Out of curiosity, does your rig still have a catalytic converter? If yes, I might look there to see if it’s clogged.
CK5
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76’ 400ci overheating bad
- Thread starter CraigFulton
- Start date
Out of curiosity, does your rig still have a catalytic converter? If yes, I might look there to see if it’s clogged.
CraigFulton
1/2 ton status
No converter. Exhaust is coming out at a high volume. Just super hot.
These old square bodies just never had the kind of sound deadening and thermal insulation the new crap does.
My 76 K5 with the 400 would get warm enough on the tunnel to heat my 12 pack of Coors.
So i always left a heavy coat laying between the front seats to rest my brew on.
So, you still don't actually have an overheat problem.
All those temps sound normal.
It hasn't boiled over.
When you originally posted this thread, i asked that question.
But the vapor lock/performance issue seems to be gone now yes?
So it was bad carburetion most likely.
The heat on the floor sounds normal.
Mine did it.
Now my 86 K5 with the 6.2 barely reaches 180 unless i am climbing a grade.
The floor never gets warm at all in that thing.
Makes sense since the 6.2 burns exactly half as much fuel, doing the same work, as my 400 did.
A superior machine with which to transport beer between the seats.
My 2001 Tahoe is like the bridge of the starship Enterprise.
You can't feel anything or even tell if the engine is running.
I am fond of this stuff.
My 76 K5 with the 400 would get warm enough on the tunnel to heat my 12 pack of Coors.
So i always left a heavy coat laying between the front seats to rest my brew on.
So, you still don't actually have an overheat problem.
All those temps sound normal.
It hasn't boiled over.
When you originally posted this thread, i asked that question.
But the vapor lock/performance issue seems to be gone now yes?
So it was bad carburetion most likely.
The heat on the floor sounds normal.
Mine did it.
Now my 86 K5 with the 6.2 barely reaches 180 unless i am climbing a grade.
The floor never gets warm at all in that thing.
Makes sense since the 6.2 burns exactly half as much fuel, doing the same work, as my 400 did.
A superior machine with which to transport beer between the seats.
My 2001 Tahoe is like the bridge of the starship Enterprise.
You can't feel anything or even tell if the engine is running.
I am fond of this stuff.
The floor of my K5 just behind the console was hot enough this weekend to warp and shrink some plastic packaging on some welding tips and a spark ignitor. It doesn't have any carpet or heat barrier right now. Package was just sitting on the floor. It was only 65 out and I had the roof off. I will probably install a heat shield on my mufflers. Your hot floor seems to be within reason from things I have seen.
I don't know how the earlier exhaust was routed, but GM obviously knew or felt there were some potential issues later on, as my '85 diesel body has two heat shields where the mufflers were, bolted to the body, and the frame from a gas truck (converter of course) had a heat shield bolted to the frame to keep some heat off the floor under the driver.
Kind of interesting, can't believe the mufflers heat was a problem that far back, especially a diesel with the dual exhaust. Floor definitely gets warm now with the 350 if the pipe is run close to it, as it is now it's about as far away as it can be and still run over the crossmember, and it's not nearly as much an issue as it was with the pipe run higher. And that's having gone back to a single 3" pipe under the drivers seat.
CraigFulton
1/2 ton status
I’ve had the EFI running a week. It’s getting better every day. Very happy I made the change.
I know this is a few months old but in the picture of the tranny lines where the battery cable has a loose clamp on it the lower motor mount bolt appears to be not tight up against the plate of the mount. If it is loose I would check all the others to make sure they are also tight. Sometimes breaks or lunch screws up a guys train of thought. I guess that's why I always was late to lunch and breaks. I always tried to finish up a sequence before I stopped. I like the audi, my son has a 2018 that has a lot of extra "stuff" on it. He sold his sti to upgrade in tech but gave up a little horsepower plus he was tired of working and tuning a alcohol based 500hp hotrod. His car is red and I told him to budget for the tickets. I have a 91 4x4 3/4 ton suburban and a 86 k5 with a 350 ramjet. The k5 has headers and duals and I robbed the shields off a 79 parts k5 that I have to hopefully keep the floor a little cooler. When I put the rj in it I wrapped the fuel lines and ran the feed outside the frame under the door area and also installed a fram filter that uses a element to add a little insurance for the injectors. The 86 has 2 1/2 inch exhaust with headers so it gets a little crowded under it, it also has the magna flows so it is also a little loud. We always wired the exhaust valve open on the ones where it was not stuck and could easily be moved. A lot of times the studs would twist off trying to remove the valve so even more work was required. Oh yeah the 79 k5 for parts has a running 400 with only 67k miles on it, that was why I thought I needed it. When I bought it the guy said it would run awhile and stop, that's why I started reading your thread. this one stops before it even gets hot. I'm thinking the fuel pickup is getting clogged from rust in the tank because it starts back up after setting about 5 minutes. It was not a problem because I really only wanted it for the motor and maybe the tranny, the tub is really rusted out.
CraigFulton
1/2 ton status
Hard to say. My issue was definitely that valve. I’ve had no problems since removing the plate from mine. I just have the oil leak on the intake still to deal with.
I’m busy repainting it now.
I’m busy repainting it now.
CraigFulton
1/2 ton status
I finally re-installed the intake manifold. Ditched the two gaskets as you all said and put a thick bead of the permatex black. No leaks!
If I remember right--
The only old school SBC's that took a different head gasket than all the rest were a 400 SB,and the 305...400 SB had the steam holes,the 305 had a smaller bore..(not sure about the 267's and 262 V8's,those may be weirdo's also)..
The only old school SBC's that took a different head gasket than all the rest were a 400 SB,and the 305...400 SB had the steam holes,the 305 had a smaller bore..(not sure about the 267's and 262 V8's,those may be weirdo's also)..
CraigFulton
1/2 ton status
Proper head gaskets. It’s in the thread. The problem with the heat riser valve on the exhaust. Now that I’ve removed it the vapor lock has stopped.
