Author Topic: 351c 4v upgrades  (Read 4966 times)

72 fastback

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351c 4v upgrades
« on: September 04, 2009, 04:43:32 PM »
hey ford freaks.
I'm new to this board and also a new mustang owner.{72 fastback}I am rebuilding the engine, and of course i want to do a few upgrades to it .I have a 351c 4v with the c6 trany.I am thinking of putting a wieand excelarator intake manifold which  has a basic operating rpm range of 1500 to 6800.The compression in the engine is around 160 t0 170 right now so it's pretty high.what I want to know is should I keep the original 4v heads and if i do what would help.{I really would like to keep those heads they are huge.}I will get the heads ported and polished and I will have the engine balanced.I also want to install a torque converter and a shift kit. Camshaft will also be changed.NOW is it possible to have a street car that will not just get up and go at high revs with these heads .ANY TECH HELP WILL BE GREATLY APPRECIATED .


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Re: 351c 4v upgrades
« Reply #1 on: September 04, 2009, 04:59:26 PM »
During the time of the Cleveland engine, those were some of the best heads you could have.  Keeping them and porting them would be worth your while, and will save you a ton of money.  But, understand that since the 60's , there have been a lot of aftermarket heads that are far superior to them.  Even the GT 40 heads are superior, but the aluminum aftermarket heads like the Air flow research 165's are even better.  It is just a matter of what you want for an end result, and how deep your pockets are.


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Re: 351c 4v upgrades
« Reply #2 on: September 04, 2009, 05:32:47 PM »
Yeah those Clevo heads are pretty much today's aluminum heads. Don't get me wrong of course the aluminum ones are better but those are still pretty damn good heads. I would just stick with those unless you are planning on racing it at the track on a regular basis, and or (like previously stated) you are willing to spend a fair amount of money.


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Re: 351c 4v upgrades
« Reply #3 on: September 06, 2009, 12:59:29 PM »
from what research I have done the heads don't need porting and polishing for most mild to moderate performance work.  The ports are already too big!  Take a look at these and then do some research.

I have been told the intake plates are hard to get to seal and that they are not as helpful as the exhaust plates.  If you want to do something to the intake side, these look like the ticket and are what I will likely be using on my build

There are also some exhaust plates made by Holstrom.

and a more expensive option

By now you are probably adding up the costs and thinking I should just get some Aussie 3V heads and have them built!  That is a good option too, but aluminum has it's own disadvantages.

That manifold looks good, but the basic operating range is pretty broad and I would expect it to lose some low end torque in order to get the top end numbers.  Decide on the operating range you want to use and try and match components to work together.  While the Cleveland will turn 6800 RPMs there are few cams that are streetable that have a power band over 6300 RPM.

Decide on what you want and start with the cam to build your engine around.  Cams need certain rear end ratios to operate best as well as the right stall speed converter or a 4 speed.  Hydraulic cams are somewhat limited at the top end and you can get more RPM's out of solid flat tappet cams or solid roller cams, but the solid rollers and matching lifters get a little pricey.

Solid lifter cams tend to need valve adjustment fairly often (every 5-6000 miles a bit more if you are lucky) but you can slightly alter valve lash to change performance characteristics a bit.

I'm still searching for a cam I like.  There are lots of makers that will custom grind a cam-I am not going this route as the cam designers are probably more in tune with what works than I could ever be.



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