Ok here goes:

350 engine, .030 bore. Will be using a Weiand action plus dual plane intake p/n 8004 and a pair of Hedman headers with 1.5 inch primaries. These headers feed into 2.5 inch collectors and are mated to 2.5 inch dual pipes. Current cam is a Crane, not sure of specs but I'm going to upgrade with a Comp magnum 280 cam.

I want to upgrade my stock 993 heads with either Sportsman II heads or Dart Iron eagles. Both will have 64 cc chambers, 2.02/1.60 valves and 200 cc runners. However I'm wondering how well will these heads work with the 1.5 primaries/2.5 collector headers? What about the intake? Replacing the headers aren't an option. Would these heads work with these headers? Or should I go with Edelbrocks performer rpm heads? (The performer rpm heads also have 64 cc chambers and 2.02/1.60 valves but 170 cc runners)

i think your headers are kinda small for 200cc heads.the 170cc heads will probably work better.the 200cc heads need plenty of air in/out and your headers would probably hold them back.you should make good low rpm torque with your intake/header combo.its too bad replacing those headers isn't an option,you could make mucho power with the 280 magnum cam and the rpm heads.if you could go with a rpm intake and 1 5/8-3" headers so much the better.

oh yeah,i used to run the comp 280H magnum,great power! :D

If i'm not mistaken Dart offers a 165cc version of their Iron eagle.

At the most i would look at 180.

So in other words, a 200 cc runner head will not flow it's very best because of the 1.5 inch primaries? But a 180 cc runner would be the max I could go without restricting the air flow?

Also anyone know how well the Weiand action plus dp intake flows?

ttt

Originally posted by Junkyard Dawg:
So in other words, a 200 cc runner head will not flow it's very best because of the 1.5 inch primaries? But a 180 cc runner would be the max I could go without restricting the air flow?

Also anyone know how well the Weiand action plus dp intake flows? =
With the engine it sounds like you are doing a 180cc head (or the 170's)will work better as would a little less cam.
Something like a Lunati 301A6LUN or Comp 268AH but I ain't the cam guru :D
The 200cc heads will flow more air but there is more to it than air flow numbers.
In almost all cases an engine will run better & be faster with a smaller head of about the same design if the head is large enough to support the HP you plan at the RPM you plan to run it to.
Again, in most cases a larger head will do nothing except slow the air down & become less efficient except possibly at higher RPM assuming the head you have is large enough.
You may make more peak bragging rights HP but you will very probably run slower.
I have no experience with the Weiand action plus as I normally use the EDE Performer series for a dual plane. Performer, RPM & Air Gap.

I believe the 165cc heads Brian mentioned are the street replacement ones like the World SR's not the performance Darts.

If you want a really nice head my choice would be the AFR 180 ;)

Well, the intake I want to use is good from idle to 6k and the cam I want to use is good from 2k to 6 k. The engine will see street and strip duty. With a 3.42 posi rear (may change to a 3.73 posi later) the engine sees the 2k-3k range unless I'm just creeping around town. So I guess what I need to know is what Dart head would work well in this combo?

Originally posted by Junkyard Dawg:
Well, the intake I want to use is good from idle to 6k and the cam I want to use is good from 2k to 6 k. The engine will see street and strip duty. With a 3.42 posi rear (may change to a 3.73 posi later) the engine sees the 2k-3k range unless I'm just creeping around town. So I guess what I need to know is what Dart head would work well in this combo? =

The 180

I agree with Wolfplace, the 180 Darts would be about perfect for the rest of your goals.

The 165s are really too small for a 350.

I'd suggest the Comp XE262 or XE268, or one from another mfr with similar duration (218-224) and the larger exhaust lobe. Get the heads set up with 1.45" springs such as Comp 987 (I think that's what Dart uses as their stock one for that diameter, actually), in case you want to bump the cam up a size or 2 late rin their life.

From what I can recall that intake flows a little better than a Performer but nowhere near a Perf RPM.

Well I think I'm sold on which sized runner to get. Now I gotta decide between the Darts and the Performer RPM's. I'm after the most performance I can get.

The standard performer intake is good up to 5500 rpm. The intake I have is good up to 6k rpm and the performer rpm is good up to 6500 rpm.

