weaz4200

iTrader: (2)

Does anyone here actually understand cams? N I'm not talking about basics, but really know them... So much so that they can figure out which one would be the best for any given application... I need to speak to someone that can answer my questions and back up their answers... Someone that can give me facts, not opinions. I don't need suggestions, I need concrete evidence. If there's anyone that can actually do this, let me know... Thanks.

dimented24x7

iTrader: (2)

There are people here who know a lot about cams, but not too many mind readers, last I checked .

Stating what your trying to achieve would be a good start to getting towards a cam selection. The intended usage, engine type and displacement, heads, CR, and induction system, and desired RPM band are some good things to establish for starters.

sofakingdom

iTrader: (1)

Yes, there are those here who do.

Misalignment with reality about intended usage (such as, high school kid wants to go "road racing", whatever that is supposed to mean, or "drifting": if I see those words in a post, I RUN AWAY from even trying to help), excessive emphasis all the way around on "cheap", extremely inaccurate compression ratio "calculations" (usually with critical pieces of data left out and plenty of "I used such-and-such calculator are you saying it's not right???") which you can usually spot either from lack of knowledge about the parts list ("I don't have a part # for the pistons and I don't know the deck clearance and I don't know the chamber volume of my heads but I know it has 10.473:1") are all good signs that any cam choice is going to be a disaster.

Another common mistake is buying a cam for the motor you're "gonna build someday", instead of the one you're building RIGHT NOW. Cams are CHEEEEP in the grand scheme of things; NEVER EVER buy any cam except THE PERFECT ONE for just exactly the motor you are building RIGHT NOW. If you change it, then buy THE PERFECT CAM for that new one at that time.

What issues have you had with whatever cams whoever has recommended for you in the past? That's another clue to what cam would suit you better.

AlkyIROC

I've gone through at least 4 cams in the last 10 years. Each time the engine gets upgraded, the old cam isn't good enough. I just finished installing a new cam. The heads I installed last year are much better than the ones I had before. The old cam worked well with the last heads but although it works with the new heads, it just isn't allowing the heads to do their full potential. This new cam should be perfect. This new camshaft was only $400 but it's also one of the high end camshafts.

Playing around with Desktop Dyno, you can do a lot of "what if" with camshafts. As long as you have good accurate numbers for the calculations, you can see what kind of changes a cam swap can do but it also depends on what you want the engine to do. Having a camshaft that starts building power at 4000 rpm when you're going to use it as a daily driver isn't a good combination.

Camaro305SB

Camshaft and engine displacement/compression should be the FIRST things decided on when building a race engine, at least an NA one. Camshaft determines where you make power, displacement more/less is how much air and fuel you can take in. Everything else you put on, like cylinder heads (which also play a part in displacement/compression), exhaust systems, intake, etc is just optimizing the cam and displacement/compression ratio.

Apeiron

Head selection is first. How much air can flow in and out of the engine determines how much power it can make. The displacement determines how many RPM the engine needs to turn to exhaust that airflow potential. Match the camshaft to that, and then optimize the other components.

weaz4200

iTrader: (2)

Wow, more replies than I had anticipated this quickly. I'll state what I'm doing so long as I don't get answers like... "Go with "XYZ" because it will work the best", I need to understand why its the best choice. Here goes...

Currently, I'm doing a 305.... Please refrain from statements like 305's are a waste of time, 305's suck, etc....

It's gonna be a daily driver.

I've got...
5 cc speed pro pistons
A set of 081 heads
Holley Street Dominator Intake
Re-ring kit with a .045" head gasket

Now with the .045 head gasket I'd have a 9.27:1 SCR
Might go with a shim gasket which will give me a 9.84:1 SCR

The 081's are going to be ported to allow for slightly better flow. (If need be, modified to allow for more lift)

Right now the rear gears are stock.. Its a 92 Camaro, so probably 2.73's. But I will change up the ratio to whatever the cam will need.

