454 GenIV to GenV Swap

[ACannell]

I have a 91' burb with a knocking 454(GenV). I also have an 89' burb with a low mileage 454(GenIV). Has anyone done a similar swap? Anyone know of any problems I might encounter? I have both complete vehicles so I thinking it should be simple right? thanks guy's.

 

[4X4HIGH]

IIRC 91 is still a Mark IV engine not a Gen V.

EIDT: I stand corrected, the first Gen V started in 1991.

 

[ACannell]

Hey there partner, thanks for responding. Any idea's as to the swap being a problem?

 

[4X4HIGH]

Isn't the 91 still a standard TBI or does it have the newer port injection?

 

[sweetk30]

should be tbi till full vortec in 96ish.

 

[4X4HIGH]

should be tbi till full vortec in 96ish.

That's what I thought, just an updated block with the old style heads and TBI. IIRC GM did not go to the "fixed" (nonadjustable) valvetrain until the Gen VI engine.

 

[boz42]

My 91 has a Mark V. It has a fixed valve train.

 

[ACannell]

Yup - that's the case here. I wondering if the exhaust manifolds will be interchangeable. I am wondering if there are any other small differences between the two Gen.s that will make a minor swap a major PITA.

 

[4X4HIGH]

Yup - that's the case here. I wondering if the exhaust manifolds will be interchangeable. I am wondering if there are any other small differences between the two Gen.s that will make a minor swap a major PITA.

Externally everything is the same for any BBC from 1965-1995 as far as "bolt-ons" are concerned with the exception of the harmonic balancer and flywheel/flexplate if it's a 454 or 502.

 

[ACannell]

That's what I was thinking but wasn't sure of. Thanks again. I'm gona play motor swap now with a friend. He has a 93' 3/4ton he just picked up with a brand new 4l80 and a knocking 454. I think his truck is sooner to get up & going than mine so I'm sorta back to square one with my 91'. I've been debating between a 'legal' 383 in place of my 350 or an illegal 454. The BB means smog issues to deal with but a lot less $ to invest. I don't know what to do yet as $ is of coarse the driving factor. Putting the 454 in his truck will at least give me access to a burb when I want it.

Thanks for the info!

 

[CGT80]

instead of rebuilding my 383 I went with a 406 small block, so that I could keep from dealing with updating smog stickers on mine. Look for the magazine article called "impersonator" it's on the net. A 454 would have made 525 ft lbs of torque with less work than the 406, but I would have pushed the 454 to the limit of a smog motor anyway, which means the big block would have cost more. I also already had ceramic coated headers for the small block. I ended up having much more work done to my 406 than the magazine article. So far it runs awesome. I may need to step up the carb from a 600 cfm though. I haven't gotten on it real hard yet, but I think the top end runs out of air. The low end torque is far better than the 383.

 

[COCHEV]

My 91 has a Mark V. It has a fixed valve train.

Really? So no valve/lifter/rocker adjustment whatsoever?

 

[nvrenuf]

Really? So no valve/lifter/rocker adjustment whatsoever?

Correct, on a Mark V. Iirc, the Mark VI went back to adjustable valvetrain.

Not that it will matter for the swap in question but another external difference is the Mark V will not have a provision for a mechanical fuel pump. This too was brought back with the Mark VI.

 

[4X4HIGH]

Really? So no valve/lifter/rocker adjustment whatsoever?

In stock form there is no adjustment, there are kits out there to convert it to an adjustable valvetrian though (I used a kit on Greg72's 502 engine I refreshed for him).