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Discussion Starter #1
Ok here goes, i have a 461 with 11.1 comp. Square port heads(fully ported and pol.) Comp cams 638int 631exh #11-605-5. (solid). weiand stealth intake with 800dp, GER 4000 stall T-400, 410 gears, [email protected] slicks 275-60-15. In a 1968 SS396 chevelle with a/c, p/s,Bench seat int, I know this car is a bit on the heavy side but this car should be running LOW 12s or high 11s right??. On the desktop dyno it showed over 600hp. Also in my bros Chevelle it ran 12:11 @116. The only diff is no ps,ac, and he has 4-speed!!. Please help me.....is my converter slipping too much?? CHRIS
 

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How much does that car weigh?
If you are in the 3600-3800# bracket you should be cracking 11s easily.
I had the same problem last year in a previous post I was told to check 3 things.
1. total timing, mine was advancing too much
2. fuel, I was losing fuel at the top of the gears
3. convertor slippage, the only questionable part left to fix...(guess I'll find out when the track opens)
(It looks like your carb and convertor may be a little on the conservative side..)
 

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You should be in the 11's for sure. I only would ask how good is your exhaust system? You may also want to drop down to 4.56's or 4.88's
 

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I go along with to small exhuast and lack of fuel. What exhaust was on your bros car, what type of fuel system? are they the same?
 

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Discussion Starter #5
Well, the exhaust is 3" mandrel bent all the way out the back from TA perf. Timing is only at 38 total. The fuel system is exactly the same as my bros car. His was run open header, as his exh. is very restrictive. I assumed the 3" i have is close to open header?? right?. The only thing i can come up with is the GER convertor is slipping too much and im losing all the power through this. The trans is new and high perf. So i dont think its this. Thanks guys.....CHRIS
 

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Chris, if you remove the tail pipes you will
probably run 12.30or 12.40 remove the hole exhuast and you'll probably drop lower. a buddy has a 427 full 3.5" exhaust and the car went 2 tenths slower with tail pipes and were talkin 3.5" mandrell. Those big blocks need to breath. Also you may check the plugs to help identify your fuel mixture.
 

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Two suggestions.
First, maybe try a true open plenum single plane intake. I know the Stealth is supposed to be the best of both worlds, but lets face it......there is ALWAYS a trade off somewhere. With the square port heads and that cam your motor is making power way up there in the powerband.....I would bet your losing a little bit of that upper power in the intake.
Second, have you tried different jetting in the carb?......no bull, I have seen cars pick up over 1/2 second w/ nothing more than changing jets.

Good Luck,
Shannon
 

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It seems that your intake manifold is on the small size for your application. I would go with an Edelbrock Victor Jr. single plane intake. Your torque converters' stall is coming in right where it should for the camshaft (4,000rpm) and a single plane intake manifold will breath much easier than a dual plane at that RPM and higher. It should be worth an additional 60+ horses in the mid to upper end. Hope this helps!

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What is the weight of your car and the trap RPM? I plugged in some rough numbers from what you wrote- 108 MPH, 4.10 rear gears, 27" tall rear tires (w/ growth), and 6500 RPM in the traps and it equals 17.5% converter/ trans slippage. Way to high! How tall are your rear tires? What size is your converter? What are your 60' times. If you can provide a little more info I will try to work the numbers for you...MK

[This message has been edited by Mkrauser (edited 03-31-99).]

[This message has been edited by Mkrauser (edited 03-31-99).]

[This message has been edited by Mkrauser (edited 03-31-99).]
 

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Discussion Starter #10
I have just bought a Victor Jr TM2R open plenum intake. Plan to install it soon. I just wanted to baseline the car and see what kind of changes worked. Im sure i need a much bigger carb too. The dyno program someone on here ran for me wouldnt accept a dual plane as an option. (said severely missmatched component *L*). The trap RPM was about 6800. 60' time was 1.953 (sad!). Tire size is 26-1/2. A friend of mine says i need an ATI convertor. He has one in his buick and he says its a lockup for T-400 at 3800 rpms. His car runs 120 in the 1/4 mile. What do you think?. The convertor i have now is a GER 10" 4000 stall. I thought about getting one of those switch pitch and 4000 stall convertor for it. It has a low stall of 1400 so i think it would lock up good!. Im sure i need to jet the carb too. Thanks guys....CHRIS

[This message has been edited by QAK (edited 03-31-99).]
 

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I wouldn't change a thing I would go back and test without exhaust and see the difference.If the motor ran hard in your bros car then why would you have to change intake when the motor is in your car? I gues you dont believe that those 3" tail pipes are hurtin you. Odds of converter slip are rare, if its slippin on the big end then your stall has probably increased and you could tell its goin away.Also heat would be
evident in fluid color. You even stated your bro ran uncorked you ran corked.
On a converter there is the stall rpm on the brake and the true stall can be found by putting the tranny in 3rd at 25mph and mash the throttle. you will see the tach rise to say 4000 and the car will lunge you fill it "lock" in might want to see how yours responds. 3500 in a small block my be 4300 in a big block all depends on torque ect.
[This message has been edited by 1bad67 (edited 03-31-99).]

[This message has been edited by 1bad67 (edited 03-31-99).]
 
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QAK...
I'd suspect the converter also. If your rpms at the finish line are 6800 but your trap speed is only 108 mph, there's something wrong. Note that 108 mph on a 26.5" tire with 4.10s should be about 5600 rpm. 6800 rpm (assuming total lockup) with 4.10s and a 26.5" tire is about 130 MPH!! 1200 RPM of slippage is not right! ...maybe a few hundred RPM slippage, but yours is out of hand...assuming your tach is accurate. And I really doubt uncorking your already big exhaust is going to pick it up a half second or more.

PS...for your cam, a quote out of the Comp
Cams catalog: SOLID-2600-3000 lb. car, 11.5 comp., 4500 stall. Excellent for 427-454. 4200-7200 RPM.

I'm not saying the cam is wrong for the car, but it is a big one...dur. @ 0.50 is 270 int. & 276 ex. With your gears and tire you should be flying. It still should give you better than mid-twelves...I still think it's the converter.


Also: a 1.95 60 foot isn't out of the question for a 12.69 1/4 mile. I'm getting 1.90 60 foots with a 12.66, but that's with a 4-speed.

[This message has been edited by Larry (edited 04-01-99).]
 
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