Gen 6 454 Questions

[00CrewCab]

I believe you need special head gaskets to put a non GenV head on a GenV block. And the GenV block is not OE roller compatible.

Gen V short-block, the heads, intake, and front cover/crank sensor/crank reluctor from your existing engine.

You'd need some gaskets 'n' sealer, a decent 3/8" torque wrench, an engine hoist and a fair bit of courage.

I put Gen 6 heads on a Mark IV block; the head gaskets I chose were not optimum. I don't think that'd be a problem with a Gen 5 block, though. Note that I've never actually done that swap.

So basically take the good top end off my Gen 6 and put it on a good Gen 5 short block? That wouldn’t be too hard to do. Sounds like a “weekend build” that I’d be able to do. What about the cams? Aren’t the G5 flat tappet and G6 roller? Are they easily interchangeable?

 

[Supercharged111]

So basically take the good top end off my Gen 6 and put it on a good Gen 5 short block? That wouldn’t be too hard to do. Sounds like a “weekend build” that I’d be able to do. What about the cams? Aren’t the G5 flat tappet and G6 roller? Are they easily interchangeable?

For the 2nd time no, the GenV block does not accept the factory GenVI roller rockers or cam. The heads and intake will bolt right up, but you may need a special head gasket to make that happen.

 

[00CrewCab]

For the 2nd time no, the GenV block does not accept the factory GenVI roller rockers or cam. The heads and intake will bolt right up, but you may need a special head gasket to make that happen.

Sorry misread that the first time. I’ll probably just hold out for a GenVI good lower end or full engine.

 

[Supercharged111]

Sorry misread that the first time. I’ll probably just hold out for a GenVI good lower end or full engine.

As @Schurkey indicated, the GenVI is better than the GenV in every discernable way. There's a reason the GenV is so much more attainable than the GenVI.

 

[Dropped88]

Gen 5 and 6 are both junk IMO not starting a argument

Anyways looked into doing the same thing and I could never find an answer if the gen 6 head would bolt on or just need a gasket so I never tried and like already mentioned you'd then lose your roller cam

Also Gen 7 fixed the issues with the 5 and 6

 

[00CrewCab]

Gen 5 and 6 are both junk IMO not starting a argument

Anyways looked into doing the same thing and I could never find an answer if the gen 6 head would bolt on or just need a gasket so I never tried and like already mentioned you'd then lose your roller cam

Also Gen 7 fixed the issues with the 5 and 6

Gen 7, that’s the 8.1 isn’t it? Were those ever available in this platform from factory? If so I’ll try and find a parts truck and do a whole “oem” swap.

 

[Road Trip]

Ok, so my 2000 K2500 454 has spun a main and or rod bearing. Don’t have the tools to do a rebuild. Found lots of Gen 5 454 motors for 600-1200 but can’t find any Gen 6 around me. So main question, can I used a G5 engine in place of my G6? What’s the difference between the two? I’ve heard cam’s are different. And a few other things. But what would I need to change on the G5 to work like my G6. This would be a temporary swap while I get the tools and parts to rebuild the G6. Thanks all.

Greetings 00CrewCab,

I've got a little different take on your situation. If you compartmentalize this temporary swap
the right way, and play your cards right, you may well be able to get a free ride out of a
'less desirable' Gen V motor while your Gen VI motor it out for repairs.

Thumbnail sketch:

1) Source the most promising yet affordable Gen V motor.

2) Pull your Gen VI engine out. Remove the intake manifold, sensors, etc.

3) Remove the intake manifold from the Gen V motor. (Bag the Gen V
intake & stash it for temporary safe keeping.) Swap YOUR Gen VI
intake onto the Gen V engine. Stuff this Gen V/VI hybrid into your truck,
hook it all back up, drive it.

4) Now you can fix your Gen VI motor -- you can now renew an engine
that was originally built with all the good bits. This way you avoid trying
to update/re-engineer the desirable Gen VI bits onto the Gen V motor.
(ie: Keeping your Gen VI rebuild as simple & straightforward as possible.)

