Cam help?

[Christ]

I've been reading about cams for about 2 weeks now, and I'm still not quite sure I fully understand the world of the camshaft...

I found, at some point, that I can install 1.7 rockers from a Chevy inline 6 into my 300, which will, in effect, give me more lift and duration, but I'm not quite sure what this will do in the line of torque/horsepower?

I want to keep the torque curve as low in the RPM range as I can get it.

Right now, the 300 peaks at 265 TQ@ 2,000 RPM.

I currently accelerate between 1500 and 2500 RPM, if that's relevant at all.

Ideally, I want to stack up the torque number, but keep it as low as it is now. IOW, I don't want less than 265 TQ @ 2,000 RPM, but I don't mind if the peak moves a bit, either up or down. I would definitely like a higher peak TQ number at 2,000 RPM, while keeping the same curve, relatively flat.

The real question is whether the 1.7 rockers will help what I want, or just be a waste of time?

Any other info is appreciated.

As a side note - What about diesel cams? How are they different from an equivalent gasser cam of relatively the same engine size? Are they designed to take advantage of the highest amount of flow possible for a given RPM range, or is there more to it?

[bgd73]

the six needs special attention. I do not know what that attention is..but a cam can make or break what I don't know about.
I wanted to make a hot rod out of a 200ci 6 cyl ford in a zephyr...mechanic advice: do not even bother.

there is indeed an assymetry built in... an old pro should really know.

if you note the intake, see all that distance change from middle cyls to outer, that is only part of it. If you symmetry eveything to perfect, the six will shutter...and I am certain the cam has alot to do with it. changing ratios on the same cam timing might reveal it..
the 300 being a big one...someone must have tried hot rodding it. the 200 I had was impossible.

[Christ]

You know there is an entire performance sector dedicated to the 200 and other "small block" I6's, right?

They've got those things revving past 7k and making quite nice numbers.

[ex-x-fire]

Is that a Ford 200 you got? Why not try an adjustable timing set, advancing the cam increases low speed torque. I think those have timing chains, as they wear the chain streches & the cam timing is retarded.
If you go w/ different rockers, try to find some roller rockers. An intake w/ long runners help build low end torque too.

[Christ]

Originally Posted by ex-x-fire

Is that a Ford 200 you got? Why not try an adjustable timing set, advancing the cam increases low speed torque. I think those have timing chains, as they wear the chain streches & the cam timing is retarded.
If you go w/ different rockers, try to find some roller rockers. An intake w/ long runners help build low end torque too.

Nope, it's a 300.

There is no timing chain, it's gear drive. I intend to change those gears eventually, as time/money permit. They wear and make annoying clanking noises, which is why I have 4 of these motors apart in the barn. (Grandfather loved 300's, hated clanking noises.)

I'll have to get my fingers on a cam gear set and count the teeth, I might be able to just move the cam forward one tooth without adjustables and see what that does. It's not too hard to set it.

Have you ever seen the intake on the 300's? It's not really long, but it's fairly long runner. And it's basically integrated w/ the exhaust manifolds, except on the EFI models, which have a loose approximation of a cast-iron tubular header on them, two 3-1's.

[Frank Lee]

When I shop cams I look at the descriptions, and the intended use and rpm range is right on there. I haven't used it, but many cam makers have tech lines for help. I think they've probably forgotten more about cams than most of us will ever know. They'd probably have recommendations about the rocker ratios too.

[moonmonkey]

all the torque cams ive seen had fairly low duration # and were very high lift,, ramp angles were pretty radical and hard on the valve train. are your stock rockers 1.5'S ?
i had a few 300 -6 fords hard to kill . 1980 f-100 3 speed od got 21 mpg

[Christ]

Yeah, the stockers are like 1.52:1

[micondie]

I have used cam timing bushings on small block chevy's. The range of adjustment is usually +-5 degrees. Any more than that will run the risk of piston/valve interference. I am unfamiliar with the Ford but if it has a pin to locate the cam gear this is a simple mod. If it has a keyway you could try an offset key. I don't know if these are available but they shouldn't be too hard to machine.. I have been thinking of trying a cam advance on my van since I think that lowering the torque curve would lower the required throttle opening for equivalent acceleration and reduce fuel consumption. As for changing the rockers, I remember reading about someone just changing either the intake or the exhaust rockers but I can't remember the reasoning behind it but I think that this would be worth some further research. The rocker change would increase the lift but NOT the duration which is what you would want for increased torque.

[MetroMPG]

Originally Posted by Christ

I found, at some point, that I can install 1.7 rockers from a Chevy inline 6 into my 300, which will, in effect, give me more lift and duration, but I'm not quite sure what this will do in the line of torque/horsepower?

I'm no cam expert. But FYI, the XFi efficiency camshaft has lower lift & duration (and more torque) than the garden variety Metros.

The Olds Turnpike Cruising Package also used an efficiency cam with lower lift, duration and advanced timing.



Turnpike Road test* Car Life apr. 1967

Both cars did this presumably to permit taller gearing at cruising RPM.