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Retarded timing sets
December 9 2001 at 7:28 PM
No score for this post Michael (no login)
from IP address 66.30.104.231

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Anyone know why Ford made the timing chains on smog era big blocks retarded 8 degrees? If the timing chain is swaped for a non retarded set, any guess on the benefits? Would this change alter the torque and HP curve? If so, how much?

Thanks,

Michael


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Walt Barnes
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4.33.181.188 Less emissions, less torque, more high end
No score for this post December 9 2001, 9:51 PM

The retarded cam helped with emissions. In general, retarding a cam reduces low RPM torque and increases high RPM horsepower. But, 8 degrees is a pretty huge retard. Although the exact effect will depend on cam and heads, expect the retarded timing set to reduce torque by 20 to 50 ft/lbs below 4000 RPM, and increase HP above 5000 RPM. FWIW, a 4 degree retard will cost less than 1/2 as much low end torque and deliver more than 1/2 as much top end improvement.

If you want to drive a car with a tight converter around town, or tow anything, FORGET the retarded timing set.

If you want to use a medium grind cam at the strip, consider retarding it, but 4 degrees would be better than eight.

BUT, and this is a big BUT, if you are talking about an aftermarket cam, especially a big one, don't retard it unless you have run the simulations and know exactly what you are doing.

My $.02.

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Michael
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4.21.180.210 Re: Less emissions, less torque, more high end
No score for this post December 10 2001, 10:56 AM


Walt thanks for the reply. Based on your comments, it sounds like retarding the cam was driven by emissions more than anything. I mean why would you want to take torque away from a street driven vehicle especially a big block in a truck??? I have a new timing set, I'm just building up the motivation to tackle swapping it out.

Thanks again,

Michael

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Brant Mason
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204.222.216.35 Did the swap on '72 429
No score for this post December 10 2001, 9:06 PM

Definitely do the swap. nI did it on my '72 Tbird w/429. It really woke car up and the gas mileage was considerably better. I get 14-16 with an Edelbrock 750 carb n intake, 3.08 gears and shift kit in the rebuilt c-6. If engine is '72 definitely change heads, they have huge combustion chambers.


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Brant Mason
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204.222.216.35 Update to earlier response
No score for this post December 16 2001, 8:52 PM

I did this swap when I initially bought car. Since then the car has a rebuilt '71 Police Interceptor engine. and a slew fo other stuff. Gets same or better gas mileage with bigger carb n lwr rear gears.

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