5) Once your engine is completely rebuilt, reverse steps #3 & #2 above.

BONUS: *Before* you remove the Gen V motor, put it up for sale as a
"Listen/drive before buying". Make it clear to the potential buyer that
you are selling a running long block except that you are keeping the
intake & associated sensors. But you have all the original Gen V intake
bits to go along with the motor that's for sale.

I know that if I'm in the market for a used engine and I can actually hear it,
drive it, and see the oil pressure & water temps *before* I buy it, then I
would be willing to pay more for it than a rebuildable core out of the
Treasure Yard.

****

If you do this right, then by treating the Gen V motor as a temporary
'Black Box' workaround you can avoid getting tangled up in the Gen V
vs Gen VI stuff. (I'm pretty sure that using your Gen VI intake on
the peanut port Gen V heads is not a problem? Others with firsthand
knowledge please chime in?)

In English, if you really did this right, you would be able to get your
money back out of the Gen V temp motor, while at the same time
giving you something to drive while working through your 1st big
block rebuild. (Which I highly recommend.) Extra work? Sure.
Personally I'd view it as extra experience. But it would also give
me a temporary free ride, more or less.

It would make a great build thread -- all of the BBC enthusiasts
would be hanging over your virtual shoulder asking for lots of
pictures & sharing their hard-won experience...

 

[Schurkey]

I've got a little different take on your situation. If you compartmentalize this temporary swap
the right way, and play your cards right, you may well be able to get a free ride out of a gen V
motor while your Gen VI motor it out for repairs...

He'd also need the front cover, crank sensor, and crank-mounted reluctor from the Gen 6.

Which MIGHT mean he'd need a different timing chain 'n' sprockets--to make room for the crank-mounted reluctor.

Can't use the Gen 6 timing set, as the bolt circle on the cam gear is smaller. Won't fit a flat-tappet cam. For the record, the Gen 6 cam will slide right into the Gen 5 block. The GM Mk IV, and Gen 5 blocks are USUALLY drilled 'n' tapped for the thrust plate. (I have seen a Mk IV block that had the bosses, but weren't drilled and tapped.) What doesn't work on the Mk IV, and Gen 5 are the roller lifters/dogbones/spider. And "conversion" roller lifters tend to be...expensive.

So intake manifold, and some front-cover work...but then the Gen 5 "should" fit and function until the Gen 6 is up 'n' running.

 

[Road Trip]

Gen 7, that’s the 8.1 isn’t it? Were those ever available in this platform from factory? If so I’ll try and find a parts truck and do a whole “oem” swap.

Here you go. Finding one of these in the treasure yard would be akin to finding a unicorn at a rodeo,
but stranger things have happened:

When my GMT400 isn't enough...

Tow rating isn't a function of engine power, but more of a balance of braking, stability and handling. Remember, those semi trucks from the 50s & 60s hauled 40k lbs with less power than today's diesel pickup trucks. I'm sure the 800's bumped towing rating came from 4 wheel disc brakes and...

www.gmt400.com

Note: Tip of the hat to @someotherguy for the above. :0)

 

[someotherguy]

Here you go. Finding one of these in the treasure yard would be akin to finding a unicorn at a rodeo,
but stranger things have happened:

When my GMT400 isn't enough...

Tow rating isn't a function of engine power, but more of a balance of braking, stability and handling. Remember, those semi trucks from the 50s & 60s hauled 40k lbs with less power than today's diesel pickup trucks. I'm sure the 800's bumped towing rating came from 4 wheel disc brakes and...

www.gmt400.com

Note: Tip of the hat to @someotherguy for the above. :0)

Oh those 8.1 3500HD's are out there for sure, just not a whole lot of them (many 2001-2002 were also 6.5td, the only other engine option in those 2 years) - and they're THE donor vehicle if you want to 8.1 swap your gmt400.

Richard