408 Stroker

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70dart340 said:
I want to thank everyone for all the great information. Car is a bone stock appearing '70 Swinger 340 with factory A/C. Book says it should weigh about 3100 lbs, add 200(Really!) for me.
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I bet it weighs a good bit more. Weigh it if you can.
I'm leaning towards a set of 3.55's for my 741 8 3/4 with some type of SG.
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IDK if your going to get all the lRs for a 741. I never really looked. Doctor Diff has brand new set ups that include everything & everything is new, case included.

Thanks to all for their sound advice.
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Your welcome.

If the cam stays small.... a rpm w/a 1/2 spacer would be very good IMO.
Carb or FI is your call.
 
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Whether it be solid rollers or just solid flat tappet lifters at the most you'll check them a couple times after break in and then again maybe once a year. Having to adjust them all the time is a mith, so don't plan on tinkering too much...
When you choose your cam please keep in mind that 90% Street you're talking about and remember you can take anything to the drag strip including your mom's minivan... I repeat don't get caught up in the numbers....
 
Bewy said:
Three key words in the original post: 90% street driven.
The comment that a single plane intake has better fuel distribution is incorrect, because you have 7 cyls interfering with the cyl drawing mixture, compared to 3 cyl with a dual plane.

The Edel RPM manifold really changed the goal posts with the SP v DP intake debate. I have seen dyno tests where the RPM was better everywhere in the rpm range over a SP intake. Not what was expected, but the numbers don't lie.

If it was my engine, I would use the RPM.
In a 408, the RPM will probably peak at about 6200-6300 rpm. Because a DP manifold usually idles better & has more vac than a SP, you could increase duration by about 5* for more HP without sacrificing street manners. Also agree with solid roller lifters, either with a sol cam or hyd.
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As far as the SP V DP......Just keep this in mind(directing comment to the OP)
The DP's Cross Sectional Area(csa) will be to small and choke the potential air flow of the Trick Flow 190.
Will the DP, make more torque down low over a SP???????? Depend on the converter.
 
Bewy said:
Three key words in the original post: 90% street driven.
The comment that a single plane intake has better fuel distribution is incorrect, because you have 7 cyls interfering with the cyl drawing mixture, compared to 3 cyl with a dual plane.

The Edel RPM manifold really changed the goal posts with the SP v DP intake debate. I have seen dyno tests where the RPM was better everywhere in the rpm range over a SP intake. Not what was expected, but the numbers don't lie.

If it was my engine, I would use the RPM.
In a 408, the RPM will probably peak at about 6200-6300 rpm. Because a DP manifold usually idles better & has more vac than a SP, you could increase duration by about 5* for more HP without sacrificing street manners. Also agree with solid roller lifters, either with a sol cam or hyd.
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This just isn’t true. While some SP intakes have some distribution issues, a DP intake is crazy with them. Unless you want to spend many hours with porting tools and at the flow bench you can’t fix them, if even then.

If ANY dual plane intake makes more power than a single plane it’s either because the carb is too big for the SP, or the cam is wrong for it or both.

You need a much smaller carb for a SP than you do a DP. Also, you can run less duration with the SP intake and get the same RPM.
 
j par said:
Whether it be solid rollers or just solid flat tappet lifters at the most you'll check them a couple times after break in and then again maybe once a year. Having to adjust them all the time is a mith, so don't plan on tinkering too much...
When you choose your cam please keep in mind that 90% Street you're talking about and remember you can take anything to the drag strip including your mom's minivan... I repeat don't get caught up in the numbers....
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Again, as I’ve said you need the RIGHT cam. There is no big or small. There is only the correct cam and a bunch of cams that perform worse.

Don’t get caught up in the numbers either way...too small or too large.
 
dump the air gap it chokes after 5600 to 5800 rpm you should be going for 6500 rpm . i tried the airgap fully ported and it just dies early made great tq though 560@ 4600 . the victor i replaced it with made the car much better all around
good luck with your build
 
YR,
There have been PLENTY of tests where DP intakes have made more power than SP intakes throughout the rpm range for street drivers. [ Talking under 6500 rpm ] Richard Holdener did a test recently. From D. Vizard: almost 570 hp from a DP airgap on a SBC sounds pretty good to me for a 90% street driver.....
 
