Pat:
You are correct, the factory manifold is good, up to a point. It was
assembled by Datsun in reverse, meaning that the individual section joints
lead into the exhaust flow, instead of away from the flow. Very difficult to
fix unless you cut the welds, trim all joints, then reweld. Also, the
collecter is undersized at the flange. We added (welded) metal to the O.D.,
then opened up the I.D. to match the max thru-opening. It worked well on the
track on a race 1600 (stock with balance/match-porting)in a class that
required a stock manifold. On a good day, 6700 RPM in 4th gear at the end of
the straight (PIR), shifting at 7000. The real power gain in the exhaust came
after the head was match-ported, and carbs rejetted. Also durable as long as
the brace was always attached. For street use, the stock header works as well
or better than a header (cheap aftermarket, not a purpose design), but is
more difficult to remove, along with the starter.
Dan & Susan
multiple 2000's
<< I have a 67.5 1600 also, actually, 2 of them. My first one had a factory
manifold on it, but it really leaked, so I put on a header from Ralley. It
lasted about 40K miles before it broke. My second car came with one. I
don't know how long it has been on.
My understanding is that the factory manifold was quite good and that you
couldn't make much of an improvement by putting on a header. Manifolds
are also very hard to find and cost big bucks.
I am planning on converting my 1600 to a stroker, so when I bought a new
exhaust system I put in a factory 2L system, so it is ready to go.
If you decide to buy a header have it ceramic coated before you put it on.
This will keep the metal from rusting out as fast. It also keeps a great
look much longer. Oh, another thing. The factory exhaust system that I
bought was painted black when I bought it, but the first time I fired it up
most of it blistered off! Strip they paint off and put on high temperature
paint while it is out of the car.
Peace,
Pat
--
- Support Habitat for Humanity, A "hand up", not a "hand out" -
Pat Horne, Network Manager, Shop Supervisor, Future planner
CS Dept, University of Texas, Austin, Tx. 78712 USA
voice (512)471-9517, fax (512)471-8885
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