Damn - another cam question.

[440beep]

My apologies straight away for yet anther cam question.

The engine is a 512 RB, has the Super Stealth heads (so evidenlty flows heaps), 1.5 rockers, 10.3:1 compression, and Six Pack setup. Car has a 4:10 gear with 28" tall tires, and a 727 with 2200 converter (street car and 4:10 gets RPMs up quickly). Car weights roughly 3,900. Car has power brakes so need decent vacuum. And mostly a street car so like an rpm range between 1500/2000-6000/6500.

Current hydraulic roller cam is:
Adv duration int 300 / exh 308
duration @50 int 240 / exh 248
Lift @ valve int 540 / exh 545
Lift @ cam lobe int .36 / exh .363
lobe separate 112
intake centerline 107
RPM range 1500-6500

I've read in here that most 440 cams specs are based on stock 440ci. The current cam is not bad, but I'm curious if a better cam could be chosen that takes advantage of the cubic inches and head flow and still gives good vacuum for the brakes. Next is to call the cam companies and see what they say, but I'm curious what the crowd here thinks.

Thanks for the help. And I'm so confused when it comes to cams, so more detail than not enough will be appreciated.

 

[68 HEMI GTS]

You current cam is small for a 512. But your converter is not large cam friendly. Even with a large cam a standard port 512 will be at max power around 6000-6300. Just to give you an idea, I run a 260/266 @ .050 cam in my 512 with a 9 1/2 vert that flashes 4800.

You could go more lift and tighten up the lobe center but I wouldn't increase duration with the present converter. my first order of business would be a converter swap if ET is the main goal. It's all about having the right combo of parts.

 

[440beep]

And that's my problem. Normal street driving I'm cruising around 3000, so hate to have the converter slipping the whole time. Only at the drag strip do I see 4,800, or at a stop light next to a wannabe Mustang. I want a good street car with good driveability, but with the nastiness when need be.

You current cam is small for a 512. But your converter is not large cam friendly. Even with a large cam a standard port 512 will be at max power around 6000-6300. Just to give you an idea, I run a 260/266 @ .050 cam in my 512 with a 9 1/2 vert that flashes 4800.

You could go more lift and tighten up the lobe center but I wouldn't increase duration with the present converter. my first order of business would be a converter swap if ET is the main goal. It's all about having the right combo of parts.

 

[68 HEMI GTS]

My car is 4.10 gear, 28" tire. Weighs 4g with me in it. Cruises just fine, I drive it all over. Just need a quality built converter. 2800-3000 cruise

 

[440beep]

Ooooh I need to go read up on converters.

But if I were to change and go with a 3K converter, how much would my cam options increase?

 

[Mike67]

You could always go less gear and bottle feed it to make up the difference..
550 HP + 4.10 or 675 HP + 3.55...??? I'm sure some of the racers can produce the formula that can show what the comparisons would be/needed to equal or improve time/HP/ratio...if your happy with the driveability of your set up now..

 

[oldbee]

I've forgotten more than I thought I ever knew about cams, but can you ever get good vacuum with over 300deg duration? At least a hi-stall converter would help a little I guess.

 

[68 HEMI GTS]

Ooooh I need to go read up on converters.

But if I were to change and go with a 3K converter, how much would my cam options increase?

A lot of it depends on what you wanna do. Is it an ET GOAL your after?

 

[440beep]

Truthfully I'm more worried if I'm utilizing the engine to its potential, and I know that's a loaded answer; and of course running out a good ET is always good. I like the driveability of her now so guess I should just stay put.

A lot of it depends on what you wanna do. Is it an ET GOAL your after?

 

[Cranky]

Have you made any passes at the drag strip with it? If so, what are the times including the 60 foot. Short time won't matter much if you're spinning off the line though....

 

[440beep]

yes, made some passes last year. Best 1/4 mile time was a 12.4822, 60' = 1.8981, 113.5 1/4 mph. Running MT 295 drag radials and spinning off the line. Think a true slick is needed. The car should definitely be an 11 second car, but I definitely need more practice with her.

Have you made any passes at the drag strip with it? If so, what are the times including the 60 foot. Short time won't matter much if you're spinning off the line though....

 

[moper]

First step is loose the power brakes. Your camshaft choices are very limited having to maintain a high enough vacuum for them. You can upgrade to a hydroboost system if you want power brakes. Personally I found no loss of braking or increased effort using a manual master cylinder.
If you have to retain the vacuum booster give Dwayne Porter at Porter Racing Heads for a custom cam.

 

[grizgtx]

For that combo I would go more lift and do a 114 lobe separation to help with the brakes, but the real question is do you have the valve clearance to go bigger?

Mopar is right tho, give a cam grinder a call and get the best one for your combo.

 

[68 HEMI GTS]

yes, made some passes last year. Best 1/4 mile time was a 12.4822, 60' = 1.8981, 113.5 1/4 mph. Running MT 295 drag radials and spinning off the line. Think a true slick is needed. The car should definitely be an 11 second car, but I definitely need more practice with her.

Your not even close to using the engine you have. I would focus on 60ft's way before adding power.

 

[440beep]

I know I know.

Your not even close to using the engine you have. I would focus on 60ft's way before adding power.