Thread: need help picking a cam

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i wanted to say thanks to those that helped with my decision. i went ahead and bought a 4bolt main block for my mini. its already in the shop, just waiting for parts. im having it done .30 over, mew pistons, rings, wristpins, the whole nine yards. now im stuck on my cam. im getting a small step up from stock convertor. maybe between 2200 to 2500. i aint worried about gas mileage. my motor will run decent but mainly its just for putting around at the shows. whats a good cam that will go with my convertor and sounds like it runs 9's??

If you want the Rough idle : 280H
If you want a smoother idle: Edelbrock Performer

If you want it to sound like it's running 9's, you probabbly want the rough idle.

IMHO I feel it's more important to not over cam a motor. You can under cam a motor and not suffer as much as if you put in a too big of a cam. It all depends on how much carb and manifold you have, size of you heads and valves ,and your compression(bore&stroke). I may be in left field but the higher the compression, you may want more duration than extreme high lift. I like the 280 range cams for street, I like the rougher idle with about 10:1 compression ratio, makes the motor sound awesome! You can always put a bottle on it too. Find the perfect combo and you will have a very strong running motor.

Now since I know there are many here that are more knowlegdable, please jump in and help me out. I'm getting ready to do a 400sbc and I want to do it right.

Only 1 thing to say here, re read Tech's post !!!!! I would only further mention to fill out HONESTLY a cam reccomendation form from any of the various camp companies, they are the experts. The only other thing I would add is re read Techs post.

i second that motion , dave
tech is right on again !!!

2200-2500 rpm stall is not slightly more than stock, 1200-1500 is. The bigger the cam you get, the worse gas milage you'll get. What kind of motor is this? Stock engines do not have enough compression to make enough cylinder pressure to keep a decent idle with the giant cams (less than 1500 rpms). I am going to build a 350 and I am going to use a Comp XE262H. It's the largest cam that will work with a stock converter and make enough vacuum to run power brakes. I will be using a 1200-1500 rpm converter with this cam and 9.5:1 compression.

Thats a great point Tech, I would rather have a motor that makes my car perform well and strong than to have that dragster sound. I am going to have to research this more, I am looking for 400 to 450 hp to put in my heavy '48 chevy. This is because I like the feeling of the hp when I'm cruizing, knowing the response is there if I want it.

76GMC, that sounds like an interesting combonation, how many hp do you think you would rate your engine?

So......Instead lets say I have some high compression pistons I have been aching to use (10:1) that are .30 overs.
I have a 400 sbc with 194 heads, can I reach the hp goal I have with a 1000-4500 rpm cam?

Stock the engine comes out with 250hp.

Wow, I love camshaft decisions. So first I'll tell what I have in my 82 'maro. 355 with comp xtreme hydraulic roller 224 intake and 230 exhaust at .050 lift. Thats 276 and 282 for the advertised I think...if I can remember that. The lift is .502 and .510. I have absolutely NO problems with vacuum even if I nail the brakes repeatedly. Albeit there is less power at low, but it really pulls well from 3000 or so on. The low end idle is quite nice and rumbly but its no pro stock, and I have a manual with 3.08 gears in the back currently and by 2200 rpm the car takes off easily, if I ever even have to idle it up that fast to get going. I think the cam works great on the car that it is in. But for a truck you might want to drop down to a smaller cam to haul that fat load around. That way you can keep the small stepped up converter and still have some rumble with the right pipes and have lots of midrange power which would be perfect for cruising the highway. But, again, read techinspectors article because it is very true. However, with my setup I have no vaccum problems and my cam runs really strong for a long duration, mostly in part to the roller setup and heads. I run 10.2 to 1 compression as well and some lighter JE/SRP forged pistons at .030 over so it spools up really fast as well. For a truck though, its up to you and the automatic and rearend ratio. If the rear is steep and your truck is fairly light, you might get away with that, but then forget the highway with steep gears. Your choice, but my suggestion is a slightly smaller cam and put some good pipes and mufflers on it if you want that rumble. Also, if your block wasnt setup for a roller cam then its gonna cost you for lifters. I went roller so I could have a good lowend with a big cam. All in the ramp rates and area under the lift curve, my friend. Good luck with your truck and combo.

