No vacum Cam swap?

[scstoddard70]

Well I am pretty new to this site, I have read a lot on here and find it to be very helpful. I have a 70 charger with a 383. It was just recently rebuilt. Its 0.30" over, has stock heads and KB pistons, compression of 9.5:1. I have a edelbrock torker intake and ceramic headers. Carb is a 750 speed demon (junk i know:/) I had a brand new engle K60 cam from a build a few years ago, anyways I decided to put the K60 in and now I have 4" of vacuum at idle.  I had a vacuum reservoir  laying around and could only get 8in/hg at idle.

I realize that this was not the best cam choice and I will be replacing it now for something that can supply enough vaccum to power my power brakes. The rear end is 3.56 and the stall is 2500. What would be a good cam choice for this?

Thanks for your help!!

[red79]

welcome to the site! the amount of vacuum a cam makes is inversely proportional to the overlap, which is affected by both the lobe separation angle (LSA) and the duration (degrees intake/degrees exhaust). I don't remember the exact specs on a k60, but it's a pretty radical cam for an iron-head 383. Your build is similar to one I'm doing on a 440, and i've got a k56 stick ground with 112˚ LSA for a mild mannered torquer with plenty of vacuum.

As always, your best bet call the cam mfg of your choice and have them recommend a grind based on your hardware and performance goals--after all, they do this for a living and have plenty of experience with how their products perform in real world applications.

[Cooter]

I wouldn't go any higher than around 225 @.050 and around .500 Lift with stock, 1.5 rockers...I'd look into Comp Cams "High energy" cams...Like a 268 Comp...

[firefighter3931]

The K60 is rather large for a mild 383.  Good cam for a hot 440 or mild stroker build. 

I'd go with a K56 or something similar to build some low end power/vacuum & throttle response. Cooter is right on the money 225*@.050 maximum for that type of build and displacement 



Ron

[scstoddard70]

Well after a fun weekend I got the cam swapped out for a comp 224 and it runs great!! I have 19in of vacuum in park and 16 in driven. Thanks for all your help!!

[firefighter3931]

Good work 

Save that K60 for a future build 



Ron

[scstoddard70]

So the next thing is going to be ditching this 8 1/4 rear end and swapping out for 8 3/4. Is there any particular case i should try to get? Or would any work that's off a b body?  Also I have 2.76 gears now don't like them very much. I was thinking about 3.55 what would you all suggest? Mainly just around town not on the highway much at all.

[firefighter3931]

A 3.55 is a nice compromise gear....good around town and livable out on the hwy 


Ron