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Discussion Starter #1
I have a motor specs are as follows:
355ci sbc 9.5:1
274H XE cam
Performer rpm intake
600cfm edelbrock carb
1.52 roller rockers
Im trying to decide which dart heads I want:
Dart Iron Eagle SS 165cc
Dart Iron Eagle 180cc
Dart Iron Eagle 200cc
This engine is going in a early Chevy truck.With a TH700-R4 and a 2400 stall,3.73 GM rear.That I will be driving often.So Im looking for the one that will be the best performance/mileage wise.Good low end and strong mid range,is what im after.Im kinda leaning towards the 180's.But I wanted to hear anyone else's opinion first,before I buy.
 

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Good low end and strong mid range,is what im after.

I wouldn't use a XE274H if that's your goal. I'd stick with a cam under 220° @ .050".
 

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9.5:1 with what sized head chambers? If they are larger than 64cc, I would go with the 200's with 64cc chambers and bring your cr up a bit which will make those 200's just about right. If you are staying with the 9.5 cr then the 180's will be the ticket, imho.
 

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9.5 with iron heads is practically the limit if this is cabureted. Make sure your quench is under .040". If you use this in a truck and plan on low RPM grunt and mid-range the 165 dart heads are adequate, but if you plan to upgrade later go with the 180's. Any larger and you will lose velocity at the lower RPMs. Go with a smaller cam like the Comp XE262. You'll be happy you did. You can run the stock converter with this setup.

I just built a 383, 9:1, dart iron eagle 180/72's, KB dish pistons, GMPP .028 head gasket, zero decked, .035 quench, Comp XE262 cam. Going in my '72 GMC 1/2 ton short bed pickup! Haven't fired it up yet...
 

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My vote goes to the Dart 165 S/S heads and the XE262 cam or equivilant with a 9:1 CR. You will be pleased with the results for what you are wanting. I just built a 9:1 383 with these heads and Z256 Crane cam for a '72 Burban with 3.08 gears and a TH350. The heads were $625 complete and thay had a very nice valve job.
 

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Discussion Starter #7
The motor had a 256H XE cam I did'nt take me too long till I decided it really wanted more.I was looking for more sound at idle.It also had a set of 1968 camel bump heads.But one of the head gaskets blew.And I really did'nt want to deal with the camel bumps.I've had those heads forever.And I only put them on at the time because I did'nt have the extra to get a nicer set.So I decided to go with a bigger cam and converter.
These heads will be a 64cc.I liked the 256H.It had real good torque,mileage.But it sounded more or less stock.Im looking to put a little lump in my idle.Im not worried too much about low end.It's just going to be driven often,I didnt want to choose a head that would bring all top end.I would consider either the 268XE or the 274XE.
 

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I'll just play devil's advocate here. The Dart SS and 180 heads are not spectacular from a flow-per-port-size standpoint. Those heads are built beefy for heavy duty use and they'll take punishment all day, but their performance use is more aimed at the porting scene. There is lots of meat in the walls to port.

Here are some intake flow numbers @ 28"H2O just for the sake of comparison.

The 180s peak their flow at .400" lift with 210 cfm (tested) using a 174cc runner.
The SS numbers I found off the bat showed 222 cfm with pocket ported 164cc runners.
Stock iron Vortecs peak flow at .500" lift with 239 cfm using a 170cc runner

For my money, the absolute best head in your situation is a set of Vortecs. I know its cliche' but they provide more flow with less or the same port volume. They have fast burn chambers (which really are MUCH better) and your 9.5:1 could be tuned to easily run on 89 octane, maybe even 87 if you're careful. Anytime you can get more flow with less port volume, its a no-brainer. You'll reap benefits in velocity from the smaller ports, and hp from the greater flow.

I'm building a 355 right now with vortecs and I expect well over 300 hp with a super mild 208/212 cam. The thing is, your Dart heads will make the same power with more cam, but then you need more stall, more gear, and mileage will get flushed down the toilet.

