JoeH

Simple til you have to change driveshaft length etc.

My napkin math says you need to be around 3.84:1 rear to hit 60mph. That would be your easiest way to get highway speed.

If you can't get exhaust manifold nuts off, just split them with a hammer and sharp chisel.  The water & intake manifold bolts require some tight access to get into, and I believe the intercooler box lid has to come off to get to some bolts on the inside.

My first "tear in" on an engine was the same motor you have there, same year and all. Our '79 broke a valve seat and it dropped into the top of the piston, ruining the head and piston.  Similar business size, it's just my dad and I plus my cousin seasonally, so I can relate.  Get the head off and see what's really broke. Many of us have the books with torque sequences and settings, so we'll post info for you as needed. 

Remember though, DONT SET THE HEAD DOWN ON THE INJECTOR NOZZLES! 

My strategy is typically remove valve covers and oil pan to get eyes on all the internals. There is a fair amount of manifold work on this particular engine to get the head ready to come off, but it's gotta be done, whether he needs a valve or a head.  I'd have that head off right away too, but I think RS is working through a mechanic, so there may be a DIY factor missing.

Time to see what's really broken and pull the head.  Also pull the oil pan to get a look at the camshaft and lifters. The carbide faces on these like to break and shave the cam lobes down.

I'd bet your head is fine, and piston may have a tiny dent in it that needs to be deburred.  When you take the head off, DONT set it down right side up, you will crush the injector nozzles! You will probably just need the one valve, maybe the guide,  and maybe a valve seat? 

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Here you go...

8 hours ago, RS Disposal said:

I have pulled one roccker cover and #4 exhaust valve is stuck down (assuming bent).  Push rod appears to be ok.  The valve spring keeper was broken.

Sounds like a bent valve then. If you're lucky you just need a valve, don't need a head.

I quit riding a) because I've got little kids now,and b) driving trucks all day I have a great view of everyone else on the road. Everyone is texting. Grandma, grandpa, kids, etc.  I always tell motorcyclists and people interested in getting into riding that if anything happens, regardless of whose fault: it's the motorcyclists fault. Because the motorcyclist is always the one who loses.

Just finished reading, looks like you don't need to do anything.

Pull the Tappet cover off the side of the block. When the 2 forward most pushrods are "relaxed" then you're on #1 TDC starting combustion stroke.

Our '79 has a weak valve spring on one of the heads, the spacer disk on top of the valve stem for the jake brake kept popping out, resulting in excess valve lash.

Probably just a bent pushrod from valve float.

Probably was a quick fix otherwise he might be back asking for other solutions.

If it does have a thermostat then it could be stuck open too. I forget how this thermostat is shaped, I had one that a chunk of the rubber seal around it had failed. Engine almost never got up to temp, and cooled back down quickly if it wasn't kept working hard.

If the truck is empty and not working hard then chances are it's right. 85 degrees outside is waaaaay cooler than the 180 degrees the engine thermostat should be functioning at.  It is possible you don't have a thermostat installed, allowing unrestricted coolant flow. This paired with a fixed radiator fan (no fluid clutch) and you'd have to work very hard to heat that engine up.

Only way to check to see if there's a thermostat installed is to pull the upper radiator hose off the engine and look in.

About $4.799 yesterday here in southeastern pa

Personally I also don't see how popping the clutch bumps the shifter out of the gates...

I don't think clutch linkage breaks when you pop the clutch. That usually breaks other things. Input shafts, crank shaft, output shaft, axle shafts, counter shafts....

Pictures great. I wouldn't switch to a 2 stick, those are geared for the Maxidyne engines, which would be either an EM6 or an EM7. The maxidynes have an 800+ rpm power and, in which they make 90%+ torque from 1000-1200 all the way up to the governor. An E7-400 is nice but it doesn't have the broad powerband. Also the 2 sticks aren't designed for THAT much torque. Plus you'd be looking at having to replace the driveshaft due to different length transmission. And cutting holes in your floor for the shifters.

For dirt stick with camelbacks. You can upgrade the rears to full lockers, but the used ones are rare and hard to find. Nothing will feel like your EM6 pulls. I'd fix the EM6.  Get a parts truck.  Going to 500hp you'll need bigger driveshaft and you'll have an easier time snapping axles. And more frame twist.

Clean truck! Watch for vertical cracks in the frame where it starts to flare out to go around the transmission. We broke both frame rails on our 79 r686st. We used a donor frame for that repair....