Bewy said:
YR,
There have been PLENTY of tests where DP intakes have made more power than SP intakes throughout the rpm range for street drivers. [ Talking under 6500 rpm ] Richard Holdener did a test recently. From D. Vizard: almost 570 hp from a DP airgap on a SBC sounds pretty good to me for a 90% street driver.....
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Yep. I’m dumb. You’re smart. I get that. What I’m saying is go back and look at ALL of those tests and you’ll see they never make the carb smaller for the SP even though they ***** about big carbs all day and all night.

Go back and look at the hideous cam timing they use and how they never change that either. The tests are skewed to the DP.

Since you are running the flag up the pole the highest I’ll ask you these questions.

When is it a good thing to put a corner in a column of air? What happens to that column of air when you add fuel to it and make it change directions?

When is it a good thing to have runner length variations of two inches or more?

When is it a good thing to let half the carb see a shallow plenum and the other half a deep plenum?

I’d like to hear your thoughts on that. Your thoughts. Not what the magazine article says.
 
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Them are some good question, need not to be taken lightly.^^^^^^^^^^^^^^^

I will add this. normal driving, light throttle and 1500-2500 rpm. i bet the DP while perform hands down better then the SP.
If you put a converter in there that stall 35000-4500(depending on the cam you choose) SP all the way.
 
Bewy said:
YR,
There have been PLENTY of tests where DP intakes have made more power than SP intakes throughout the rpm range for street drivers. [ Talking under 6500 rpm ] Richard Holdener did a test recently. From D. Vizard: almost 570 hp from a DP airgap on a SBC sounds pretty good to me for a 90% street driver.....
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You have experience with 4" motors? Not being smart at all, just curious.

I would use a DP on a 408 only if it was a low compression, non performance engine going in a heavy car or truck. I've stated this here many times, if you build a performance 4" small block and it's soft on the bottom end with a single plane intake you have made some mistakes choosing parts for the build.

If I were building it I'd probably go with a flat solid in the high 240° or low 250° @ .050" and .580" to .600" lift with around 10.5-1 compression, a Weiand X-Cellerator intake, then have a converter built for it. If you are seriously considering FI talk to whoever your buying from and see what type intake they recommend.

IMO, even with 3.55 gears it would be plenty strong on the bottom. I tend to build more on the race side so take my advice for what it cost.

Also call Dwayne Porter at Porter Racing heads and pick his brain.
 
Cudafever said:
Them are some good question, need not to be taken lightly.^^^^^^^^^^^^^^^

I will add this. normal driving, light throttle and 1500-2500 rpm. i bet the DP while perform hands down better then the SP.
If you put a converter in there that stall 35000-4500(depending on the cam you choose) SP all the way.
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Then you most likely bought the wrong SP intake. Almost all DP intakes have relatively small runners and the SP intakes are much bigger.

If you don’t account for that with cam timing and the fact that you almost DOUBLE the size carb (because all four venturi are now exposed to the plenum rather than half the carb being exposed to two venturi) you just kill power everywhere.

You can’t just thumb through the Summit website and pick a bunch of parts out and expect them to work together. You have to plan.
 
I'm not arguing,
Them are some valid point above that the OP need to investigate.
I have already said that the CSA is too small and will choke off the potential of the Trick Flow 190's
 
I'm still here and paying attention. Every one has at least one valid point. Now, I'm leaning towards the TF SP and my brand new 2009 Quick Fuel 750 mechanical secondary.Any thoughts on decking the block and CR? Thanks, Paul.
 
YR.
My answers & suggestions are predicated on what the OP said in his initial post. I will repeat it again: 90% street driving.
If it was 50/50 street & strip, I would certainly look at a SP intake.
Certain parameters that are different between the two designs don't change because of engine brand or intake brand. The SP has a larger plenum, all else being equal. That softens carb signal at low rpms. Air has weight [ 100 cu ft = 38 tons ] & therefore inertia. Shifting that large slug of air in a SP plenum is not want the engine wants to do at low rpms, hence the sluggish response. The larger plenum becomes a bonus at higher rpms when the weight of air can be 'rammed' into the engine.
Since a street driven car is going to have to idle, it then needs to pass through the low rpm range to get to higher rpms. It is also more likely to be at 3000 rpms more often than it will be at 5500 rpm. Hence the need in my opinion for a DP manifold for this OP.
 
