FE Power Forums

FE Power Forums => FE Technical Forum => Topic started by: jimeast on May 15, 2015, 07:49:41 AM

Title: Vacuum and CAM selection in 445 build
Post by: jimeast on May 15, 2015, 07:49:41 AM

I'm pondering a 445 build with my 390.  It will be for a street car, 67 Mustang Convertible.  I'ts a fairly standard build, 4.25 stroke. 10:1 comp, C6AE-R heads (or stock C7 GT heads) with CJ size valves, pocket port and good valve job.  CJ intake, carb and exhaust manifolds with a 2-1/4 or 2-1/2 stock fitting exhaust.  Transmission is a C6, (I'm collecting parts for a toploader conversion).  The car has power brakes, AC, PS.  It has a 3:0 open differential now.  I plan on changing to a 3.25:1 trac-loc.   

It seems like with this combination, the biggest consideration regarding cam selection is to end up with a responsive engine that revs well from 1,500RPM to as close to 6,000RPM as possible and holds good vacuum at low RPM for the brakes, automatic transmission, etc...

I am thinking about using a solid lifter cam like the 282s from comp.  Any cam specs to consider for vacuum?  I've read that for good vacuum, staying below 220 exhaust duration at .05 lift is a good rule of thumb, but I'm not sure if this holds as the cubic inches grow.

Does anyone have experience with a similar build and resulting vacuum?  Ideally I'll end up with a very responsive fun ride with vacuum enough for the brakes, automatic transmission, etc... 

Title: Re: Vacuum and CAM selection in 445 build
Post by: My427stang on May 15, 2015, 12:50:31 PM

I run a Bullet version of the 282S lobe in mine, but I spread the centers to 112 to clean up the idle a little and run it on 104 ICL.

It runs really good in my pickup with ported D2 heads and a ported RPM intake, although a little fussy on fuel, I'd probably rock it back to 106 if I had a reason to take the timing cover off.

I do not know what it pulls for vacuum, never had a gauge on it and not at home right now, but the power brakes work fine.

Title: Re: Vacuum and CAM selection in 445 build
Post by: ScotiaFE on May 16, 2015, 05:05:44 AM

If the option is there to use the C6 heads I would use them.
They will out perform the C7 head at every level.
Including making more power for less work. :P
You should consider the 3.50 gear. I have run both the 3.25 and 3.50 gears
for lots of long distance and in town and basically every situation you could think of.  ::)
The 3.50 is a better all around gear. The 3.25 is a better gear for long distance highway runs.
And a wide ratio TL is like a scoop of ice cream on top.