Cam help?

[Christ]

Originally Posted by 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.

Changing rockers will increase open duration on the valve, as well as lift.

Comp lists valve opening and duration for 1.5, 1.6, and 1.7 rockers for their cams, each number shows progressive increases.

Clearly, it won't affect the cam's duration, but it does effect the number of degrees that the valve is open/closed.

I can't remember ATM if it has a pin or a key, but, IIRC, it's interference fit w/ the cam shaft. I believe someone makes adjustable cam gears for them, though.

Unfortunately, since there is no chain, there is no way to change gear sizes to use gears from some other application, either, without retrofitting a chain tensioner and a better oiling system for it.

PS - The gears are made of fiber. Thank you, Ford.

[micondie]

I couldn't find a chart on Comp Cam's web site that compares rocker lengths but the duration of a cam is measured at .050 valve opening and a longer rocker will reach that opening slightly sooner when opening and later on the closing side so that will change the effective duration slightly but not significantly and not enough to affect low speed torque which is what you are looking for.
RE your fibre gears:
Chevys have a nylon cam sprocket which wears over time. I have an old motor from a 74 Nova that was so worn that the loose timing chain wore through the timing cover but the motor kept running and is still running.

[Christ]

Originally Posted by micondie

I couldn't find a chart on Comp Cam's web site that compares rocker lengths but the duration of a cam is measured at .050 valve opening and a longer rocker will reach that opening slightly sooner when opening and later on the closing side so that will change the effective duration slightly but not significantly and not enough to affect low speed torque which is what you are looking for.
RE your fibre gears:
Chevys have a nylon cam sprocket which wears over time. I have an old motor from a 74 Nova that was so worn that the loose timing chain wore through the timing cover but the motor kept running and is still running.

LOL on the Nova. If I have to do engine service at some point, while it's apart, I'll swap those fiber gears for some steel ones, probably adjustable.

I can't find the chart that shows comparisons to rocker sizes now, either. They may have removed it since the last time I bought a cam from Comp? (Years ago.) I specifically remember looking at it to determine the size of rockers I could use on my 351, though, with the cam I was ordering for it.

[ex-x-fire]

I've heard that the steel gears, on a ford 300 w/ efi, will drive the knock senser crazy.
If anything, you could call a cam company & see if they can grind a torquer cam for you.

[Christ]

Knock sensor = disconnectable. You're not going to get pre-ignition with a retarded motor that only has something like 8.5:1 compression... at least not enough to destroy the motor, unless you're really lugging it, and I can demonstrate how difficult it is to lug this motor. I've pulled it all the way down to 800 RPM on the tach at WOT in 5th gear and it doesn't shake or sound like it's coming apart at the seams. As soon as I got off the knoll, back to the flat, it just started accelerating happily.

I do this in Gerald (the mtn truck, granny 4 spd) all the time, and that carb'd 83(?) has never complained about it, either.

[Christ]

Originally Posted by ex-x-fire

I've heard that the steel gears, on a ford 300 w/ efi, will drive the knock senser crazy.
If anything, you could call a cam company & see if they can grind a torquer cam for you.

I only wonder about the rockers swap because it only takes about 40 mins to do it, and pulling/swapping the cam requires a bunch more work, and additional cost.

I could probably get the rockers free from a junkyard, but to get a custom ground cam (probably) will cost me in the $100 range, and I'll probably have to send them a core, too.

[ex-x-fire]

I was saying the steel gears made too much noise, the knock senser can pick it up. I've seen this happen.

[Christ]

I understand that, but the knock sensor on these engines can be removed without any trouble, I meant.

Most people would say "OH NOES!!! You'll blowz up yer moter!" or some variant, but it's just not necessary on the EFI 300.

[Christ]

I wonder if there is anything to be gained by swapping just the intake rockers (if I can do that) for the 1.7's, and leaving the exhaust rockers alone?

[micondie]

I have been thinking about that article I read about just changing intake or exhaust rockers and I think the idea was to balance out the breathing characteristics of a motor which was more efficient on one side than the other. Some research might suggest which side of you motor needs improvement. For example: if power increasing mods for this motor include the increase of one or the other valve size, that would tell you which side needs improvement. Or maybe just a careful examination of your intake and exhaust system might give you a clue.