I have a 77 F350 Supercab "Trailer Special" w/460 and a C6 trans, 4.10 gears that I geting ready to start towing a 26ft fifth wheel trailer (approx. 6000lb)

Out of curiousity, what is the thing with the timing gears retarded 8 degrees? I know it is for emmissions and reduces power, but a local speed shop told me that simply changing the gears to zero would make it feel like I picked up 50 hp. I have read here that you would really not notice the difference without a cam to go with it.

What gives?

Thanks

 

The speed shop is correct in that changing the timing gears will increase your bottom in performance. It's all about cylinder pressure. The more you make the more torque you get. The factory cam was indeed retarded at the gear by 8*. As you have heard this was done as a cheap way for ford to meet EPA. The plus side is it gives us a cheap way for more torque.

Think of the pistons in your engine has suction pumps, and the cam has a door opener. With the cam retarded 8* it opens that much later as the pistons are on the intake stroke (moving down the cylinder). When the pistons hit bottom they stop drawing in the intake charge, but that doesn't mean the charged stop flowing.

There’s this little law in physics that a guy by the name of Newton came up with. He said that an object in motion (the intake charge) would stay in motion, until acted on by an outside force (that force is the piston starting to go back up in the cylinder).

Until the piston generates enough force to stop the flow of the intake charge, it's still filling the cylinder. At idle an engine is pulling around 20lbs of vacuum. This means that when the piston starts its upward stroke it has to produce 20lbs of positive pressure against the intake flow before the intake charge stops flowing into the cylinder.

Where the two points meet (the vacuum or negative pressure, and the positive pressure) is called the point of equilibrium. On a performance engine this is where you want the valve to snap close, but on a smog engine you want that valve to stay open to force a little of the fuel mixture back into the intake. This is what those pesky engineers call “the revision cycle” (don’t you admire the way engineers love to name everything?).

As engine speeds increase things happen a lot faster. At some point (an educated guess on my part says around 3000 to 3400 rpms for the 460) the pistons are moving faster, the valves are closing quicker, and the revision cycle on the intake side cannot occur. Note: I said on the intake side, revision also occurs on the exhaust side, but that’s another story. This point is where the max torque of the engine is.

By moving the cam forward 8* you’re allowing the engine to open the valves that much sooner. As you might have guessed that means you’re letting the engine take in a little more fuel from the get go. This also moves the revision timing down the ladder a little (normally around 500 to 750 rpms) and lets your engine hit the torque peek faster. Also it makes your engine feel more efficient because the torque is down where you need it.

Because you’re burning a little more fuel at lower rpms your emission will be a little higher at idle, but your gas mileage will increase because your more efficiently using the engines torque curve. You’re not really gaining 50HP, but you’ll diffidently feel like you did because the torque is now down where you can really feel it.

 

Hey Wayne, nice reply. What year do you buy to get the benifit? Thanks

 

68-71 429/460 Timing gears & chain



[font color=red]Dennis

Calgary,Alberta,Canada[/font]
[link:www.ford-trucks.com/guidelines.html|FTEModerator]

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Please Don't Ask Me Any Tough Questions,
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[font color=blue]78 F-150 429CJ,Silver,Explorer Pkg.
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Cool...You guy's knowledge is impressive...
Now...do the more expensive "performance" chain/gear sets make any difference if you're not drag racing? Are the cheaper regular one's sufficient?

 

>Cool...You guy's knowledge is impressive...
>Now...do the more expensive "performance" chain/gear sets
>make any difference if you're not drag racing? Are the
>cheaper regular one's sufficient?


BUY A DOUBLE ROLLER CHAIN!!! You get what you pay for
Tony

'77 F250, 4X4 460 transplantee, "Flamer"
'74 F250. 460, "beater" now "1 dead ford"
'73 F250, "midnight auto" now a trailer for the flamer

 

In my opinion the sets from company's such as Crane and Comp cams are the best and at a cost of under $30.00 you can't beat them. Both company's have offset crank gears, and their sets come with complete instructions for advancing the cam.

 

When you pick up a Crane or Comp Cams timing set, do you tell them it's for a 71 460? Or will you get the same set regardless of year? (since they sell performance stuff)
Mark


>In my opinion the sets from company's such as Crane and Comp
>cams are the best and at a cost of under $30.00 you can't
>beat them. Both company's have offset crank gears, and their
>sets come with complete instructions for advancing the cam.

Ford started it; Ford will finish it!