It does make sense thanks. Though the rpm to have it at when setting it and choosing springs isnt really clear to me. 2500? My vacuum is currently limited at 9. If I rememebr right my initial is 11.
Do you know what knock sounds like? That's the best way to tune- try something, and if you hear a knock then back off until there is no more knock. I think I had the two lightest springs in mine, so my mechanical advance came in early - but if you hear knock then you might want to step up to one light and one medium spring. -BC
2500 is a good RPM to shoot for. It is very easy to verify when all your advance is in by using a timing light. Do you understand how to do that?
Yep I should anyway, did it once on this car, will have to do it again to even rememeber what its at currently.
Because while looking for a crack in my flexplate I will be separating engine and trans, and if there is no crack I will be replacing the converter because it would be the last thought of what could be making the strange sound my car makes... ..I am still looking at what converter would be put in, in that case. Assuming I leave the engine as it is. It seems like I would be looking for a converter that engages at a slightly higher stall than stock. Nothing crazy. But I dont even know what the stock one engages at. So three questions, 1. Does anyone have a torque curve read out from a dyno or such on a stock 72(ish) 350? 2. Does anyone know the stock 72 converter engagement rpm? 3. If down the road, I swapped from 2.56 to 3.08 gears, things would only get better not worse regarding whtever converter was in there correct?
An 11" 1800-2000 is all I would get for a 3:08 gear. If you get something custom made,they can taylor it to your car,and give you something tighter,where it needs to be.Any off-the-shelf aftermarket converter is a vague application,and does not always produce the intended results because of this. As for the whole vacuum/timing thing. I run all my cars with the vacuum advance plugged or unhooked.I don't use it.If you have one of those spring lots,use the lightest set.You have a heavy car,and it will help the advance come in quicker,and the distributor will advance mechanically.Have your total timing in by 3,000rpm,or slightly less.When setting timing,focus on the total timing,not initial.You may need to bump up your idle slightly when doing this,but I have done everything this way,with positive results,and the cars see plenty of driving.
Whats the advantage to running no vacuum advance? About the converter, I may need to replace mine anyway due to noise it seems to be making, so I was thinking get one that would be beneficial instead of just stock. (Unless there is no benefit)...
JAson, I have a quick question... What is it you want your car to do? Burnout better? Accelerate quicker? 1/4 mile runs fast/ quicker E/T etc? What is the most important thing you like to do with the car? You need to answer these question as YOU will be driving YOUR car not the rest of these guys. So sit back figure out what means the most to you - 2.56 gears are great for driving around and a little more converter can help you get the snap and burn out you want at low end... as you know the converter does need to get close to lock-up over that Stall aRPM and you really should not cruise too much below that Stall RPM. Biggest trouble MOST cars have after years of people tinkering and swapping parts is getting it all to run correctly. Timing and CARBURETION are the 2 BIGGEST issues most all guys / Girls fail. YOU must know that all these parts are in sync before knowing if the car needs more performance help and in which area. ALL the trick parts in the world will not help a bad timed and carb-ed motor. Gears- Will accelerate the car quicker and get the mass moving quicker and easier.... IT WILL NOT GIVE THE CAR ANYMORE HP. Gears are also a mis-guided band aid to a bad timed motor and timing issues. I get more people in thinking they need gears when the motor is just not running correctly. OR you they have picked too big of a camshaft profile and low end suffers from duration. IE - I installed a 2000 B&M converter into a 1967 camaro with a 327 flat top motor + 350TH + Budget table Aluminum summit a tech heads 2.02+ 252 comp cam+ Stock 2.73 10 bolt 8.2+ posi+ good ignition and 600 Holley electric choke and it runs like a top.... 15.00 flat in the 1/4 Very well mannered car wife loves to just cruise around. I am the one that ran it at the track...lol. DOES GREAT burnouts with the 2000 stall and freeway gears. . LOSTS OF SMOKE! Thick like... because the freeway gears are going 120MPH but the motor is only doing 3500 rpms LOL So I say PICK what is important to you and your car and will try to help you get there. Start with all the basic components working as these guys are going over for you. Good Luck. Jim J D
JMO, but I believe any street car should utilize vacuum advance. The problem is when you couple it with a quick mechanical advance it can cause surging and or part throttle ping. The solution is to limit the canister degrees to 8 or 10* max. Cruise timing at around 40* or so will give you the best efficiency. It's just one more thing to tune, that's all. You can pick up 2 MPG or more if you do a lot of highway driving, and hooking the vacuum advance to manifold vacuum makes that advance available at idle and low speed stop and go driving. That can allow the engine to run cooler under those conditions. Under full throttle and high load driving, the vacuum advance drops out. As far as converters go, the cam really dictates whether you need one or not. As Brian stated, the best option is to have one built for your specific combination. That is much more expensive, but a converter is one of the most important parts of any combination. Off the shelf converters are a gamble. There is no such thing as a converter that stalls at ____ (fill in the blank) in every car.
