Thanks for everyone's input. I was aware of the Extrude Hone process and
unfortunately it's cost. I had also heard that there were "old timers" who
ran a pumped slurry into manifolds as well to enlarge/clean-up the passages.
I was curious about the acid porting due to the simplicity and cost of about
$3.00 for the acid.
I know that headers obviously have their advantages, but also disadvantages
as well (leaks, fit, noise etc.). I was considering this acid process for
all my cars, one of which is my daily driver, 318, Plymouth Valiant.
Interesting was testing done with all stock cast manifolds and headers for
their slightly larger 360 motor. The stock manifolds were only 5 HP less at
5,000RPM than their rare factory "cast headers" (similar to the 289 HP
manifolds) and only 10 HP less than the headers. Hence the stock manifolds
might not be as big a disadvantage as one might think. Opening up the
passages (with acid porting) might even make the difference less.
So, to get back to my original premise, 'will the acid process make the
cast material more likely to crack due to embrittlement?' thanks for any
help.
Tom Witt
|