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Discussion Starter #1 (Edited)
Looking at a flattop piston Scat 408 rotating assembly, but should I run 205 or 225 AFR heads? thinking about the 72cc comb chambers. Going to be running a Mighty Demon 800CFM carb and Vic Jr intake manifold. The motor is mostly gonna be strip but will see the street a few times a year for shows and cruise-ins to scare the crap out of a few of my friends.
 

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I believe the 225's are set up to run with the larger 4.125" bore.
And the 205's are too. You won't get full flow on a stock type block. I have AFR 205's on a 4.030 bore and part of the chamber next to the intake valve overhangs the block deck on both heads. Even so, The AFR's are a good bang for the buck for a in-line type head. I saw a substantial increase when I swapped from some 210 ProComps to the 205 AFR's.

If you want AFR's--go with the 225's (although the 205's would work too.) You can never have too big of a head on that 4" stroke motor.

You may also want to look at the TFS TW (CNC) or Canfields. There is additional HP to be found with the increased valve angle of these heads and either will be cheaper or on par with the AFR's that were mentioned. You have to watch the TW's though as they will require a modified header flange.
 

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A 408 stroker will make 667 HP on pump gas with the AFR 205 heads if you know what you are doing. You will need to rev the engine up to 7000 RPm, and you will want a bigger carburetor too- I have made 750 HP with the AFR 205 heads- They will be a very good choice for you

JOE SHERMAN RACING ENGINES
 

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And the 205's are too. You won't get full flow on a stock type block. I have AFR 205's on a 4.030 bore and part of the chamber next to the intake valve overhangs the block deck on both heads.
I built a 383 small block Chevy with AFR heads, and the chamber was a little wider than the bore. What I did, was to lay the head on the block and mark the portion of the cylinders where the chamber overlap was with a felt tip pen from underneath. (bare block, no rotating assembly installed) I then removed the head and installed the gasket. I then notched the cylinder out to the gasket in that area, being careful to stay well above where the top ring would travel. Sure made it look a lot better.

dennis111 said:
If you want AFR's--go with the 225's (although the 205's would work too.) You can never have too big of a head on that 4" stroke motor.
Yes, when you're feeding 'big block' cubic inches through small block cylinder heads... it's best to go big.

dennis111 said:
You have to watch the TW's though as they will require a modified header flange.
The TW has a stock exhaust port height and bolt pattern. If you are referring to the TW-R RACE head, then yes, it has a different setup. However, the common TW is easy as far as exhaust is concerned... easier than the Canfield or TFS Hi-Port, which have the exhaust port raised 0.400". The AFR 225's also have a raised exhaust port. Be aware of this when thinking about headers.

Good Luck!
 

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I'm gonna tell you from first hand experience that the Victor Jr heads are a better value. You get basically the same head but for half the cost. Not much less power than the AFR205's. I made the swap to the 225's last year. Wish I'd have spend $2000 on a block instead of heads. Thought maybe the 225's would pick up some ET and/or MPH. Nope.

I can also guarantee you that most of the big name engine builders will sell the AFR's over the Edelbrocks, promising you more power. No doubt they will make more, but the difference is, what? 20 HP? Hardly an issue unless you're chasing EVERY tenth of a HP.

The thing about the AFR's is that you can slap them onto a block and put a cam in it, and they'll make power. Set up a 408 with a pair of Jr's and put the RIGHT cam in it, and they'll work almost as good. Main thing to understand is to not undercam.
 

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When I tested the Edel vic jr heads with the AFR CNC ported 205 heads there was a 51 HP differance on a pretty hot 347 stroker-- It made 501 HP at 7200 with the Edelbrock vic jr, and it went up to 552 with the AFR heads out of the box-- They cost about 500 dollars more, but you get so much more for your money

JOE SHERMAN RACING ENGINES
 

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A 408 stroker will make 667 HP on pump gas with the AFR 205 heads if you know what you are doing. You will need to rev the engine up to 7000 RPm, and you will want a bigger carburetor too- I have made 750 HP with the AFR 205 heads- They will be a very good choice for you

