Is J-Code worth it?

[COYOTE102076]

I just picked up a 6.2L NA "J-code" or "J series" engine last night
out of a 1993 3500 truck. Has 128XXX miles on it.
Was advertised as a "6.5 Diesel Motor" but when I drove
50 min. to get it and got there it was a 6.2L

Reguardless, I bought it for a song & dance as they say. I WAS
going to drive away from it, but then looked closer at it and
it was the non-emmisions "J" engine, so I took it home with me.
Dont NEED it, but thought "Awwww, why not! "
NOW, MY QUESTION IS THIS!
Would it be WORTH the time / effort to remove the intake
off of the 2 engines and install the "J" intake on my "C" engine?
I mean, what kind of real world power gains can I expect to see
in normal every day driving? And fuel milage gains? Fuel milage
gain is really my TOP priority.
Lastly (and I have not looked close enough to tell myself yet)
can you swap out the intake without removing the injection pump and lines?

THANKS!!! -------------- Kevin

[More Power]

Other than the intake manifold, there is precious little difference between a C & J longblock. The intake and the fuel injection pump are the primary differences between the light-duty and heavy-duty emissions engines.

If this is a 1993 6.2L engine, it was made using a "599" block, which could be the best that GM produced. The 599 6.2L can be bored to a standard 6.5. The 6.2 and 6.5 shared the same block in the 1992 and 1993 model years. Jim

[Robyn]

The J manifold does not use the EGR, and this is GOOD THING.

The 6.2 dumps oil vapor from the crank case into the intake, and this ads a thin layer of oily residue to the entire inside of the intake due to the slight oil pull over.

Now, add in all the soot from the EGR (EXHAUST) and the inside of the intake turns into a real sloppy nasty mess.

It gets worse too.

All this grunge slowly builds up and migrates towards the valves and then over time cooks onto the backside of the intake valve, leaving a huge mound of carbon.

Sooner or later, this ball of crud will fall off and down into the engine through the open valves.

The results can be little to nothing with only a minor stumble, or if the amount of crap is large, the engine can hammer and pound terribly while the piston/s beat that carbon up and it gets blown out.

I have seen the stuff fall off while a rig is sitting (cold weather with a long sit) and the engine lock up and the starter won't crank it.

Get rid of the C manifold, and make sure your ports are clean.

You can carefully roll the engine and with each intake closed, use a suitable tool to dislodge the crud on the back of the valve and suck it out with a shop vac.

The idiot that thought up the use of the EGR on these engines should have been tarred and feathered.

Missy

[More Power]

The idiot that thought up the use of the EGR on these engines should have been tarred and feathered.

Missy

The industry is still using EGR. I'm sure the engineers hate it too, but the required NOX reduction by the EPA is not possible otherwise. What's new now is "cooled EGR", which uses engine coolant to cool the hot exhaust gases before being ingested by the engine. A search for EGR problems in recent Ford and GM diesels will reveal a plethora of soot and leak problems. This is why EGR blockoff kits and EGR upgrade kits are available through the aftermarket.

At least for the 6.2L diesels there is no MAF sensors to deal with. So it's a simple matter to disable the system. Jim

[ginger743]

The J manifold does not use the EGR, and this is GOOD THING.

The 6.2 dumps oil vapor from the crank case into the intake, and this ads a thin layer of oily residue to the entire inside of the intake due to the slight oil pull over.

Now, add in all the soot from the EGR (EXHAUST) and the inside of the intake turns into a real sloppy nasty mess.

It gets worse too.

All this grunge slowly builds up and migrates towards the valves and then over time cooks onto the backside of the intake valve, leaving a huge mound of carbon.

Sooner or later, this ball of crud will fall off and down into the engine through the open valves.

The results can be little to nothing with only a minor stumble, or if the amount of crap is large, the engine can hammer and pound terribly while the piston/s beat that carbon up and it gets blown out.

I have seen the stuff fall off while a rig is sitting (cold weather with a long sit) and the engine lock up and the starter won't crank it.

Get rid of the C manifold, and make sure your ports are clean.

You can carefully roll the engine and with each intake closed, use a suitable tool to dislodge the crud on the back of the valve and suck it out with a shop vac.

The idiot that thought up the use of the EGR on these engines should have been tarred and feathered.

Missy

Hi Missy,
I think we've probably all seen it built up so bad on the intake valve stem that the only limiting factor was the size of the area in the head surrounding the intake valve. I once tried , " everything " to cut it, and nothing worked, also it's not hard enough to be brittle and break off when you hit it, it just kinda , " dents it " . I ended up replacing the valves !!

Jerry

[Robyn]

The engineering mistake was, that the engineers missed dropping the EPA through the shredder as they left the office

Another Govt agency with far too much power.

The amount of lost productivity that the EPA causes directly and indirectly is staggering, not to mention the total brainwashing of the children coming up.


The last heads I worked on a few years ago, I yanked the valves and ran them past a wire wheel on the bench grinder, this made quick work of the carbon.


