small block 427, what heads should I run

Chosen7

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how is everyone doing, the problem that I am running into might be simple but honestly I am not an engine specific guy, I have a 66 mustang coupe, has a c6 tci super street fighter in it, also I put a PAW SB 427 in it, I know that this is an older kit but I was stationed in Germany for a while and a divorce so car sat for a while. know the issue I am trying to fix is my power curve is way left, and rev max is only about 5200, with a sharp drop of, I would like to shift it to the right currently I am peak torque at 3800 with 523 and peak HP of 430 at 4700. I was talking with a buddy and he suggested different heads and maybe a different cam. I know stroker engines tend to be non rev motors and high torque, I just would like to know if I can adjust it a little more for the top end. currently my cam is a comp cam camshaft 240/246. 541/544/110 lash. my heads are running RHS iron heads that are runners 200c, chambers 58cc, valves 2.02/ 1.600 with valve train max lift of .560. any info is appreciated
 
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RaggedGT

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Hello,I have no real helpful input,but I would like to hear/read some useful input for your issue. As that monster of an engine you have already sounds like a real healthy build-I’m going to tag a knowledgeable guy who should have some helpful suggestions (if he’s not busy)
@FastDriver
 

FastDriver

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Can you post the dyno? Did you get an AFR reading while it was dynoing? What Carb do you have? I presume those cam duration numbers are at .050" lift. The cam could use more lift to take full advantage of the head, but the duration is in the ballpark... semi-aggressive, IMO. I would expect that motor to rev out with a bigger head, like an AFR205 or 225. Not all that familiar with the heads you have, so I looked up their flow numbers:

1556036225425.png


If I'm not mistaken, builders use a 2 hp max per CFM rule of thumb for N/A builds. You're only seeing ~244 CFM at your cam's lift. At 430 rwhp, you're probably making over 500 hp at the crank. So, it looks like there's your limiting factor. Looks like you'd stand to pick up nice power with more lift, but even more lift with a premium head like an AFR205, which has flow numbers that look more like this would be ideal:

1556036449192.png


Your 427 wants to move a LOT of air, sir. If you want to support it, you have to pay for it. An AFR205 or 225 still has an inline valvetrain, like your heads, which means it is less likely you'll need to flycut the pistons. However, the intake valve is bigger at 2.08 vs. 2.02 on your RHS's, so no promises.

AFRs cost a pretty penny. A custom cam from a guy like Ed Curtis costs ~$375. If you went just the cam route, you'll probably need to upgrade the valve train to handle more lift. There are other head options, but AFRs are the ones I'm most familiar with.

Hope this helps. Good luck with your build!
 
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Chosen7

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Apr 22, 2019
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Can you post the dyno? Did you get an AFR reading while it was dynoing? What Carb do you have? I presume those cam duration numbers are at .050" lift. The cam could use more lift to take full advantage of the head, but the duration is in the ballpark... semi-aggressive, IMO. I would expect that motor to rev out with a bigger head, like an AFR205 or 225. Not all that familiar with the heads you have, so I looked up their flow numbers:

1556036225425.png


If I'm not mistaken, builders use a 2 hp max per CFM rule of thumb for N/A builds. You're only seeing ~244 CFM at your cam's lift. At 430 rwhp, you're probably making over 500 hp at the crank. So, it looks like there's your limiting factor. Looks like you'd stand to pick up nice power with more lift, but even more lift with a premium head like an AFR205, which has flow numbers that look more like this would be ideal:

1556036449192.png


Your 427 wants to move a LOT of air, sir. If you want to support it, you have to pay for it. An AFR205 or 225 still has an inline valvetrain, like your heads, which means it is less likely you'll need to flycut the pistons. However, the intake valve is bigger at 2.08 vs. 2.02 on your RHS's, so no promises.

AFRs cost a pretty penny. A custom cam from a guy like Ed Curtis costs ~$375. If you went just the cam route, you'll probably need to upgrade the valve train to handle more lift. There are other head options, but AFRs are the ones I'm most familiar with.

Hope this helps. Good luck with your build!
9C05B957-5905-41FF-AB89-6852703664B5.jpeg
9C05B957-5905-41FF-AB89-6852703664B5.jpeg
 

FastDriver

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Well James, unless those A/F ratios are something else, they don't make sense. A/F is sometimes given in "lambda," which is a ratio that is based on "stoichiometric" mixture of the fuel you're using. Assuming it's gasoline, stoich is 14.7, which would make 1.1 equal to 16.17. But that's so lean, you'd almost certainly be detonating. So, I guess that means the AFR gauge wasn't hooked up or it's on some scale I've never seen.
 
