torque converter question

by mikei1253 Tue Sep 10, 2013 11:07 am

i have a 77 grand prix with a very mild built 400 in it. eddy performer intake, comp xe256h cam. mild ported 6x-8 heads so it has very low compression. rear end gears are low 3's im pretty sure. and i'm wondering what size stall i should put in it. it'll will be a street/strip car just for fun. but it does get drivin on the street more. any suggestions would be awsome. thanks

by Joe73 Tue Sep 10, 2013 11:48 am

Comp cams lists the operating range for that came as 1000-5200 rpm. You might do better with a slightly "looser" convertor. But I wouldnt bother. With that cam coming in at only 1000 rpm, you can definitely power brake or use a line lock to have the rpms in the power band of the cam to launch the car nicely. But if you want to do the work and change it, then I would go with something in the 2000-2200 range. That would also leave you room in case you decide to change the cam later on. Just my 2 cents. Good luck with it.

by 77mali Tue Sep 10, 2013 12:45 pm

You need to know your rear end ratio, transmission ratios as well as your Cam specifications-(expected HP & Torque #'s too). I've been looking at both TCI and B&M for a replacement converter (I've yet to order) but they'll both fit the bill for what you seem to have there & will be about $300-$400 depending on what you need. Give them to go over your specs.

by mikei1253 Tue Sep 10, 2013 1:00 pm

i've got a th400 trans

by 77mali Tue Sep 10, 2013 5:51 pm

I forget what the ratios are on a TH400 but either one of those companies can help you figure it out if it's original to your car. IDK about Poncho's but the chevy rear end codes are located on the axle shaft between the diff & the brake hub on the side that faces the front of the car. There are some codes here:

http://www.g3gm.com/t3202-updated-rear-end-codes-page?highlight=codes

by pila Tue Sep 10, 2013 8:36 pm

The 252 cam is just one step above a good stock cam. I've used a few of those, and on Chevys I use them in place of the stock cam, on a stock rebuild. They even work great to wake up a little 305.
With the torque you have with the 400, I would be inclined to use a stock converter. I built a 400 (406) for my '67 Bonnevlle a few years ago, and used a stock Pontiac 340 HP grind cam from Wolverine, which worked quite good.

by bracketchev1221 Tue Sep 10, 2013 11:31 pm

If you have to put a converter in, I would stick with around 2000 rpm. But to just go and change it, I wouldn't. Stock t-400 gear ratio is a 2.48 first gear. Try to see what gear is in the rear. If it is a 3.08, you would probably see a better gain going to a 3.42 gear than a converter.

by mikei1253 Wed Sep 11, 2013 8:25 am

THANKS I WAS JUST THINKING OF REPLACING IT WHEN I REDO THE TRANS SINCE I'LL HAVE IT OUT ANY WAYS. BUT I WAS THINKING OF PUTTING NEW GEARS IN TOO. JUST TRYIN TO PEP IT UP ALITTLE BIT WHILE I START MY BUILD ON ITS NEXT MOTOR BUT THANKS FOR THE INPUT GUYS

by Wallyuph Wed Sep 11, 2013 9:09 am

I have bought two converters from pro torque I have one in my 56 chevy and one in my 73 malibu. They are not cheap but you give them your specs and they ask what you intend to do. Shred tires or drive it. They will build it to what you want it to do. Really woke both my cars up.
Here is a link.
http://www.protorque.com/

by mikei1253 Wed Sep 11, 2013 9:30 am

thanks wally. i'll probably give them a call here sometime soon. see what they get for one and there opinion on it. thanks for the link.

by Wallyuph Wed Sep 11, 2013 9:39 am

At least you will get some knowledge on them and know what they recommend. It weird to put in a little 9"-10" converter but makes it easy to lift if just doing a swap from below.

by pila Wed Sep 11, 2013 3:49 pm

I'm too old to lift even a 9 inch.... Very Happy

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