Full port and polish on a set of 452's

[patmckinneyracing]

Basically I'm building a sleeper stock 440 to go into my 71' Roadrunner. I pulled a 440 out of a 78' winnebago and it has the cast iron reinforcement ribs all alongside the engine and what not. I have the origional #'s matching drivetrain but don't want to put any wear on it so I'm putting it on the side. I'm open to opinions on whether to keep it stock or just put in the 440 cause I'm torn at the moment.

My question is is it worth doing my own full port and polish job on a set of 452 heads. I have the templates and everything and the heads already came on the 440. Or would it be better to have close chamber heads? I already considered the stealth heads as well.

One last question does the port and polish job help with the flow rate of the heads and is it possible to reach the same flow rate as a set of aftermarket aluminums? Thanks.

 

[Meep-Meep]

I'll comment on the heads. I personally prefer closed chamber heads, which have little to do with port flow but can greatly improve combustion efficiency. I think this will be a bigger benefit in your quest for making power and having good street drivability over polishing the ports. Also, you can duplicate the benefits of a closed chamber head by using a quench dome piston.

I have always been of the understanding the the flatter port floor on 452 head is not as good as the raised hump on the 906 and 915 heads. My reasoning is the hump helps with the bend in the port to provide a more laminar flow as the mixture enters the valve pocket, but I could be wrong. If you look at the flow numbers for all the production heads they are pretty darn close and some may argue the difference is "in the noise". I think to get some serious improvement out of the iron heads you will need to put big valves and do a flow bench port job. With the advent of performance designed aluminum heads it may be more efficient to just use those out of the box. The best thing you can do (in my opinion) to a set of iron heads is to pocket port them without altering the shape of the port. A little smoothing or polishing will reduce the boundary layer in the port, which effectively makes the port larger because less air is sticking to the sides of the port, and that may be a good thing. I also believe that using a more efficient free breathing head you don't need as much cam to get to your performance goal as you would with a restrictive head. The engine with the more efficient heads should make more average HP throughout the RPM range.

 

[69 Runner]

Port and polish will help, but NOT for the street. It kills the flow velocities at low RPM's and will cost you power. Something I did before (kinda as a test) was I smoothed up the walls and ceilings, but left the floors rough. My theory was that the rough floor would create drag on the mixture and cause it to "roll" through the port and in to the cylinder.

Did this actually make a difference? I can't say. But I CAN say that the car ran well, and the last three years I owned it I never had to change (or even clean) a plug.

 

[383man]

I use 906 heads on the 440 in my 63. I ported them myself and installed 2.14 & 1.81 valves. I can do this because my brother has a machine shop and I can use all his valve tools to cut new seats in my heads and cut the valve guides down. I do agree on a mild street eng the pocket porting works good. I went further with mine as I hope to build my eng up much stronger one day and may have to use the 906 heads. I also use a quench pad piston for nice .042 quench and 10.0 comp so I run on 92 pump. But unless you can do all the porting and valve work I would definetly consider the aluminum closed chamber heads (440Source or Eddy). With the aluminum closed chamber head you can run a flattop zero deck piston and then use a .039 head gasket for perfect quench and the aluminum head will flow as good stock as fully ported iron heads. Here is a pic of my 906 heads I did. I think I will just go with aluminum heads when I build my next eng for my 63. I went with the iron heads to save money since I do all my own head work. Good luck , Ron

 

[dantrap]

383man, Heads are looking Good. I always clean up my heads, even fresh aluminum can always be polished up a bit. The as cast surfaces on the eddys is pretty good but after a few hours of tweaking they polish up nice.

 

[daredevil]

i have an almost identical set ot 906,s i used b4 i went indy