I've got a 78 bronco with the 400 and was wondering what the lift was on the stock camshaft. How much power would I expcect to gain from diffrent sized cams? If I had a cam with an opperating range of 2000-6000 rpm's would I feel underpowered while running lower rmps? What cam did you/would you put in? I'm planning on using it as both a daily driver, and a compitition truck. I need power for towing too.

Thanks

 

http://home.earthlink.net/~bubbaf250/parts/parts03.html

don't miss this down the page...

Stock intake valve springs go solid (coil bind) at 0.490" valve lift. The stock springs on early non-rotating exhaust valves allow the same lift as the stock intake valve springs, but the springs on the later rotating exhaust valves go solid at just 0.480" valve lift. That is less lift than many popular performance cams provide, even the milder ones like the Edelbrock #2172 (0.484/0.510 gross lift) and the Comp Cams 255DEH (0.469/0.505 gross lift). Using the stock rotating exhaust valve springs and retainers with either of those cams will cause bent push rods.

 

I've got a 78 bronco with the 400 and was wondering how big of a cam to put in. I'm planning on changing the valvesprings and timing either way. How much power would I get from the diffrent lifts? I want to use the truck for towing as well as comp mudding. Will I feel underpowered when running rpms below the operating range?

 

I have a 400 in my 78 as well and I recently called comp cams and they recommended a 256 xtreme energy. However I did some research on here and heard that the valve springs would bind, so I called comp cams back today and they said that a 260h High energy would probobly work without changing springs, but I know you said you were going to change them anyway. I would give them a call and tell them what you want, their number is 1-800-999-0853 if you want to.

 

it might not be the springs specifically that is going to cause the bind problem, the retainers are an important part of the puzzle too. just be aware that y'all might be buying retainers too. then everything has to set up for installed height and checked for bind clearance.

 

A 255DEH or an XE256 cam will give you lots of power at low RPM. They will give you plenty of lift for stock heads. You should get the kit to go with the cam, and still check for coil bind.

The 260H has the same duration on both the intake and exhaust lobes. Even the stock cams are dual energy cams. The longer exhaust duration helps to overcome the flow defiency in the exhaust port.

 

So basically its best to use the 255DEH or XE256 then? Which do you prefer the most?

 

255DEH 255/265, 0.465/0.495
Torque = 422@2500 RPM
HP = 295@4000 RPM

XE256 256/268, 0.487/0.493
Torque = 424@2500
HP = 303@4500

Cam selection is very subjective, my choice may not be your choice. There is only a slight difference between these cams, but here is the data for you to make the choice.

 

cool, thank you very much