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78 k5 6.5td swap questions

Head Trauma Johnny

Head Trauma Johnny

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I have a 2000 gmc 3500 with a 6.5td and 4l80e trans I'm replacing the head gaskets on and a few other things. Thinking of putting it in my k5 but but want to keep the nv4500 and do a mechanical IP swap on the 6.5. Its an early nv4500 with the granny gear, will it bolt to the 6.5? or will I need to find a nv4500 from 96-on. I know I will need to modify the a.c. box and route the exhaust on the outside of the frame rails. Thanks for any info.
 
So from what I've read I have the last updated block gm made before navistar/international took over. The block has the same marks without their logo. Suppose to have beefier mains and other improvements. Can anyone on here confirm this? Is it as good as the optimized blocks? Decided I'm doing a full rebuild so I can take measurements to compare.

20171013_143533.jpg
 
Head Trauma Johnny said:
I have a 2000 gmc 3500 with a 6.5td and 4l80e trans I'm replacing the head gaskets on and a few other things. Thinking of putting it in my k5 but but want to keep the nv4500 and do a mechanical IP swap on the 6.5. Its an early nv4500 with the granny gear, will it bolt to the 6.5? or will I need to find a nv4500 from 96-on. I know I will need to modify the a.c. box and route the exhaust on the outside of the frame rails. Thanks for any info.
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Both versions of the GM NV4500 will bolt onto the block identically, the differences are all behind the bell housing flange. Both versions were used by GM behind the 6.5, so you're not doing anything outside of their expectations.

The mechanical IP is an easy enough swap, but not really needed if your current setup is working. Make sure the PMD has been relocated to a cool area and the electronic pump works quite well. Operation-wise, I don't think you'll be able to tell the difference unless you are hot rodding (in which case you definitely want the electronic pump, as it can push more fuel).

The A/C box does interfere with the 6.5 turbine setup, but otherwise it's almost identical to a stock square-body 6.2 installation. I'm not sure what your K5 has now, but be sure to use a 6.2/6.5 flywheel instead of the sbc flywheel (they're weighted differently). And avoid the dual-mass 6.5 flywheel like the plague! The built-in damper has a high failure rate.
 
Head Trauma Johnny said:
So from what I've read I have the last updated block gm made before navistar/international took over. The block has the same marks without their logo. Suppose to have beefier mains and other improvements. Can anyone on here confirm this? Is it as good as the optimized blocks? Decided I'm doing a full rebuild so I can take measurements to compare.

View attachment 248027
Click to expand...

I know the blocks improved over the years, but I'm not sure what all they changed. Your engine is new enough to have dual thermostats and the high-flow water pump. So cooling shouldn't be an issue.

Overheating under abuse was the primary failure mode of these engines, so I would say you are good to go unless you are drag racing. And if you are, you have the wrong engine. :wink1:
 
I bought the 3500 from a neighbor for $500, and had many of those upgrades done. After tearing the 6.5 down to the heads the injection pump looks pretty new. I'm just not a fan of electronics and don't want to deal with them. Not planning to do anything crazy with the motor. Want to keep it mainly stock with the normal bolt on mods(4" exhaust, maybe hx35, mishimoto radiator, ect)
 
Head Trauma Johnny said:
I bought the 3500 from a neighbor for $500, and had many of those upgrades done. After tearing the 6.5 down to the heads the injection pump looks pretty new. I'm just not a fan of electronics and don't want to deal with them. Not planning to do anything crazy with the motor. Want to keep it mainly stock with the normal bolt on mods(4" exhaust, maybe hx35, mishimoto radiator, ect)
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I'd keep a pretty new DS4 injection pump, but there's nothing wrong with the DB2 (Roosa-Master) pumps, either.

What's in the K5 now?
 
Head Trauma Johnny said:
454tbi, I like it but want to do something different.
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Well, the 6.5 counts as different. :haha:

You've already got your fuel return line, then. Check your fuel pump pressure, the GM TBI pumps are similiar to what the Stanadyne IP needs, IIRC. Might not need a new pump. Should be pretty much a bolt-up affair if you have all the little brackets and pieces from the donor. Engine mount locations, bell housing, and overall length should be the same.
 
Head Trauma Johnny said:
Has Anyone ever run an airdog lift pump with the 6.5? Pricey but nice.
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If you do get one make sure to get one that's limited to 10 psi. Any more will blow the seals and messes with the timing on the db2 pumps. I believe the ones geared towards the duramax have the right pressure setting. You will have to change out the tbi sending unit for a standard diesel one.

As for the blocks if it's a 2000 or newer itll be the better gm block or possibly a gep/Navistar block. The two marks that look like a paused symbol should be a gep block.
 
campfire said:
What are the differences?

Definitely keep the baffle if your tank has one. That is something that GM should have introduced much sooner.
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The baffled tank is a plus. I'm pretty sure the tbi sending units have a pump built into them. Not needed with a diesel. Plus I think it's too high of pressure to convert to diesel.
 
KirsL said:
The baffled tank is a plus. I'm pretty sure the tbi sending units have a pump built into them. Not needed with a diesel. Plus I think it's too high of pressure to convert to diesel.
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Is it? The IP is expecting 7-10PSI, IIRC the GM TBI setup is running 10 or 12PSI. If he has an adjustable regulator he may want to turn it down a bit, but it's not like the newer MPFI systems running 60 or 70PSI. :dunno:

The mechanical pump spot is taken by the turbine oil return on the 6.5 engines,so the mechanical lift pump isn't an easy fit. But electric options abound.
 
campfire said:
Is it? The IP is expecting 7-10PSI, IIRC the GM TBI setup is running 10 or 12PSI. If he has an adjustable regulator he may want to turn it down a bit, but it's not like the newer MPFI systems running 60 or 70PSI. :dunno:

The mechanical pump spot is taken by the turbine oil return on the 6.5 engines,so the mechanical lift pump isn't an easy fit. But electric options abound.
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Honestly I'm not sure about the tbi since I've never had one. If it's a 10-12 psi pump I'd be tempted to see if it would work.

All electronic 6.5s got a external fuel pumps. So plenty of stock and aftermarket options there.
 
blazinzuk said:
@yellowK20

Gus didn't you just toss one of these on a 6.5?
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Yes, I put a FASS fuel system on Smokey , spendy but I feel it was well worth it . I eliminated the stock mechanical lift pump that is a pain in the ass to change and has failed twice since I have built the truck .

Edit: I liked it enough that I am buying another setup for my Blue Suburban in my Avatar.
 
Fass is a much better product than airdog especially when it comes to how many get warrantied.
 
Just picked up a 94 or 95 6.5 to replace the current one in 3500 that's going in my k5 after a complete rebuild. Since its an obd1 do I need to transfer everything from the 2000 to it?(injection pump, sensors)or does the older IP plug in?

Never mind, finished power washing the 95 and the injection pump is the same so should be an easy swap.
 
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