what heads for a 408 street car

jromeo · Jun 6, 2010

I thought I hurt my new 347 so I pulled the motor without even looking under the valve covers.Well as we took it apart we found that I just broke a rocker stud . While I was having the block checked out I was offered a $ 1000 and a 351 stock block for my AFR 185 heads. Long story short, I want a streetable 408 with at least 450 horse to the wheels. I'm looking at the AFR 205's and the 225's but AFR says the 205's are good for 331- 392 cubes and what worries me about the 225's is that they are good from 4000 to 8000 rpm. NOT TO STREET FREINDLY. any suggestions ?

revhead347 · Jun 6, 2010

Big Motor = big heads. AFR 225s, Trick Flow hi-port, Trick Flow Twisted Wedge R or a set of well ported Canfield 17 degree heads. The Twisted Wedge Rs are going to yield the most power, but they are balls expensive. The Canfields will probably be the most streetable.

Kurt

95BlueStallion · Jun 6, 2010

I vote AFR 225's, depending on the cam and how high you want to rev it. At least with them you have room to grow (forced induction) if you wanted to in the future. I dont think 205's would hold you back too aweful much if you wanted to stay N/A for the long term, would they?

1slow95 · Jun 7, 2010

205 or 225 either one will be fine. They both flow pretty much the same below .600" lift, which is where you'll be at with a mild street car.

rj95svt · Jun 7, 2010

revhead347 said:
Big Motor = big heads. AFR 225s, Trick Flow hi-port, Trick Flow Twisted Wedge R or a set of well ported Canfield 17 degree heads. The Twisted Wedge Rs are going to yield the most power, but they are balls expensive. The Canfields will probably be the most streetable.

Kurt

Ditto!! I would go with some cnc'ed high ports or the cnc'ed 205cc TW heads.

The 205cc TW's are as big as the 225 afr's

revhead347 · Jun 7, 2010

I think they have a TW like 235cc head out now.

Kurt

jromeo · Jun 7, 2010

thanks for the in put guys! I want to find out a little bit more on the hi ports . I was leaning toward the afr 205's, but now I don't know. I just don't want the car to be a pig in the 2000-4000 rpm range. I guess I want the best of both worlds.

jromeo · Jun 7, 2010

1slow95 said:
205 or 225 either one will be fine. They both flow pretty much the same below .600" lift, which is where you'll be at with a mild street car.

I see you have the afr 225's and a tko trans. What gears do you have in the rear. My setup will be kinda like yours. How well does your car drive in the lower rpms with the 225's ?

Pratice · Jun 8, 2010

Dont skimp on the cam..A custom will give you drivabilty and hp you long for..

Black95GTS · Jun 8, 2010

The custom cam maker of you choose will set you up with their preference. AFR 225s would work great for your goals in my opinion.

Adam

BlackVert · Jun 8, 2010

my 410 street car has AFR 205 heads.

but i agree with the others ... talk to your cam grinder of choice, tell him what you want to use the car for, and follow his advice. and since it sounds like a mostly street car, don't foget to mention your state's emissions rules. it would suck if you do all this work and then can't drive it because you can 't pass emissions.

1slow95 · Jun 8, 2010

jromeo said:
I see you have the afr 225's and a tko trans. What gears do you have in the rear. My setup will be kinda like yours. How well does your car drive in the lower rpms with the 225's ?

I have 3.73's right now. The heads won't affect the low rpm power as much as the intake and cam. I was worried about using "too big" parts too when I was building it, but with 400+ ci you need to move up to mega huge parts before they're too big.

jromeo · Jun 8, 2010

Once again, thanks for the help! It's looking like the afr 225's. So what do you all think about the trickflow box R intake ? I was told that I could just get a truck lower to go with my holly upper, but you can't open up the holly to 90mm. most likely going to sell it along with my 347 short block.

Pokageek · Jun 8, 2010

jromeo said:
I thought I hurt my new 347 so I pulled the motor without even looking under the valve covers.Well as we took it apart we found that I just broke a rocker stud . While I was having the block checked out I was offered a $ 1000 and a 351 stock block for my AFR 185 heads. Long story short, I want a streetable 408 with at least 450 horse to the wheels. I'm looking at the AFR 205's and the 225's but AFR says the 205's are good for 331- 392 cubes and what worries me about the 225's is that they are good from 4000 to 8000 rpm. NOT TO STREET FREINDLY. any suggestions ?

205's are more street friendly in the manner you are thinking.

whitesqual · Jun 9, 2010

jromeo said:
Once again, thanks for the help! It's looking like the afr 225's. So what do you all think about the trickflow box R intake ? I was told that I could just get a truck lower to go with my holly upper, but you can't open up the holly to 90mm. most likely going to sell it along with my 347 short block.

The holly upper will only bolt to the 302 truck lower, the 351 has oval ports and is completely different.

revhead347 · Jun 9, 2010

I think you can get a Holley Systemax lower for the 351. It will be restrictive with the AFR 225s. However, keep in mind, a box intake is for high rpm power, which was the same reason you wanted to avoid the AFR 225s in the first place.

Kurt

1slow95 · Jun 9, 2010

The TF box intake will be perfect for a 408. I would have went with it if it would have cleared my hood. You need about a 4" cowl or some drop mounts.

jromeo · Jun 10, 2010

1slow95 said:
The TF box intake will be perfect for a 408. I would have went with it if it would have cleared my hood. You need about a 4" cowl or some drop mounts.

I really don't want to buy another hood. I think my cervinis stalker hood is 3 inches. maybe it will fit with the drop mounts.

BlackVert · Jun 11, 2010

1slow95 said:
The TF box intake will be perfect for a 408. I would have went with it if it would have cleared my hood. You need about a 4" cowl or some drop mounts.

how about a junior victor with an elbow?

1slow95 · Jun 11, 2010

BlackVert said:
how about a junior victor with an elbow?

I know super victor with elbow clears a stalker hood, with some slight modifications though. Not sure of the height differences between the junior victor and supper victor...

what heads for a 408 street car

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