Torque convertor is stock for now as well... (same applies here, will be changed per cam requirements)

Also most likely a 570/600 CFM carb (not too sure yet)

So now the questions begin.

How do you choose the best possible lift/durations/overlap? Where would i start first?

Orr89RocZ

iTrader: (20)

Main items to look at are desired rpm range using the heads/intake/cubes you have. Based on head flow characteristics, valve sizes, and if possible cross sectional areas of the port, you can get an idea of what the valve lift curve should look like to best pick the valve events needed for the engine combo and useage.

Things like port velocity also come into play in determining the cam valve events and lobe lift. Rod length is another that can make a slight difference in performance and a cam valve events need to be selected to account for that.

How the head port behaves will determine rate of valve lift (acceleration) and the overlap needed. Usually lobe designs are picked with certain timing events at various lift points and that will give you an idea what the intake and exhaust centerline are degrees, and from that the lobe seperation (LSA) is determined.

There are some really good software programs out there that can be used to determine "optimal" valve events as long as the information is accurate. Most custom cam companys should have something like this and use it to select/design lobes. Also they can make selections from dyno/track/racing experience.

For the absolute best cam, a custom grind from a reputable and knowledgable grinder/company will produce the best results but you need to give them information. Get your heads cleaned up and ported, then flowed to get an idea of the flow characteristics for the port. Even flowing it with the intake manifold attached helps to see that actual flow the head port sees and that can influence cam choice.

Its not all that difficult to guess what duration and get an idea of what lift you may need for an application to "work", but to select actual timing events becomes a good bit more challenging to be optimal. For instance, your setup looking for good daily driver manners but some performance with ported heads and decent intake/carb combo, i'd probably go with a hydraulic roller (assuming its a roller block) with around 218 deg duration at .050 and around .500" lift. 10 deg more than stock to peak near 5800-6000rpm range. A strong runner for sure but with good manners.

InjectorsPlus

iTrader: (1)

To give an honest answer, I have not seen many people at all who understand cams on forums. Very few on hard core racing sites, but on forums, no not that many, and honestly not on this one.

Cam selection has to do with compression, operating range, intake capability, head capability, etc....

I will give you the same advice I give everyone....if you really want a STRAIGHT answer on a cam, call BULLET or CROWER those guys actually know their stuff and make a great product to back it up.

I have seen too much garbage on forums about cams pass as information. Talk to the experts. The cam is the heart of your engine, if you get it wrong, or mis match the other components, you'll pay.

http://www.bulletcams.com/

http://www.crower.com/

AlkyIROC

You could have 3 different cams all with the exact same lift, duration and overlap but all 3 could perform differently. It also depends on the valve timing. When the valves actually open and close during the cam rotation. Intake valves that close earlier can make more cylinder compression etc.

Chances are if you try 10 different cams all very similar in grind, you won't notice much of a difference. You need to do big cam changes to notice a big difference. Identical cam grinds but one has 112 LSA and the other is 108 LSA is a big change. Going from 240 duration at .050 to 270 is a big change etc.

sofakingdom

iTrader: (1)

EXACTLY what I was talking about above, re. compression ratio. You hit the head right on the nail. This is a prime example of where cam selection takes a left turn down the dirt road, misses the curve, goes off into the weeds, and ends up in the pond.

You left out the DECK CLEARANCE. This is how far below the deck the pistons are, at TDC. Stock, they miss making it up there by .025", -.000" +.010" more or less. Those pistons ADD .020" to that. Therefore, your pistons leave about .045" - .050" up there. Your ACTUAL compression ratio will be down in the 8s, unless you have the block decked to the pistons.

IMO the cam is THE VERY LAST component of the engine to select. Heads & short block are first, rest of induction is next, cam and peripherals such as carb and ignition are last.

Camaro305SB

How do you know how much air you need to flow if you don't know what RPM your target horsepower/torque is going to be or how much total volume you are displacing?

