What camshaft would be best with my setup?

200ci66

Well-known member
200 block
250 head w/ large log intake modified with a Holley 5200 direct mounted. Also had sixty thousandths taken off.
1.6 rockers
Split headers w/ the port divider and cherry bombs
Running a 68 distributor with pertronics but thinking about switching to a DUI
3.20 gears in rear end

2200 stall converter with a stage 2 kit freshly rebuilt tranny. Thinking it's a 71 or a 72 tranny. Currently I shift at 5000 rpm.

I have a lot of pull in first gear, but after shifting into second I feel like I loose a lot power.I know it's hard to say without a dyno but I'd like more power in the 3500-4500 rpm range. I might be talking crazy, but from my understanding with a higher thank stock stall converter I can sacrifice some lower end torque with higher end power. Can someone educate me specific to my application what would be best? I know it depends on what I want exactly.. I do drive it on the street quite a bit but I'd like better times. My last question is; how exactly do camshafts hurt drive ability on the street? I've heard people say to stay away from radical cams in street cars and I've heard from others it's one of the best things to do for power.
 
first decide what rpm range you will be running the engine in about 80% of the time. for instance, for a street engine, you want a cam that makes power in the 1000-4500 rpm range. you can fudge these numbers a by about 500 rpm or so, but try to keep them close.

then look at as many cams in that rpm range as you can and select the one that would work best for your application. for instance, in your case i would look at cams in the 286-272 advertised duration range from a variety of manufacturers. i like the comp cams 268h grind for instance, but comp does have a couple of grinds that might work for you as well, as does crane, and other cam grinders.
 
Thanks for the input, that gives me an idea for what range I should be looking at. What is the rpm range for a stock cam by the way?

From the selections on Classic Inlines, I was looking at a couple cams in the 274 range. One in particular lists its rpm range as 1400-5100, however most any higher than 264 say that the recommend a manual trans or a stall converter. Does my 2200 rpm cut it? Final question, when cams are listed as 264/264 108* for example, what exactly does the 108* represent? I know the 264 is the duration.. Thanks in advance.
 
200ci66":2ccics7j said:
Thanks for the input, that gives me an idea for what range I should be looking at. What is the rpm range for a stock cam by the way?

the stock cam works in the off idle to about 3500-4000 range.

From the selections on Classic Inlines, I was looking at a couple cams in the 274 range. One in particular lists its rpm range as 1400-5100, however most any higher than 264 say that the recommend a manual trans or a stall converter. Does my 2200 rpm cut it? Final question, when cams are listed as 264/264 108* for example, what exactly does the 108* represent? I know the 264 is the duration.. Thanks in advance.

a 220 rpm stall converter will work fine for that cam. the 108 degrees is the lobe separation angle, that is how far apart the centerlines of the lobes are to each other. the wider the separation angle, the higher the dynamic compression ratio, the more torque the engine puts out at lower speeds.
 
To not kill your lower end power, i would run the Clay Smith 264-264@112 L/C 4 degrees advanced.
If you want more low end go with the Isky 262 super cam 2 degrees advanced.
 
So in other words, literally any of the cam selections on classic inlines offers a giant improvement on the stock camshaft, if it really works at that low of an rpm range.

rbohm":2o5nulzx said:
200ci66":2o5nulzx said:
a 220 rpm stall converter will work fine for that cam. the 108 degrees is the lobe separation angle, that is how far apart the centerlines of the lobes are to each other. the wider the separation angle, the higher the dynamic compression ratio, the more torque the engine puts out at lower speeds.

So if my engine is already at very high compression (180 pounds in each cylinder with no more than 10 pound variation) would I want a small lobe separation or a wider one?

And if the wider the angle the more low end torque, would a wider angle be better for a street engine or the other way around (wider lobe separation seems to create much higher rpm ranges, some don't start till 2200 or higher). Right now I'm leaning towards a 264/274 or a 274/274 cam.


EDIT: Wsa - I'm seeing a cam with the same specs showing 2000-5700 rpm and that is pretty close to what I'm running, maybe a tad bit high but I guess that's what I have the torque converter for.
 
200ci66":3k1potom said:
So in other words, literally any of the cam selections on classic inlines offers a giant improvement on the stock camshaft, if it really works at that low of an rpm range.

yes and no. it depends on what you want out of the engine. just sticking a big cam in a stock engine isnt going to give you any improvement, in fact it can even degrade performance. select based on the rpm range as i noted before.

[/quote]So if my engine is already at very high compression (180 pounds in each cylinder with no more than 10 pound variation) would I want a small lobe separation or a wider one?[/quote]

if you are running high compression then you do want the narrower separation angles to prevent detonation at low rpms.

And if the wider the angle the more low end torque, would a wider angle be better for a street engine or the other way around (wider lobe separation seems to create much higher rpm ranges, some don't start till 2200 or higher). Right now I'm leaning towards a 264/274 or a 274/274 cam.

the problem is that the charts for cam rpm ranges are wrong. wider separation angles means lower rpm range. the reason is that it traps more cylinder pressure at low speeds.
 
Wont a narrower lobe separation result in higher dynamic compression and theoretically a lower rpm power range than a wide LSA?
 
My 200 has the 264/274/112 advanced a tooth with a stall of around 2200 on a slushy C4.
The head is fully modified except I still have only the 1bbl carb. Stock exhaust.
I can tell you that it really starts to pull at about 3000rpm and on my setup tops out at just over 4000rpm and just wants to keep going but the engine runs out of air.