The vortecs will make more power on the same cam, be more detonation resistant, more fuel efficient, cost about half as much (even with valve lift modifications) and I don't see any reason not to use them. You'll get skeptics talking about the thin decks being crack prone on the Vortecs, but the truth is they don't crack any more than beefier stock heads. Just because the decks are thinner doesn't make them crack prone. Changes in metallurgy and head design make them lighter without compromising strength.
 

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curtis73 said:
I'll just play devil's advocate here. The Dart SS and 180 heads are not spectacular from a flow-per-port-size standpoint. Those heads are built beefy for heavy duty use and they'll take punishment all day, but their performance use is more aimed at the porting scene. There is lots of meat in the walls to port.

Here are some intake flow numbers @ 28"H2O just for the sake of comparison.

The 180s peak their flow at .400" lift with 210 cfm (tested) using a 174cc runner.
The SS numbers I found off the bat showed 222 cfm with pocket ported 164cc runners.
Stock iron Vortecs peak flow at .500" lift with 239 cfm using a 170cc runner

For my money, the absolute best head in your situation is a set of Vortecs. I know its cliche' but they provide more flow with less or the same port volume. They have fast burn chambers (which really are MUCH better) and your 9.5:1 could be tuned to easily run on 89 octane, maybe even 87 if you're careful. Anytime you can get more flow with less port volume, its a no-brainer. You'll reap benefits in velocity from the smaller ports, and hp from the greater flow.

I'm building a 355 right now with vortecs and I expect well over 300 hp with a super mild 208/212 cam. The thing is, your Dart heads will make the same power with more cam, but then you need more stall, more gear, and mileage will get flushed down the toilet.

The vortecs will make more power on the same cam, be more detonation resistant, more fuel efficient, cost about half as much (even with valve lift modifications) and I don't see any reason not to use them. You'll get skeptics talking about the thin decks being crack prone on the Vortecs, but the truth is they don't crack any more than beefier stock heads. Just because the decks are thinner doesn't make them crack prone. Changes in metallurgy and head design make them lighter without compromising strength.
The vortecs won't support the lift he's going to get with that cam and the vortec heads with the mods to support that lift will be as much as a nicer set of dart heads. Plus, he can use his old intake with the darts, a vortec set will require him to buy a new one. I bought my darts fully assembled for 750 bucks, I seriously doubt you can get a modified set of vortecs and the intake for that!

What data are you referencing that the combustion chambers on the vortecs are any more efficient than the darts? I have a 750 holley on my 3700 pound firebird running a 2500 stall and 3.73 gears. 280 comps cam and 388 cubes and it gets 16 miles to the gallon on the highway. By the way, I run 10:1 (thats a conservative guess) and I dont have any problems with detonation.

K
 

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I was going to add that the Dart 165's I bought had some nice heart shape combustion chambers...I was pleased with the build quality.
 

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killerformula said:
The vortecs won't support the lift he's going to get with that cam and the vortec heads with the mods to support that lift will be as much as a nicer set of dart heads. Plus, he can use his old intake with the darts, a vortec set will require him to buy a new one. I bought my darts fully assembled for 750 bucks, I seriously doubt you can get a modified set of vortecs and the intake for that!
We just have different sources. You can buy new fully assembled Vortecs already modified for just over $600 a pair, and they're all over ebay for $300-400. I picked up a rebuilt set modified for .500" lift and pocket ported for $435 shipped with Manley Stainless valves. I also just bought a rebuilt set of stock Vortecs for $300 shipped two day air :) I also may have misinterpreted his post, but he said "I wanted to hear anyone else's opinion first,before I buy." I assumed that meant all the parts, but he could have just been saying the heads. You're right; if he has already bought the intake it won't be as easy. He could sell the intake or return it to the vendor, which is what I would do. I like the Vortecs that much.