Apeiron

Air flow requirements come from your target power level.

sofakingdom

iTrader: (1)

Each molecule of fuel releases a certain amount of energy when burned.

Each molecule of fuel requires a certain number of molecules of air.

Therefore, to get a certain amount of energy, you need a certain amount of air.

The definition of power, straight out of your high school physics book, is energy per time. Therefore, all it takes is a conversion factor, to get from CFM of air (air per time) to power (energy per time).

The induction system, including the heads, carb, intake, & exhaust, is chosen to support that flow level.

RPM is ultimately determined by power and CID. The higher the CID, the lower the RPM has to be to reach a certain power level.

Once the desired CID, induction system, and RPM are known, a cam can be chosen to fit the requirements.

This is why the cam comes at THE END of engine design, not the beginning.

Orr89RocZ

iTrader: (20)

Based on your engine parameters (stroke/rod length, bore, etc), you can calculate piston cfm demand for a certain rpm and that will determine head cross sectional area and flow required to hit that point. The amount of flow you get thru that cross section and valve size can determine the power made at that rpm.

I guess target power and rpm go hand in hand, but I'd select the heads based on a target RPM for the motor and then select the cam. Worry about the power it makes later unless you have a power cap for a racing class or something.

Apeiron

For a street engine there are slightly different considerations, like keeping RPMs within comfortable limits.

Orr89RocZ

iTrader: (20)

True. When I built my 383, I had a goal of peak power in the 6200-6300 rpm range as the PE mode fuel control in the 6E chip code could only go to 6400, so I thought I'd leave peak power below that point so I could get good fuel control. I selected heads that i knew would support the rpm range for that 383 setup. Then I sent out the request for cam thru a custom grinder. I did give a target hp based on his LT1 setups I've seen dyno'd across the internet, but I reallly wanted to target the peak rpm and let HP fall where it would fall.
Although the cam turned out different than what the LT1 cars got with similar components minus the intake manifold (and different from what I was expecting) it did peak right at 6250 rpm held power to 6500 and made my 400whp requirement....I think rpm is a good way to select heads/cam. Heads will determine the rev range available to the motor, and the flow curve of the head will determine the cam specs.

weaz4200

iTrader: (2)

No i didn't, with the piston at TDC i get 4.49 cc's. As far as cam being chosen last, thats true.. This is why I posted a list of parts...

305
9.84:1 SCR
Idle-5500
Street dominator intake
570 CFM street avenger
eddy headers with s 1 5/8 primary and a 2 1/2 collector
081 TPI heads with 1.84/ 1.5 valves 1.5 rockers

There's the whole engine setup... What else you need to know?

You guys need to give me a little more as far as how its done. Not just what parts contribute. I know that heads/intake/cubes play a role.. I need it broken down for each specific component...

Orr89RocZ... You need to elaborate further... I'd like to know how you came to the conclusion that those are what will be good..... I already had cams recommended to me by cam companies and you basically are close to the same cam specs that they recommended... HOW DID YOU FIGURE IT OUT?

Apeiron

You measured with a burette and got 4.49 cc?

You can't break it down by component simply. It's a system of interacting parts.

Honestly though, you're way over-thinking things for a daily-driver. You're not optimizing anything else, so there's no point trying to optimize the cam timing. Put in an XR258HR or something similar from whatever manufacturer you want, give it some more gear and some more stall, and just enjoy driving it.

iroc-z_23

iTrader: (1)

if your expecting someone to teach you how to read a cam and understand it, and the theory behind it, thats a little hard to explain in just a forum in my opinion,

look at the specs on your heads and whats the maximum lifts, etc are that it can handle. on stock heads its not worth messing with if your looking for a big cam. correct me if im wrong but a stock head cant take more than like a 380 lift or they have a good chance of pulling out the rocker studs? by the time you pin the rocker studs you have enough money in that to buy a set of aluminum heads that flow better, stronger, and everything has 0 miles on it. too big of a camshaft causes poor vacuume and a need to change torque converter and gears, idk how carried away your planning to get.

look into RV cams they are right about .370 lift per say if you plan on using your heads you have now.

weaz4200

iTrader: (2)

No. Correct me if I'm wrong, but with a 3.736 bore and the pistons 0.025 under the deck that should come out to 4.49 cc's... Sound right?