Exactly my thoughts. Thanks. In short, what I would like is "get the mass moving quicker and easier" (more fun) sure burnout, quicker quarter, but still cruise at a decent rpm. This car will probably never strip race, street fun and cruise ins and shows are common for me. It also needs to be able to freeway for hours. Which it has happily done so far. I am now getting a 3.08 posi assembly from a guy (that is even from a 70-72 Lark) and that will help. My converter seems to be clicking, and when I get the engine separated I expect the flexplate to not be cracked, because it doesnt sound the same a as crack. This means I am likley replacing the converter anyway, so am thinking how can I choose a converter that is s a little higher stall than stock but is for sure not gonna slip bad at 55 or so mph so I dont have to deal with heat issues. Also do I need a trans temp gauge, and how? Do I need a tach? Have none. Would love a hood tach someday. Timing is good. There are alot of opinions out there so I went in between them I believe I was at about 38 degrees total at about 3000 had it wrote down somewhere. Sounds like I could be at 40 at 2500 as an alternative. Carb seems dialed in pretty good. Was PMing with Jim Wiese and he seemed to think the short bog I was still getting when floored from a stop was just due to trying to overcome 2.56 gears with a motor thats not built up.
Thanks, I was going to go and replace the CAM with a 212 if I had to take to cover off. But at this point we can assume I will keep the stock cam in there. Since my timing gear is a metal replacement as I can see thru the Fpump hole, and the play measured in the chain by turning it backwards and waiting for the rotor to turn was acceptable. Also since I found a 3.08 diff to upgrade to and that'll help low end. So I dont even know what the original converters stall is on a factory 2bbl 350 car (originally with AC) witha 2.56 diff, was. For example if it was 1600, maybe 2k would be ok?
Part of my problem is most converters seem to list a range of 400rpm, and I also hear it can differ alot in each cars setup, so it makes it nearly impossible for me to try and figure out what one to get. Per calculators, with the 3.08 assembly I will have on my TH350, my engine's rpm should be 2248 at 55mph, and 1839 at 45mph. If I got a converter rated for 1600-2000... think car show cruises would be ok? I mean they go thru towns where limits are 30 sometimes... If that stall estimate is off by 200 rpm it could change things a lot.
I think it is a mistake to think of a torque converter as an on/off switch when it comes to stall speed. The difference between the wrong converter and the right converter for your car will be night and day. The right converter should stall to it's maximum when the engine is up towards it's maximum torque range (for a race car, peak torque). If you feed it less torque, it should stall less. That is called converter efficiency. Sorry, but you can't get that off the shelf unless you are very lucky. Have a converter built for your car. It will cost substantially more. This is from the Gear Vendors Overdrive site, common questions. "Can I run a high stall converter in overdrive with a 3.42 axle? Yes, this is one of the most often confused questions (even when you ask people you would think would be knowledgeable). Here is the detail. Our example could be this 3.42 Chevy guy. In overdrive he is going to be a 2.67 final drive ratio. He is a Cutlass body with 27 inch tire and so at 75mph in overdrive the motor will be turning 2484 rpm and he has a 3500 stall speed on the back of a pretty nicely built 350ci motor making close to 400hp. 95% of the people you would ask (even tranny guys) would say no-way and yet we know this is an awesome package (drives wonderful, no high temps in the trans etc) why does it work? When his converter was made it was set up to stall at 3500 with 400hp. However if you put 600hp to it it would stall at something like 4500. Conversely if you only put 125hp to it (as when you are just crusing at 75mph not accelerating) then the stall is way down at 2,000 rpm. So his stall with a 3500 converter is not 3500 at cruise because he is not making 400hp. Car drives wonderful. If he romps on it while cruising then the trans is going to downshift to a lower gear and get him into the powerband. (note: read gear vendors passing gear in this section) So, this is why you never lie to you converter builder (because if you overstate your hp you will not get the stall you wanted)."
I'm running a 3000 stall on my Mercury with 550hp and weighing in at 4500lbs with me in it. At light (less then 1/2) throttle it stalls between 1400-1800 depending on how much you press the pedal. The more you mash the skinny pedal the higher it stalls. I only see it hit 3000 with drag radials at the track, it'll blow street tires away past 2500 from a stop.
Sounds like you got it right. Was the converter built for the car? A good converter should stall progressively higher as more and more power is applied. It is designed with the engine torque curve, car weight, and gearing in mind.
I was reading things like that on other sites and it made me ask myself why dont the converters for sale say what HP or torque they are rated for at the given stall rpm. Its a part of the puzzle that means the numbers are near worthless without isnt it?
Forgive the newbie to converters question, but I thought "stall" and "lock up" wasnt the same thing? Stall meant you are now moving and lockup meant there is no slip generating heat?
