How do I know if I have the correct converter?

[Mike Brichta]

I've often wondered if I have the correct torque converter in my car. Is there a way of telling? What are the symptoms if it too low or too high?

 

If I currently have a 383 stroker (410HP), th400 trans and 2.73 posi and I want to switch to a 3.55 posi, should I change the torque converter?

 

This is not my every day driver. I would like to drive it every so often and would like it to have better launch for pulling out and acceleration.

 

Thanks,

Mike

[Guest]

What is your cam / intake / head combo. Typically you want the stall to come in on the low side of your power curve. If you have a stock convertor now (1600 - 1800) and you put in say a 2400, you may see a little higher rpm on the highway as well, since that trans does not have a lock type convertor. I had a 2400 in my old 72 and thought it was perfect. I just put in a 2800-3000 stall in my current 72, but I have a 700r4, so it's a lockup with overdrive. Big J

[Mike Brichta]

Thanks for the reply. My cam / intake / head combo is as follows:

 

Cam: Fed Mogul CS-1062R

Intake: Edelbrock Performer RPM

Heads: Trick Flow G2 Alum Heads

 

I don't know the details of the items above, so I'm still not sure which is the correct converter, but you are not the first person who has suggested a 2400.

 

What if I switch to a 355 rear? Will a 2400 still be the correct choice?

 

Thanks for all of your help!!

Mike

[Mike Brichta]

I forgot to include the part numbers for the heads and intake. They are:

 

Heads: TFS-31500001

Intake: EDL-7104

 

Also, the carb is a Holley Street Avenger (770cfm) and I have Flowmaster Dual Exhaust.

Thanks,

Mike

[Guest]

Yeah,

 

I would reccommend a 2400. It may be a range, like 2400-2600. I think you'll really like it. Have you ever had down the quater mile. Your 60' times should drop quite a bit, espicially if you do the gears to. Big J

[wallaby]

With the gear change you'll have less need for the high-stall converter. If the gears are going in either way, i'd do them first THEN decide if you need more RPM from a stall converter.

[Mike Brichta]

Hi Wallaby,

 

Thanks for your reply/help. Now, I know this may sound like a bunch of dumb questions, so don't laugh, but it sounds like what the torgue converter does is determine at what RPM the power from the engine translates (or locks) into the rear tires? Is that kind of how it works? So what you are saying is that with the 355 rear, I may not need a 2400 converter because the RPMs will be much higher than before? I was just trying to weigh all options since I am going to swap the rear from 273 to 355 anyway. I really would not like to change the converter because it is much harder than chaging the rear, but if it would make the car faster, then I would. Does all of what I said make sense to you, or anyone out there? I just want to make the correct changes.

Thanks for all of your help !!

Mike

[Guest]

There would be less need for the converter because the 3.55 gears would get the engine from 1600 (stock stall) to 2500 (power curve with your set up) in less time than the 2.73 gears. However, the convertor would definalty improve quarter mile times. Now your starting out the race right at that power curve. Here is a sight with some FAQ's about torque converter. Big J

 

questions about torque Converter

[chuckash]

While I dont mean any dis-respect to the knowledge of this board, your best selection will come from contacting one of the converter manufactures tech lines and explaining your setup and usage with them. Pick any one you like, they do this every day and have the in depth knowledge of the subject.

 

While changing the rear will certainly wake up the car, I'm not sure that changing a rear is any easier than changing a converter. That is, unless you are changing the entire rear assembly and not just the gears. Even then you are still into bleeding brakes, a job that I personally despise. Changing gears requires special knowledge and tools to set up properly on a 10 bolt or 12 bolt.

 

Remember too that the looser converter will make more heat for the transmission and an aux cooler may also be required.

[wallaby]

Yea, you pretty much got the idea there Mike. The higher stall converters introduce what feels like slippage, and it lets the engine rev higher where it can make more power instead of bogging at low speed. Mostly this is an advantage when you try to accelerate from a dead stop, but it can help some at gear changes also. The magic of a torque converter is that it converts torque. A good converter will multiply engine torque maybe 1.5 1.8 times, so that explains why auto trans cars get by with the 2.73 rear gears when manual trans cars use 3.33 gears. (stock converters do this too).

Personally, I don't like high-stall converters. The slippage makes the engine seem disconnected sort of. I like the feel of instant hookup like you have with a manual trans. Snap the throttle and it snaps your neck. Stall converters remove that sensation it seems. The way I see it, if you have trouble with wheelspin, your motor is reving freely already and a converter won't help you go any faster.

[dbreese]

Mike

 

Try this site

http://www.coanengineering.com/

 

Just email your combo and they can get you set up with the conveter that will work well. They actually called me about two days after I sent the info up. The tech was very helpful and we were able to come up with a converter that works well with my powerband and gear. It also idles at 750 rpm in gear with a 240/238 @ .050 cam. Tech also said that they could tighten or loosen it to get it just right.

So far no problems.

 

Helps take alot of the guesswork out.

 

David