The obvious thing is that this cam can really rev up if it's got good induction.
I was recommended the 112 by Mike for an easier idle and more vacuum for the transmission.
Since you have headers you can take advantage of the 264/274.
 
Did some calling around -

One recommended 268/270 *10
Another recommended 272/272 *8

The man at Clay Smith sounded pretty sure that street engines run best with *8 so to not sacrifice low end. The duration of both these cams are pretty close as are the rpm ranges (1800-5500 and 1900-5600). Any thoughts on the 8* vs 10*? Would 10* set me back quite a bit on the low end and would I have to worry about preitgnition with a 10?
 
If you go with a 108 L/C you will kill your idle quality on any camshaft 264 or over 214 degrees @ .050" lift.
The torque converter will strangle the engine with that duration with a 108 L/C.
If you lower the duration for more low end, you can get away with a 109 L/C.
The Isky 262 super camshaft because of the shorter duration can get away with the 109 L/C.
 
XMFalcon221":2r0q8dgj said:
Wont a narrower lobe separation result in higher dynamic compression and theoretically a lower rpm power range than a wide LSA?

no, what happens is with the narrower lobe separation angles, you get higher valve overlap, and from there you have compression leaking out the exhaust until the exhaust valve closes. at low speeds that bleeds off compression pressure, which reduces the dynamic compression ratio at low speeds.
 
I wrote a little script to compute SCR and DCR based upon block, head, and cam specifics. If I did my maths right, this would be right about where you would end up with a 264 *10 cam, advanced 4 deg. I use 2.17 cc per 0.010" milling of the head and I arrive at ~49cc (assuming the head was at 62 cc before mill and you removed 0.060"). I also assumed the Felpro gasket as opposed to the Corteco.

===================================
Cylinder Bore = 3.68 in
Deck Height = 0.019 in
Gasket Crush Height = 0.05 in
Gasket Diameter = 3.81 in
Combustion Chamber Volume = 49 cc
Piston Dish Volume = 6.5 cc
Advertised Cam Duration = 264 deg
Lobe Separation Angle = 110 deg
Camshaft Advance = 4 deg
Intake Valve Closing Angle = 58 deg
===================================
Static Compression Ratio = 8.99:1
Dynamic Compression Ratio = 7.60:1
===================================

Disclaimer: I've been fiddling with this script so I might still have some minor errors to deal with, but in general, the numbers come out about right.
 
I agree that you have more valve overlap with a narrow LSA for any particular camshaft duration but the exhaust valve is closed during compression so this shouldn't bleed any compression pressure, the intake valve is still open at the start of the compression stroke though so this will bleed pressure however for identical cams with a different LSA, the narrow LSA cam will close the intake valve sooner than the wide LSA resulting in higher dynamic compression?

The valve overlap period is at TDC between the exhaust and intake strokes which results in communication between the intake and exhaust ports which affects vacuum and therefore idle quality

As an example using my engine specs, the DCR with a 108 LSA is 8.59:1 and with a 112 LSA it is 8.29:1

This is my understanding anyway but I've been wrong plenty of times before :mrgreen:
 
I think you will be happier with a 110 cam centerline. If you are worried about low end grunt just advance the cam 2 to 4 degrees. Just my 2 cents. ;)
 
XMFalcon221":1kr57n3z said:
I agree that you have more valve overlap with a narrow LSA for any particular camshaft duration but the exhaust valve is closed during compression so this shouldn't bleed any compression pressure, the intake valve is still open at the start of the compression stroke though so this will bleed pressure however for identical cams with a different LSA, the narrow LSA cam will close the intake valve sooner than the wide LSA resulting in higher dynamic compression?

The valve overlap period is at TDC between the exhaust and intake strokes which results in communication between the intake and exhaust ports which affects vacuum and therefore idle quality

As an example using my engine specs, the DCR with a 108 LSA is 8.59:1 and with a 112 LSA it is 8.29:1

This is my understanding anyway but I've been wrong plenty of times before :mrgreen:

valve overlap is when both valves are open at the same time. this is generally right near TDC on the exhaust stroke, so perhaps i shouldnt have said you bleed compression pressure, though that is the net result. what i should have said is you lose cylinder filling at low speeds, which does in fact compromise cylinder pressure. it does affect the dynamic compression though, and that is what is key, especially at low speeds when you are wanting to build low speed torque.

also note that forced induction engine builders will decrease valve overlap to increase cylinder pressure at low speeds, especially when the engine starts seeing boost pressure, to maximize cylinder pressure at lower speeds. at higher speeds it doesnt have as much effect, though you still have to take dynamic compression into account then as well.
 
my experience with a 264/274 110LC .450Lift

it was too much on exhaust... and the loob was agressive... what helped the MOST tuning wise was a re-curve... WORLDS different...and I was running a t5.

IF i was to do it again... I'd go either 260/260 110 .450 or 258/258 112 .450 for more low end and better vacuum. 264/264 112 .450 would be good choice but I prefer the others.

that's my $.02

good luck with build!
 
What other parts would I need? Obviously lifters, but would I need to change the length of pushrods or my valve springs.
 
I see 2 that have posted are running a 2,200 stall converter......what are the details.....manufacturer.....do they actually stall close to 2,200?......much of a noticeable improvement.....thinking of doing this on my tri power with comp 260 cam...sorry to stray off the main subject........
 
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