Blowing thru converter?

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hugger73hatch
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Blowing thru converter?

#1 Post by hugger73hatch » Fri Sep 25, 2009 10:32 pm

So went to track tonight and took a buddy of mine for his help on tuning. He owns and runs a shop in my hometown and also builds engines and is a truck puller in the two wheel drive class. This is what we found out.

After changing jets and timing we found out the car did not really respond to the changes. Here is my run data:

1st run 60' 1.534, ET 7.099, MPH 97.632 Timing at 35* Primary 76, Scondary 84
2nd run 60' 1.522, ET 7.076, MPH 97.603 Timing 35*, Primary 78, Secondary 84
3rd run 60' 1.525, ET 7.080, MPH 97.631 Timing at 37.5*, Primary 78, Sc 86
4th run 60' 1.530, ET 7.136, MPH 96.907 Timing at 32*, Pr 78, Sec 86

He said on the last run the car pulled the front wheels and carried them further than on any of the other passes. He thinks the converter is too tight, since all the previous changes did not really affect the et, or the mph. As you can see the 60' time hardly changed at all, even when the timing was retarded. I just want to know what other people think about this as well. I would think with as much timing as we pulled out on the last pass the 60' would have died more, as well as the mph.

I've always felt as if this converter may have been too tight.
73 Nova Hatchback, 408 Small Block 13-1, Iron Heads, 6.972 @ 98.362, 1.468 60', 3450 lbs, still tuning
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Re: Blowing thru converter?

#2 Post by John_Heard » Sat Sep 26, 2009 6:03 am

Hmm, I would have figured pulling that much timing would have knocked it down in the 60' for sure. Would have lost that bet.

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hugger73hatch
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Re: Blowing thru converter?

#3 Post by hugger73hatch » Sat Sep 26, 2009 9:00 am

Me too. That's why we are thinking it is converter related. I am just curious as to what others think too.
73 Nova Hatchback, 408 Small Block 13-1, Iron Heads, 6.972 @ 98.362, 1.468 60', 3450 lbs, still tuning
28 x 9 Slick, N/A

http://www.esquireservices.net

coony278
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Re: Blowing thru converter?

#4 Post by coony278 » Sat Sep 26, 2009 9:35 am

Pulling just a few degress or timing will actually gain torque. But you will loose mph.

I would think your converter is probally ok, when you blow threw your converter you suffer on the big end.

The changes you made in my opinion was kinda drastic and too much at once.

I would suggest advancing timming till your mph falls off then back up 2 deg.

Then add fuel (jet) till your mph falls off and then drop back one jet size.

This is just .02 cents

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hugger73hatch
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Re: Blowing thru converter?

#5 Post by hugger73hatch » Sat Sep 26, 2009 8:55 pm

coony278 wrote:Pulling just a few degress or timing will actually gain torque. But you will loose mph.

I would think your converter is probally ok, when you blow threw your converter you suffer on the big end.

The changes you made in my opinion was kinda drastic and too much at once.

I would suggest advancing timming till your mph falls off then back up 2 deg.

Then add fuel (jet) till your mph falls off and then drop back one jet size.

This is just .02 cents
I should have mentioned on that last pass the car was real squirmy. My buddy said it was like the converter was wanting to lock up. I would have thought with those drastic changes, especially trying to kill the timing that the 60' would have really fallen off. I feel like my car will not et. I know another guy who has a nova that has a very similar setup and has run a 6.84 leaving on the converter at 3000, and his MPH is only about .5 mph faster than mine. I can't hold mine at 3000, it wants to push through the beams.
73 Nova Hatchback, 408 Small Block 13-1, Iron Heads, 6.972 @ 98.362, 1.468 60', 3450 lbs, still tuning
28 x 9 Slick, N/A

http://www.esquireservices.net

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supernova
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Re: Blowing thru converter?

#6 Post by supernova » Sat Sep 26, 2009 11:19 pm

I ran a 406 for a while that had Brodix heads on it and a .630 lift solid cam that ran best at 41* of timing in it. Some times when you lower timing it's at a point that nothing will change until you really take it down low. In other words lower to medium set timing will make the motor run with almost no difference.
Now the question I have is have you tried to raise the timing to see what it does? What I've seen in performace built small blocks is thay have needed more timing to make power depending on the combination. Try moving it up and see if responds to more timing.

Might be worth a try!!!!
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et: 5.28
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Re: Blowing thru converter?

#7 Post by 572 BBC » Mon Sep 28, 2009 5:23 pm

if u want a few more rpm outta converter,spray it...lol

Marty Chance
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Re: Blowing thru converter?

#8 Post by Marty Chance » Mon Sep 28, 2009 5:37 pm

can you tell us what rpm you shifted at and what rpm the motor droped after the shift? This will tell you what the converter is stalling with your power curve and let us know how much room you have to either raise or lower the stall on the converter.
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vegaracer
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Re: Blowing thru converter?

#9 Post by vegaracer » Mon Sep 28, 2009 6:03 pm

Marty, how does noting the rpm drop between gears tell you what your stall speed is? Or is that another kind of stall?
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hugger73hatch
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Re: Blowing thru converter?

#10 Post by hugger73hatch » Mon Sep 28, 2009 7:24 pm

Marty Chance wrote:can you tell us what rpm you shifted at and what rpm the motor droped after the shift? This will tell you what the converter is stalling with your power curve and let us know how much room you have to either raise or lower the stall on the converter.
Thanks for chiming in Marty. I shift at 6500, but I haven't really payed much attention to how much it drops. I will have to check that and let you know.
73 Nova Hatchback, 408 Small Block 13-1, Iron Heads, 6.972 @ 98.362, 1.468 60', 3450 lbs, still tuning
28 x 9 Slick, N/A

http://www.esquireservices.net

Marty Chance
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Re: Blowing thru converter?

#11 Post by Marty Chance » Tue Sep 29, 2009 9:03 am

vegaracer- (good question) the rpm drop on the shift tells you exactly what the converter is stalling in your car, and it tells us how much room we have to raise stall or tighten converter. for example if you shift at 7500 and it only drops to 7000 that would be on the loose side and you may want to tighten the converter but not raise stall more.
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