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Thinking about swapping heads but are they really worth the 700 bucks more? I mean my heads are 61cc i know going to a 58cc head off the back ill net 10-15hp in compression change but is it really worth it.? Iv been throwing the idea of AFR 205's (maybe CNC) and go with the P.I.M.P ECU, ditch the MAF sensor and go 30LB's (currently have 24lb) and net around 380-400 wheel? Current numbers dynojet 333/350 ...
 

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Whats your compression now..... stock 9 to 1 ?

Is your plan to do AFR 205 with 58 cc chambers ?
 

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Just check PTV clearance again, because if I'm not mistaken, AFR 205s have 2.08/1.60 valves.

You wouldn't be disappointed though, as flattus said. It's not even so much about the numbers, it'll pull a LOT harder man. It's more of what should be on a 331/347. In my opinion a 185cc head should go on a 302. Go 200cc or so for a stroker.

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And yes adding compression is worth it. All these small things add up and at the end of the day, it can be the difference between making 400hp and 450hp.

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Depends what you do with the car. If you like to keep your R's up on the street, go for it. Bigger is not always better. Are we really getting back to that again on here. Biggest parts possible........???? My 185 cnc's are actually a little big for my 306. The flow numbers of the head will determine which one is best suited for your combination along with your cam.
 

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Dude i still havent done a compression check :-O . Itll be funny if all this time i thought i had some 61cc heads and they turned out to be something bigger lol.. Ill get a compression check Monday forsure at work, and yes AFR 205's CNC with 58cc heads and hopefully to be around 10.1 if not a little more on 93 pump. Yea I should be more then good with PTV stuff because even with the 185's I had alot left over (I did the clay method).. Ill try to get a few dyno runs on the 185's this week since its colder here in FL and some more dyno runs after the 205's are installed and everything else is still the same.
 

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Depends what you do with the car. If you like to keep your R's up on the street, go for it. Bigger is not always better. Are we really getting back to that again on here. Biggest parts possible........???? My 185 cnc's are actually a little big for my 306. The flow numbers of the head will determine which one is best suited for your combination along with your cam.
Not so much flow numbers...

Usually the intake runner size is a good reference point.

IMO your 185s are perfect for a 306.

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Do they cc out to bigger than a 185? Didn't you have them ported by hand?

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I think his heads started life out as 170s but i might be wrong, but i thought i read some thing where they were flowing around 300 cfm or a little over. Not sure though
 

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Not so much flow numbers...

Usually the intake runner size is a good reference point.

IMO your 185s are perfect for a 306.

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Actually, it is about flow numbers and velocity, not port size. I'll touch base more on this when I'm near my computer and not typing on my phone.
 

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Actually, it is about flow numbers and velocity, not port size. I'll touch base more on this when I'm near my computer and not typing on my phone.
I just read a LOT on the bullet. Many of the cam grinders/engine builders don't believe in flow numbers just like most don't believe in dyno numbers.

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Actually, it is about flow numbers and velocity, not port size. I'll touch base more on this when I'm near my computer and not typing on my phone.
I do agree with velocity, though.

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Alright... I'm back for my explanation for why I feel the way I feel. Flow numbers and velocity, those are great things to consider when choosing cylinder heads from my reading/researching. Not necessarily peak flow numbers, but high flow numbers under the curve. Pretty much all my research states that you want the best flow, in the smallest hole. Meaning great flow for the (relatively) smaller intake cc size. The larger the intake cc, generally the less torque it makes and the higher gear you need to run, when it's not sized appropriately for your size of engine. And torque is what makes a good all around motor, especially for the street. Most people here street their cars. According to different calculators, my heads are oversized according to flow numbers for my engine and rpm capabilities. They would take my car to nearly 10,000 rpm at this cubic inch. That is obviously alot higher than I can run, and therefore I'm giving up velocity where I need it most. The only savior in my combo seems to be my Track intake with it's 12 inch runner. I can tell you from driving my car, it doesn't seem to come alive until around 4k. Not the best all around motor.

Here's a site for a lot of good calculations: http://www.wallaceracing.com/Calculators.htm
 

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I'm sorry, I just assume everyone wants the most horsepower and best E.T's.....:lol

I never think to build for torque because honestly, I don't care about it, lol. I would rather have a 4000-7000 screamer than a 2500-5000 torque monster.

Yes, flow numbers under the curve matter, I see what you're saying. Twisted wedges have GREAT mid-lift flow numbers and that's another reason why I like them over a Victor Jr., comparable AFR, RHS etc.

Also, that's what I mean about flow numbers. I see AFR's flowing great numbers for their runner cc. But I've seen them outperformed by other heads the same size and flow less... Just what I've seen on forums, anyway.

Like I said, I think the heads on your car are perfect for it IMO. I would give up the bottom end power for your upstairs. Plus your heads leave room to grow. You can slap em on a 347 and go 10s n/a with a good cam, no problem.

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High horsepower, low torque, heavy car. How well does that work? It's about a balance...

For more good reads, start down the list: Click here Bigger isn't always better.
Thanks man, but I've stared quite a few threads like this over on the bullet and got some great answers.
His car isn't so much HEAVY, it's just not as light as it could be. But yes, most people want balance opposed to the highest horsepower.

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Do they cc out to bigger than a 185? Didn't you have them ported by hand?

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Hehe......
I think his heads started life out as 170s but i might be wrong, but i thought i read some thing where they were flowing around 300 cfm or a little over. Not sure though
Mine actually started as 185s, then a guy I know that works at fox lake did some work to them for me, but nothing major. Then I had some other work done when I built the 408 ;)
 

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Mine actually started as 185s, then a guy I know that works at fox lake did some work to them for me, but nothing major. Then I had some other work done when I built the 408 ;)
My bad, thats a good set of heads though
 
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