Yeah, true.. Then it comes back to the same thing. Now I'd have different heads that flow better instead of the original 081's i posted as reference.

As i stated before... I called the cam company and they told me what cam to use. The cam specs they mentioned to use and what Orr89RocZ suggested are not too different... I need to know how?

If you guys want I can give you a hypothetical build with a different motor.. Its all the same to me whether I'm talkin about a 305 or a 350. In the end it all comes down to the same thing, you have a certain combo of parts and you need to choose a cam for... In my case its a 305 with the parts I listed.

sofakingdom

iTrader: (1)

Those pistons have the extra .020" of deck clearance mentioned above. Their "eyebrows" are about 6cc. Yes I have a set (H354CP-030) and I have measured these things.

Your static CR will be almost exactly 9:1 with a .039" gasket, and 9.4something with a .015" gasket; assuming that the valves have not receded into the seats.

NO WAY you will have anything close to 9.8:1 in this setup.

Since I happen to have the exact same setup sitting in my driveway ATM except with 186 heads (double-humps... yeah I know, but I had em laying around ready to bolt up at the critical moment), I can tell you that with a Comp XR264HR, it made 237 HP and 278 ft-lbs on a dyno at a Mustang club event. There were some Rustnag owners with 4.6s that looked sort of green, because their cars were putting down 210-220 HP for the most part.

I drove that car from California to Ohio a couple of years ago; it got 23 mpg average on a 2200 mile trip with 3.73 gears and a T-5, the stock Q-jet carb, air cleaner, ignition, etc., and Edelbrock TES headers (CA smog legal and licensed).

I'd suggest that very cam, since I'm getting satisfactory results from it. Your motor should make more power than mine since my CR is only in the mid 8s (64cc nominal chambers, .039" gaskets, minor decking) and yours will be about 9:1.

DO NOT use a shim gasket unless your deck surfaces on both the heads and the block are ABSOLUTELY FLAT, STRAIGHT, AND SMOOTH!! The existing finish WILL NOT DO. THey will both need to be surfaced in order to have any realistic hope of long-term survival. It really is teh sux to build a new motor and have to tear heads off in 5000 miles.

Apeiron

No, because there are valve reliefs in the pistons and I can practically guarantee that the pistons aren't exactly .025 below the deck.

Pinning rocker studs is cheap, but so is installing screw-in studs. You won't be running a cam that needs spring pressures that come anywhere near needing them, so don't worry about either.

For your application, any similar cam is going to get you virtually indistinguishable results. Don't worry about it too much. Anything of an appropriate size is going to work well. If you want to develop a theoretical understanding of cam design, treat that as a separate matter from choosing your cam.

skinny z

If you want theory check out this book. It will answer ANY question you have about ANY build you may have in mind.
How to Build and Modify Chevrolet Small-Block V-8 Camshafts and Valves By David Vizard.
With that information, you will know WHY certain choices are made and HOW to make them.
It's simply something that can't be explained in a forum such as this.

Orr89RocZ

iTrader: (20)

Just based on my own personal experiences of what actually works and some cam software simulation programs. There are certain detailed equations they use to calculate cam events based on cylinder head flow and other variables. I dont know all of them. I usually can get you very close on sbc's but there could be a 10-20hp difference in cams with similar duration specs at .050" but different lobe shapes and such. Maybe even more if you are talking larger hp engines.

The guys that do know these details and truely have the understanding of valve events are the guys that do custom cam selection and grinding for a LIVING. They are not going to share their techniques with the average enthusiast or atleast not all of the details.

