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post #1 of 15 Old December 19th, 2015, 02:06 AM Thread Starter
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408w street/strip

I'm new to pushrods a bit. Currently have a 4.6 boat anchor if you will lol My car is street/strip. When I say street/strip I mean its a weekend warrior. Not a daily driver. Drive around to shows and to the track.

What i'm a bit lost about is i'm trying to find a broad power curve up to about 7k rpm on a boss 351 block or a dart block which ever. I only want to spin it to 7k because I hear other engine builders don't recommend spinning a 408 past that.

What heads would you recommend for this build? It'd be nice to stay on pump gas but i'm open to mixing race gas concentrate to get 100 octane if a little bit of a bump in compression is needed.

I'm trying to get 500-550hp at the crank as a minimum. That should get me a mid 10 1/4 which is what i'm trying to achieve from this build. Down the road i'd like to spray it, but for now it's going to be n/a.

also how much money do you think I should have set aside for a build like this?

I'm also a bit confused as to how aggressive of a cam I would need to hit 550hp. Sometimes cam specs are a bit confusing to me, however I would like to run a carb or one of those efi self learning systems seem pretty cool too.
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post #2 of 15 Old December 19th, 2015, 10:11 AM
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A few thoughts on this.....

What goal is the most important? Because they don't exactly go hand in hand. What I mean is wanting to turn 7K, making a horsepower goal, and making an ET goal, are not the same thing. You don't need to turn 7K to make 550 hp, and you don't need to turn 7K or make 550hp to run mid 10s.


It takes a good set of heads to make power all the way to 7K with that displacement. Something like the TEA TF high ports.

Now to run mid 10s with a 408, you don't need race gas, or any of that. I think aiming for a horsepower number is not the best way to set a goal. It's all about how fast you want to go, which doesn't always coincide with a peak hp number. You can use a set of the new TF 11R 205 heads right of the box, with a Super Vic intake, and a mild solid roller at 10.5ish:1 compression, and run mid 10s. If that's the goal, there's no need for a Dart block because the stock 351 blocks will do that with ease.


If if you were to use a Dart block, your worry about RPMs goes away, because they use the smaller Cleveland mains, but again, you don't need to turn that many RPMs anyways.

Just an example of a few things here, my 408 in my old turd was 10.28:1 (straight pump gas), with a Vic Jr, TW185s with some mild port work and clean up, a hydraulic roller (.626/.608 244/[email protected]). It only made 384rwhp, but it ran 10.90s @122 on the motor with a nitrous converter, and went [email protected] on the bottle, which would be a 9.60-9.70 pass in the quarter. This was all in a stock block, with a cast crank, at 3380 lbs in my leaf sprung turd.

With the bigger 11R 205 heads, bigger intake, and a mild solid roller, you could easily run mid 10s.

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post #3 of 15 Old December 20th, 2015, 10:24 AM
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I completely with 69Fastback, you don't need to turn that kind of RPM but with a dart block you can without to many worries.

As stated what is you goal? ET or HP? My Maverick ran in the low 10's on pump gas but with some serious work done on my Victor Jr's with solid rollers and caltrac's to hook me up.
What is your budget? Speed costs! My advise is to build the bottom end as strong as you can and get the best heads your pocket can afford, no matter how much fuel and air you dump if you can't get it out it won't do you any good!

One last thing I learned a long time ago, we are "bracket" racers it's a lot more important to see the win light come on than how fast you can go!

As always just my .02

Terry

I don't drive fast... I just fly low
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post #4 of 15 Old December 29th, 2015, 03:25 PM
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Quote:
Originally Posted by maverick3429 View Post
I'm new to pushrods a bit. Currently have a 4.6 boat anchor if you will lol My car is street/strip. When I say street/strip I mean its a weekend warrior. Not a daily driver. Drive around to shows and to the track.

What i'm a bit lost about is i'm trying to find a broad power curve up to about 7k rpm on a boss 351 block or a dart block which ever. I only want to spin it to 7k because I hear other engine builders don't recommend spinning a 408 past that.

What heads would you recommend for this build? It'd be nice to stay on pump gas but i'm open to mixing race gas concentrate to get 100 octane if a little bit of a bump in compression is needed.

I'm trying to get 500-550hp at the crank as a minimum. That should get me a mid 10 1/4 which is what i'm trying to achieve from this build. Down the road i'd like to spray it, but for now it's going to be n/a.

also how much money do you think I should have set aside for a build like this?

I'm also a bit confused as to how aggressive of a cam I would need to hit 550hp. Sometimes cam specs are a bit confusing to me, however I would like to run a carb or one of those efi self learning systems seem pretty cool too.
Get a Dart block and a forged rotating assembly with a 4-inch stroke. At that point, you're actually starting at 427cid without over-boring. If you want to go to 7k RPM *reliably* (and repeatedly), you need shaft-mounted rockers and a solid roller cam/lifters.

For heads, I highly recommend AFR 220's with appropriate springs and other upgrades appropriate to your build (I think you can get them with the rockers I described, but you have to get the heads direct from AFR if you go that way). With a Dart block and forged bottom end, your biggest worry will be setting up the valve train.