Missy

[COYOTE102076]

THANKS FOR THE GREAT INFO GUYS!
From reading the replys it has me kinda worried anout the
current 6.2 engine in the truck.
I am thinking about also buying a new harmonic ballancer
from reading all the horror stories all over the www about
broken off crankshafts.
Due to limeted budjet and (most importantly) the LACK of free
time I really dont want to "Open Pandora's Box" and try to
deal with swapping out the entire engine at this time.
MAIN issues with the swap is:
1) the '93 engine is serpentine belt driven and has NO a/c compressor.
2) IF I were to swap the engines, the A/C compressor on the '93
engine mounts on the Right side, the current '82 compressor is
mounted on the LEFT, so allong with a new compressor (+$$$+)
I would also have to have custom A/C hoses made up/ (+$$$+)
3) Since my '82 is a 4x4, it looks like a real bear of a job to
swap out the engines! (Getting to, or shall I say, NOT being able to
REACH the torque housing bolts!)

In summary, I will go ahead and swap out the intakes. Looks like maybe a 3 hour job, so as long as I can do it in 1 night after work it should go well. :-) -----I hope-----

[AKMark]

If you struggle removing the bolts on an 82, never try to do one on a 99 or newer.

Those old ones are easy, really easy....

Just lower the crossmember and grab a few extensions. It's a piece of cake.

[OIL BURN]

SO,if i block off the egr valve,eliminating hot exhaust gas cooking the oil vapor,then the normal crankcase venting laced with some oil vapor will not be a problem as far as caked on build up behind valves that occurs with the egr?
Was just wondering if an oil seperator used on race motors would eliminate the oil in the crankcase vapors before entering the intake.

Thanks
OIL BURN

[Kennedy]

Using the block off plates in the J code Fel Pro intake gaskets was always an economical way to get near the J code or F code without replacing hard parts. This blocks the exhaust gases at the head and keeps the heat out of the intake.

[COYOTE102076]

Using the block off plates in the J code Fel Pro intake gaskets was always an economical way to get near the J code or F code without replacing hard parts. This blocks the exhaust gases at the head and keeps the heat out of the intake.

Just out of sheer curiosity: Why not just weld the C series EGR valve shut???
Or just remove it and install a flat metal plate instead?

[DmaxMaverick]

Just out of sheer curiosity: Why not just weld the C series EGR valve shut???
Or just remove it and install a flat metal plate instead?

No need to weld. If the EGR is left in place and disconnected, it will stay closed. It's normally closed and vacuum operated to open.

You could use a plate, or frost plug, or anything that blocks it. No big deal. Ideally, the manifold should be upgraded, or blocked with the gasket-blocks to stop the hot gas from passing through, in any case. Hotter manifold => hotter intake air => less dense air => less power/economy. The EGR manifolds are also more restrictive.

[Edahall]

Just out of sheer curiosity: Why not just weld the C series EGR valve shut???
Or just remove it and install a flat metal plate instead?

Better yet would be to chip out the EGR pedestal and block the hole at the bottom. I actually did this to a C-Code manifold.

[COYOTE102076]

Better yet would be to chip out the EGR pedestal and block the hole at the bottom. I actually did this to a C-Code manifold.

I am doing this now, as well as installing the J-Code intake gaskets,
while I have the intake and fuel pump out for rebuild I figured I may as well
while waiting for the pump to get back from Taylor Diesel of Jackson TN.
Having it built for the new (used Holset HC1) turbo going on the truck.
Was a leaky mess and the elasticast washer in the pump was going bad.

[More Power]

Be aware that "if" your truck has dual exhaust and you install J code intake gaskets, you could actually see a decrease in engine power and hear significantly more "blatt" from the exhaust.

The EGR passages within the "C" code intake manifold act like an exhaust crossover pipe, in that it helps balance exhaust pulses between the two banks of cylinders. Balancing exhaust flow improves efficiency.

So, if your truck has dual exhaust "and" if you install J code intake gaskets, your truck will benefit from getting an exhaust crossover pipe installed that connects each bank (as close to the exhaust manifolds as conveniently possible).

Exhaust crossovers are easy and not too expensive for an exhaust shop to install.

Jim

[COYOTE102076]

Good to know Jim.
However, I am curious, does that effect the performance (decrease) since it is now getting the Holset H1C turbo on it?
You mentioned the dual exhaust. It came from the factory with the true dual
exhaust set up. Still has (had) the original 1982 mufflers on it! :-D
But now am waiting for the exhaust shop to finish building the crossover tube to go from the LH manifold into the rear of the RH manifold.
Still have to run the oil lines to & from the turbo, and just installed the rebuilt fuel pump tonight. Have yet to start it as I have 1/2 the exhaust off, and have to relocate a heater hose and move a remote 5 micron fuel filter that WAS just behind the RH battery where the turbo is sitting (well, awfully darn close!)

[MajMike]

Good to know Jim.
However, I am curious, does that effect the performance (decrease) since it is now getting the Holset H1C turbo on it?
You mentioned the dual exhaust. It came from the factory with the true dual
exhaust set up. Still has (had) the original 1982 mufflers on it! :-D
But now am waiting for the exhaust shop to finish building the crossover tube to go from the LH manifold into the rear of the RH manifold.
Still have to run the oil lines to & from the turbo, and just installed the rebuilt fuel pump tonight. Have yet to start it as I have 1/2 the exhaust off, and have to relocate a heater hose and move a remote 5 micron fuel filter that WAS just behind the RH battery where the turbo is sitting (well, awfully darn close!)

Just fyi, the Banks turbo comes with a single exhaust to replace the factory dual.