360 in a 75 Roadrunner

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Changing the rear end is a band aid.

As already mentioned, the cam that is installed is your biggest handicap.

That 3.21 rear end keeps the rpm down at freeway speed, that's a good thing.

Without an overdrive, you will regret changing the rear end because your sluggish launch will still be there.

When the rear end doesn't satisfy your goal, a complete rebuild will happen and now you won't like your gear ratio

I have 3.55 sure grip for my 3100 lb dart, the correct cam for getting out of the hole,lower planetary gear works out to 3.98 in first gear. It will get out of the hole but I'll pay for it on the freeway. An overdrive unit is being planned for the future when funds permit.

Change the cam.
 
Changing the cam does seem the way to go and I think I have been talked out of the rear end change. I am going to do some digging in to the cam recommendations that were made here like the Crane H-260-2 and the Voodoo cams. Thanks everyone
 
MOA said:
Changing the rear end is a band aid.

As already mentioned, the cam that is installed is your biggest handicap.

That 3.21 rear end keeps the rpm down at freeway speed, that's a good thing.

Without an overdrive, you will regret changing the rear end because your sluggish launch will still be there.

When the rear end doesn't satisfy your goal, a complete rebuild will happen and now you won't like your gear ratio

I have 3.55 sure grip for my 3100 lb dart, the correct cam for getting out of the hole,lower planetary gear works out to 3.98 in first gear. It will get out of the hole but I'll pay for it on the freeway. An overdrive unit is being planned for the future when funds permit.

Change the cam.
Click to expand...


There is no possible way you have a 3.98 overall low gear with a 3.55 rear gear. I'm not sure how you did the math but ratios are multiplied.
So.....
3.55 X 2.44 = 8.662 and....
3.55 X 2.77 = 9.8335

IIRC that is the two most common torqueflite low gear sets. If my numbers are not exact they are pretty close.

You don't have a 3.98 overall first gear. At least not by my math.
 
Yellow rose. That's what I was told by the guy that built it, very well respected so Cal 904 specialist. I'm not going to argue with him, I will ask again to double check. The exact gear ratio was not the point.

My point was, I'm building mine to be quick and I know I'll pay for it on the freeway.
 
A down and dirty way to improve your hole shot is to bottle feed that 360. A small shot on takeoff will get you to the 30 mph mark in a hurry. After 30 your natural power band will take over and provide plenty of giddy up. The best part of this solution is, the boost is only there when you really want it. Most of the time you have a mild mannered cruiser. On The Bottle Baby. NOS rules.
 
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