Converter recommendation.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 109
Likes: 0
From: Nassau co. NY
Converter recommendation.
Sorry I am posting questions all over this forum, but I really tore into the car this winter. A little further, and I will be close to pulling the body off the frame...not what I was planning at all.
Anyway, the motor/tranny is out due to reasons posted elsewhere on the forum, and I am changing the compression and cam. The combo so far is:
350 .030" over.
9.8:1 comp.
Edelbrock RPMs cleaned up bowls and streamlined guides, gasket matched.
Edelbrock RPM intake
Holley 750 vac sec
Comp Cams Magnum 280: .480 lift, 230 dur @ .050, 110 LSA
1 3/4" block hugger headers and full 2 1/2" mandrel bent exhaust.
turbo 400 with stock converter.
stock 3.08 posi rear. (will be changed to 3.55 within the year)
With this combo, what is the stock converter stall (approx. with a small block 350)?
How much will we benefit from having a new converter for the combo?
What would you recommend for this combo.
This vette is my wife's, and will be street driven with an occasional blast down the quarter by myself for her viewing pleasure.
Thanks for the recommend's,
Greg.
Anyway, the motor/tranny is out due to reasons posted elsewhere on the forum, and I am changing the compression and cam. The combo so far is:
350 .030" over.
9.8:1 comp.
Edelbrock RPMs cleaned up bowls and streamlined guides, gasket matched.
Edelbrock RPM intake
Holley 750 vac sec
Comp Cams Magnum 280: .480 lift, 230 dur @ .050, 110 LSA
1 3/4" block hugger headers and full 2 1/2" mandrel bent exhaust.
turbo 400 with stock converter.
stock 3.08 posi rear. (will be changed to 3.55 within the year)
With this combo, what is the stock converter stall (approx. with a small block 350)?
How much will we benefit from having a new converter for the combo?
What would you recommend for this combo.
This vette is my wife's, and will be street driven with an occasional blast down the quarter by myself for her viewing pleasure.
Thanks for the recommend's,
Greg.
Last edited by 69VetteAngel; Jan 4, 2010 at 12:33 AM. Reason: spelling
Drifting
Joined: Apr 2006
Posts: 1,911
Likes: 2
From: gold coast queensland
i could ramble on for ages about why,what if this and what if that but with the info you gave a 2500 should do nicely in my opinion .
stock converter is prob about 1200-1800.
you will benefit with the higher stall with more launch .
if you go to the 355 gears your cruise speed should put you above the stall speed which is what you want.
stock converter is prob about 1200-1800.
you will benefit with the higher stall with more launch .
if you go to the 355 gears your cruise speed should put you above the stall speed which is what you want.
Last edited by gingerbreadman1977; Jan 4, 2010 at 06:05 AM.
Pro
Joined: Sep 2009
Posts: 629
Likes: 6
From: columbus ms
off topic a little but my mom has a 1970 396 chevelle ss. it has a strong motor but she went back with a stock converter. because of that, she now complains about it snatching when she puts it in gear. transmission and torque converter are very tight. as far as power goes, the thing is kind of slow untill the rpms get up to around 2200 rpms. the tight stall converter starts pulling at 1200 rpms and it takes awhile to buld the power. results. slow as car. will break the tires lose when it hits 2200 rpms but it's just slow to rev till then. if her car had a 2000 to 2200 stall it would be alot funner to drive and a lot quicker. plus the snatching when you put it in gear would be gone as the torque converter would not be wanting to pull right at idle.
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
i could ramble on for ages about why,what if this and what if that but with the info you gave a 2500 should do nicely in my opinion .
stock converter is prob about 1200-1800.
you will benefit with the higher stall with more launch .
if you go to the 355 gears your cruise speed should put you above the stall speed which is what you want.
stock converter is prob about 1200-1800.
you will benefit with the higher stall with more launch .
if you go to the 355 gears your cruise speed should put you above the stall speed which is what you want.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
2500-2800 should be good. That 230@.050 is gonna want some stall. Not to mention it will idle smoother in gear etc with stall. You might try the Hughes GM25. It's a decent converter and pretty cheap, not overly inefficient.
Safety Car
Joined: Oct 2004
Posts: 3,921
Likes: 731
From: Youngstown Ohio
.....been there, and the OP would be very satisfied with a 2500 stall converter on the street.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 109
Likes: 0
From: Nassau co. NY
Thanks Guys,
I am looking into the Hughes GM25. I noticed it does not have the anti-balloon plates. Is this something that matters as mostly a street car (tracking it mayber twice a year), or is that strictly for serious HP?
Thanks again,
Greg.
I am looking into the Hughes GM25. I noticed it does not have the anti-balloon plates. Is this something that matters as mostly a street car (tracking it mayber twice a year), or is that strictly for serious HP?
Thanks again,
Greg.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
You don't need the anti ballooning plate...If you are spraying a bunch of dope or leaving off of a transbrake then yes but....For a street car its not necessary.... I don't even have an anti ballooning plate in my custom built converter behind my 650 horse rat motor.
You'll be fine with the Hughes GM25...
You could also go with an ATI converter if you wanted to spend double the money....You could get more stall speed but be tighter around town and more efficient....These are almost 5 bills though.....over kill for what you are doing.
You'll be fine with the Hughes GM25...
You could also go with an ATI converter if you wanted to spend double the money....You could get more stall speed but be tighter around town and more efficient....These are almost 5 bills though.....over kill for what you are doing.
