your thoughts on a street cam

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ir3333

ir3333

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For a 9.5:1 360 with stock x heads and 323 or 355
In an A body..how much cam duration before you start to lose lo end torque?
..214/ 220, 218/224, 224/230? (in/ex)
 
Auto? Convertor? More engine details? Intended use?
 
There's no real answer. What's good for others might be too small for you and your package. I generally stay around 220-225 @ .050 in a mild 360 if it needs to run brakes and pull low down. You can get bigger, depending what you do for gearing and convertor, and what you're happy with driving.
 
A body,4 speed,3.23,9.5:1,stock x heads,stock manifolds
2 1/4" duals...street only
 
The cam works with the cars weight, converter, rear gear and tire size.
The duration has an intended rpm range. It should work with your needs and the above.
If your heads are stock, then I would stay under .500 lift.
If your gear ratio is a 3.55 and your tires are 26 inches (235/60/15) or smaller, generally speaking a Hyd. Flat tapper cam of 230*.050 is a good match for a street machine and the above. The converter works with the cam to overcome the missing (very) low end torque. You'll never know its gone.

If your keeping the stock converter, stay under [email protected]. (A [email protected] is excellent) It will work with 3.23 gears & up.

Adding gear makes torque at the wheel. So a lack of engine torque is overcome by adding gear. Also, adding converter.
 
I run a 230/236 comp xe274h in my 340. 10:1, iron heads. Some port work. 2.02 valves. Has great low end torque. Right off idle it pulls hard to 6000. I love that cam. I wouldn't go bigger though. I idle at 900 for power brakes and steering. But it's not as simple as picking a duration. Like other's have mentioned there is more too it. One thing to watch when picking a cam is the change from static to dynamic compression ratio. For top performance. You want 7.5 dynamic on iron heads. That generally is the limit of 91 pump gas. Other considerations aside of course.
 
Hummmmm, nice combo, I like it.
What else is on that baby?!?!
 
rumblefish360 said:
Hummmmm, nice combo, I like it.
What else is on that baby?!?!
Click to expand...

I assume you mean my setup?

340. .040 over. Keith black +6 flat top pistons. 1.88 style J heads redone with 2.02 intakes, while they did the bigger valves they cleaned up the bowl/the turn in, then said "while we're in there" and cleaned up the runners, not a full port job but a good cleanup for better smoother flow. Blue printed. Balanced. RPM airgap. Comp XE274H. Stock stamped steel rockers. Holley 670 street avenger. Exhaust manifolds, x pipe and tiny 2-1/4 exhaust with some turbo style chamber muffler. Should be good for around 400 horse. Pulls hard. I surprised and beat one of them new fancy Camaro ZL1's the other day. Had him off the line, even with my tiny 205's I had on then that basically laid rubber through all 3 gears. He was starting to catch up when we decided to back off. Smoked some mid 90's GM f-body with ease (not really something to brag about I suppose, shooting fish in a barrel).The 245 cobras now hook decent. Some spin off the line but after about 10 feet they just go.

Going FItech 600 power adder throttle body. 1-5/8 hookers 3 inch collectors. Into 3 inch H pipe then dynomax bullet mufflers dumped right after the muffler. Hoping to get into the 420/425 horse/torque area with the new exhaust. With 727 transmission. Cheetah manual/automatic throttlebody. Custom torque converter (haven't decided which yet). 4.10 ratio 489 case. If I saw 350 at the wheels I'd be happy. As for the future? Who's to say. The goal this year is N/A 12's. Nitrous 11's maybe. Next year? N/A 10's?

Overall a solid street setup in my opinion.
 
Ya you Luslte, thanks for listing the combo and I do believe you went over 400HP in the first list.
For sure a nice solid street combo.
F bodies? Smok'em if ya gottem!

ir3333, 4spd's rule. Love to row my own boat! But it is crazy hard to beat a good automatic and a worthy driver. Doesn't bother me none on the twisties or on the back roads.
 
ir3333 said:
4 speed...
i won't have a 3000 stall converter for a high duration cam
Click to expand...

Nice suddenly the focus is on someone else's car in your thread.

I think the largest of the three will be fine since you have a light car and a 4 speed. I think it will be just right.
 
I would think with a 4 speed you would go bigger than automatic. The rule I've always heard is what you run in an automatic, you run one step (5* duration) bigger in a manual. As they generally live at higher RPM. I would think you wouldn't see loss of torque until past the 230 mark. And even then, you wouldn't notice it. We'd be talking maybe 5 ft lbs kinda thing.
 
It's not that you lose torque. It gets moved up the rpm band. Actually bigger cams and heads help torque per cid. To me if you need a cam bigger than say a comp cams xe275h for a pure street car your probably building to small of an engine.
 
ir3333 said:
For a 9.5:1 360 with stock x heads and 323 or 355
In an A body..how much cam duration before you start to lose lo end torque?
..214/ 220, 218/224, 224/230? (in/ex)
Click to expand...
Wonderful cam,with your setup,Crower 31916.. Short advertised,semi quick ramps,works with fresh 340 replacement springs.. Really likes a 2400-2800 stall..
 
ir3333 said:
4 speed...
Click to expand...
As said, that makes it easier to go with a larger duration; you can rev over a dead torque range when taking off. But you can still kill it to where it is truly dead below a certain RPM; keeping the DCR up as noted avoids that.