JOE SHERMAN RACING ENGINES
Joe, how about a 393 stroker. I'm taking off the EDELBROCK PERFORMER rpm heads and putting AFR 205's on. I'm hoping for 500rwhp. The Motor is completely forged and has an SVO race block S-351. Compression is 10-10.5:1. It has a Comp cam solid roller with a mild 246 duration and 580 lift. Steve Ridout over at Powertrain Dynamics says I should be right around 500rwhp with a 2500 stall converter and 378 gears. The motor was built a few years ago by Jim Larr at Orange Engine in Anaheim, Ca. It's got about 5500 miles on it. Jim said it dyno'd at 550hp on the engine dyno, but that seems a little high with Edelbrock performer rpm heads. I'll be satisfied with 500rwhp, I don't want more than that for the street anyway, even that's probably too much for my tires to handle

Steve said the edelbrock performer rpm heads are way to small for that motor and I should pick up almost 100Hp with AFR 205's and possibly a bigger Roller cam. He said the AFR 165's even outflow the Edelbrock performer rpm's.

The cam that's in there now is only making power up to 6,000rpm. I don't want to go over 6500rpm because I want the motor to last at least 50-60k before it needs freshening up. Reving it to 7000rpm will decrease the life expectancy won't it, or not. How many miles can I get out of such a motor as long as I take good care of it and don't over abuse it. Definetly never using nitrous. All motor because I'm not rich and I don't want to blow up a $15,000 race engine.

Joe, can you give me the specs on the two strokers that made 667 and 750hp with pump gas. Like I said, I don't want more than 500rwhp.That's plenty for the street. The car's putting down 380rwhp now, but that was with way too big of a stall and a lousy built c-4 tranny. Don't ever buy a tranny from MPH Transmission in Santa Ana,CA. Mike Myers is a scam artist and him and George build really crappy transmissions. They ripped me off for over $2500 and built me a POS C4.
 

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I'm gonna tell you from first hand experience that the Victor Jr heads are a better value. You get basically the same head but for half the cost. Not much less power than the AFR205's. I made the swap to the 225's last year. Wish I'd have spend $2000 on a block instead of heads. Thought maybe the 225's would pick up some ET and/or MPH. Nope.

I can also guarantee you that most of the big name engine builders will sell the AFR's over the Edelbrocks, promising you more power. No doubt they will make more, but the difference is, what? 20 HP? Hardly an issue unless you're chasing EVERY tenth of a HP.

The thing about the AFR's is that you can slap them onto a block and put a cam in it, and they'll make power. Set up a 408 with a pair of Jr's and put the RIGHT cam in it, and they'll work almost as good. Main thing to understand is to not undercam.
wow, i'm suprised you didn't pick up with AFR 225s , there must be something wrong probably a cheap torque converter not transfering full power to the track and acting as a governor. everyone knows 225s will whip up on victor jrs, they are called jrs for a reason. most edelbrock stuff is overated
 

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ive got a set of afr 185's that i plan on putting on a 408 in a couple of years but from what it sounds like, they're gonna be to small. is that right or would it be better to sell the 185's and upgrade to 205's or 225's? im also planning on making around 500 rwhp.
 

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When I tested the Edel vic jr heads with the AFR CNC ported 205 heads there was a 51 HP differance on a pretty hot 347 stroker-- It made 501 HP at 7200 with the Edelbrock vic jr, and it went up to 552 with the AFR heads out of the box-- They cost about 500 dollars more, but you get so much more for your money

JOE SHERMAN RACING ENGINES

Thanks Joe. Yeah, I can't wait to slap the AFR 205's on.
 

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What kind of cam and compression are we speaking of for this build?
Typical 408 build with an AFR205 will have a cam around 256/266 I/E @ 0.050 with a 108-110 LSA, around 11:1 compression... and make around 550-575 hp... and shift around 6500 to 6800 rpm. Pretty much a bulletproof, reliable combo that will last a long time if put together right.

351W blocks have 3" mains, and like a solid 0.0030" to 0.0035" main clearance. 0.0025" on the rods.

Yes, this is an ancient thread, but the above is a proven combo.

Good Luck
 
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