Pyro on stock 3B

[Green Lantern]

Y'all asked what my pyro read under stock conditions and here's the data.

Stock 1981 BJ42 with 3B (approximately 75,000 miles on this rebuild)
I had 500 lbs in the truck and I was pulling an M416 trailer with another 300 lbs in it. Light wind. I baby my truck and mostly drive long distances with light wheeling.
VDO pyrometer installed in the top of the manifold between the last two exhaust ports.

On flat road cruising at 60 mph the temp is 1050 F.
Going up grades (nothing steep in Texas) the pyro goes up to 1250 F.
Around 1300 F the truck significantly loses power and I downshift (even before the pyro I did this because the 3B is so weak). After downshifting, the pyro drops to 1050-1200 depending on the power needed to maintain speed.

My gut feeling is that 1400 F is too hot, but maybe I'm wrong. As soon as I get off the accelerator she cools off quickly. I appreciate y'all and your observation that a pyrometer really slows you down. Life is good in the slow lane.

Happy Trails! N

 

[cruiser user]

EGT

I have a 82 bj 42, Isspro pyro mounted in exhaust pipe just below the manifold. Back here in New York its very hilly . On the level parkway I can do 60 at 800 to 1100 , but the moment I hit a grade it will quickly climb to 1400-1500, so I keep my foot off it and let it slow down. On steep hills 35-40 keeps me below 1100, which is where you should try to stay, according to what I've read here on this forum. I've turned the fuel down quite a bit, and tossed the K&N filter the PO had on it and that helped . Next I'm gonna replace the crappy 2" midas exhaust because that constricts down to about 1.75" in the bends. Probably go to 2.5" stainless and tuck it closer to the frame rails for more ground clearance. By the way , Can anyone suggest a good muffler for this? Tim

 

[Lantec]

I think 1250F is the number you'd want to stay under to make sure your head doesn't crack

 

[Rig of Mortis]

...Can anyone suggest a good muffler for this? Tim

I've enjoyed my Flowmaster for a few years.

 

[brownbear]

I think there are many many 3b's that have spent years at 1400-1600 pushing head winds and what not.

Preferable to stay below. But remember the engine still manages to survive after years of this abuse... pretty good testimony to how good 3b's are.

These are numbers in stock 42's...can you imagine in a 60 series?

I think the engine can handle little blasts into the 1400's... but I would not do it often, and would tune the fuel to keep it out of there. I drive first, look at my pyro second.

When I get the chance on a hill I would look at it and back off the power or downshift.

 

[Green Lantern]

Good advice Brownbear, thanks!

For me, I'm glad to hear what folks think is normal. Not too many BJs down here and it helps to know what you guys think.

Thanks and Happy Trails! N