Will a 3000 -3200 stall converter let my sbc with a big cam idle like its in netrul when I put it in gear, or will it still drop the idle down? Right now I have to have the idle higher then I want to keep it running and it wants to creep foward in gear. Thanks.
How big a cam ? How heavy a car ? How much torque ? All three will play a role in converter slip, I think it will still creep. Later, Mark
It will drop the idle slightly and you will be able to move the vehicle around on level smooth ground, without having to turn 3000 rpm.And you will still have to foot brake the car to the converters flash point for a good launch.But it should stop the creeping issue.
It will still drop the idle down, and it will NOT idle like in neutral when in gear. The minute you remove your foot from the brake, it will start down the road, but you should no longer be " fighting the brake " to hold it back, make sense? Unfortunately that's what most people think with thier first higher stall converter. Lots of factors play, gearing, weight, and mostly the amount of available torque at said RPM. You WILL be able to hold it back on the converter and bring the revs up, to where it wants to " flash " but that's all. Flash stall is different than your actual stall speed which has many variables. Remember too, you are building a LOT of heat with the higher stall speed, especially when your loading the converter. You need to seriously consider your coolers ability to keep the temperature in a reasonable range. I work very closely with one of the biggest names in the racing/performance auto-trans business, and are just conveying to you what they have drummed into me for many many years. My daily driver hot rod has a 10" 3500 stall converter. TR
How heavy is this car? A 3000-3200 stall converter from a 3600 lb Chevelle will react TOTALLY different and want to creep like crazy in a 1700 lb Model A. It might flash as low as 2300-2500 in the lighter car. Big Block engine or Small block engine, it all makes a big difference, hope that helps, TR
Its in a 65 c10 truck, I bought the engine used so I dont know the specs. 350 with lumpy cam, said it had mild head work, 750 carb, headers, 373 gears. Its just a bitch to hold it at a light with manual drum brakes. When I say it wants to creep foward in gear, I mean at stop lights with the brakes on as the idle is set higher. I just looked up the weight ,its about 3300 lbs.
chainsaw, I'm saying this VERY respectfully o.k., so dont take this wrong. There is a BIG diiference from a $250 converter and a say $600-800 converter. Believe me I understand the "options" you can get for a high dollar converter, thats not what I mean. If you have a " entry level " converter, they just dont have the high tolerance lets say of the high dolllar one. Meaning stall speed can be all over the place, you take 10 3000-3500 entry level conveters, and maybe two will have the same results in the same application. Maybe you have a high dollar one, I dont know. Thats a fairly heavy rig, if your really having trouble with the brakes at idle, lets look into the brakes for now and get them dialed in or at least know that they are not the culpret. We have race cars as heavy as your rig, cams that are in no way streetable and manual brakes. As far as idle speed, hopefully your rig is in a good state of tune, now with the engine FULLY warmed up, set your idle while in gear, have a buddy help you on that one. If you set it in nuetral, when you put it in gear, it will likely stall. Now another very important problem arises with a big cam, have you checked your manifold vacuum? You will find that it will be considerably lower than a stock cam. Now you have another problem with the vacuum advance canister on the distributor. You can A- send it to GMC Bubba for a recurve, B- once you find out the engines manifold vacuum, you can go to NAPA and go through the vacuum canister listings and find one that will work with your cam. This is where things get tricky and you will need to have a good understanding of ignition timing and curves to get this part right. If you dont, send it to Bubba, he will take GOOD care of you, TR
I like to tell folks to " give it time ", if this is your first converter, you are exactly like most folks, they think you can sit there idling in gear like you have the clutch in and it's not so. You almost feel cheated on the converter or the dang blasted thing is just junk. I tell them give it some time. If everything else we talked about is in good condition and cool, then just give it time.
Yeah a looser converter would help with those issues, I have the same ones with my car. I'm running a SBC, big cam (10 inches of vacuum), th350 and tight converter. I'd like a 2800 stall at some point but I might change the motor so we'll see. Right now my idles at 750 in drive and 1000 in park/neutral. It surges and strains but it lopes good.
Thanks for the info guys. I'm guessing I have a cheap converter, dont really know as it came with the engine ,trans combo and he said it was 3000 + stall. I used my stock trans and converter as I knew for sure it worked. I'll be the first to admit I'm not an engine guy (did paint and body back in the lacquer days) so I'm still learning to tune engines. I'll take the advice given and make sure everything else is working right before swaping converters.
Good deal, chainsaw if the 750 carb is a Holley, you definately need to check the engine vacuum, so you can match the " Power valve " to the engine vacuum. Power valves are very simple to calculate for the correct one, and they are cheap too. It will be a sweet running truck when your done.
I'm a "stick" kind of guy and not into automatics. I've heard the term "flashing the converter" over the years and always what that meant. Can you give me an explanation or example? Thanks!
Having them creep at a stop light is no fun. I had a Maverick that I could sit at the stop lights and listen to the studded snow tires spinning, while the car did not move. The front brakes kept it still, I guess. I put a next size up from stock into an o/t C10. And I am quite pleased with it. The engine idles a bit high, due to the cam, but no creeping is going on.
The Jalopy Journal