I learned this from Mike Jones, a great cam guy who did my cam and a few members here with good results. You calculate engine airflow requirements for a given rpm. From that you can determine optimal cam lift required to meet that air flow demand by looking at head flow points at various lifts. Throughout the operating cycle of the engine, the piston has an airflow demand. It can be simulated in programs to each degree of rotation. Cam grinders will try to meet this demand through the cam lift curve. Too much cam lift at a certain point you loose pressure differential across the valve and in the port, too little and you choke the port (velocity will get to high). That gives the lobe its shape.

example
I assume your heads mildly ported will flow ok to .500, maybe even .550 lift but you really dont need to go that high with the cam. Flow in the .200-.450 range will be what makes the power because the valve stays open longest in those areas. I like to get a cam with lift near peak flow but not always necessary for the power/rpm goals for the application as shown above. So with around .500-.525" lift, i think you get a good lift curve for the head, and good potential to make power.

Duration is calculated too based on various engine parameters. Piston position and velocity as well as air flow demand all have input on duration. Its quite a detailed science.

weaz4200

iTrader: (2)

Alright... Well thanks guys.

Orr89RocZ

iTrader: (20)

A test done a good while ago about how picky some cams can be with different head flow characteristics

Apeiron

Keep in mind they're not talking about stock heads or street cams.

weaz4200

iTrader: (2)

So then whats your take on these flow numbers?

Intake lift (in) Flow (cfm) Exhaust lift (in) Flow (cfm) Ratio E/I flow (%)
0.050 31 0.050 15 49
0.100 63 0.100 37 58
0.150 92 0.150 61 67
0.200 116 0.200 78 68
0.250 134 0.250 92 69
0.300 157 0.300 101 64
0.350 170 0.350 105 62
0.400 182 0.400 107 59
0.450 189 0.450 109 58
0.500 195 0.500 110 56

sofakingdom

iTrader: (1)

Typical of typical stock heads with very mild port work. Especially the exh side.

Unported, the better stock heads usually do in the neighborhood of 180 on the int side. Good porting can get the best ones up into the 230ish range with good valves.

A very small amount of porting in the right places - mostly in the bowls, NOT in the ports themselves or "gasket matching" which are largely a waste of abrasive- can make a pretty big difference. So can undercut valves.

dimented24x7

iTrader: (2)

What kind of heads are those? Stock LB9s? The flow is pretty bad. Youll have a hard time making good power with them w/o porting.

One thing Ive found is that the better the head, the less cam duration is needed for a particular operating band. This is good as it can not only make good power, but also get good fuel economy. Think LS1. The reson is the port flow. There is less time needed for the cylinder to completely fill. I was running a single pattern isky flat tappet with 221 duration @ .05 and .470 lift and a 108 LSA with trickflow 195's. This yeilded measured VEs at 99-100% up to 6k. Sounded nice too, but got lousy fuel economy. Switched to an XE 256 roller, which is smaller, and the VE dropped to 94% at around 6k. Slight loss in power from the 0-100 MPH time, but huge increase in fuel economy as the cylinder isnt bleeding down due to the overlap. This results in much higher dynamic compression at low RPMs.

weaz4200

iTrader: (2)

081 305 TPI heads... They will be modified...

So how can i tell how much time is required for my 305 to fill?

dimented24x7

iTrader: (2)

Sort of have to estimate it based on known combos. You cam probably get a reasonable estimate of teh VE and power if you know the cam profile, flow at various lifts, and so fourth using one of the desktop dyno type programs. I know comp has one to help select cams. When it gets warmer out, Id like to dyno my car and see if the predicted 400 HP at the crank is correct for my combo. Based on teh performance, Id hazard at around 325-350 HP at the crank in real life with the engine in the car since it performs about the same as an SS with a stock LS1.