Bewy said:
YR.
My answers & suggestions are predicated on what the OP said in his initial post. I will repeat it again: 90% street driving.
If it was 50/50 street & strip, I would certainly look at a SP intake.
Certain parameters that are different between the two designs don't change because of engine brand or intake brand. The SP has a larger plenum, all else being equal. That softens carb signal at low rpms. Air has weight [ 100 cu ft = 38 tons ] & therefore inertia. Shifting that large slug of air in a SP plenum is not want the engine wants to do at low rpms, hence the sluggish response. The larger plenum becomes a bonus at higher rpms when the weight of air can be 'rammed' into the engine.
Since a street driven car is going to have to idle, it then needs to pass through the low rpm range to get to higher rpms. It is also more likely to be at 3000 rpms more often than it will be at 5500 rpm. Hence the need in my opinion for a DP manifold for this OP.
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DAM, 1OO CUBIC FT OF AIR WEIGHS 38 TONS ? --NO ONE WILL EVER MAKE ME BELIVE THAT , REGARDLESS OF SCIENTIFIC THEORY , MY HOUSE AND GARAGE WOULD BE CRUSHED .
 
Bewy said:
YR.
My answers & suggestions are predicated on what the OP said in his initial post. I will repeat it again: 90% street driving.
If it was 50/50 street & strip, I would certainly look at a SP intake.
Certain parameters that are different between the two designs don't change because of engine brand or intake brand. The SP has a larger plenum, all else being equal. That softens carb signal at low rpms. Air has weight [ 100 cu ft = 38 tons ] & therefore inertia. Shifting that large slug of air in a SP plenum is not want the engine wants to do at low rpms, hence the sluggish response. The larger plenum becomes a bonus at higher rpms when the weight of air can be 'rammed' into the engine.
Since a street driven car is going to have to idle, it then needs to pass through the low rpm range to get to higher rpms. It is also more likely to be at 3000 rpms more often than it will be at 5500 rpm. Hence the need in my opinion for a DP manifold for this OP.
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That’s not what I asked you. When you honestly answer the questions you;l see the fallacy of the DP intake manifold.

I’d still like to hear the answers to the questions I asked.
 
70dart340 said:
I'm still here and paying attention. Every one has at least one valid point. Now, I'm leaning towards the TF SP and my brand new 2009 Quick Fuel 750 mechanical secondary.Any thoughts on decking the block and CR? Thanks, Paul.
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Paul, what’s the highest octane is available to you. Here on the island, readily available is 93. I’m running an 11-1 engine with it now. The 360 is zero decked and a thin head gasket is in use.

For me, the use of a dual plane vs a single plane is more rooted in the intended usage of the car. So far, what I have gleamed off the forum from the been there and done that is the RPM intake has an edge over the single plane down to somewhere around the low 11 second range. But this is also dependent on what’s being done with the car and what parts are used under the intake & the weight of the vehicle.

The wife’s Cuda is using a dual plane and has 3.55 gears on 26X10 tires. A very similar cam to the cam card above.

Gear ratio, tire size, trans and converter (if it applies to other readers of the forum) need to work with the camshaft with the CID of the engine.

Fact, trying to push a 3400+ lbs car into the 11’s requires a bit more power than a sub 3000 lbs car does.

As I show above, the dyno chart of the 408 that created 460 HP and mounds of torque, will be a fun street car. Going with a bigger cam will push the power leaks up the rpm scale. That was done with a rpm intake and a 750 w/an inch spacer IIRC.

Going up in cam duration to a 250@050 will get you to your 6000/6500 area a lot better. (Not Guaranteeing that peak power is there.) And around here (IMO) the engine will like the single plane better when under a W.O.T. condition.
 
One makes more power always “IF”....what “IF” there “IS” no option for “IF” but only “IS” like there “IS” one 750 on a tunnel ram, a rat roaster , single plane or a dual plane? Not changing anything else. I think we all know which one will make the most power, but only “IF”..... So “IT” depends on what the definition of “IF” “IS”!:lol:
 
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all i know is i changed my air gap for a victor and the car is much better all around, pulls harder and gets better gas mileage . now it pulls hard all the way to 6500 rpm used to die at 5600-5800 . there is not one area the dp performed better than the sp . that is just my impression , dyno results next week will show if there are any differences
 
Nag, that sounds great. Post up them results and the combo would ya?!?!
 
famous bob said:
DAM, 1OO CUBIC FT OF AIR WEIGHS 38 TONS ? --NO ONE WILL EVER MAKE ME BELIVE THAT , REGARDLESS OF SCIENTIFIC THEORY , MY HOUSE AND GARAGE WOULD BE CRUSHED .
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I'm just a dummy, but I think its more like 8lbs for 100 cubic ft of air.
 
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