[PLAY400]

3500#s, 4.11 gear, 315/60 R15 tire, 6000rpm thru trap. From what I can see the converter is slipping over 13%, looking at replacing it with ~4200 coan, and I have crappy acceleration between the 1/8 & 1/4 mile. Or is it about what I should expect? Heads flow 250 and cam is a SD custom solid that should pull 6k

60' 1.6429
330 4.7808
et @ 594' 6.9658
1/8et 7.4588
1/8mph 91.28
1000et 9.8131
1/4et 11.8318
1/4mph 111.11

Thanks, Alan

[71 Ventura II]

If the 315's are 30" tall the converter is slipping 14.75%! Looking at the split times your dropping off on the topend. Running a 7.45 1/8th should be +- 11.69 1/4 mile.
What's your fuel system look like? Your definitely at the performance level where the fuel system can hold you back easily. JD

[firechickenman]

I agree, your 1/4 ET and MPH don't match up with your 1/8. See my ET and MPH in my sig. I also cross the line at 6000 with a 275/60R15 (28") tire. What converter is in it now?

[grandville455]

11.50@117 crosses at 55-5600,94 mph at 1/8th, 3.89 gear, 29" tire,It's either fuel related or more than likely too much slippage from the convertor

[PLAY400]

Well it is a redneck 3000. Must have got the last 1 off the shelf and its a dud. My other 1 works like a charm in the Bird. For fuel I have a mallory 140, #6 supply, #8 return and am running a Wenzler with 2 660s. Fuel pressure seems good for the run. Going to start with the converter because it slips too much but can't decide on brand or type. Anywhere from a 3500 to a 4400 stall has been recommended. Not looking for any street manners

[TheSilverBuick]

This isn't a rule or anything, but when comparing time slips with a few others, mine being the slowest at 13.3, the quickest running low 11's, the mph averaged a 23%-26% increase from the 1/8th to the 1/4th. Your's is around 18%. Definitely looks like there should be more mph in the 1/4 to me.

[Ron H]

What are the specs for the cam are you running?

Last time valve springs were checked and installed pressures, seat and open?

What rpm are you shifting at?

If your engine is lacking power the converter will also slip. Though I am sure you will find a fair chunk of performance switching to a quality converter.

[71 Ventura II]

Originally Posted by grandville455

11.50@117 crosses at 55-5600,94 mph at 1/8th, 3.89 gear, 29" tire,It's either fuel related or more than likely too much slippage from the convertor

Dang Darby that larger Continental converter is still super efficient only showing 5.8% slippage!!! Sweet!!! Sorry to high jack that's just amazing... Carry on... JD

[Brent Flynn]

Originally Posted by PLAY400

3500#s, 4.11 gear, 315/60 R15 tire, 6000rpm thru trap. From what I can see the converter is slipping over 13%, looking at replacing it with ~4200 coan, and I have crappy acceleration between the 1/8 & 1/4 mile. Or is it about what I should expect? Heads flow 250 and cam is a SD custom solid that should pull 6k

60' 1.6429
330 4.7808
et @ 594' 6.9658
1/8et 7.4588
1/8mph 91.28
1000et 9.8131
1/4et 11.8318
1/4mph 111.11

Thanks, Alan

Im sayin you are loosing ET all the way through your run... Coan makes good converters...as does ATI... have had great results with both....
My bird does 1.48-1.50 60fts, 7.00/97mph-11.12/119mph with 8'' ATI 4200 with 4.11gears/30'' tires...5600-5700 trap rpm

[71 Ventura II]

Originally Posted by PLAY400

Well it is a redneck 3000. Must have got the last 1 off the shelf and its a dud. My other 1 works like a charm in the Bird. For fuel I have a mallory 140, #6 supply, #8 return and am running a Wenzler with 2 660s. Fuel pressure seems good for the run. Going to start with the converter because it slips too much but can't decide on brand or type. Anywhere from a 3500 to a 4400 stall has been recommended. Not looking for any street manners

Deep breath but your converter purchase will be a bit pricy. Brands in no particular order Continental, PTC, ATI. More info on the engine is needed to select the footbrake and flash needed. JD

Sorry you had a negative experience with the Redneck unit. It must be the 10" unit they use to advertise on ebay. I wish you were closer I'd take the Redneck unit off your hands.

[71 Ventura II]

Originally Posted by Brent Flynn

Im sayin you are loosing ET all the way through your run... Coan makes good converters...as does ATI... have had great results with both....
My bird does 1.48-1.50 60fts, 7.00/97mph-11.12/119mph with 8'' ATI 4200 with 4.11gears/30'' tires...5600-5700 trap rpm

WOW That ATI unit, especially at 4200 "Tree Master" I bet, is coupled amazing showing only 3.89% slippage!!!! Definitely an option if he needs this much converter! JD

[PLAY400]

Originally Posted by Ron H

What are the specs for the cam are you running?

Last time valve springs were checked and installed pressures, seat and open?

What rpm are you shifting at?

If your engine is lacking power the converter will also slip. Though I am sure you will find a fair chunk of performance switching to a quality converter.