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dennis112

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As is, that's a fairly decent power combo for the street. Unfortunately the parts mentioned are probably near their max.

I for one have never had issues getting decent power/rpm out of windsor strokers. Your cam is really shy on lift and I can see how it is very limited by the valve train. I do not see an easy way to get more RPM's out of it unless you didn't upgrade the valve springs specifically for the cam. I am very curious of the rest of your combination-compression ratio, carb size, intake manifold, and header type (full tubes or shorties?) and tube diameter. Also what transmission and rear end gear?

I agree with the above poster that an AFR 205 is a great out of the box head for street or street/street strip 427w. They far exceeded the fully ported 210 Procomps that I originally bought during my divorce and the 393w gained a full 50 hp by installing them with no other motor changes. I shifted that one at 7000 and when I cammed it upmore I got just over 550hp out of that motor with pump gas. When I built a 427w with a 254/258 cam, a Holley HP carb, ported Victor Junior intake and 1 3/4" full tube headers it put out 600hp.
 

dennis112

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Thank You FD--Yeah, I missed it . . . .

The RPM intake and 750 carb would be on par with the rest of the build--a powerful street motor combination that would be enough to satisfy most drivers. The design rpm range of the intake ON A 351CI motor is 1500-6500. The larger 427CI motor ( which is nearly a 20% larger air pump) would need more air flow volume to actually achieve the same upper RPM's. ( I realize that 6500 is probably not Chosen7's goal but wanted to use published specs to make the point about air flow on larger motors.)

Likewise the carb is perfect for the street but would be limited on a more performance oriented engine build-it makes outstanding torque and with good HP. I feel from the data we have that there is no one item in the current engine build that if changed would give a huge increase in the performance.

If I was spending his money on the motor I'd start with improving the heads (for a healthy street or street/strip car AFR 205--(works with inline pistons) OR an equivalent trick flow 205 11r--(needs piston work to relocate valves?) and then build on that. A lot of guys think that the cam/intake/carb is the secret to finding great HP but its the heads that determine how well a motor can run. Everything else gets built around the heads (plus the driver's desire.) The dual plane would have to go--it is not needed as a single plane will make wonderful torque on a large CI motor (although an rpm airgap may qualify depending on the Chosen7's end desires.) Just an intake increase will have little effect on the current engine build and might even hurt current performance.

I would still like to know the rest of the drivetrain build as a rear gear change may be a low cost improvement that would increase the car's performance. It could be a better bang for the buck.

Chosen7, what is your desired max rpm's?
 
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FastDriver

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Thank You FD--Yeah, I missed it . . . .

The RPM intake and 750 carb would be on par with the rest of the build--a powerful street motor combination that would be enough to satisfy most drivers. The design rpm range of the intake ON A 351CI motor is 1500-6500. The larger 427CI motor ( which is nearly a 20% larger air pump) would need more air flow volume to actually achieve the same upper RPM's. ( I realize that 6500 is probably not Chosen7's goal but wanted to use published specs to make the point about air flow on larger motors.)

Likewise the carb is perfect for the street but would be limited on a more performance oriented engine build-it makes outstanding torque and with good HP. I feel from the data we have that there is no one item in the current engine build that if changed would give a huge increase in the performance.

If I was spending his money on the motor I'd start with improving the heads (for a healthy street or street/strip car AFR 205--(works with inline pistons) OR an equivalent trick flow 205 11r--(needs piston work to relocate valves?) and then build on that. A lot of guys think that the cam/intake/carb is the secret to finding great HP but its the heads that determine how well a motor can run. Everything else gets built around the heads (plus the driver's desire.) The dual plane would have to go--it is not needed as a single plane will make wonderful torque on a large CI motor (although an rpm airgap may qualify depending on the Chosen7's end desires.) Just an intake increase will have little effect on the current engine build and might even hurt current performance.

I would still like to know the rest of the drivetrain build as a rear gear change may be a low cost improvement that would increase the car's performance. It could be a better bang for the buck.

