Thanks for the advice, still need more

chiefdave

chiefdave

Member
Thanks to everyone that replied to my previous posts. It made the intake manifold/carb and head install much easier. I'm ready to move on with more mods and am looking for more advice.


1. The Mallory dual point I have, ZC275AX, has a provision for vacuum advance. Should I use this feature or block it off and go centrifugal only?


2. Has anyone used the Mac's spin on filter conversion? Any problems?


3. The car ('49 sedan) currently has dual exhaust using the stock exhaust manifolds. Would like to upgrade with something that would not require any fitting or grinding.
 
1, By all means. Hook it to manifold vacuum.
2, Not used one.
3, Again, no experience on that model.
 
Mart said:
1, By all means. Hook it to manifold vacuum.
Click to expand...


Manifold or venturi? The manifold vacuum on the engine is 20.5"hg at idle. I think that would pull it to full advance. The Holley 390 that I'm using has a port for metered venturi vacuum that is zero at idle and increases to 10" at 1500 rpm.
 
Dunno. I'd use manifold, but maybe someone else can say if venturi would be better.
 
Thoose mallory distributors had something called a spark control valve mixed into it just to complicate things if i remember right...
Taking vacuum from intake and having venturi controlling the valve...
 
All of the Mallory distributors with vacuum I have seen have a "vacuum brake" like the pre-'49 Ford distributors. (Actually, it should be called a "vacuum unbrake, but that's kind of awkward). As such, I believe that it should be hooked up to manifold vacuum rather than venturi vacuum. I would try it both ways. I had a vacuum over mechanical converted SBC distributor on my '51 and couldn't get it to work right. I changed in a mechanical only Mallory flattop and am much happier with the way the car runs.
 
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