I hate second guessing myself, CAM question....

[Anonymous]

So I have spent considerable time today reading through old posts looking for information on Carbs and Cams for the Aussie 2v...

My question is, I notice in the posts there is concern using high duration cams shortens engine life.... by how much?

For my setup I am planning in running a 200 with 250 2v, Holey 2300 (350cfm), 4cyl T5, 3.25:1 rear gears and cam duration of 268/274 208/215 @.50 460 lift 110 degree centers.... my RPM range will be round 2000-5500 larger valves (1.75 and 1.5)

This is for a daily performance driver. Figure about 12,000-18,000 miles a year easy....

I am considering going back to a more stock build on the cam, to make things last a bit longer.... but by longer what are we talking here... before I sacrifice performance for lifespan, I would like to know what length of lifespan we are talking about.....

Can anyone give me an example of what life a stock 200 would have versus one built like this? This cam is pretty wild, but not as wild as a 280/300.....

I am putting a lot of money into this setup and I want to make sure I get some years out of it... otherwise I would drop this back a bit and maybe just up the stock cam to a little better dual pattern cam.

Since I am also running Full Rollers 1.65 on the 2v I am going to get some benefits of increased lift without actually increasing the cam....

 

[xctasy]

The cam I have in my Falcon is a high-intensity item that raises the valves quicker than a stock cam, but for the same 256 odd crank degrees. The truth is, any aftermarket cam will be more designed for performance than the auto maker intended. Ford would not run the lift rates that a 268/274 cam would produce for fear of getting a warranty claim from some dude running a summer grade oil in a cold climate! Ford, Chev...everyone designs the cam profile for reduced warranty claims, unless its an COPO 427 or Moody Fairlane!

However, you're getting cutting egde technology in a nice reliable six cylinder combo. You've wisely looked at splitting the difference for a wild cammed impracticle streeter, and a low compression plodder. The cam you are looking at will do just fine. Running roller rockers will save on guide side loads and the nose tension the cam face will run. The valve springs and whole combo will be great. The free flowing 2V head has a good amount of port area, and a smaller cam like you propose will love the freedom from restrictions of the stock log. With the shortish rods, you'll have a good deal of low end torque, and I'm picking you'll be running top gear and enjoying less revs than a stock 200 I6 would need, while still keeping up with more modern traffic. So any extra cam stress will be minimal!

In terms of durability, only the GM or BMW test standards can cover how much extra valve gear load, and consequntly, lose of lifecyle longevity, a 270 degree high intensity cam will have verses a 252 degree stocker. Ford has it's own QC-type tests to verify wear rates before and after. The general thought is when you go over 270 degrees total duration for both intake and exhast, or 220 duration at 50 thou, or run a very intense cam or solid lifter design cam, the reliability declines.

Spend big, and enjoy the fruits of your hard work!

 

[CobraSix]

Jimbo,

That is one of the reasons I went with Comp Cams...they have some near stock duration cams. I got the entire kit which included springs and lifters set up for the cam. Basically, I'm just getting extra lift and slightly longer duration (260).

Slade

 

[67 Falcon]

Slade the stock cam for a 200 six has duration of 252/256 and lift of .348 The Comp Cams 260 has 212 duration at .050 and .440 lift. big differnce. Russell

 

[67 Falcon]

I could not fined the .050 specs on the stock cam, but I think it was around 178 duration. Russell

 

[Anonymous]

no offense to...anyone but...

How the hell does a higher duration cam shorten engine life? Maybe I could see higher lift doing that but..., the higher duration just keeps the valves open slightly longer.

I'd go with the crazier cam, especially since you'll have a T5 and 3.25 gears. -Thing would fly.

 

[xctasy]

KC is right. If you just want performance, cam it up with a Jumbo profile!

In the real world of traffic jams and the need to profile along the pike without getting asked to put five on the fender...things are different.

The valve seat on a hot cam with long duration and higher lift cops an absolute hammering for each rise in specs. In the days of production based V8 Sedan racing in Australia, valves would almost spot weld themselves to the heads valve seat area. The nose tension on a cam gets bigger, the crashing and banging action on all the valve train components increases. With the added spring pressure needed to keep the followers on the cam, the stock fibre tooth timing gears break up. In bigger cams, the engine falls out of tune in lo-speed situations because the gas mixture is not atomised properly, and the flow falls out of suspension. So the ignition system and spark plugs need to be changed. Then you need a little extra cranking power than the stock 0.9 hp starter. The list goes on and on!

 

[CobraSix]

Falcon...I think you are looking at two different numbers:

.050 for Comp cam: 212
.050 for stock cam: 185

Advertised:
Comp Cam: 200
Stock: 256

Just another question...what is the .050 thing all about?

Slade

 

[67 Falcon]

Duration at.050" lifter movement. Russell

 

[MLINE]

From what I understand different cam manufacturers tend to measure their advertised duration at different points on the profile. The @ 0.05" lift allows you to easily compare cams.