what would happen (to tranny or motor) if you dont have enough stall still not sure I really understand the concept of stall converters:confused:

The motor would stall when you put it in gear.

The torque converter serves a similar purpose to a clutch in a manual transmission; it allows the engine to slip enough to keep from stalling when you bring the car to a stop with the motor in gear. Since you can not physically disconnect anything in the drive line the torque converter allows the transmission to slip a couple of hundred to a few thousand RPM below the motors actual speed.

When you install a non stock cam with a longer duration you shift the power band that the motor makes useable horse power up in the RPM range. Horsepower is calculated from Torque measured over time; the more time the motor has to make the torque the more horse power we generate. By spinning the engine faster (more revolutions per minute) we make more power, but if we are using the stock converter (which is made anticipating stock RPM's) it can not slip past what was welded into it.

Think of a torque converter as a water wheel. It converts the power of the motor into oil pressure which sprays against the paddles (blades) inside the converter. There is a fixed gap between the blades on the flywheel and the blades on the transmission, the blades have a set pitch (angle of attack), and the distance between the blades (like the number of teeth in a comb) is set by the size of the blades. All of these features determine the stall or amount of slip the torque converter will have, and they are all fixed at the time it is made by brazing everything together. Additionally a torque converter rated at 3200 RPM for a SBC 350, might slip to 3600 RPM behind a 302 SBC, but if the same converter is bolted behind a 572 BBC it will lock up at 2800RPM (flash) at the lower point; this is because the big block though making fewer horse power per cubic inch than the small block makes gobs more torque at lower RPM; and it is the torque that is being converted into mechanical energy.


Big Dave

thanks Dave I had the basic ideas just wasnt sure if my ideas were right I've been out of rod building for quite awhile and just built my first big block and I'm trying to put it in my ventura but want to make sure I do it right the first time cuz I cant afford to do it again (LOL) I have two th400s and both came from bbc in 1ton trucks and was trying to figure out if I had to get the stall converter now or if I could hold out guess not

Check cam grinder first for their recommendation of RPM then call a tranny builder to shop around for a converter. If your running a lot of cubes opt for their heavier duty nitrous plate reinforced units so you don't blow them up like a kids balloon. Like I said a torque converter works off torque, more cubes (or nitrous in your future) equals more torque. The manufactures list their BBC torque converters based upon a 454 cube motor, so if your bumping up against 540 cid or 632 cid or 710 cid act accordingly.


Big Dave

I'm thinking of going with a Redneck Performance 3500 stall which should flash at about 4100 since my motor peaks its torque at 4000 unfortunately my roller cam was a used unit from my machinist they couldn't find the cam card (the cam was used only for a dyno test wasnt enough so it was replaced ) but it was perfect for my street and strip motor , also putting a manual reverse valve body in possibly a trans brake so I guess the stall converter is going to be a priority thanks guys

is there a difference between a pontiac 8.2 10 bolt and a chevy 8.2 10 bolt I've heard some say the pontiac doesnt have C clips maybe i read it wrong

Pontiac has "C" clips Olds 12 bolt rear (which is actually a ten bolt inside ) doesn't use the "C" clips (flange bolts to axle housing) but there are no common parts with any other GM ten bolt so it isn't used much. If you can find a 8.5" you'd be ahead of the game, 12 bolt is better yet.


Big Dave

will the 8.5 fit in my housing and use the same axles

8.5" ten bolt replaces your existing housing, internal parts do not fit as the 8.5" is bigger and stronger. If you have a '71 Nova it should already have a 8.5" ten bolt because all Nova's from '68 to '76 have 8.5 ten bolts installed from the factory. They put 12 bolts in the '68-'72 Nova SS 350 and 396 cars. The only way you could have a 8.2" 10 bolt is if some one ripped off your 12 bolt and put a 10 bolt out of a first generation Camaro under it. (the '77, '78, and '79 Novas had a 7.5" ten bolt rear installed under them if it came with a six cylinder).


Big Dave

The 66-67 Pontiac 10 bolt shouldn't have c-clips, this is the one with the cover having 2 cut out in the sides of the cover.. And any other years with this cover.. And this bearing should be pressed on the axle..

referring back to your TH400's and the 1 ton truck conv.........if you put that conv. behind a mild small block the conv. will be tight (low stall 1200 rpm or less) and the car will lunge and jerk when put in gear. Those convs. were meant for the big low rpm torque of a truck motor. The more torque you put to a conv. the looser (higher stall) the conv. will be. small block = low torque = the conv. will be tighter...The weight of the car playes a big factor also. If you take the exact same motor, trans, conv, rear from a 3000 lb car and transfer it into a 4000 lb car it will stall higher in the heavier car. If you need help figuring out stall speed for your application I can help. You must though give me all your motor, trans, gear specs...(and I mean everything) and the weight of the car with driver and I will tell ya what ya need for your type of driving.

Thanks Jay for the winter I'm sticking my sbc in front of my glide but this spring the combo will be

454
10.25:1 cr
2.19 Intake 1.88 exhaust valves
jones solid roller cam .714 in lift .708 ex
dur @.050 256 in 250 ex
performer rpm gasket matched and slightly polished
holley 750 dp
Approx 550 to 575 hp at 6000
580 tq @ 4500
3200 lb ventura
10 bolt 8.2 posi 3.42 gears
28 x 10 x 15 mt drag radials
turbo 400 from an 89 chevy 1 ton truck (was told by a friend thats a tranny guy it was the heavy duty version for heavy towing and hauling)
redneck performance transbrake valve body
hope to be a street driven car with occasional trips to the track

sounds like a nice little combo foir the Ventura. You'll need to get rid of the 8.2 soonewr or later. The pinion will only take so many launches at the track with the right conv. it'll go bye bye. Well.....I always use ATI for my race convs.....they are second to none. I tell Charlie what I need and it's dead on everytime. For a street strip motor like yours that has good HP & TQ numbers you can get an off the shelf piece from someone like Hughes , Coan , TCI , Trans Specialties. You'll want to be able to hold the car on the footbrake at 3500 and have the conv. flash to 4000 so you are in the meat of your torque range at launch. If it were going to be mostly a strip car I'd go even a lil' looser.

oh....you'll wanna step up that gear too. The perfect street gear for a 28" tall tire is 3.90 with a 3 speed

3.90 and 3.55 are no longer sold by GM. If you want GM numbers on the ring gear (which is really stretching the concept of numbers matching in my opinion, but some people insist) you will have to buy used. You can get just about any gear ratio Chevy offered still through the aftermarket, but you get what you pay for as far as quality goes.

Big Dave

No prob. with the after market. Moser is the only choice for me.