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Thread Starter
Instructor
Joined: Dec 2009
Posts: 109
Likes: 0
From: Nassau co. NY
You don't need the anti ballooning plate...If you are spraying a bunch of dope or leaving off of a transbrake then yes but....For a street car its not necessary.... I don't even have an anti ballooning plate in my custom built converter behind my 650 horse rat motor.
You'll be fine with the Hughes GM25...
You could also go with an ATI converter if you wanted to spend double the money....You could get more stall speed but be tighter around town and more efficient....These are almost 5 bills though.....over kill for what you are doing.
You'll be fine with the Hughes GM25...
You could also go with an ATI converter if you wanted to spend double the money....You could get more stall speed but be tighter around town and more efficient....These are almost 5 bills though.....over kill for what you are doing.
I'll let you guys know how it runs in a few months, but I am sure it will be sweet.
Thanks again,
Greg.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
All of the above recommendations were biased toward the quarter-mile speed at the strip. No one has mentioned that normal driveability of the car will be impacted significantly with a higher stall speed converter. You should really have her drive a car (it doesn't have to be a Corvette) which has a 2500-2800 rpm converter in it before you make that decision.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 109
Likes: 0
From: Nassau co. NY
Thanks for all the suggestions. I received the Hughes converter today (GM25). We are looking forward to seeing how it responds with this. I think it is going to be just what the car needed. Felt a little sluggish off the line, and then started to pull real nice all the way up to around 5500.
One thing though, I noticed the mounting tabs on the hughes conv. doesn't have any threads for the bolts. Is this a standard type of thing with aftermarket converters? I bought an ARP bolt set and it came with nuts, but I would think the threaded lugs (as on the stock conv. would locate the flexplate much more solidly. The bolts are not a perfect fit in the mounting holes...there is some play, and all the power the motor makes passes through these bolts (from the flexplate to the converter), correct?
Thanks,
Greg.
One thing though, I noticed the mounting tabs on the hughes conv. doesn't have any threads for the bolts. Is this a standard type of thing with aftermarket converters? I bought an ARP bolt set and it came with nuts, but I would think the threaded lugs (as on the stock conv. would locate the flexplate much more solidly. The bolts are not a perfect fit in the mounting holes...there is some play, and all the power the motor makes passes through these bolts (from the flexplate to the converter), correct?
Thanks,
Greg.
Race Director
Joined: Oct 2000
Posts: 14,997
Likes: 79
From: central FL, near the beach.
almost as bad as a too low stall, is early shifting.
cure:
http://community-2.webtv.net/mattgru/TH400/
cure:
http://community-2.webtv.net/mattgru/TH400/
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
The ARP bolt/nuts are a far superior mounting device then just having blocks welded on the converter and tapping threads in em. Most good aftermarket converters use the "ring style" mount that has only holes drilled in the ring therefore requiring bolts and nuts. However those holes do need to match the flexplate. Usually the flexplates will have 2 sets of holes drilled for differen bolt patterns on the converters. One set of the holes should line up when the snout of the converter is inserted into the pilot hole of the crank. Get the bolts/nuts in and tight and you will be fine.
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
When you are transferring rotating motion from one object to another, like a flywheel to a torque converter, the motion is transferred by the friction between the two surfaces. The friction is created by the tension in the bolts holding the two surfaces tightly together. As long as the bolts are tight, there is no shearing action on the bolts. Therefore the bolts don't have to fit tightly where they pass through the flywheel and the converter itself.
Lug nuts holding a wheel onto the brake rotor is the same principle.
Lug nuts holding a wheel onto the brake rotor is the same principle.
Drifting
Joined: Apr 2006
Posts: 1,911
Likes: 2
From: gold coast queensland
When you are transferring rotating motion from one object to another, like a flywheel to a torque converter, the motion is transferred by the friction between the two surfaces. The friction is created by the tension in the bolts holding the two surfaces tightly together. As long as the bolts are tight, there is no shearing action on the bolts. Therefore the bolts don't have to fit tightly where they pass through the flywheel and the converter itself.
Lug nuts holding a wheel onto the brake rotor is the same principle.
Lug nuts holding a wheel onto the brake rotor is the same principle.
On the other hand if there is excessive play in the hole on converter bolts which dont have a bevel then just tightening up the 3 of them may still cause back and forth movement and worse case sheering and is not going to hold jack S**T.
Last edited by gingerbreadman1977; Jan 8, 2010 at 07:26 PM.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
I will say that sometimes you have to put some washers or spacers inbetween the converter mounting holes and the flexplate IF the converter is pulling out of the tranny pump too much to contact the flexplate. This time I had to add 1/8" washers to all the mounting points between the converter and flexplate so I would have to pull the converter so far out....I didn't want to chance sheering the ears off the inside of the pump. 500 miles so far with 650 hp, 3700 flash stall and no problems...and I am not easy on it...
Thread Starter
Instructor
Joined: Dec 2009
Posts: 109
Likes: 0
From: Nassau co. NY
I understand. I will use the Arp bolts and nuts and torque them down. Makes sense to me.
How much end play should I look for at the converter to trans pump. I want to check this and put spacer shims, if required, before I button it up.
Thanks for the info,
Greg.
How much end play should I look for at the converter to trans pump. I want to check this and put spacer shims, if required, before I button it up.
Thanks for the info,
Greg.