Blocking MFI Ports

gsjohnson · 02-21-2009, 09:36 AM

I am putting together a hot rod 2.4 motor with Webers and I would like to know what the preferred method for blocking the off the MFI ports is in the heads? Can I just fill the small orfices from inside the chamber? Are there any other pitfalls I should be aware of? Thanks

Flieger · Flieger's Garage

Sell them and find some heads that have no MFI holes. Those MFI heads are too special to ruin.

Dick Shift · Dick Shift's Garage

Blocking MFI Ports
Brass Pipe thread plugs or bolts at a hardware store.

Can I just fill the small orfices from inside the chamber? Other than welding them shut no. To much work. I would Just plug or get different heads.
Prevent pitfalls? Teflon tape on plug threads to prevent air leaks.
Good Luck!

BK911 · BK911's Garage

I flowed 2.2 carb and mfi heads a couple of years ago. I can't remember the exact numbers, but the carb heads flowed a lot better. The injector port causes a lot of turbulence. I would try to plug the holes flush with the inside somehow. Maybe a long bolt and grind it down?

Zeke · 02-21-2009, 02:29 PM

Long bolts don't work. It's a pipe, or tapered thread, IIRC. Unless it's a race engine, I wouldn't worry about the performance loss due to any turbulence.

As mentioned, if you haven't re done the heads yet, trade them. Or, you could weld the holes up.

Jeff Jagusch · 02-21-2009, 02:35 PM

I could be wrong, but I have a mtoro that has very nice allen head plugs, my guess is that the guys at EBS sell them?

Jef

175mph951 · 02-21-2009, 03:24 PM

are they bigger then the 930 air injection plugs?

Zeke · 02-21-2009, 03:28 PM

12mm X (x) X 1.5 if that helps.

rvanderpyl · rvanderpyl's Garage

PMO sells them

BK911 · BK911's Garage

Quote:

Originally Posted by milt

I wouldn't worry about the performance loss due to any turbulence.

Normally I would agree that a street car just doesn't 'need' the same as a track car. However, the flow was reduced pretty significantly. Personally if I could spend the same time and money plugging the port and get ~10% more airflow, it would be a no brainer.

gsjohnson · 02-22-2009, 05:55 PM

I have a set of 2.0 heads, but they have smaller valves and ports. So I am to assume that you are speaking of the 2.2 heads as an equal trade in terms of valve and port size?

roaddog84 · roaddog84's Garage

I ordered a set of "mfi plugs" from Tom Butler (Tom1394 racing) for $20 plus shipping. The problem from what is see is there is too narrow of a shoulder on the case without damage, but on the mfi injectors they are tighten about 1 inch above the case.

Tom won't be back until 3-8.

I don't see why something along these lines would not work either.

george