Cam

[reast83]

I am about to start rebuilding the 440 super commando 4 barrel with automatic in my 1970 GTX and would like to bump the cam up a little. It is a numbers matching car so I want to stay original looking but add a little bump to it, nothing to radical. I started with Comp in my 454 Chevelle but had problems with it and went to a Lunati and that solved my problem. Since this is my first Mopar I am looking for suggestions on a brand and size up a little over stock from you Mopar experts? Also should I stay with hydraulic lifters?

 

[rumblefish360]

All brands have had and will again have a problem sooner or later with the quality of metal that the cam is made out of. So Comp is not the only cam maker to have this issue.

Staying with Hyd. lifters will make it easy and cheaper overall. You'll be able to re-use the pushrods and rockers without issue unless the lift is really alot overstock. Pushrods can be customed ordered easy.

What is your gear ratio by the way? Stock stall converter?

Lunati has a cam with just a few degrees over stock that will make a noticeable improvment IMO. http://www.lunatipower.com/Product.aspx?id=1579&gid=287

This particular Huges cam comes in a hair smaller @ 050 but the action of the cams lobes are much quicker and lift is much higher. http://www.hughesengines.com/Index/...RmxhdCBUYXBwZXQsIEh5ZHJhdWxpYw==&partid=21849

While this Huges cam is the next step up and may require a converter change and head work in addition to it's high lift; http://www.hughesengines.com/Index/...RmxhdCBUYXBwZXQsIEh5ZHJhdWxpYw==&partid=21852

 

[Deleted member 214]

Summit has their own brand of cam that is a step up from the Road Runner cam - PN SUM-K6401. Split duration (224/234@.050 lift), .465/.488 lift for only $63. Kit with lifters is $111. Nice choice if you are on a budget and using stock exhaust manifolds.

 

[wedge5]

Go with a Hughes. Give them a call and they will advise you on which one to get.

 

[Meep-Meep]

I'd keep the lobe center at 112 for a slightly hotter mid range. The idle will be good as well as the vacuum and it works just fine with the factory iron intake.

I am currently running this cam in my 440 with stock intake and headers but I have a bit too much compression for pump gas http://www.summitracing.com/parts/DCC-4286677/ It runs really good though, however lowering a half point to 9.6:1 should get me on to pump premium without too much of a sacrifice on power.

 

[Superfreak]

I'd keep the lobe center at 112 for a slightly hotter mid range. The idle will be good as well as the vacuum and it works just fine with the factory iron intake.

I am currently running this cam in my 440 with stock intake and headers but I have a bit too much compression for pump gas http://www.summitracing.com/parts/DCC-4286677/ It runs really good though, however lowering a half point to 9.6:1 should get me on to pump premium without too much of a sacrifice on power.

11 to 1 is good for pump gas.

 

[snakeoil24]

Comp cams makes very good cams, if you had problems it might have been with a lack of zinc in the motor oil. I would feel safe with Comp or look at crane who is finally back in business.

 

[Meep-Meep]

11 to 1 is good for pump gas.

Maybe on your pump gas but not mine. 190 PSI of cranking pressure does not like 91 R+M/2.

 

[reast83]

Thanks for all the help.

 

[reast83]

What is your gear ratio by the way? Stock stall converter?

The converter is stock but I am not sure about the gear ratio I have not been in the rear end yet. I do not have a build sheet and the fender tag does not give me that information.

 

[Cranky]

Static compression is only one part of the equation for cam selection. I can make an engine with 8-1 ping it's *** off with the 'wrong' cam and can made an engine with 11-1 run well on 93 with the right cam but the total combination has to work together to accomplish that. That said, picking a cam involves knowing everything about the car and knowing the gear ratio is only just one of the many things needed to make an educated choice. Even the weight of the car is important but there's also custom grinds available and it's not that much more expensive and usually makes a difference. Off the shelf cams are much better these days but they are still somewhat generic.

As for finding out what your rear end ratio is...you can figure out pretty dang close without going into it. All you got to do is count drive shaft rotation vs wheel rotation. One turn of the wheel and the drive shaft turns 3 and a 1/4 turns puts you right at a 3.23 gear. A common gear for an X would be a 3.23.....but who knows who has been into it. Does it have a SureGrip still? If so, then that makes it even easier to check.

 

[reast83]

The gear ratio is 323, I talked with the previous owner that has been into the rear end. I want to keep the motor as close to stock as possible on the outside. I just thought while building it I wanted to get a little better sound and thump out of it. I will never race the car and do not care how fast it is. My Chevelle is built for speed and to be a bad ***, now I want something that looks and runs pretty much stock.

 

[67 GTX]

11 to 1 is good for pump gas.

that'll make you have to retard the timing
9.5 to 1 is safe
10 to 1 can run on 93 octane, but without headers, you are beginning to push it