Recommended 4bbl carb for stock 318
I'm not sure what you are saying here, only hiway tractors, and such, make 1800ftlbs
An 1800TC is rated to stall at 1800rpm with a given amount of input torque. Stall-speed is what the the engine revs to at zero mph when you floor it.
Your engine has a torque curve that starts at the stall rpm and ends when you shift. It varies from a low number at low-rpm to peak at a higher rpm when the engine reaches peak efficiency, and then begins to decline on it's way to the shift rpm.
One cam-size is an increase of about 7* at .050.
Each increase in cam-size will move the power-peak up about 200 rpm
Beginning with a stock teener cam of 240*adv , and for street, ending around a 276*adv, that makes about a 6 size range for a street-teener. Therefore,
Peak efficiency usually falls in the range of 1200 to 1400 rpm centered somewhere around 3800, and depends principally on the cam for a given sized engine. Peak power usually falls about 1500 rpm later, but depends on more factors. The shift rpm is kindof dictated by the transmission ratio splits, but sometimes other factors reduce that.
Put simply; if you move the power peak up 200 rpm, you will lose a minimum of half that at the bottom,probably more.The 268 cam is about 4 sizes bigger than stock, moving the power peak up about 800 rpm, and going soft at least 400 rpm sooner. The factory 1800TC while not particularly soft for a DD, for performance is already 400 to 600rpm short of where it should be. So that make your new TC requirement for the 268* cam,to be about; 1800+600+400=2800rpm.
I got my first 2800 in about 1980, for a 225 in a 69 Barracuda. That TC has been with me ever since, going from one engine to the next,in almost every DD,ever since.It's got a great little "hit". At that time it was called a "Dirt-Jerker 2800". You need one.lol The company I worked for at that time, made those.
Because I now know for sure I will be adding a new torque converter to the mix... To avoid further confusion I think this portion is going to have to take a back seat for a bit until my head is cleared of the fuel and air issue and is cleared up with everyone else.
Sorry I was thinking rpm in my head but put ftlb.
That gave even more to think about with more info.
Again thanks, that's been a lot of info and it's good to know what types of numbers I will be looking at when I hit that step.
Keeping in mind this is my first ever automatic tranny, I do want to be sure I can utilize what I will have get the proper understanding.
My issue seems in the TC itself and how the TM works with the stall speed (bogging, quick reaction, whatnot).
Your last post added even more understanding but more info to process.
I know gear ratio no problem. That's easy to understand ( gear ratio of 2.5:1 is 2.5 turns of the input to 1 turn for the out put ), great for higher speed, not low end torque. Compared to say ( 4:1 ) better for slower speed and low end torque.
If my understand is correct in a manual, each individual gear is also a ratio output to multiply tranny duty for the horsepower vs. torque in the rpm range from the engine to the rear wheels. Say for example 3rd gear is the 1:1 ratio at 3000rpm for 60kph, switch to say 1st gear with the 3:1 at 3000rpm gives 20kph. this compered to 5th gear 1:3 giving 100kph. Assuming this has all been on the same cam and running with a rear gear of 3:1, simply by changing the rear gear ratio up or down you can lean further toward low end slower speed higher torque or high end horsepower and faster speed allowing each individual gear to perform better for torque or horsepower.
The key being finding the correct final ratio's for each application.
Then trying to transfer that power through the clutch ( basically a brake pad and disc ) with springs for locking the two together. And this combination dictates the ability to transfer direct output rpm from the engine to the direct input of the tranny. And this is effected by the clutch using different materials for the disc (organic to Ceramic), flywheel (mild to high carbon steel), and pressure plate spring rate, as well as the number of disc's.
That being said I hope it was correct, but the tranny info will have to wait.
