Date: Tue Dec 17 01:34:30 1991
Subject: L-series internal plumbing....
> Will plugging the coolant passages to/from my intake manifold
>cause any problems (ie. stop coolant flow to another critical area)?
>Is this a common performance mod? I've seen this done to OHV V8 motors...
NO don't do it. The car will run like sh*t until it gets real hot.
That heat is there for a reason. This heat is distinctly different
from the air intake heat which can be eliminated. The heated manifold
offsets the cooling effect of gasoline and it promotes the
vaporization of gas that would otherwise adhere to the manifold walls
and flow to the cylinders as liquid.
Some models had a thermostat in the water path that kept the
temperature at a uniform level. I can't recall which models are
affected. An alternate solution, the one I use, is to put a
heater valve in water line. This will allow you to stop the flow in
hot weather after the car is warm and turn it back on when needed.
You'll be surprised how often it's needed.
Date: Wed Dec 18 00:47:44 1991
Subject: Re: L-series internal plumbing....
>>NO don't do it. The car will run like sh*t until it gets real hot.
>>That heat is there for a reason. This heat is distinctly different
>>from the air intake heat which can be eliminated. The heated manifold
>>offsets the cooling effect of gasoline and it promotes the
>>vaporization of gas that would otherwise adhere to the manifold walls
>>and flow to the cylinders as liquid.
> Thanks. The car in question is being set-up as a
>road-race vehicle, so streetability is not too important. I just
>wanted to make sure no "hot spots" on the head would result from
>blocking these passages off. I seemed to remember that these
>ports could be tapped/plugged in the "how to hotrod your OHC datsun"
>book, which is packed away in a box someplace (we just moved).
I'd still recommend retaining the heat but with a cockpit-operatable
valve. You'll likely find that unless the weather is very warm,
midrange and off-idle throttle response will suffer. I know
THE BOK (Pause in silence while facing Datsun heaven :-) recommends
doing it but I've found that a lot of pesky transition throttle carbutation
problems go away with just a little bit of carb heat.