I have a 67 with a 90 model 302 pretty much stock bottom end has e303 cam edelbrock rpm heads rpm intake 670 street avenger carb c4 of course and at moment 289 rear but was going to change in future to 355 or something like that what stall should i use if staying with current rear or changing to 355 or will it matter much? currently have 2500 in it i believe it may be too much stall but got told by so called expert (transmission rebuilder) that that is what i needed I was thinking 2000 any thoughts or ideas would be greatly appreciated

 

You need to tell us about your cam. You want your stall to be a couple hundred rpm up onto the power band of your cam. This way, when you launch, the initial loading might pull you down off the power, but rpm will flash back up and get you out of the hole and ready to climb.

Now, all this is crap on the street. You need to consider your cruise rpm for your usual driving. If your stall is above that cruise rpm, you'll destroy your gas mileage and create a lot of waste heat that will spell a short life for your transmission. If you drive it on the street much, you will need to select a stall below your cruise rpm and just suck it up at the track.

You might do Ok at 2000-2200. 2400-2600 is pretty agressive for a daily driver.

 

I would never call 24-2600 aggressive. I have a 2500 behind a trickflow stage 1 cam and it's begging for a 3000 which is THE MOST popular number amongst those talking about converters. I regret my 2500.

 

I'm not getting the impression that dragstrip performance is all that important here, just a desire for streetable response that's a little better than stock.

No, 2500-ish isn't aggressive for a car that only makes quarter mile runs or other short duration "drives".

But it is aggressive as far as a daily driven or distance driven car with the OE cooling system and only the OE tranny cooler is concerned.

This is where OP needs to define his needs, what supporting mods he's willing to also include, and what he'll be able to live with.


Norm

 

Thanks Norm.

People forget that a guy really needing a 3500 stall already answered his own questions like this a long time ago.

 

The AOD came with 1800 to 2200 stock in land yachts and I know we're talking about c4s, but just for the record. I'm not referring to 2500 for drag racing. Anyone putting a letter cam in their car is obviously looking for a little more than stock performance and 2500 is barely above stock. The OP is looking for a performance boost to match the cam and 2500 is hardly worth pulling the trans for unless the C4 comes with 1600. The E303 will agree. I'm wondering if either of you have actually owned a 2500? It's simply not all that much of a change. If happy with the 2500, I sure wouldn't drop it to 2000. The cam/heads/carb will hate it!

 

It's been a while, but I do have a little AT experience to fall back on.

A brief search consistently turns these C4's up as having stall speeds in the mid-teens.

When my daughter had a C-code '66, the stall speed wasn't a whole lot past the fast idle rpm. Eventually I swapped a newer engine with its AOD into that car, and the increase in stall speed was more than you'd be able to explain away based on the new engine having 13 more cubic inches. It's easier to justify running a "looser" torque converter at both the OE and enthusiast levels when the converter has a lockup feature and the tranny has an overdrive.

A LONG time before that, I had a car with a slightly looser than stock torque converter. Not a lot looser, but somewhere over 2000 rpm in that particular car, which had only a few more cubes than these thinwall Ford motors, a progressive-linkage dual-quad intake and some unknown cam. Yes, it was a little too soft off the line for drag racing or "serious" street match-ups, but it was fine otherwise.


Norm

 

I have done some reading on this recently...here is what I learned. The stall is the point where the driven blades spin roughly at the same rpm as the driving blades. Lock up TCs actually mechanically lock in at this point to help with fluid life, etc. If the rpm is under the stall then the engine is more free to spool up because it is not hindered by the load of the car as much. The problem with this is the fluid is taking a pounding during this condition.

Now on a street car, you want the stall to be at a point so that the torque converter is not slipping all the time going down the street and wearing out your fluid, etc. This is often not related directly to the torque curve as most of us do not gear our street cars per speed and torque...we gear then for mileage or performance or somewhere in between.

On a race car, you are going to be driving the car all the time at and above the torque peak. Because of this, drag cars set the TC stall at or around the torque peak (some slightly above and some slightly below depending on testing, conditions, etc). That allows the engine to spool up quickly as they are not really expected to perform below the stall speed anyway. For drag cars, the stall could easily be 4500-5000. That would be terrible for a street car.

I would say the ball is back in the OP's court. What is your torque peak? What kind of driving are you doing? At what rpm are you doing it?

 

I have an E-303 in my 408 powered manual trans coupe, IMO the cam IS NOT that aggressive, and certainly not as aggressive "as advertised"

http://www.summitracing.com/parts/FMS-M-6250-E303/

The RPM range claimed in the specs claims 2500 to 6000, but I think this is too optimistic. if it were me I would be considering a 2,200 stall, or even a 2,000. Going from my seat of the pants feeling with this cam I say 2,000. I can start the car moving quick and easy without giving the car any gas.

When this cam is compared to this Comp cam, and the numbers compared, the range starting at 2,500 does not wash. Besides, my E-303 cammed 408 idles smooooth at 600 RPM... The increase in displacement is part of the reason, but it isn't going to make that big a difference.

http://www.summitracing.com/parts/CCA-31-600-8/

 

I just looked up the E303 on DynoSim5

Advertised Duration 282/282
Duration @.050 220/220
Lobe Centerline 110
lobe lift .332/.332
Valve lift w/1.5 .498/.498
Roller Hydraulic

It has some decent valve lift for a hydro roller small block cam, but the duration is pretty small. Compared to comp cams performance stuff, it is pretty mild...which is what I have always heard of the Ford letter cams... Advertised as a good idle (since it has a 110 centerline with 62 overlap). Making a whole lot of assumptions, it looks like peak torque is around 4500 and peak horsepower is around 6000, if you have good heads, intake, and carb.

The torque starts around 2000 and flattens out until 3500 or so. Given that, I would say anything above 2000 stall TC would be totally wasted unless you went to a race TC at 4500, but as I mentioned above, that would be totally unstreetable. Not knowing your street driving trends and rpms, a 2000 would probably be at or slightly below your cruise, so you would not wear out your fluid very quickly.