What you do end up fighting is the RPM range if you go too big: With certain large steps in manual gearing, you can drop into a dead RPM zone with too aggressive a cam and a long gear step after the upshift. In general, I would also be thinking about where the top usable RPM will be with the stock head flow (and other parts like intake and exhaust), and with the tallest gear step (1-2 or 2-3), see what the low RPM is right after the upshift.

But, off the cuff, I don't see any of the durations you list as being quite so big as to cause this problem; you're just gonna slip the clutch more with the higher durations. So that kinda brings up the age old question: how will you being using this combo?

FWIW, I had a 4 banger race engine with a 300-ish (advertised) duration cam and a miserable DCR that made the usable RPM range 3800-8000 RPM.... that was indeed a problem on the 2-3 shift. A 2:1 usable RPM range is not very useful in most applications LOL.
 
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The manual Trans cars use a "Next step up cam and gear ratio" to match the automatic trans cars in performance.

As a note, he mentions lack of torque. It was said your not missing/loosing the torque, it moves up in the RPM range.

This is what the poster said in his first post. At what point does it leave the lower end? Which depends on the gear ratio and tire size and if you have an automatic trans, the stall of the converter. The OP gets this.

But at some point, there comes a dead spot on the lower rpm range that nothing overcomes. It's just flat despite a gear ratio, tire size and converter increases or even over increases.

I agree, none of the cams listed will be a problem. Also in the OP's car, a 4spd manual, I would certainly go for the bigger cam.

I have run a manual for the hot rod almost my entire life and had a hard time relay hung things up for a better more rounded package. Thanks to this forums members, I have a much better handle on it.

I also like the thoughts on not neediest a bigger cam than the XE275 for a pure street engine /car set up. There should be plenty of power available for that. A OD trans (4or5) or a 5 or 6 spd manual would be a monster on the road.

Ir3333, I think your set up will be very good. If your going to have stock size tries on the rear or to a max of 26 inches, I would use the 224 duration cam. Ether gear ratio would work but I myself would choose the 3.55's.
 
I have a Lunati 10200704 (60404) in my 340. I don't think I'd want to go any bigger for a car that's used frequently on the street. For a "weekend car" or a street/strip car I think you could still do a little more, but IMO anyway I think I'm at the limit for a daily driver. With 3.55's and 26" tires there's a bit of a flat spot if I just let the clutch out normally, to take off strong requires a bit of clutch slip and a rapid increase in rpm's and then it's more like launching than typical street driving. It's not horrible, but the next cam smaller would probably be easier to drive. That would put you at the top step of the three durations you listed, the cam I'm running is a bit past that top step.

Specs on the cam:
Lunati 10200704 (60404)
Basic Operating RPM Range:2,200-6,400
Duration at 050 inch Lift:234 int./242 exh.
Advertised Duration:276 int./284 exh.
Valve Lift:0.513 intake/0.533 exhaust
Lobe Separation (degrees):110

Specs on my engine/car
1968 340, .060" over, KB 243 pistons
compression 9.8:1
308 heads, 2.02/1.60, stage II ported and flowing 264 cfm @ .500"
Eddy air gap rpm intake
Holley 750 Ultra DP
Doug's headers
Lunati 10200704, 1.5 ratio crane ductile iron rockers
2.5" dual exhaust with dynomax ultra flow's

8 3/4 rear, 3.55's, 26" tall tires, 833 4 speed. All in a '74 Duster that's been converted over to '71 Demon parts with a decent amount of chassis stiffening. Probably 3,300 - 3,400 lbs realistically.

Here's the old girl at idle...

 
very helpful guys...with 3.23 i'm leaning toward
Comp XE262 218 224 .462 .470 or
Lunati ...702 220 226 .475 .494
...look to be sweet from a low of 1000/1400 and pull hard to 5500/5700
with 3.55 maybe XE268 or ..703
 
I have a 703 in the 318 for my Dart, but I haven't put that one on the road yet so I don't know how it'll behave. That's one's an auto though, Lunati recommends a 2400 rpm stall. If I don't go with a custom convertor it'll probably get a hughes 3k stall convertor, based on the way they rate them it should stall around 2,500 with the small block. I fully intend to run it with 3.23's, I don't think it'll be a problem. I bought a 702 for that car originally, but I got a little carried away and put a set of RHS heads on it and decided that it needed a 703 to not completely waste having bought the heads. Based on how the 704 performs I don't think the 703 will be any problem at all on the street. The 704 is totally manageable, I drive the Duster close to 10k miles a year and frequently do boring stuff like get stuck in traffic. It's a little much, and it runs a heck of a lot better with a little peddle behind it, but it's not horrible. If I weren't using the car as a daily it would be perfect.
 
If you put in the XE268H -or a cam on a similar pattern. I think you would be very happy. They are known to be low end torque monsters. Guys commonly put them in 318/360s on their trucks to give them grunt and pull.
 
My truck has the XE262 with stock heads, stock pistons. It idles well, and will pull right off idle. I think, if it were me, I'd go up one to the XE268. The better compression and much less weight will be fine with it. The 262 will work, but I think the 268 will work, without hurting - if that makes sense.
 
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