Cam selection isnt an exact science, and there is a range of cams that will provide acceptable performance. Obviously, there are cams that wouldnt work, like using those heads stock with a magnum 286 roller. That would result in an engine with no low end torque, terrible idle, and no top end power as the cam and heads would be opposing eachother. Theres enough people out there running various combos, so some searching and asking will give you an idea of what works once you know what parts youll be using and what the intended usage will be.

sofakingdom

iTrader: (1)

Sure would be nice if it was that easy!! We wouldn't need camshaft "designers" at all, only "draftsmen".

Best you can do out here in meatspace is to estimate, compared to other similar situations. There are altogether too many variables for someone with an uncontrolled, incompletely characterized engine such as mst here would have, to accurately "calculate" things like that. Now, a NASCAR engine let's say, with CNC'ed heads and every other detail meticulously measured and prepared, maybe; but as demonstrated by the MASSIVE errors in your initial compression "calculations", out here in meatspace we simply don't have reliable, accurate, repeatable, believable, useable numbers to just "plug in" to some magic equation. And if you think your CR "calculations" were off before .... ,,,,, ...... try cc'ing your heads and see how much variability THAT has; or cc the ports and see the variation there; or start flowing things and see how inconsistent THOSE nmubers are; or, even for just some super-SIMPLE underlying "assumptions" that we all tend to take COMPLETELY for granted without blinking an eye, but that just AREN'T SO, go see if your cyl banks are actually 90° apart, or your crank throws are 90° apart or the same length. So you want a formula that you can just plug in the numbers, crank the handle, and have the answer fall out; WHICH CYLINDER would you like to plug in? the best? the worst? the average? how do you know? which is why MACHINE WORK is so important: that's our chance to take at least SOME of the variation out of things.

"Measure with micrometer, mark with chalk, cut with axe". Except sometimes it's in reverse.

Anyway, you've been given a couple of cam recomendations. Both Orr's and mine will work fine in your setup, with the various compromises that cams involve (power, RPM range, gas mileage, parts life, and so on) shifting along their scales. Other mfrs with MODERN cams could be used as well, notably Lunati's Voodoo line. But as long as you stick with a cam of MODERN design (not for example, Edelbrock, the cheeeep Summit ones, and other older generic designs) having an intake duration in the mid 2-teens, an exh lobe about 6-10° higher duration than the int, and a lobe separation of about 110° - 112°, you'll have a good-running, ECONOMICAL to operate, FUN, reliable combo. It's near impossible to "calculate" things much closer than that. After all, NOT ONLY is there a great deal of mechanical variation, there's ENORMOUS variation in individual OWNERS' opinions of which of those various attributes are most important and which ones they're willing to sacrifice in order to improve others. No cam gives it "all", you always have to give up SOME things in order to get OTHERS.

/ramble mode off

weaz4200

iTrader: (2)

I don't get why people can't seem to understand my questions. Let me phrase this a different way.... SOFAKINGDOM... You obviously sound like you know what your doing, so answer me this... Say one of your friends came to you and said, "Hey, can you suggest a cam for me, I've got everything I need except for the cam/valvetrain." So you find out what the intended use and everything else about what the car will be used for.. NOW WHAT? You got a pile of parts in front of you, whats your first step?

I dont think my question can get any simpler then that... And if you say something like... .. elaborate... Cause thats vauge... Remember that you have a pile of parts in front of you.... So now how would you gather/what would you do to find out the flow levels?

Apeiron

You want a cam recommendation? You've got at least 3 of them in this thread, all very similar.

Orr89RocZ

iTrader: (20)

It was already explained...the method to chosing the cam design for a given application is not an exact science but the simulation software out there based on some theory and equations will provide a good starting point.

If you know the flow and velocity of the port, you can develop a cam to provide the lift curve necessary to make good power or to meet the intended goal.