What data are you referencing that the combustion chambers on the vortecs are any more efficient than the darts? I have a 750 holley on my 3700 pound firebird running a 2500 stall and 3.73 gears. 280 comps cam and 388 cubes and it gets 16 miles to the gallon on the highway. By the way, I run 10:1 (thats a conservative guess) and I dont have any problems with detonation.
K
Its just test data retrieved from dyno runs. Quench, turbulence, and detonation resistance has just been shown to be a little better on the Vortecs than the Darts. It shows up in the BSFC numbers, emissions numbers, and timing requirements.

I just think that the Vortecs (even modified) are cheaper, have better chambers, flow more with less port volume, and make more power with less advance and less fuel. Its not a huge difference, but why pay more (or even the same) for heads that perform slightly less.

The smaller Dart heads like the SS and 180 are designed primarily for race classes that require them so that racers can port the heck out of them. They are an incredibly high-quality head, no doubt, but out-of-the box performance is not what they're designed for. They're great out of the box, just not quite as impressive as the Vortecs in my opinion.

Any time I can get more flow from a smaller port and less money, I'm happy. Even if the Vortecs cost more, it would be worth it to me for the much better characteristics. For a street engine like this one, I feel confident that its a great recommendation and he'd be ecstatic with them. There is also a huge mental association with big performance names like Dart versus a cheap stock iron casting... But Vortecs are really that good in this application.
 

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Discussion Starter #12
could the vortecs be drilled and tapped for the older style valve covers ?I say this cause I have a really nice set of Polished aluminum valve covers and polished billet aluminum wire holders that I already bought.My friend has a set of reworked 906 Vortecs 7 degree locks and retainers,.500 lift springs,screw in studs and guides,bowl blended,3 angle valve job,stainless 1.94/1.50 valves,and a performer intake.He only wants $500 for the everything because he needs money on his house.Should I pick it up and use those?The only thing is I wanna keep those valve covers and wire holders.
Also on the cam everyone is telling me the cam I choose is too much.Im looking for a mild lope at idle is the 274H too big?
 

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You would be better off with the XE268 for the application you described and a slight lope.....that's my opinion.
 

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bonzipenguins said:
I have a motor specs are as follows:
355ci sbc 9.5:1
274H XE cam
Performer rpm intake
600cfm edelbrock carb
1.52 roller rockers
Im trying to decide which dart heads I want:
Dart Iron Eagle SS 165cc
Dart Iron Eagle 180cc
Dart Iron Eagle 200cc
This engine is going in a early Chevy truck.With a TH700-R4 and a 2400 stall,3.73 GM rear.That I will be driving often.So Im looking for the one that will be the best performance/mileage wise.Good low end and strong mid range,is what im after.Im kinda leaning towards the 180's.But I wanted to hear anyone else's opinion first,before I buy.
Just another reference point.

I bought a crate motor that is supposed to be 430HP. It has the Dart Iron Eagle 200's on it - with some port work by the builder - don't know how much. ENgine now has the Crane Energizer 284 = 228,228 @ .050, 112 LSA. The engine is 10.5 SCR - with the cam the DCR is in the acceptable range - I don't remember the actual number right off hand. The motor has to be run on 91 or 93 octane, but I run vac. advance and all and when tuned properly, it doens't have any detonation problems. And has lots of power. Even with the 284 cam, it idles like a *****cat with the vac advance hooked up to manifold vacuum. I have a 500RPM over stock converter - works great with the combo (though I have 3.73 gears)

I would think the XE274 cam and the 200 darts woudl be great for 9.5:1
 

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You can use the valve cover adapters, but on Ebay you can score a nice set of polished aluminum centerbolt covers for $35 and they'll seal much better. I think that's cheaper than the adapters, and you can sell your perimeter bolt covers and recoup some of the cost.
 

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I just sold my "old style" AFR 195 heads for $800.00, they would have been a good deal for your new motor, sorry. :(
 
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