With a Vic Jr intake and a 850 or bigger carb, I predict closer to 600 crank HP.

As to cost, expect to spend about $13k for the motor described above. If you want the engine to be bullet proof, you simply HAVE to spend some decent money on it.

I'm currently running a Dart block with forged rotating assembly (10.5 compression ratio) AFR 205's and a hydraulic roller setup with 1.7 rockers and a TrickFlow Stage 3 cam, and a 850 FM quickfuel carb, and I'm running 530 crank hp at 6500 rpm. If I had used the bigger heads and a solid cam, I'd be closer to 600 crank hp.

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post #5 of 15 Old December 29th, 2015, 03:55 PM
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The Dart blocks are available in either a 4" or 4.125" bore size. If you choose to go with a Dart block, there is no reason to go straight to 4.030" (which is what a 408 is). So you'd be looking at a 402 cubic inch motor, with a nice square 1:1 ratio (4" stroke, 4" bore). Or the 427 with a 4.125" bore block.

I'd agree with the shaft mounted rockers, but disagree with the hydraulic roller part. A good set of solid bushing Iskys would work great, and you'll never have to mess with the valve lash. However, being that this is a weekend warrior, a solid flat tappet wouldn't be too bad, providing you don't mind getting into the rocker covers every once in a while. Break-in can be a bitch with a flat tappet, is the only possible downside.

Whatever head you choose, the valvetrain is going to have to be pretty sturdy for 7k runs. Nice thick pushrods, sturdy guideplates, etc. are what'll work the best. Dual or beehive springs, lightweight one piece valves, stuff like that.

A lot of this is going to depend on what sort of budget you have to work with.
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post #6 of 15 Old December 29th, 2015, 04:11 PM
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Quote:
Originally Posted by WillyT View Post
The Dart blocks are available in either a 4" or 4.125" bore size.
I believe the 351w Dart blocks start at 4.125. The 302 based blocks are 4.0. Since he's talking about a Windsor block, it would be 4.125.
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post #7 of 15 Old December 29th, 2015, 05:52 PM
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SHP, Sportsman, Iron Eagle and the aluminum Race Series are all available at either 4.000" or 4.125".

SHP is available with the following deck heights:
8.200" (302)
9.200" (no idea)
9.500" (351)

Sportsman is available with the following deck heights:
8.200" (302)
9.500" (351)

Iron Eagle is available with the following deck heights:
8.200" (302)
8.700" (no idea)
9.200" (no idea)
9.500" (351)

Aluminum Race Series
8.200" (302)
8.700" (no idea)
9.200" (no idea)
9.500" (351)

All of them are available with a 302 main journal size, which is ideal.
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post #8 of 15 Old December 30th, 2015, 11:39 AM
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Quote:
Originally Posted by jsimmonstx View Post
I believe the 351w Dart blocks start at 4.125. The 302 based blocks are 4.0. Since he's talking about a Windsor block, it would be 4.125.
You can get them with either bore.


A Dart block is 100% waste of money for a 500-600 hp 9.5 deck build. That's stock block, cast crank levels all day. That's what my engine makes on motor, and I spray the crap out of it on top, with a stock block and cast crank. There's just no need to spend the money.

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post #9 of 15 Old December 30th, 2015, 01:30 PM
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When I ordered mine last July (SHP 9.5 deck), it was only available with 4.125 and one larger (I don't recall what the size was), and it came with Cleveland sized journals (no option that I saw for anything larger or smaller).

I believe the 9.2 deck blocks are for special CID-limited racing series and require a modified intake manifold. That deck height didn't come stock in anything that I know of.
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post #10 of 15 Old December 30th, 2015, 09:48 PM
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Quote:
Originally Posted by jsimmonstx View Post
When I ordered mine last July (SHP 9.5 deck), it was only available with 4.125 and one larger (I don't recall what the size was), and it came with Cleveland sized journals (no option that I saw for anything larger or smaller).

I believe the 9.2 deck blocks are for special CID-limited racing series and require a modified intake manifold. That deck height didn't come stock in anything that I know of.
Well, you may want to check out the early 351W blocks, because they were 9.2 decks.

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post #11 of 15 Old December 30th, 2015, 11:57 PM
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My 1969 C90 is a 9.480 block. I think the 9.2's were Ford Racing (Boss).

BUILD THREAD


'84 Hatch, Bracket Car, [email protected], but I'm working on it
'71 Mach One FB 351c, Slow
'73 Torino, 302, Slower


~
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post #12 of 15 Old December 30th, 2015, 11:58 PM
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Nope. Many '69 blocks were 9.2 deck. My white '69 had one.

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post #13 of 15 Old December 31st, 2015, 08:34 AM
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Quote:
Originally Posted by 69fastback View Post
Well, you may want to check out the early 351W blocks, because they were 9.2 decks.
I thought those were 9.4 or something like that.
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post #14 of 15 Old December 31st, 2015, 12:34 PM
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The early 69 blocks were 9.2 deck.
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post #15 of 15 Old December 31st, 2015, 04:14 PM
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Interesting. There's a guy selling a 9.2 Dart locally. But it needs a sleeve. Hmmm.
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