Chosen7, what is your desired max rpm's?
No problem, and good info. Carbs are not my bag. I'd also like to know the deal with 205 11R piston clearance. I have no personal experience, but I'm under the impression that the angled valve allows even more clearance than the inline valve. Still, I'm sure they notch the pistons differently, and I'd steer clear unless I knew for sure that my piston/head combo would work. Also, if previous head comparisons from AFR to TFS are any indication, then the 11R 205 is probably more equivalent to the AFR 225 in the cross-sectional area of the ports, not that either would be a bad thing.
 

dennis112

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TFS used to recommend different pistons on the old twisted wedge versions. Although I have not personally messed with the 11R heads I currently run 15* angle in line valve Victor Sr heads (they require a special piston or piston work) so I added the "?" mark after the statement since I'm not sure but wanted to throw that out there in case it applies.

As always one needs to check PTV clearance when using a cam that is beyond stock.

I too am curious about what valve reliefs the TFS 11R heads might need as they have a lot going for them performance wise. The relocated angle does help clearance but the radial valve angle (the outer edges of the valve head) will approach a stock 20* piston from a different angle which might require clearance more toward the center of the piston. Interference in any given situation would be based upon the cam used. Any clearancing (if needed) would possibly be minor and easy to do on an assembled shortblock.
 
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Ray65-71-73

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I have a fresh 351/427W in a 65 convertible. This is the third 351W I have put in this car. I have run it a few times, driven it once; ten miles-park-return. Initial start was easy, seems to run OK.

Trick Flow heads w/studs
Trick Flow roller cam
Single plane, air under runners
Fitech rail injection, 80# injectors
Two wire distributor, timing controlled by Fitech
AODE
3.5, 9 inch, Long nose, Torque worm
235-60-15 rear, may go 245-60-15

I am currently on the road; Mustang Owners Museum opening, Charlotte, NC, currently on way home to SoCal. This is the only info I have at this time. I will post more as time goes on if anyone is interested.

Ray
 

TT670

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The 11R's don't necessarily require special pistons to work, the 11* & 13* valve angles offer more clearance than previous TFS heads. As an example, although not a 427 windsor, I'm running TFS 11R 190's on a stock 302 short block with .565 lift and have tons of piston clearance.
 

dennis112

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LIFT is not the cam spec that matters . . . .

The valve is closest to the piston in the cam overlap area when the exhaust valve is just closing and the in intake valve is just opening. This occurs within a 20* window when the piston is near the top in the non-compression stroke. This spec is designed into the cam by the cam designer and its effects vary motor to motor and does not need to vary based upon lift. The piston is always way-far-away from the piston when either the exhaust or intake valve are anywhere near full lift.

I agree that special pistons may not be required BUT clearances must be verified specifically in the area of cam action that I just referenced.
 
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TT670

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Im aware there's more than just lift and should have been clearer. My point was don't listen to the naysayers who simply say you need custom pistons, a custom cam shop can set you up and there plenty who run TFS heads without special pistons. I went with a custom cam and am running much more cam than the internet experts claimed i could get away with and have .120" clearance.
 
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Hack

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There are lots of great small block Ford heads out there, but if I were looking to buy I would go with something from Jon Kaase. For a small block 427, perhaps the P-38 heads? They say 700-750 HP on a mild 427.

http://www.jonkaaseracingengines.com/html/kaase_p-38_canted_valve_small_block_ford_heads.html

Small Block Ford Canted Valve Cylinder heads for Windsor Series engines.
P-38 Features:

  • Generates more power by means of canted, larger diameter inlet and exhaust valves; improved port velocities; deeper bowls with sweeping short turns in the intake and exhaust ports.
  • Accommodates original equipment intake manifolds and exhaust headers for convenience
  • Features intake valve angles of 8 x 4.5 degrees and exhaust of 10 x 4 degrees to increase air flow.
  • Introduces maximum clearance between intake valve and cylinder wall, even at low valve lift with standard bore. This attribute also boosts the performance of small camshafts.
  • Provides optional mounting holes for larger diameter headers as standard.
  • Actuates valves that open toward the cylinder centers, hence gases are less encumbered by shrouding effect of cylinder walls.
  • Equipped with Kaase P-38 cylinder heads, a modest camshaft, and an Edelbrock Junior intake, the 302, running on pump fuel and barely 9:1 compression ratio, easily generates 500hp @ 7500rpm.
  • Produces dyno numbers of 700 to 750hp on a mildly built 427.
 
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Hack

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I agree - heads with canted valves can make big power. In my opinion, Jon Kaase has also proven himself to be good at getting power out of engines with all his Engine Masters wins.