I am wondering if the water heated manifolds are necessaryfor the operation of my Jag 4.2 engine. I assume they were provided to helpwith cold weather starting and running. I live in Phoenix and rarely would haveneed for them. Of course, if I don'tfully understand their purpose, then I will put them back on.

With the talent and experience of the participants onthis forum, I have to believe there are many opinions.

1977 XJ6-C, withdown draft Webers

Thanks geneo

 

The water provides the heat for the choke or AED. The carburation process cools so the carbs need to be kept warm to prevent icing.

 

Heating or not heating the intake fuel air mix practice dates way back.


In olden times, it was done by exhaust heat. I recall my "T" Ford days.
from 1909 til 1925, HENRTEY 3

 

Spot on.

 

Messed up, errant fingers!!!
Henry provided no heat for the intake mix. In 26, the improved T did have a vaporization improved intake. I found it useful. Easier to modify to use an "A" Ford carb. Still sans heat, but ran so much better...


Skip a decade or more. In to flat head Ford V8's. A strange passage in the block to allow exhaust heat to the underside of the intake manifold.


Many of us learned that a copper penny would just fit and close that passage. One coin to a side. Result, Stumbled a bit at a cold start and drive. But, a definite sharpness, which we felt as added power, in the
exhaust note.


More decades forward. The Lt1's have a similar method to heat the incoming charge. Many, disconnect sand report more power. In theory and possibly proven. yes. Loss of drivability, no. Advanced engine management over comes that.


Have I blanked off the hot water from my Lump's intake? No. It has more than enough power for me. For others, apparently not. They blank it off and make claims of more....


In moderate or warm climes, probably just fine sans the heat. In cold, probably much less so.


And intake ice in the really cold places, I think so...


Carl

 

On my old air cooled motorcycle, it had exactly that issue: carb icing in wet and cold weather. A 21W light bulb in the airbox, connected to a switched lead fixed that... ;-)