Torque convertor advice
Okay, here's what I've got: 5.0 out of a 96 Explorer, Ford Racing E-303 cam and lifters, Trick Flow Specialties valve spring kit, Edelbrock Performer RPM intake and Edelbrock 1404 carb. The transmission is a C-4 out of a 77 Thunderbird rebuilt with a shift kit. Rearend is a 9" with 3.50 gears currently (I have a set of 3.70's too). The tire size is 205/60/15 with a height of about 24.5" tall. This combo is in a 62 Falcon which will weigh in the neighborhood of 2400-2500 lbs when done.
PLEASE NOTE: This is and will be a street car, not a race/drag car. Of course I won't mind laying some black strips now and again. :D So, I don't need some exotic built torque convertor, just an off the shelf convertor that I'll probably buy from Jegs or Summit. With that being said, what would be a good stall speed to look for with this combo? Thanks in advance for your help.
P.S. Not trying to be a smart-*** with the exotic convertor thing, but I have gotten some pretty crazy recommendations from other sources and I just need a short and sweet suggestion.
3K rpm stall. I'd seriously consider the 3.70s, too. Add an axillary cooler if you don't already have one.
The distributor will need a performance curve in it.
2500-3000 is a lot of converter for a light street car that gets driven a lot.
A converter will stall lower in a lighter vehicle than a heavier vehicle, all else being equal.
My recommendation is conservative if anything (what do you think FB88 would recommend :mwink:).
Find a engine dyno test of a 302 ford engine using the E303 camshaft. Look on the dyno test to see
the RPM point that peak engine torque occurs. Pick a stall speed that is 500-700 rpm belows that point.
so if peak torque occurs at 4000 rpm get a tork converter that creates a 3200-3500 real max stall speed when used on a 302CID motor.
The advertized stall speed may not be the real stall speed as the stall speed you are going to get is relative to engine torque input. A bigger 347 or 351 CID will see a higher stall than a 302 with the same torque converter.
Therfore is is very common to come up short on real stall speed behind small CID engines.
So before you buy the torque converter for your 302. CALL THE MANUFaCTURER.
They will advise you on the real stall speed you will get behind a 302 with any one converter.
That way you will get it right the first time.
A high stall converter is pretty tame when in a light weight car. So don;t be shy on stall.
You want the stall well up on the engine torque curve at launch.
302's need stiff gears too, especialy when cammed.
Th E303 cam is really intended for a 5 speed manual trans car. So when using with a auto transmission it may benefit from a bit of camshaft advance to build engine torque. More torque is better, with a auto transmission. Especially if the engine is a little soft on compression ratio. On a 302Ford its a real good idea to verify valve to piston clearance when ever messing the camshaft advance-retard phasing adjustment.
Again... if you want to get it right the first time call the converter manufacturer so you get the converter stall you need, from a off the shelf high stall converter. The phone call can make the difference between getting the right and wrong torque converter.
Here is the Fbird88 method of street strip torque converter selection.
Based on 35+ years experience and looking at the engine torque-power curve.
This is for a street strip car,,, not full race.
For street strip a good target area is the blue point.
The minimum stall for good street performance with that cam is the lower Red arrow
which indiates the lower point of equal engine torque from the peak horsepower point.
You really don;t want a real stall speed less than this, unless you are a real wimp.
Full balls out race you want the stall speed right at or even a bit higher than the peak torque point.
This happens to be a dyno test graph of a 5.0L ford with the E303 cam in it....so.....
The smaller the engine CID the more critical the torque converter choice is.
At 2500 RPM you are at 75% of your maximum torque. If you race,then use a higher stall speed.With small tires,you do not need as much converter,especially the shorter tires you are driving on the streets.
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