshaft nose is different on the Gen 5/6 (stepped nose hyd roller cam) as wellas the timing set. MK4 uses a 2 pc rear seal while the Gen 5/6 use a one peice so the crank shafts are different also. Oil pan is different rear seal area).
If you can get a good rebuildable Gen 5 or Gen 6 454/502 for $350 you better get one. There is plenty of aftermarket support for these engines. The rods, pistons, brgs, intake manifold ect are all the same as the old MK4 so you can still build a good motor.
Will
Last edited by rklessdriver; 07-03-2007 at 02:14 PM.
07-03-2007, 03:03 PM
#3
Le Mans Master
Do you want a buildable 454? I have a '73 2-bolt 454 from a 1/2 ton truck. Was a junkyard pullout in about '74 and put in a motorhome. Broke a timing chain in '90 with about 70k miles. Bent all the intake valves but otherwise unhurt and you probably wouldn't use those heads anyway. Apart and sitting indoors since then. I think the pistons/rods were lost when I moved, but otherwise I have all the parts. I also have a standard steel 427 crank. I was going to build a 427, but don't see it happening so I am ready to get rid of my BB stuff. Send E-mail if interested.
07-11-2007, 08:52 AM
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Do you want a buildable 454? I have a '73 2-bolt 454 from a 1/2 ton truck. Was a junkyard pullout in about '74 and put in a motorhome. Broke a timing chain in '90 with about 70k miles. Bent all the intake valves but otherwise unhurt and you probably wouldn't use those heads anyway. Apart and sitting indoors since then. I think the pistons/rods were lost when I moved, but otherwise I have all the parts. I also have a standard steel 427 crank. I was going to build a 427, but don't see it happening so I am ready to get rid of my BB stuff. Send E-mail if interested.