It's a custom Comp Cam 260/265 dur. @ .050" lift .370"/.375" lobe lift on a
110 lobe sep. Springs have a couple dozen runs on them but were checked by my machinist when we tore the motor apart last year for an inspection. Shifting anywhere from 5000-5500. Majority of my runs had a 1.5~ 60'er but times were slower due to my errors. Only had the car out once last year so I spent the time enjoying the rides and didn't change the tune at all. Running 36 locked advance

[71 Ventura II]

Originally Posted by PLAY400

It's a custom Comp Cam 260/265 dur. @ .050" lift .370"/.375" lobe lift on a
110 lobe sep. Springs have a couple dozen runs on them but were checked by my machinist when we tore the motor apart last year for an inspection. Shifting anywhere from 5000-5500. Majority of my runs had a 1.5~ 60'er but times were slower due to my errors. Only had the car out once last year so I spent the time enjoying the rides and didn't change the tune at all. Running 36 locked advance

Based on the limited cam specs above and accounting for the "5" cams I tried in my 400, I'd stick a 4000-4400 converter in it and get a fresh set of stickies. Also, short shifting your combo might work for bracket racing but the combo will live at or above 6300+ rpm's. I ran the Crower #60311, which is a smaller cam than yours, one Summer and it didn't run the numbers unless I shifted at 6500 rpm's. With your dual carb setup, big cam, and gear it's gonna love RPM as long as the heads can support it.

Throw an ATI "Tree Master" in it or call PTC to get a flash stall in the 4200-4500 rpm range. Hook it and let it breath and you'll be amazed. Good Luck! JD

[Cliff R]

Here is a good formula to determine what RPM you should/would be running with no converter slip:

GEAR RATIO x MPH x 336 divided by TIRE DIAMETER.

For my combo using a Continental 10" (Jim Hand model), 3.42 x 120 x 336 divided by 28". The calculator shows 4924rpm's, we go thru right at 5100rpms, or about 175rpm's slippage in high gear.

That works out to 3.5 percent slippage if I did my math right.

I don't know the exact diameter of your tires, but it looks like trap rpms should be around 5100rpms with no slippage (30" tires). 900rpm's is quite a bit of slippage.

You can have your cake and eat it too with converters, it just doesn't come cheap.....Cliff

[grandville455]

Originally Posted by 71 Ventura II

Dang Darby that larger Continental converter is still super efficient only showing 5.8% slippage!!! Sweet!!! Sorry to high jack that's just amazing... Carry on... JD

JD Just think that was in my 4550 car! It's very tight yes.

[mchell]

Originally Posted by PLAY400

It's a custom Comp Cam 260/265 dur. @ .050" lift .370"/.375" lobe lift on a
110 lobe sep. Springs have a couple dozen runs on them but were checked by my machinist when we tore the motor apart last year for an inspection. Shifting anywhere from 5000-5500. Majority of my runs had a 1.5~ 60'er but times were slower due to my errors. Only had the car out once last year so I spent the time enjoying the rides and didn't change the tune at all. Running 36 locked advance

curious.....whats the cubes and compression ratio?....race only or street/strip?

agree with others that you are probably pushing thru your converter.....a tight converter may cause you to lose some 60...depending on motor........could just be too much gear and converter combined for motor charictaristics....

[PLAY400]

Originally Posted by mchell

curious.....whats the cubes and compression ratio?....race only or street/strip?

agree with others that you are probably pushing thru your converter.....a tight converter may cause you to lose some 60...depending on motor........could just be too much gear and converter combined for motor charictaristics....

462@9.6 A little higher than I wanted. I was told I had enough compression to run the cam and it should pull to 6k with my heads. Only running it at the track as its a heat score on the street.

But this brings up another question after I did some reading. I'm running 660 center squirters. They do not come with a power valve and and apparently it is recommended to only change the jet up or down 1 size. Running 72s. From what I read without a pw Holleys tend run rich at top end. Fact or fiction??

[71 Ventura II]

Originally Posted by PLAY400

462@9.6 A little higher than I wanted. I was told I had enough compression to run the cam and it should pull to 6k with my heads. Only running it at the track as its a heat score on the street.

But this brings up another question after I did some reading. I'm running 660 center squirters. They do not come with a power valve and and apparently it is recommended to only change the jet up or down 1 size. Running 72s. From what I read without a pw Holleys tend run rich at top end. Fact or fiction??

Sorry my bad, I misunderstood your combo! I should have asked first, your 462 is a way different animal than my 400. Ooops It moves the power band down the scale. I'd still stick with the ATI Tree Master based on your cam, intake, gear, and CID. All you need to do is compare 455+ cid combos running the Comp 290b cam to yours. Running low 11's high 10's if the heads are right. JD

[Brent Flynn]

Originally Posted by 71 Ventura II

WOW That ATI unit, especially at 4200 "Tree Master" I bet, is coupled amazing showing only 3.89% slippage!!!! Definitely an option if he needs this much converter! JD

Yea....thats what it is... its a great converter... ATI has it on the ball, for sure... I wouldnt hesitate to buy another one...

[Ron H]

You have a #6 line from the tank through the pump to the regulator and then # 6's to the carbs?

With that combo you should be able to see 6000, or close to it.

What is the redneck flashing to off the line?

I agree with Brent, you are losing all the way through the run. Your ET is not actually far off for your 60', but your MPH is low.