[Sagacious]

i want some nice 200cc heads for my 357, im thinking either Sportsman II or Dart Iron eagles. i see the flow #'s on the sportsman II's are better but but i dont know how much they are yet. anyway, i want to match the runner size on the heads to the intake manifold gasket. is doing it yourself advisable? i take it all you need to do is match the intake gasket on the head and get a magic marker to outline the areas that need to be shaved off. a simple grinding tool? also, i know you're not suppose to go farther than about a half an inch down. i have some junk heads to test on, but i was wondering if this is better left to a shop. thanks

 

[NAIRB]

Alot of first time do it yourself porters always want to grind around on the intake port opening, thinking that somehow horsepower will appear.

Actually, the intake port opening is one of the least restrictive areas of the intake port.

It's okay to use a gasket as a template, just as long as you don't grind all the way to the edge of the gasket. Removing metal right at the port opening, in front of the push rod pinch area actually decreases flow. Reducing the push rod pinch area increases it. You can grind away horsepower if you aren't careful.

If the intake manifold runner is smaller than the gasket and the intake opening on the head, your okay. If it's bigger, you are not.

I suggest you purchase a book on basic cylinder head porting, like one of Vizard's books. If you've never done it, I would do a little studying before you start grinding away on a 700 dollar set of heads.


Brian

 

[lluciano77]

The heck with all that, just get the Motown IIs. They have the bigger intake valves, and bigger runners.

 

[trees]

Some of the good after market heads warn against doing any thing to their ports because reduced performance will be experienced. CNC heads are a thing of beauty and most have peen perfected so you can only mess them up. The gasket is there to seal and the only matching I would want to do would be to remove any gasket material that may be blocking the port opening..

Trees

 

[1BAD80]

The best thing you can do is port match the gaskets, which is the easiest to do, and is needed on most heads to intakes & headers.

http://www.chevyhiperformance.com/techarticles/95518/index.html

 

[Sagacious]

motown II's

motown II's are nice but thats way too large for my application. i mean how/why would i go bigger than 200cc? motown II's are 220cc starting for 383's and up. i cant find a pair of sportsman II heads with manley pro flow racing valves for less than $749 each. anyone have any better resources?

 

[camaroman7d]

200cc heads are already on the LARGE side for a 350 (357).

Gasket matching is simple and if you have a steady hand and the proper tools you can do it. I would not suggest using a magic marker, I prefer to scribe a line. As mentioned above don't get carried away.

If you are going to do the heads make sure you match the intake manifold as well or you are kind of wasting time (IMO). I am a firm believer in gasket matching, as long as it's done right. The port mis-match that you get with some combinations is pretty bad. Find a gasket that is just big enough to take care of the issue.

Royce

 

[coldknock]

Drag strips, car shows and e-bay. I just bought a set of Sportsman II's for $450 bare from a fellow racer. Be patient.

Larry

 

[lluciano77]

I got mine in a trade for $300, + an old carb.