Is there a certian rule of thumb when matching a cam and a converter?

Like say for example...should the converter have at least a stall speed of 500 rpm past the cam's starting rpm range?

IMO you want a converter that flashes close to or just past an engines peak TQ.

So if you pick a cam with peak TQ at 4000 RPM a converter that flashes to 4000-4500 would be just about right.

That is not always practical though -- I run a cam with peak TQ just over 4000 and my converter flashes to just below that. It still works fine.

And remember this converter flash RPM vs peak TQ RPM thing is kind of a "which came first the chicken or the egg" type debate because engine TQ DOES affect the RPM at which a converter stalls. ;)

So would it be best to wait until it's done seen the chassis dyno before I select a converter?

BTW, what's flashing?

Flash is the rpm the engine hits when you hit the gas and the car takes off. Some converters foot stall 2500 but will flash 3500 when the gas is hit and the car starts to move.

No you don't have to wait to buy a converter, just be ready to pull the converter and have it adjusted if you insist on having everything dead nuts on the money.

Just talk to whoever you have build your converter and the cam company so that you know the approximate peak TQ rpm the engine will have. Pass this info to the converter guy so they put the right stator, etc in your converter.

Flash RPM is the RPM that the engines revs to when the tires are dead hooked and the gas is floored (no brakes applied). Flash RPM is usually several hundred RPM higher than brake stall. Brake stall is the highest RPM you can rev the engine to while holding the car with the brakes.

For example -- my Coan 10" converter foot-brakes to about 3200 RPM. But when I launch the car at the track and it dead hooks the engine "flashes" to about 3800 or 4000.

A good way to test flah stall rpm is to disable the transmissions down-shift feature (disconnect the detent cable on a TH350 for example) and nail the gas from a lower RPM when in high gear. The RPM the engine goes to is the flash stall rpm. Their are other ways to measure flash stall rpm, but that is the easiest way I have seen.

There are many variables when it comes to building the proper converter. A rule of thumb is that many Glide-equipped race cars like stall speed at 300-500 over the torque peak. Three speeds may like stall closer to, or at the peak. But again, you need to look closely at the whole enchilada first before generalizing the number to use. Also a chassis dyno is not accurate IMO with a non-lockup trans due to variables with torque multiplication. The true test for engine numbers is a run-in on an engine dyno. That way you have apples to apples for numbers to compare.