Stall Converters

[G_Body_Enthusiast]

Your cam seems ok and I'm betting dollars to donuts it's the rear gear giving you issues. While a higher stall will give you a higher RPM at launch once you launch the rear gear kind of dictates how fast you get going, so a high gear can make an engine fall flat on it's face. Everything has to match to get whatever it is you want from the car. With the cam you have I'd want a 3.23 or lower (numerically higher) if you have an OD trans. Changing the gear that much will make the car feel and act completely different.

195 isn't a bad temp, stock thermostats open at 195, anything over 210 would be an issue IMO. Just remember, you don't want it to run too cool, the temps you're at are fine and normal.

 

[Clone TIE Pilot]

Overheating can also be caused by vacuum leaks leaning out your fuel mixture.

 

[olds307 and 403]

I had a converter that flashed at 2400 rpm behind my 403. It launched very hard even with 2.56 gears. I personally hate 3.42's without OD with my short tires, 3000 rpm at 60 sucks.

 

[565bbchevy]

I would personally step up the rear gears first to as already stated something around a 3.23, you might find that a new convertor might not even be required since your engine will get in it's powerband sooner and you might be happy with that and I would say mileage would be comparable since you are probably using more fuel right now just to get it moving.

 

[Intragration]

I had a converter that flashed at 2400 rpm behind my 403. It launched very hard even with 2.56 gears. I personally hate 3.42's without OD with my short tires, 3000 rpm at 60 sucks.

I agree that gears are a matter of taste. I was afraid that going from 2.41s to 3.42s was going to be too much, and that I'd have to change to 3.08s. As it turns out, 3.42s are just fine for me, even with the 455. At 60 MPH with 26" tall tires, I'm spinning around 2,650 RPM. With 3.08s, that would be reduced to about 2,400 RPM. Not a big enough difference for me to worry about. Now 3,000 RPM, that might cause me a little more concern, but I'd need 3.90 gears or 23" tall tires on my setup to spin that fast.

For me, 2.41s and a tight converter and a decent 455 lugging to get going just didn't work. I thought about a higher stall, and it would have provided some benefit I'm sure, but it would amounted to a torquey motor that lugged less to fight against the 2.41s. Instead I went with 3.42s and left the converter alone, and it was a shocking difference. I've thought about converters now, and it seems almost unnecessary. But again, I have torque to spare.

In the OPs case, a 305 with a fairly healthy cam for such a small displacement, gears AND a higher stall might be the answer. If only ONE could be done, I would think the gears would be the better answer. Some of you have mentioned that a converter with the stock gears helped. Does anyone think that this is the BEST solution though?

 

[1980Bu2Dr]

I do think a rearend swap would make a big difference...guess i need to decide what i really want from the car. Do I want it to be fast off the line or keep the gears i got now and keep enjoying my 24.5 mpg.

That being said I was hoping a 2000 or so stall may give me the best of both worlds. Anyway...temp doesn't seem to be an issue, the other day i was in a long line at the mcdonalds and decided to leave it in gear. Never got above 200 so I guess I shoulda just trusted it from the get go. I've probably been way to nervous about things since this is the first motor I ever rebuilt on my own.

 

[lilbowtie]

You got a lot of advice so far and mine would be not to buy a used converter unless you know the history and who you are getting from.

 

[Intragration]

24.5 mpg

?! Is this the mileage you get on a regular tankful, or is this what you get when you put it on a flat highway and drive 200 miles at the same speed? And what does a typical tankful look like, in terms of driving conditions?

 

[565bbchevy]

You got a lot of advice so far and mine would be not to but a used converter unless you know the history and who you are getting from.

X2 on buying a used converter of unknown usage, I would only by used if it was a friend of mine and he is only changing it because he wants a different stall speed.

 

[1980Bu2Dr]

24.5 mpg was the best mileage i've seen and it was all highway driving at 60 mph. Around town it is lower but I do like to cruise in it so I would like not kill the mileage too much.