What's so special about the 268H cam? Looks like it's a basic street cam. Plus it says these cams are good for 8.1:1 to 9.1:1 c.r. With my current bore and stroke and those 64 cc heads I'm guessing my c.r. will be closer to 10.0:1

The magnum cams they say are for higher c.r. engines with higher stall converters and lower rear gear ratios.

The magnum cam I want makes power from 2k rpm to 6k rpm. That should go with my intake.

A flat piston, 64cc heads, 6cc valve pockets, and a .040" quench distance is about 10.14:1. With the 280 cam the DCR is about 8.02. This is excellent. A good DCR with little worry about detonation. The smaller headers, IMO, should help build low end torque but be a restriction at higher rpm. It may pull all the way to 6000 but power might be down from what a 1-5/8" header would give you.

As for heads, I'd go with the 180 port but look at the chanbers. An old stock style chamber will cost power. You want one of the newer "Fast Burn" designs. I'm not familiar with either head. The aluminum Edelbrock might cost you power with the CR you have because it will pull heat out of the chamber faster than iron. I'd recommend bumping up the CR to 10.5 (8.29 DCR) for the aluminums. You could have the Eddy's milled to 61cc to do this.

Originally posted by Junkyard Dawg:

What's so special about the 268H cam? Looks like it's a basic street cam. Plus it says these cams are good for 8.1:1 to 9.1:1 c.r. With my current bore and stroke and those 64 cc heads I'm guessing my c.r. will be closer to 10.0:1

The magnum cams they say are for higher c.r. engines with higher stall converters and lower rear gear ratios.

The magnum cam I want makes power from 2k rpm to 6k rpm. That should go with my intake. The 268AH is not the same as the 268H.
The 180 dart have the good chamber the 165 do not they have a stock chamber & 1.94/1.5 valves unless Dart came out with a new head.

The Cams RB recommended are also not the standard 268H.
The AH series is in the marine section & the ones RB listed are XE series cams.

Originally posted by RB69SS396Conv:
I'd suggest the Comp XE262 or XE268, or one from another mfr with similar duration (218-224) and the larger exhaust lobe.What's the specs (gross lift, advised duation, duration at .050 in, lobe seperation, powerband range, idle quality) of those two cams you have listed?

TIA! :D

http://www.compcams.com/catalog/056_057.html

Looks like somebody hijacked their home page.... check out www.compcams.com (http://www.compcams.com) quick, no doubt they'll fix it as soon as they get to work

Looks like the CR is a bit high for a 262 or 268 cam. DCR comes out quite high for a pump gas engine. You could run the 268 with the Edelbrock heads (DCR 8.38 with the 268), but that's pretty high for a street engine that needs to run many miles between tear downs. About the smallest cam I'd use is a 272 for a DCR of 8.27.

Thanx Pat. What's the DCR you keep referring to? What does it mean and how does it work?

Well after reading something on compression ratios this morning I'm starting to wonder now if I should go with a 70 cc chamber head instead of a 64 cc chamber head? Both Dart and Edelbrock have these cc chambers in their selections. Remember I currently have a 75 cc chamber head.

I'd like the c.r. to be around 10.0:1, and be able to run off of 93 octane pump gas. I figured this would give me the best performance with pump gas.

But since I didn't build this engine I dunno if my engine has the right internal parts or not. I read that higher c.r. engines require stronger bottom ends and I don't know how well the bottom end is built, plus I don't know what kind of pistons I've got.

I'd hate to order my parts only to find I can't use them. Worst I'd hate to put this engine together only for it to blow up later.

So that's got me wondering if I'd be better off with a 70 cc chamber head over a 64 cc chamber head?

Follow the link in my sig to the Dynamic Compression Ratio page. Basicly, it takes the cam into account, using the intake closing specs. It's not perfect but works pretty well for determining the octane needed in a particular CR/cam combo.

Mike's advice is dead on, you want the 180cc intake ports.

the exhuast ports should match up fine.

I have a 200cc intake runner Sportsman II head. I had to work the 1-5/8" flanges a little to get it to not overlap the port, but ONLY becuase the flange was a round port, not retangular like the exhuast port.
No big deal.

Thank Guys I've decided on getting a pair of heads with 180 cc runners. Now I gotta decide if I want 64 cc chambers or 70 cc chambers. Since I dunno what this engine has in it I'd hate to get the wrong stuff.