what stall do i need??

here's what i have, 355 cu.old dirt track motor, 500 something lift, john reed cam, double hump heads 1.94 valves, offy single tunnel w/600cfm summit carb pulling 10" va***e headers msd ign. turbo 350 trans manual valve body, here's the ? i have a hughes 2500 stall, at idle 1200 rpm the stall is almost nill , oh yea 3.73 gear, what stall do i need? and can i have mine redone it's brand new and i'm broke..... thanks guys

 

Stall is affected by torque and vehicle weight. The stall speed that you bought when you bought the converter is just a nominal number, in a perfect world it would be correct and the world you live in is far from perfect.

In order to set stall speed in a converter it must be dis***embled. In 99.9% of the cases that involves cutting the converter apart. Not a viable option I'm afraid. The general rule of thumb is that you start with the RPM that your engine starts to make torque, or the bottom of your power band. Some fellas set it where it makes max torque but in most cases that is not an acceptable option. For instance my 355 makes max torque @ 4,800, of course my torque curve is pretty flat.

Take a look at your cam card to find the RPM range if your usable RPM starts @ 2200 then that is what your stall speed would be if an altered stall converter is necessary.

Does any of that make any sense?

OH the 1200 that you are experiencing is most likely where your converter flashes and not the stall speed at all. Stall speed would be where your engine would stall if you reached that point and you were able to keep it from moving, hence the name. Again in a perfect world.

 

motor was built in the 80's cam card is long gone, reed cams is out of business, i've searched, it stalls when i put it in gear.... thanks

 

So you're saying the motor loads up and wants to stall when you put it in gear at 1200 RPM idle?

 

That is probably not a converter issue.

Before you start throwing money at it look for simple stuff like a vacuum leak. That is a common problem when one stalls when put in gear. Get yourself a can of WD-40 or starter fluid or the like. With the engine at idle spray it in the obvious areas if it revs up a bit when you hit it with the spray you found your leak.

If it turns out that you don't have a vacuum leak then just start going through a basic tune up. At least that is what I would do.

 

For street use your convertor should be just fine. Look at your carb---vac leaks ect. You said it has a manual valve body-Do you have a trans brake also? Either way your stall is fine for street application period.

 

thanks , i start looking....

 

Not sure where your timing is set now, but you might try advancing a bit to pull more vacuum at idle and see what it does. When I did that, the load on the motor when putting it into drive was much less severe.

 

its 4deg. btdc now, what would i try?

 

I adjusted my timing using the vacuum gauge... with a lumpy cam and automatic, I found a good spot that starts easily, pulls 12" vacuum at 900 idle, and doesn't ping under load. That meant advancing a bit from the nominal SBC settings that gave me 10" vacuum at idle, but it also fixed the problem you described with the motor loading when putting it in drive. The thing starts/idles/runs great now, but I'm gonna experiment further with full manifold vacuum advance to see what that does.

 

I had a car that did just that. It would stall the motor when I put it in gear. The engine and trans had been sitting for a few years before I bought it. Turned out it had a stuck converter. I got lucky and it came unstuck by revving up the engine and sticking it in gear a few times. So... maybe your converter is just stuck from sitting.

 

Just remember you want the stall speed to be lower than your cruising RPM. If you cruise at 1800 rpm and the stall is 2500 rpm your trans fluid temp will sky rocket.

 

At what vacuum do your metering rods raise? I'm ***uming your Offy carb is an AFB/AVS clone.

 

12 degrees advance with the vac line pulled off from the dizzy. Like I said go through a tuneup. Most of my books show 12 degrees advance on a stock small block.

 

I'd set the timing by the total, not the initial....you probably want it to be around 32 degrees at 3000 rpm

That engine is begging for a 4 speed trans

 

He says he has a 373 gear--Wont be any 1800 cruise speed with that rear and a 350 trans

 

I would say you want 14 degrees initial timing and 32-34 total, time to recurve the distributor.

 

its an offy intake and a summit carb, a knock off of a holley, thanks everybody for the help, ill try it all until it works....BT

 

also , no vacuum line on the dizzy ive got a 6al and dist that came with it...

 

I agree with Blake on the vacuum gauge method of determining ignition advance. The only way that you can get a better idea of what the engine "needs" is to put the engine on a dyno with knock sensors. Everything from combustion chamber shape/condition, to cam profile, to piston shape/design, to atmospheric conditions, to bore stroke combination come into play in determining the ignition timing of an engine, there are probably other factors I have fogotten to mention. Sense you dont have all of the specs for the engine there is really no way to pick a number and set it. Dont get wound up in what your actual advance numbers are, doing that you have to ***ume that your timing pointer is accurate. Never ***ume that the pointer is accurate. I have found that if you will advance the timing to acheive your highest guage reading then retard the timing to lower your guage reading 2 to 3 hg you should be pretty close at idle. This is done with the vacuum advance disconnected. from there you will need to drive the car to see if you will need to retard the timing further. If you want to check you timing marks with a light at that point for reference dont put too much credence on the actual number as balancer rings are notorious for slipping and pointers are rarely accuate. I agree with Squirrel in that you are probably going to end up with about 32 degrees total, but without setting the pointer on a known good balancer you will never know for sure. A sure sign that your ignition timing is retarded would be if your headers are glowing. There are probably other things I am forgetting to mention. Others will surely chime in.

 

Well that's what I get for ***uming too much! In that case think aboout the power valves instead of the metering rods. If they're wanting to open at 12" of vacuum and the engine wants to idle at 10", then it's going to flood itself out and die. The above advice about keeping the ignition timing advanced is a step in the right direction. More timing equals higher manifold vacuum, at least up to a point. May need to experiment with some different power valves as well. Wonder if a distrubutor with a vacuum advance might help out as well on a street driven car.

Your converter may work out fine. I'd work with the tune-up first.

 

thanks gotta go to town and get a va***e gauge....