I go all the way on the downstream side, and a little under on the upstream side.
On a injected turbo'd motor Polish / Smooth flow is more effective then volume.
When I assemble, I set the gaskets on the downstream side in a tiny dab of adhesive (not silicone) on the outside of the bolt flanges and let it dry to hold the gasket right where I want it until it's bolted up.
-Enjoy
fh : )_~
OK...... so I will target a smooth transition from gasket match and do a general clean-up of the bowls and call it good. These 12ver bowls are herendous! OMFG! It's amazing the power that we still are able to push out of these motors....
Looking good. I like to smooth out/round off any sharp edges such as those I can see around the valve guide, and some of the biggest gains are to be found by simply smoothing the short side radius, I.E. the sharp transition from the bowl to the port (barely seen in the bottom pic above.) There's usually a very sharp edge left there by the factory machining process and if you spend a few minutes per port there rounding that off, it helps a bunch.
Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.
Just about all done with the exhaust ports.... I still want to work the bottom of the valve guides a bit...
Comments/suggestions?
I've got a comment. Well, more of a request... Want to do mine?????
__________________ Have you flown a ford lately? 1938 Ford Pickup = hot rod
1970 Ford F250 long bed & 1974 Ford F100 Supercab - 2wds
1974 Ford F250 4x4 Crew cabthread in "motor swap" forum 1989 Ford Ranger= Never gonna be done...
1972 Alfa Romeo GTV & 1999 Toyota Tacoma 4wd = DD
I like this guys write up, it's for Go-Karts, but can be easily up sized. DIY Flow Bench
Great for port flow matching... And knowledge!
The biggest issue with DIY porting is wall thickness, thats not easy or cheap to measure, at least it wasn't back it the late 80's early 90's, I quit doing this stuff in 90 and went into the computer business, now I'm retired (Thanks M$) and returning to the love of my life ... Making things go!
(At least I will be when I get our burnt out house finished)
Finally got back at it...... ruffed in the intakes today. It seems that most of the information found on porting the Cummins 12 valve revolves around the exhaust ports... not much information about the intakes?
In between the porting action... I had this adapter/spool piece made to bolt the NV4500 to a NP205 (Ford case w/Dodge gears).... Then I read a thread on CompD about the cast iron tail housings, so I need to check my runout!
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