If you gave me a list of engine parts and a desired range, based on experience with other combos i've seen and ones i have had myself, I could get a starting point cam for you but it may not be the best for power and torque... simulation and theory can only model things to a certain point, then trial and error on real time running motor will make the difference. I dont have them on hand, but there probably are some rough equations you can use to get a "quick" estimate for duration/lift/lsa for the cam. To explain the entire induction and exhaust process which all have influence on cam design will take 100's of pages and are published in many books out there.

Case in point, a custom grind from a well known respectable cam grinder was made for a certain 383 motor with highly ported modified vortec heads. It made good power, but by playing with the cam's installation (ie intake centerline install point...advance/retard the cam a few degrees) more power was made. So the original cam was CLOSE but not optimal. Infact, the data obtained from the engine dyno and the cam moving around on different centerlines gave the cam grinder a better idea of what the port was doing and what the motor really wanted. Recommended another grind to hopefully pick up more power. It was alreay over 554hp on the engine dyno. A STOUT setup for a hydraulic roller 383

iroc-z_23

iTrader: (1)

Are you kidding me? You've been given plenty of cams if you really want to know how everything works be a god dam machinist and don't get p*ssdd at people who can't elaborate more than they already have. Pick a cam given and GO WITH IT

weaz4200

iTrader: (2)

My point exactly, nowhere did I ask to be given cam recommendations, but whatever...
Thanks.

dimented24x7

iTrader: (2)

I think the thing to take home at this point is that you still only have a rough idea of what your parts will be capable of, so the uggestions will not be run xxx grind and you should be good to go. Nor will you be told "use formula x, plug in the CR, divide by the square root of the displacement raised to the power of the RPMs, and the result is the cam duration you need." It jsut doesnt work like that...

If you decide to port the heads, youll want to get some flow numbers and CC them when your done to know what your dealing with. The head flow will help determine which cam you ultimately want to go with. Good intake and exhaust flow, you can err on the side of caution and run a little less duration, and maybe a single pattern to help the engine have good idle and fuel economy charicteristics, while still making good power. If the heads are closer to stock and have marginal asymetrical intake and exhaust flow, then something like a dual pattern would be what you want to help the cylinders to fill and exhaust. In reality, something like an XE256-XE264 would be in the range of grinds that youd want to choose for your parts. If you want a flatter torque curve and a good idle, choose a larger LSA. Want a peakier torque curve and are willing to sacrifice a little idle quality, you can go with a tighter LSA. Want to emphisize low end torque, stick to the smaller grind. Have gears, stall, and want more high end, go for the larger grind. Those cams arent so large that youll have a disaster if you choose this way or that. Ive run a variety of grinds in that range, and theyre all relatively mild, and will work well provided your running decent gears, stall, and exhaust.

weaz4200

iTrader: (2)

YES! Thank you. That's the route I was trying to start going down... Maybe I should have titled the thread differently, but ultimately it will lead back to choosing a cam... Now, hopefully we can continue further.

Okay, so once ported I'll CC the heads and see what numbers I acquire... Now what about the intake? I assume i"ll want to flow that as well. Should I mess with porting it or should I get flow numbers for that first, then decide whether it's even necessary?

DeltaElite121

Get an Airgap RPM if you're going to even bother investing dollars into an intake. It's about as good as you're going to get. It's a nice dual plane with an updated design. It's a great intake all the way around (I've got one). IMO don't mess with porting until you get a decent set of heads to match the intake to. Invest your money into something you'll continue to use later.

Also, just a little FYI: flow #'s aren't everything, just a piece of the puzzle. Port design and velocity play a key role in your engine's ability to produce power as well.

dimented24x7

iTrader: (2)

The street dominator is sort of like the edel performer. I did back to back runs with a performer and RPM, and there is a big difference between the two. The performer has very good low end torque due to the longer runners, with less power out top due to lower flow, while the RPM sacrifices some of this for top end power. I might also say to go a little larger on the carb if you want to lean towards more top end power. But, with carbs, its a balance between flow at high RPMs, and still having enough velocity at low throttle for proper fueling.