Hi all, I have a mild built 455 out of a 73 Electra in my 70 Skylark. 8.6:1comp with Edelbrock b4b intake headers and for some odd reason the previous owner put a TA-413 cam in it. Here is my plan I am planning on swapping out the heads with a set or nice flowing stage1 heads off bought. Compression will have a slight bump up to about 9.0:1 comp. I am wondering should I get a different cam or run the TA-413 with the set up? If a cam swap is in order what do you suggest? Looking to make this a nice mild street/strip car. It always starts that simple anyway?
Have to tell us what you expect from the car. What do you think of the 413? How do you like the idle and is there enough vacuum for the power brakes?
Honestly, I feel this engine is way overcammed for the engine. It feels like the bottom end torque is lacking. Again that might be due to lower comp and non performing heads, but it certainly doesn’t have the earth shattering torque the 455 is built on. I am looking for a moderately hot street strip car low 13’s to high 12’s performance wise
The 73 engines were rated at 8.5:1 compression, but they were likely lower than that. One of the things to consider when trying to choose a cam is Dynamic Compression Ratio. DCR is why you see a static compression requirement for cams. Read more about this , http://www.empirenet.com/pkelley2/DynamicCR.html To figure DCR, you really need to know what your static compression is. You really can't guess, assume, or estimate it, you need to know. The range for DCR to run on pump gas is 7.5 - 8.4. Assuming you even had 8.5:1 static, the 413 would produce a DCR of 6.4. That will produce less power, it's overcammed. Something like the TA 212 would produce a DCR of 7.05, still a bit low. If you are going to replace the heads, you should actually measure what you have so you'll know what your true static compression is. You'll want to aim for 9.5:1 static.
You could always leave the cam in and try a different converter. If the whole combination isn't right, it isn't going to be much fun on the street or fast at the strip. A 413 with 3.73s and a 3500 stall converter would probably get you where you want to be. A cam with a narrower lobe separation angle and a little less duration would probably work better with your compression. I would probably use a 284-88h with a small converter and 3.42 gears for street/strip.
This is a four speed car, so I can make a converter any way I want it to be Thank you Larry, I found your take on DKR really interesting. I will attempt to figure this out using the info and the new stage one heads which are 71cc Mike
Try and measure your piston dish cc, how far the pistons are in the hole, and combustion chamber. With lower static compression, a smaller cam will work better.
Well the piston is about 65000th in the hole with dish being 27.8 cc, everything else stock with the current heads being 76cc and the new ones being 71cc The 212 might be a good option.
Larry is correct at 8.5:1. I had a .030" overbore in my calculator. I don't really think you absolutely have to run a tiny cam just to get any performance out of the motor. The whole DCR calc is more about what will run on pump gas, so the higher numbers are more relevant when you're maxing out a street combination. I know of a budget street/strip motor in a full weight 70 gs running your compression that has a cam with a 300+ degree intake lobe and still has run 12.20's (and it was a 430, no less). The DCR has to be abysmal, but the car makes enough torque to lift the front wheels 6". It's more about getting the right gear and converter (obviously not with your 4-speed, but you get the point). I would pick a cam that puts the RPM range where you want it to run and not worry too much about the DCR. Narrow lobe centers will help boost it, at the cost of idle quality due to more overlap. Since you think the 413 is too doggy on the low end, maybe something between a 212 and a 288-94h. You could always have it ground on a narrower lobe center to boost your dcr.
Yeah, I agree, combination is everything. Depending on how good the heads he is bolting on are, he might get a boost out of the head flow as well. He definitely needs something smaller than the 413.
I bet a 284-88H would work really well, but it's on the tame side. Heads can only help things, for sure. I really think something on a 110 degree or less LSA would wake it up and maximize what he has. Then, getting the right amount of duration for the RPM range he wants it to run in would be key. With compression and head flow you can open up the LSA and get a more streetable idle and wider power band.
Here are the flow numbers on the head. Mild port job.. by the way you guys are awesome thank you all for the help!
I have been running a 413cam for many years and really like it.462motor-portmatched heads-stage1valves-sp1-mt headers-holley780-3500t400-3:73chevy lots of torque off idle pulls hard top end. low13s at 6500ft.not enough vacuum for power brakes-depend on vacuum pump.car weight 3975 with my skinny but in. lost my licence last year. no driveis killing me 75in a 30--okjudge I promise --never again kenny462