And brickman, you can get 1hp per CI with a little work on that, give it a good manifold, carb and a good low/midrange cam. You will NEED to give it headers for that torque to pull that monster around. You can give it 400 hp and about 450 torque without putting a whole lot of money into the setup. With 10-1 compression and a cam change you should be gettin close. Maybe step up the rockers if you want more lift but then it might idle like trash. If you plan to do even a little cleaning of the heads, I would highly suggest a small pocket porting job, you can keep your stock valves but with a 400 you are really coming against the heads' flow capabilities when you try to make power, so even a small increase there will give you quite a bit.

In both cases.....Bigger is not always better....

Good luck on those combos guys, hope I gave some worthwhile advice

Comp has a dyno sheet on the webpage for the XE262H. Their test engine has 9.25:1 compression and I think Dart's version of the Vortec head. It makes 325 hp and 415 lbs of torque. I am going to be using unmodified Vortec heads and a QJet carb, so I figure my hp numbers will be a little lower, but I will have higher compression so that might put the HP numbers right back where the test engine is. I am also hoping the higher compression will bring the torque curve down in the rpms just a little bit.

Well, I kind of misread your post, you said you didn't care about gas milage and I thoght this was going to be in a daily driver or something. Go ahead and get the 280 or something simlilar. The XE cams are supposed to give pretty good low end for their duration, so you could use a fairly big cam and not have to use a ridiculous stall converter.

Hey Chris if you want a lopey idle and stall speed is slightly higher than stock, I would go with a Comp Cams X-treme Energy Cam . Start at the bottom of your stall speed. 2300-6500 284'-296' it will be lopey .Jeg's part no. 249-CL12-250-3 KIT you probably going to want a single plane with this cam .Either a Torker or victor series I personally like Edelbrock , but it's your motor. Good luck.

Thats good advice 1st gencamaro, I will get out the summit and Jeg's books and start over again.

As far as the porting job, I will do that myself and not so much increase the size of the ports as make it match gaskets and smooth it up slick as a baby's behind. I am really looking forward to getting into my engine rebuild.

I am rebuilding my 70 chev PU. 350 .030 over 1.94 heads nothing to extravagant . I am going to be installing the Magnum 280H Comp Cam. Cant wait.

I am pondering the same question for building a 350 for the street in a light 29 roadster, but I do not care about the rumpy idle, and my wife would not understand anyway! I asked this question in another thread about SBC mileage but received no answer yet. The comment/question is that you CAN have both low and high rpm performance with Rhoads lifters which provide at least a 10 degree variation in cam timing. My question is why don't more people use Rhoads/Crane lifters for low rpm idle and mileage and keep longer duration performance at higher rpm? Are they noisy? Do they work? Does a high volume oil pump defeat the whole idea? If you say you want the rumpity idle just for effect that is what you will get, but if you can live without that inconvenience on the street why not use variable lifters? Comments?

Don Shillady

I am pondering the same question for building a 350 for the street in a light 29 roadster, but I do not care about the rumpy idle, and my wife would not understand anyway! I asked this question in another thread about SBC mileage but received no answer yet. The comment/question is that you CAN have both low and high rpm performance with Rhoads lifters which provide at least a 10 degree variation in cam timing. My question is why don't more people use Rhoads/Crane lifters for low rpm idle and mileage and keep longer duration performance at higher rpm? Are they noisy? Do they work? Does a high volume oil pump defeat the whole idea? If you say you want the rumpity idle just for effect that is what you will get, but if you can live without that inconvenience on the street why not use variable lifters? Comments?

Don Shillady