Thinking of ditching the iron

Well as the title says I am thinking of losing my iron head in favor of the aluminum one. My engine has a bone stock bottom end and factory head now with Clifford headers,petronix,and a Weber32/36. I guess what I am getting out is what kinda power will I be looking at with the new head? I will most likely keep the Weber initially(to save a few bucks) then swap to something bigger. Any and all info is appreciated. Thanks John.

On a stock motor with headers, your probably looking at 40 HP or so. Not really sure, as no one has dyno'd their motor before and after the head swap? At least, not that I am aware of....

Is that at the wheels? Is it with my Weber? What if I use a 4 bbl?

anotherhassel":3hghx3r2 said:

Is that at the wheels? Is it with my Weber? What if I use a 4 bbl?

Click to expand...

It's super hard to say, there's so much to engine performance. at the very least, the CI head will flow better, not just more flow, but a lot less leaning out on cylinders 1 and 6. that means more power. it may end up that your weber might become a limiting factor, after you get rid of the log intake. Becasue the aluminum head can run about a point higher in compression than steel, there's potential there if you do more than just bolt it on. There are also several low-buck upgrades people usually do before/during the ugrade that squishes the ratings, like a DS2 electronic ignition upgrade (with mechanical advance, which your pertronix upgrade dizzy might not have).

even if your carb could breath enough for the increased flow, it very likely would get you more from a retune, and back to your dizzy, if you have mech advance, you'd get a lot from having it professionally recurved.

Like Mike said, you'll get more from your car, but becasue of the huge variety of different ingitions, compressions, and carburetor options, it's really tough to put a number on it.

I agree, power wise, it's easy to bolt on the head than swap to an 8cyl, you will get better than a stock v8 power, tons more torque as your small weber will help fuel mix better. just the HP will be limited to carbs max flow...

IMO, stay with what is known and tested. that way you have something to compare your tests of before and after. like a 50mile round trip to measure MPG before/after. and a track time cause you don't want a ticket for 'exhibition of speed'. and a daily driven route for x days. it really helps let you know the differences going on.

So even with my stock motor and the new head the car will feel way more powerful than it does now right? If so that is what I am looking for. Then later down the road maybe a four barrel and the dizzy. Someone mentioned v8 power that is what i would like but i want the wow factor of the six.

While you may not put up the power figures of a v8 exactly, the near square torque curve and reduced weight of the six will make that power pull quicker.
Question would be, are you goin to do a bit of cam while you have the head off?

It would be the best time since it has to be off.

There is a video on YouTube with someone who just did the head with nothing else and I'm pretty sure that they were very pleased with the turnout.

Gerald.

Just do it. For the rest of us. For yourself most of all. And do before and after as best you can arrange, since that's where the story is. The CI head is beautiful just to look at. I want one for my 300 but it isnt here yet.

Ok I am really considering this. I sure you guys are gonna get tired of all my questions lol. Burro I need new pushrods if i keep my stock rockers? How do you determine how much to mill the head?

Stock rockers and push rods could work, if you have the right prelode on the lifter. Head is milled to adjust to the compression ratio that you want. Add the Head combustion chamber volume (CC's), the head gasket thickness (CC's), block deck height above piston (CC's), and piston dish volume if it has one (CC's) and divide into the cylinder volume bore x stroke (CC's to get the static compression ratio.

When the time comes, we'll help you with the order, making sure everything is correct for your application (such as the compression ratio). You just need to tell us the deck height and bore size, and we'll do the rest. We can also help with the cam selection, carb, and so on, to make sure you get the right combination of parts for a successful build.

Thanks Mike that would be awesome!

AzCoupe":1aacyik8 said:

On a stock motor with headers, your probably looking at 40 HP or so. Not really sure, as no one has dyno'd their motor before and after the head swap? At least, not that I am aware of....

Click to expand...

I can affirm that 40 hp is net flywheel hp increase, or 28 to 42% depending on what you would have had stock. Ball park rear wheel hp is 67 rear wheel hp. Figures for a reworked alloy head 2-bbl without headers are about 85 to 95 rear wheel hp.


There have been some historic early iron head 2V verses stock 200 log comparisions, and 40 flywheel hp is certain on an engine with no cam, ignition, compression and exhast changes asside from optimisation. You get a 2-bbl carb right off, great flow rates and sensational cylinder to cylinder flow efficiency.

Benchmark is the early Cross flow alloy head engines in Australia, where the 2-bbl versions put out 121 hp net, compared to the 85 to 94 net flywheel Hp of the US 1-bbl log head. 24 to 34 hp up on stock without anything but one alloy bolt on and a better carb. A set of headers brings that up to 143 hp, generally an 18% increase, and so with Mikes head, 2-bbl and headers, you'll see a 49 to 55 hp flywheel increase with reasonable certainty.

The real delight is that all the hard work has been done by Mike, and it exceeds what was done on the Aussie Iron 2V and alloy 2-bbl X-flow heads, without all the hassels that go with an imported head.