Reverb

I've been looking at a few sites quoting a 246/256 cam when doing power runs. The operating range of this cam is very high - 3.8k to 7k. What I want to know is how undriveable will the cam be below 3,800? I realise it will still have power, but will I have to rev it at every red light just to get it off the mark?

dodgestang

If you put that cam in an otherwise stock motor you will create the ultimate dog.

Does that help?


Here I'll expand, the short answer is 'not nessecarily'. My car makes peak power at 7200 RPM. But it also has more power than I know what to do with sometimes from a dead stop, from a roll, merging onto freeways starting at low speed etc. But I have the whole combination built. If you build your motor around the cam you will have plenty of power at lower RPM and then you will have MORE power once you hit the cars power band. IF YOU DON'T build the rest of the motor around a cam like that, for instance if you have a stock or a performer intake you'll have a car with poor low end performance IMO and a very short 1000-1500 power band. If you are running stock heads...same problem regardless of intake.

Reverb

I'm lucky (?) enough to be doing a full rebuild to the 351c, so I'm picking and chosing my parts at the moment. What I want is basically the best I can get that isn't stupid money. I'm still at the drawing board phase of the rebuild, all I know is that it will be .040 overbore. I'm still toying with a 408 stroker. I have the option of 2V and 4V heads, but am looking into 2V aussie. I have a WC T-5 to go in, and thats staying in until I find I've outgrown it.

dirtydave289

Would a cam that's RPM range is fairly high have any effects on my car sitting at a red light?
A time or two my car's suddenly bogged while sitting at red lights, before and after she runs perfect. That's what sparked my question, can the cam be too aggressive? or is that not a posibility?

dodgestang

I've never had any luck picking cams. Everytime I've had a stock grind I was never happy which is why I switched to getting custom cam grinds. If you know all the parts in the engine and have a very strong opinion about the performance level you want, a custom cam will be very satisfying. If you are unsure and are just about trying to maximize things on a budget, the same guys who gring cams are often more than happy to offer suggestions (for a small fee of course) about what cams you might like and how they might function for you.

If you go stroker...I would just go straight custom because anything advertised will not contain useful info for how it will perform.
If you want to build a car to run to 7k use 4v closed heads. If you want to build a stroker use 4v open or closed since the extra cubes will really take advantage of the ports. If want to have peak power lower than 6500+ use the 2v, if you are going to go through the expense of getting the aussie 2v and setting them up, why not just go aftermarket with 3v or bluethunders and a matching intake? I would stay away from the new edlebrock heads for the 351c everything I have read that wasn't a paid magazine ad/article held poor opinions of these heads, but I do not have any direct experience with them so you can take that for what's it worth

What is your:
Performance goal?
Slated use for the car?
Budget?

Reverb

I want it to be around 500 lbs ft eventually (which will probably break the T-5). I'll be investing in gears for the 9 inch back end when I read up on them (all i've worked on previously is european FWD cars). I want the car to behave in traffic and be controllable, not jumping on the cam too quickly, but have plenty of power when I need it. It's going to be street/strip basically. I'd say my budget for parts will be around 5k

dodgestang

Honestly....I think you need more budget.

My last 408 stroker build cost me more than that and I had the heads (and I'm on my third version of this motor so I had many of the performance parts reusable...stuff like rocker, pumps, ignition, etc)

How many miles you going to drive a year...if its more than say 5k a year...I wouldn't build a stroker I would just built a warmed up c.

You put down the number of 500ft/lbs what is driving that number? That isn't really a performance goal it is a number so the goal is to build a motor that puts down 500ft/lbs on a engine dyno? on a chassis dyno? Turn that number into a different type of performance goal....like I wanted a true street car that I could drive anywhere anytime that would run on pump gas 91/93 octane and run the 1/4 mile between 11.5 and 11.99 in street trim and be able to handle open track road course events with respectable times. I am very close to this goal but I have a very heavy idle and I am not at 500 ft/lbs and I feel like I am at the edge of streetability with my setup as it is now.

67mustang302

A couple other things to keep in mind with cams, is the build will affect how the cam functions. A larger displacement engine will generally bring the rpm range of the cam down lower than on a smaller engine. In other words, the exact same cam, all else being equal, in a 302 will run in a higher rpm range better than it would if it werestuck in a 351. Heads and intake also change this as well, better heads/intake will move a cams rpm range up some, crappy ones will moveit down. A good example of this is dynos of stock 302s to show what heads do with a stock cam. In some cases with a good intake and heads, the stock 302 cam that is designed to make peak power at around 4,500-5,000rpm, instead makes power at around 6,000rpm. This matters if you select an off the shelf cam for an engine, but have a stroker, IE a cam for a 351 that's put into a 408 is going to end up operating in a lower than advertised rpm range, since it's advertised for a 351 and not a 408. Basically a bigger size engine needs a bigger cam, and better heads/intake can use a smaller cam, to maintain the rpm range of the cam.

In the end though like dodgestang said, it's all how the engine is built TOGETHER. Every part interacts with the other, you change one and it changes the dynamics of what the others do

Reverb

dodgestang - how much are you running at the moment - just to give me an idea of power vs et times. Also what is your setup?

That 500 lbs ft was plucked out of the air, but I have to work towards something, I havet dyno'd the engine yet so I wont know what the base figure is. I wont know a realistic figure to aim for until thats done.

So, if you had 5k+ to spend on a 351c what would be your choice of parts?

dodgestang

330/350 or so at the back tire last time I was on the chassis dyno. Not really sure anymore since I have made some changes to parts of the setup.

Its a 410 stroker with 4v open chamber heads with the exhaust side ported. Custom cam in the .620 lift range with all the goodies like a strip dommy intake, biggs 750 carb, 1.73 roller rockers, high flow water pump with under drive pullies, AOD trans (which is a power hog), 3500 stall, 3 inch exhaust, long tube headers, 4.11 rear gear, 26 inch tall drag radial, electric fan, mechanical fuel pump, etc...

My 5/16 fuel line is holding me back right now and needs to be updated to a 3/8 line from the tank to the pump (I have the lines sitting in a box waiting to install)