Analyze my run please
 

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

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

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?

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

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

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.

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.

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 :)

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

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.

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

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

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

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

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....

[email protected] 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

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

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.

Ron with all the problems/errors I had when I took it out last year I didn't pay much attention to the flash. Was surprised I had to shift into 2nd so fast. I have a crane shift light with the bells and whistles I'm going to install this winter. It has a play back that is supposed to show all shifts but it looks cumbersome to use

Can you confirm the size of the fuel line from the tank? Is the tank sumped or are you running a cell?

-6an is small IMO for where you are.

Put it in myself. 5 gal sumped fuel cell, about 1' of 8an to Mallory 140 filter, Aeroquip push lock 6an to Mallory 140 pump, to Mallory bypass regulator. 2 6an off reg to carbs. And I have an 8an return line dumping into the top of the cell. Also using 8an for fc vent. I was watching the fp and rpm at the top end and pressure was around 6#s. Running 72s in carbs.

Need bigger supply line from tank to regulator running dual quads...IMO..
I run dual modified 750 Comp.AFB's on a Wenzler TR myself.
Have # 10 to pump & then to regulator. From regulator I use two #6 lines to carbs...one to each. I want to go a #12 from cell to pump...
I would go at least a #8 from pump to regulator...
Not to say you don't have a converter issue too...;)

Well I do have enough 10an to rerun both lines and it wouldn't be a problem as I had to drop the lines to install the cage but I didn't think I was there yet. If I have a fuel issue could it be caused by the angle of the motor. Since I lowered the back of the car the motor sits on more of an angle than I would like with the Wenzler or Victor. Back was so high I couldn't recline my seat enough to see traffic lights. Had to drop the bowl fuel level a fair bit as I set the motor angle with a SD intake on it which compensates for the motor angle. Guess I grasping

Definitely run a bigger line to the regulator. You won't need to increase the return line. You may have pressure, but the volume is most likely not enough.

Talk to a converter company and give them your specs. Personally, Continental has been right on for me with 3 different changes over the years. PTC, ATI have been well recommended here. I think Continental will come in a bit less overall cost wise and will deliver.

Thanks Ron, I have sent in my specs to ati. That treemaster mtr looks like a lot of converter for the buck. Will also send Cont. the specs too to see what they come up with. Have a TB I haven't used yet but once I get the appropriate conv. I may give it a try. I have talked with Coan but they are leaning to a 4200 stall.

Alan

I have everything to change over but after giving it some thought I either don't understand my fuel system or I'm still okay with the #6. My Mallory 140 is supposed to output something like 110 @ 12psi as I have no regulator in the pump. I have it going a #6 running to a return style regulator. The return is a #8 so there is very little resistance going back to the tank which means the pump isn't working hard. I have the regulator set for a max of 7psi for argument sake which is also the point here the regulator starts bypassing. So the way I see it if I do not see a drop in fuel pressure I still must be bypassing therefore I should have enough fuel going to the carbs. If the pressure was to drop that would mean I cannot supply enough fuel at a given pressure and am no longer bypassing.

What am I missing as the fuel system appears ok to me?

Thanks,
Alan

Here's a way to check the resistance: Turn the fuel system on and open the regulator to full by-pass. Watch the pressure on the gauge it MUST be below 3# of resistance with a preference towards less. I had all -8 feed/return lines, 140 Black pump, Holley return regulator, Klushmann stainless log pre-filter. When I trsted mine it had 1.75# resistance well into the acceptable range. If you have higher than 3# of pressure on full by-pass then your system is not setup right. JD

Good advice JD.

http://forums.maxperformanceinc.com/...d.php?t=681346

Here is a couple converters for good prices that might be an option.